JP2021106458A - Inverter device - Google Patents

Abstract

To provide an inverter device capable of effectively eliminating or suppressing generation of common mode noise due to an inversion of a phase current even when influence of dead time and delay time of a switching element is taken into consideration.SOLUTION: A control device 21 synchronizes switching timings of upper and lower arm switching elements 18A to 18F of each phase taking dead time and delay time of the switching elements into consideration, and performs a switching operation that cancels change in a phase voltage applied to a motor 8 with change in other phase voltages. In a carrier period in which a direction of a current flowing through the motor 8 is reversed, the switching operation is changed so as to eliminate or suppress fluctuation of a neutral point potential of the motor 8 caused by the dead time and the delay time of the switching elements.SELECTED DRAWING: Figure 1

Description

The present invention relates to an inverter device that is driven by applying a three-phase AC voltage to a motor by an inverter circuit.

Conventionally, an inverter device for driving a motor has a three-phase inverter circuit composed of a plurality of switching elements, and PWM (Pulse Width Modulation) control of the switching elements of each phase of UVW to obtain a voltage waveform close to a sine wave. It is driven by applying it to a motor.

FIG. 19 shows the phases of each phase current (motor current) flowing through the motor. In addition, iu is a U-phase current (solid line), iv is a V-phase current (dashed-dotted line), and iwa is a W-phase current (broken line) (all are corrected to -1 to 1 and normalized values). Since each phase current iu, iv, and iwa (motor current) has a sinusoidal shape, zero crossing occurs every 180 ° and the direction of the current is reversed. In this example, for example, the V-phase current iv crosses zero in a phase of 30 ° and is inverted from a negative value (direction flowing out of the motor) to a positive value (direction flowing into the motor).

Next, FIG. 20 shows the three-phase modulation voltage command values Vu', Vv', Vw' and the carrier signal, the U-phase voltage Vu, the V-phase voltage Vv, and the W-phase voltage Vw in each phase voltage (PWM signal) in the conventional inverter device. ), It is a figure which showed the neutral point potential Vc of a motor. The phase voltage command calculation unit (not shown) is a three-phase modulated voltage command value Vu'(U-phase voltage command value) applied to the armature coil of each phase of the motor based on the electric angle, current command value and phase current of the motor. Calculate Vv'(V-phase voltage command value) and Vw'(W-phase voltage command value). The three-phase modulation voltage command values Vu', Vv', and Vw' in FIG. 20 are values after normalization (corrected to -1 to 1) with the DC voltage Vdc.

Further, since the carrier signal of the sawtooth wave is used in the embodiment, the U-phase voltage command value Vu'has a start command value Vu'up and a start command value Vu'down within one carrier cycle. Similarly, the V-phase voltage command value Vv'also has a start-up command value Vv'up and a start-up command value Vv'down within one carrier cycle, and the W-phase voltage command value Vw'also has a start-up command value Vv'down within one carrier cycle. There are a start-up command value Vw'up and a start-up command value Vw'down.

Next, a PWM signal generation unit (not shown) has a U-phase voltage command value Vu'start-up command value Vu'up, a start-up command value Vu'down, and a V-phase voltage command value Vv'start-up command value Vv'up. By comparing the magnitude of the carrier signal (saw wave carrier) with the start-up command values Vw'up and Vw'down of the start-up command values Vv'down and W-phase voltage command value Vw', the drive command signal of the inverter circuit Is generated as a PWM signal. This PWM signal becomes each phase voltage of the U-phase voltage Vu, the V-phase voltage Vv, and the W-phase voltage Vw after normalization.

The neutral point potential Vc of the motor is calculated by the average value of each phase voltage (Vu + Vv + Vw) / 3, but conventionally, the neutral point potential Vc fluctuates as shown in the lowermost stage of FIG. Therefore, there is a problem that common mode noise is generated.

In the case of a motor constituting an electric compressor, for example, this common mode noise is generated by a common mode current leaking through a stray capacitance between the compressor housing and the ground. In the past, measures such as installing a large noise filter were taken, but in addition to this, measures are taken by selecting the voltage vector and switching timing, and by using a special carrier signal, the neutral point potential can be increased. Those that suppress fluctuations have been proposed (see, for example, Patent Documents 1 to 4).

Japanese Unexamined Patent Publication No. 10-23760 Japanese Unexamined Patent Publication No. 2003-18853 Japanese Patent No. 4389446 Japanese Patent No. 5045137

In Patent Document 1, regarding the switching operation in the three-phase two-level inverter, since only two phases are driven, it becomes difficult to apply a smooth sine wave voltage, which causes noise. Further, in Patent Document 2, it is necessary to perform a switching operation in consideration of the operation of the PWM rectifier circuit, and the usable operating range and products are limited. Further, since Patent Document 3 does not assume that the control device utilizes the function of the PWM signal generation unit, it is necessary to use an expensive control device, and it is difficult to apply it to mass-produced products. Further, in Patent Document 4, it can be implemented only by a microcomputer having two carrier signals. Further, in Patent Document 4, since switching is performed at the timing of clearing the carrier count, when the directions of the phase currents are the same, the switching timing is shifted due to the influence of the dead time, and the fluctuation of the neutral point potential cannot be suppressed. There is.

Therefore, the voltage command values Vu'and Vv'Vw'of each phase are corrected to obtain the voltage command correction values Cu, Cv, and Cw, and as shown in FIGS. 21 and 22, the switching of the upper and lower arm switching elements of each phase is performed. It is conceivable to synchronize the timing and cancel the change in the phase voltage applied to the motor by the change in the other phase voltage so that the neutral point potential Vc does not fluctuate. Note that FIG. 22 is an enlarged view of the frame Z1 portion of FIG. 21. The conditions in this case are a carrier frequency of 20 kHz and an electric angular frequency of 800 Hz.

In each figure, Cup is a U-phase voltage command correction value Cu start-up command value, and Cudown is a U-phase voltage command correction value Cu start-up command value. Similarly, Cvup is the start-up command value of the V-phase voltage command correction value Cv, Cvdown is the start-up command value of the V-phase voltage command correction value Cv, Cup is the start-up command value of the W-phase voltage command correction value Cw, and Cwdown is the start-up command value. It is a start-up command value of the W-phase voltage command correction value Cw, and in this case as well, the above-mentioned PWM signal generation unit uses them (start-up command value Cup, start-up command value Cudown, start-up command value Cvup, start-up command value). By comparing the magnitude of the carrier signal with the voltage (Cvdown, start-up command value Cw, start-up command value Cwdown) and the magnitude of the carrier signal, a PWM signal to be a drive command signal of the inverter circuit is generated.

For example, in the phase P1 after the phase of 30 ° in FIG. 22, the upper arm switching element of the V phase is turned off, and the dead time (the time lag for preventing the upper and lower arm switching elements of the same phase from being turned on at the same time). The same applies hereinafter.) When the lower arm switching element is turned on in the subsequent phase P2, the V-phase voltage Vv is the lower arm switching element when the V-phase current iv is a negative value and does not reverse in the direction of outflow from the motor. It changes with the operation of, and falls at the phase P2. Considering the dead time, the U-phase voltage Vu is corrected so that the rise command value Cup rises in the phase P2 according to the timing when the V-phase voltage Vv falls, so that the neutral point potential Vc does not fluctuate. Since there are turn-on delay time, turn-off delay time, etc. of the switching element before the PWM signal generated by the control device is actually output by the switching element, the control device uses the delay time of this switching element (of the switching element). The PWM signal is output in consideration of the turn-on delay time, turn-off delay time, etc.). In addition, although the turn-on delay time and turn-off delay time of the switching element differ depending on the characteristics of the IGBT and flywheel diode used, they can be determined by determining the positive or negative of the phase current flowing through the motor (the delay time can be determined), similar to the effect of dead time. , It is possible to correct the dead time in the same manner as described above. As described above, since the turn-on delay time and the turn-off delay time can be performed at the same time as the dead time correction, the correction method will not be specified hereafter, but the dead time correction shall be performed at the same time.

After that, when the lower arm switching element of the V phase is turned off at the phase P3 and the upper arm switching element is turned on at the phase P4 after the dead time and the delay time of the switching element, the V phase current iv flows out of the motor with a negative value. When the voltage is not reversed in the same direction, the V-phase voltage Vv changes due to the operation of the lower arm switching element and rises in the phase P3. Considering the dead time and the delay time of the switching element, the W-phase voltage Vw is corrected so that the V-phase voltage Vv falls at the phase P3 according to the timing at which the V-phase voltage Vv rises. Does not fluctuate.

However, when the V-phase current iv is inverted from a negative value to a positive value (direction of flowing into the motor) at a phase of 30 ° as in the example of FIG. 19, the V-phase voltage Vv changes due to the operation of the upper arm switching element. Therefore, as shown in FIG. 22, the upper arm switching element falls off at the phase P1 in which the switching element is turned off. Therefore, even if the U-phase voltage Vu is raised in the phase P2, the neutral point potential Vc fluctuates in the direction of decreasing in a pulse shape having a width corresponding to the dead time and the delay time of the switching element.

Similarly, since the V-phase voltage Vv rises in the phase P4 in which the upper arm switching element is turned on, if the W-phase voltage Vw is lowered in the phase P3, the width of the dead time and the delay time of the switching element is widened. The neutral point potential Vc fluctuates in a pulsed manner in a downward direction. That is, in this example, since the neutral point potential Vc fluctuates four times in total in the phases P1 to P4, there is a problem that common mode noise is generated in each (four times in total).

The present invention has been made in consideration of the conventional situation, and is effective in generating common mode noise due to the inversion of the phase current even when the influence of the dead time and the delay time of the switching element is taken into consideration. It is an object of the present invention to provide an inverter device that can be eliminated or suppressed.

In the inverter device of the present invention, an upper arm switching element and a lower arm switching element are connected in series for each phase between the upper arm power supply line and the lower arm power supply line, and the voltage at the connection point of the upper and lower arm switching elements of each phase. Is provided with an inverter circuit that applies the above as a three-phase AC output to the motor and a control device that controls the switching of the upper and lower arm switching elements of each phase of this inverter circuit, and the control device is the upper and lower arm switching of each phase. The switching timing of the upper and lower arm switching elements of each phase is synchronized in consideration of the dead time when switching the elements and the delay time of the switching element, and the change of the phase voltage applied to the motor is changed by the change of the other phase voltage. In the carrier cycle in which the direction of the current flowing through the motor is reversed while executing the switching operation that cancels out, the direction of eliminating or suppressing the fluctuation of the neutral point potential of the motor caused by the dead time and the delay time of the switching element. It is characterized by changing the switching operation with.

In the inverter device of the invention of claim 2, in the above invention, in the control device, a specified section of switching is performed from a state in which the lower arm switching element of any one phase is turned on and the upper arm switching element of the other two phases is turned on. It is characterized by starting.

The inverter device according to the third aspect of the present invention is the control device according to the first aspect of the present invention, in which the lower arm switching element of any two phases is turned on and the upper arm switching element of the other one phase is turned on. It is characterized by starting the specified section of.

In the inverter device of the invention of claim 4, in each of the above inventions, the control device stops switching of the upper and lower arm switching elements of the phase in which the direction of the current is reversed in the carrier cycle in which the direction of the current flowing through the motor is reversed. By synchronizing the switching of the other two-phase upper and lower arm switching elements, the first change control for canceling the change in the phase voltage applied to the motor by the change in the other phase voltage is executed.

The inverter device according to the fifth aspect of the present invention is the control device according to the first to third aspects, in which the switching of the upper and lower arm switching elements of all phases is stopped in the carrier cycle in which the direction of the current flowing through the motor is reversed. It is characterized by executing a second change control.

The inverter device according to the sixth aspect of the present invention is the upper / lower arm switching element of the phase in which the direction of the current is reversed in the carrier cycle in which the direction of the current flowing through the motor is reversed. By stopping the switching of the other two-phase upper and lower arm switching elements and synchronizing the switching of the other two-phase upper and lower arm switching elements, the first change control that cancels the change of the phase voltage applied to the motor by the change of the other phase voltage and the motor It has a second change control that stops the switching of the upper and lower arm switching elements of all phases in the carrier cycle in which the direction of the flowing current is reversed, and among the first change control and the second change control, the switching operation is performed. It is characterized in that the one that is close to the switching operation before the change is selected and executed.

The inverter device according to the invention of claim 7 is the control device according to the invention of claims 1 to 3, other than the phase in which the direction of the current flowing through the motor is reversed in the carrier cycle in which the direction of the current flowing through the motor is reversed. When the specified section of switching is started with the upper and lower arm switching elements of the phase different from each other in the ON state, the upper and lower arm switching elements of the phase in which the direction of the current is reversed are switched, and the other two upper and lower arm switching elements are switched. It is characterized in that the third change control for canceling the change of the phase voltage of the two phases is executed by synchronizing the two phases.

The inverter device according to the invention of claim 8 is the control device according to the invention of claims 1 to 3, other than the phase in which the direction of the current flowing through the motor is reversed in the carrier cycle in which the direction of the current flowing through the motor is reversed. When the upper and lower arm switching elements of the phase start the specified switching section in the same ON state, the upper and lower arm switching elements of the phase in which the direction of the current is reversed are switched, and the influence of the dead time and the delay time of the switching element. By synchronizing the switching of the upper and lower arm switching elements of the other two phases with the timing of the change of the phase voltage of the relevant phase, the change of the phase voltage of the phase in which the direction of the current flowing through the motor is reversed is changed by the other. It is characterized by executing a fourth change control that cancels out by a change in the voltage of any one of the two phases.

In the invention of claim 1 to 3, the control device according to the invention of claim 9 is a vertical arm switching element having a phase in which the direction of the current is reversed in a carrier cycle in which the direction of the current flowing through the motor is reversed. By stopping the switching of the other two-phase upper and lower arm switching elements and synchronizing the switching of the other two-phase upper and lower arm switching elements, the first change control that cancels the change of the phase voltage applied to the motor by the change of the other phase voltage and the motor In the carrier cycle in which the direction of the flowing current is reversed, the second change control for stopping the switching of the upper and lower arm switching elements of all phases, and in the carrier cycle in which the direction of the current flowing in the motor is reversed, the direction of the current flowing in the motor. When the specified section of switching is started with the upper and lower arm switching elements of the two phases other than the phase in which the current is inverted, the upper and lower arm switching elements of the phase in which the direction of the current is inverted are switched and the other two phases are switched. By synchronizing the switching of the upper and lower arm switching elements of the above, the third change control that mutually cancels the change of the phase voltage of the two phases and the carrier cycle in which the direction of the current flowing through the motor is reversed, the current flowing through the motor When the specified section of switching is started with the two-phase upper and lower arm switching elements other than the phase in which the direction is reversed, the upper and lower arm switching elements in the phase in which the current direction is reversed are switched and the dead time is set. And by synchronizing the switching of the other two-phase upper and lower arm switching elements with the timing of the change in the phase voltage of the relevant phase, which changes due to the influence of the delay time of the switching element, the direction of the current flowing through the motor is reversed. It has a fourth change control that cancels the change in the phase voltage by the change in the phase voltage of any of the other two phases, and is characterized by selectively executing each change control based on the operating state of the motor. And.

In the inverter device of the invention of claim 10, in the above invention, the control device executes the first change control or the second change control in the first region where the rotation speed of the motor is low, and the rotation speed of the motor is the second. The second region, which is higher than the first region, is characterized by executing a third change control or a fourth change control.

In the inverter device of the invention of claim 11, in each of the inventions, the control device eliminates or suppresses the change in the line voltage over the carrier cycle in which the direction of the current flowing through the motor is reversed and the carrier cycle continuous thereto. It is characterized in that the switching operation in the continuous carrier cycle is changed in the direction.

According to the present invention, the upper arm switching element and the lower arm switching element are connected in series for each phase between the upper arm power supply line and the lower arm power supply line, and the voltage at the connection point of the upper and lower arm switching elements of each phase is set. In an inverter device provided with an inverter circuit that is applied to a motor as a three-phase AC output and a control device that controls switching of the upper and lower arm switching elements of each phase of this inverter circuit, the control device controls the upper and lower arm switching elements of each phase. Switching that synchronizes the switching timing of the upper and lower arm switching elements of each phase in consideration of the dead time at the time of switching and the delay time of the switching element, and cancels the change in the phase voltage applied to the motor by the change in the other phase voltage. Since the operation is executed, it is possible to eliminate or remarkably suppress the fluctuation of the neutral point potential of the motor depending on the switching timing of the switching element.

In particular, in the carrier cycle in which the direction of the current flowing through the motor is reversed, the control device switches in a direction that eliminates or suppresses the fluctuation of the neutral point potential of the motor caused by the dead time and the delay time of the switching element. Since the operation is changed, the inconvenience that the neutral point potential fluctuates due to the error due to the dead time caused by reversing the direction of the current flowing through the motor and the delay time of the switching element is also eliminated or suppressed. You will be able to do it. As a result, it is possible to eliminate or suppress the generation of common mode noise extremely effectively.

Further, as in the invention of claim 2, the control device starts the specified switching section from the state in which the lower arm switching element of any one phase is turned on and the upper arm switching element of the other two phases is turned on. Alternatively, as in the invention of claim 3, the control device starts the specified switching section from a state in which any two-phase lower arm switching element is turned on and the other one-phase upper arm switching element is turned on. Then, the change in the phase voltage can be smoothly canceled by the change in the other phase voltage.

In this case, as in the invention of claim 4, in the carrier cycle in which the direction of the current flowing through the motor is reversed, the control device stops switching of the upper and lower arm switching elements of the phase in which the direction of the current is reversed, and the other two phases. By synchronizing the switching of the upper and lower arm switching elements of the above, if the first change control that cancels the change of the phase voltage applied to the motor by the change of the other phase voltage is executed, the direction of the current flowing through the motor The upper and lower arm switching elements are switched synchronously so as to cancel each other's changes in the phase voltage of the other two phases without changing the phase voltage of the phase in which the current is reversed, and the carrier period in which the direction of the current is reversed. It becomes possible to eliminate the fluctuation of the neutral point potential in.

Further, as in the invention of claim 5, the control device may also execute a second change control for stopping the switching of the upper and lower arm switching elements of all phases in the carrier cycle in which the direction of the current flowing through the motor is reversed. By keeping the phase voltage of all the phases unchanged, it becomes possible to eliminate the fluctuation of the neutral point potential in the carrier cycle in which the direction of the current is reversed.

Then, as in the invention of claim 6, the first change control (invention of claim 4) and the second change control (invention of claim 5) are similar to the switching operation before the switching operation is changed. By selecting and executing the method, it is possible to minimize the adverse effect of the change in the switching operation on the operation of the motor.

Further, as in the invention of claim 7, in the carrier cycle in which the direction of the current flowing through the motor is reversed, the two-phase upper and lower arm switching elements other than the phase in which the direction of the current flowing through the motor is reversed are turned on. When the specified section of switching is started in, the upper and lower arm switching elements of the phase in which the direction of the current is reversed are switched, and the switching of the other two upper and lower arm switching elements is synchronized to synchronize the switching of the two phases. By executing the third change control that mutually cancels the voltage changes, the fluctuation of the neutral point potential can be changed only once by switching the upper and lower arm switching elements of the phase in which the direction of the current flowing through the motor is reversed. It is possible to reduce it. This makes it possible to suppress fluctuations in the neutral point potential during the carrier cycle in which the direction of the current is reversed. In particular, in this case, since it becomes possible to correspond to a higher modulation rate than the first change control and the second change control described above, it is advantageous when an operating state in which the rotation speed of the motor is high is required.

Here, when the two-phase upper and lower arm switching elements other than the phase in which the direction of the current flowing through the motor is reversed starts the specified switching section in the same ON state in the upper and lower sides, the control device can be used as in the invention of claim 8. In the carrier cycle in which the direction of the current flowing through the motor is reversed, the upper and lower arm switching elements of the phase in which the direction of the current is reversed are switched, and the phase voltage of the phase that changes due to the influence of the dead time and the delay time of the switching element. By synchronizing the switching of the other two-phase upper and lower arm switching elements with the timing of the change, the change in the phase voltage of the phase in which the direction of the current flowing through the motor is reversed can be changed to any of the other two phases. If the fourth change control that cancels out by the change of the phase voltage is executed, the fluctuation of the neutral point potential is similarly caused only once by switching the upper and lower arm switching elements of the phase in which the direction of the current flowing through the motor is reversed. It is possible to limit to. As a result, it becomes possible to suppress the fluctuation of the neutral point potential in the carrier cycle in which the direction of the current is reversed, and it becomes possible to cope with a high modulation rate, so that the rotation speed of the motor can be increased. This is advantageous when high operating conditions are required.

Then, as in the invention of claim 9, the control device performs the first change control (invention of claim 4), the second change control (invention of claim 5), and the third change control (claim 7). (Invention of claim 8) and the fourth change control (invention of claim 8) are the first change control in the operating state of the motor, for example, in the first region where the rotation speed of the motor is low as in the invention of claim 10. Alternatively, select and execute the second change control, and select and execute the third change control or the fourth change control in the second region where the rotation speed of the motor is higher than the first region. For example, it is possible to appropriately eliminate or suppress fluctuations in the neutral point potential according to the operating state of the motor.

Further, as in the invention of claim 11, the control device continuously eliminates or suppresses the change in the line voltage over the carrier cycle in which the direction of the current flowing through the motor is reversed and the carrier cycle continuous thereto. By changing the switching operation in the carrier cycle, the inconvenience that the voltage applied to the motor changes by changing the switching operation in order to eliminate or suppress the fluctuation of the neutral point potential is solved. Alternatively, it can be suppressed and stable operation control of the motor can be realized.

It is an electric circuit diagram of the inverter device of one Example of this invention. It is a figure which shows the voltage command correction value and the carrier signal, the PWM waveform, and the neutral point potential of a motor for demonstrating the first change control of the control device of FIG. It is the figure which expanded the frame Z2 part (carrier cycle in which V-phase current iv is inverted and the carrier cycle continuous with it) of the frame Z2 of FIG. 2, and added the ON / OFF state of a switching element. It is another figure which shows the voltage command correction value and carrier signal, each phase voltage (PWM signal), and the neutral point potential of a motor for demonstrating the first change control of the control device of FIG. 1 (phase current). If the orientation does not change). It is still another figure which shows the voltage command correction value and carrier signal, each phase voltage (PWM signal), and the neutral point potential of a motor for explaining the 1st change control of the control device of FIG. 1 (W phase). When the current iw is inverted, but zero cross is not considered). It is still another figure which shows the voltage command correction value and carrier signal, each phase voltage (PWM signal), and the neutral point potential of a motor for explaining the 1st change control of the control device of FIG. 1 (W phase). When the current iw is inverted and zero cross is taken into consideration). It is a figure which shows the voltage command correction value and carrier signal, each phase voltage (PWM signal), and the neutral point potential of a motor for demonstrating the second change control of the control device of FIG. 1 (U-phase current iu is inverted). However, if zero cross is not considered). It is another figure which shows the voltage command correction value and carrier signal, each phase voltage (PWM signal), and the neutral point potential of a motor for explaining the 2nd change control of the control device of FIG. 1 (U-phase current). When iu is inverted and zero cross is considered). It is a figure which shows the voltage command correction value and carrier signal, each phase voltage (PWM signal), and the neutral point potential of a motor for demonstrating the third change control of the control device of FIG. 1 (V phase current iv is inverted). However, if zero cross is not considered). It is another figure which shows the voltage command correction value and carrier signal, each phase voltage (PWM signal), and the neutral point potential of a motor for demonstrating the third change control of the control device of FIG. 1 (V-phase current). When iv is inverted and zero cross is considered). It is a figure which shows the voltage command correction value and carrier signal, each phase voltage (PWM signal), and the neutral point potential of a motor for explaining the 4th change control of the control device of FIG. 1 (W phase current iw is inverted). However, if zero cross is not considered). It is another figure which shows the voltage command correction value and carrier signal, each phase voltage (PWM signal), and the neutral point potential of a motor for explaining the 4th change control of the control device of FIG. 1 (W phase current). When iw is inverted and zero cross is considered). In the case of FIG. 20, in the case of FIG. 21, the neutral point potential of the motor by each change control of the control device of FIG. 1 is the first change control, in the case of the second change control, the third change control, the fourth. It is a figure which compares with the case of the change control of. It is a figure which shows the line voltage of the motor by the conventional usual three-phase modulation system (in the case of FIG. 20). It is a figure which shows the line voltage of a motor when the inversion of a phase current (zero cross) is not considered (in the case of FIGS. 21 and 22). It is a figure which shows the line voltage of the motor by each change control of the control device of FIG. It is a figure which shows the phase voltage and the line voltage by the 1st change control and the 2nd change control of the control device of FIG. 1 (at the time of the maximum phase voltage). It is a figure which shows the phase voltage and the line voltage by the 3rd change control, 4th change control of the control device of FIG. 1 (at the time of the maximum phase voltage). It is a figure which shows the phase of a motor current (each phase current). It is a figure which shows the three-phase modulation voltage command value, a carrier signal, each phase voltage (PWM signal), and the neutral point potential of a motor in a conventional inverter device. Voltage command correction value and carrier signal, PWM waveform, to explain the control that synchronizes the switching timing of the upper and lower arm switching elements of each phase and cancels the change of the phase voltage applied to the motor by the change of the other phase voltage. It is a figure which shows the neutral point potential of a motor (when the W phase current iw is inverted, but zero cross is not considered). FIG. 21 is a diagram in which the frame Z1 portion (carrier cycle in which the V-phase current iv is inverted and the carrier cycle in which the V-phase current iv is inverted) is enlarged and the ON / OFF state of the switching element is added.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The inverter device 1 of the embodiment is mounted on a so-called inverter-integrated electric compressor in which a compression mechanism is driven by a motor 8, and the electric compressor is, for example, air conditioning for a vehicle that air-conditions the interior of an electric vehicle or a hybrid vehicle. It constitutes the refrigerant circuit of the device.

(1) Configuration of Inverter Device 1 In FIG. 1, the inverter device 1 includes a three-phase inverter circuit 28 and a control device 21. The inverter circuit 28 is a circuit that converts the DC voltage of the DC power supply (vehicle battery: for example, 300 V) 29 into a three-phase AC voltage and applies it to the motor 8. The inverter circuit 28 has a U-phase half-bridge circuit 19U, a V-phase half-bridge circuit 19V, and a W-phase half-bridge circuit 19W, and each of the phase half-bridge circuits 19U to 19W has upper arm switching elements 18A to 18C, respectively. And the lower arm switching elements 18D to 18F are individually provided. Further, flywheel diodes 31 are connected in antiparallel to each of the switching elements 18A to 18F.

In the embodiment, each of the switching elements 18A to 18F is composed of an insulated gate bipolar transistor (IGBT) or the like in which a MOS structure is incorporated in a gate portion.

The upper end side of the upper arm switching elements 18A to 18C of the inverter circuit 28 is connected to the upper arm power supply line (positive electrode side bus line) 10 of the DC power supply 29 and the smoothing capacitor 32. On the other hand, the lower end side of the lower arm switching elements 18D to 18F of the inverter circuit 28 is connected to the lower arm power supply line (negative electrode side bus line) 15 of the DC power supply 29 and the smoothing capacitor 32.

In this case, the upper arm switching element 18A and the lower arm switching element 18D of the U-phase half bridge circuit 19U are connected in series, and the upper arm switching element 18B and the lower arm switching element 18E of the V-phase half bridge circuit 19V are connected in series. , The upper arm switching element 18C and the lower arm switching element 18F of the W phase half bridge circuit 19W are connected in series.

The connection point between the upper arm switching element 18A and the lower arm switching element 18D of the U-phase half-bridge circuit 19U is connected to the U-phase armature coil 2 of the motor 8 and the upper arm switching element of the V-phase half-bridge circuit 19V. The connection point between 18B and the lower arm switching element 18E is connected to the V-phase armature coil 3 of the motor 8, and the connection point between the upper arm switching element 18C and the lower arm switching element 18F of the W-phase half-bridge circuit 19W is the motor. It is connected to the W-phase armature coil 4 of 8.

(2) Configuration of Control Device 21 The control device 21 is composed of a microcomputer having a processor. In the embodiment, a rotation speed command value is input from the vehicle ECU, and a motor current (phase current) is input from the motor 8. Based on these, the ON / OFF state (switching) of each of the switching elements 18A to 18F of the inverter circuit 28 is controlled. Specifically, the gate voltage applied to the gate terminals of the switching elements 18A to 18F is controlled.

The control device 21 of the embodiment includes a phase voltage command calculation unit 33, a PWM signal generation unit 36, a gate driver 37, and U-phase current iu and V-phase, which are motor currents (phase currents) of each phase flowing through the motor 8. It has current sensors 26A and 26B including a current transformer for measuring current iv and W-phase current iwa, and each current sensor 26A and 26B is connected to a phase voltage command calculation unit 33.

The current sensor 26A measures the U-phase current iu, and the current sensor 26B measures the V-phase current iv. Then, the W-phase current iw is calculated from these. As for the method of detecting the motor current of each phase, in addition to measuring with the current sensors 26A and 26B as in the embodiment, the current value of the lower arm power supply line 15 is detected, and the current value and the operating state of the motor 8 are detected. Since there is a method of estimating by the phase voltage command calculation unit 33 from the above, the method of detecting and estimating each phase current is not particularly limited.

The phase voltage command calculation unit 33 controls the armature coils 2 to 4 of each phase of the motor 8 by vector control based on the electric angle of the motor 8, the d-axis current obtained from the current command value and the phase current, and the q-axis current. Three-phase modulation voltage command value Vu'(hereinafter, U-phase voltage command value Vu'), Vv'(hereinafter, V-phase voltage command) for generating the applied U-phase voltage Vu, V-phase voltage Vv, W-phase voltage Vw. The values Vv') and Vw'(hereinafter, W-phase voltage command value Vw') are calculated and generated.

The PWM signal generation unit 36 inputs the three-phase modulation voltage command values Vu', Vv', and Vw'calculated by the phase voltage command calculation unit 33, and these three-phase modulation voltage command values Vu', Vv', Vw' Is corrected as described later, and by comparing the magnitude with a single carrier signal (saw wave carrier in the embodiment), the U-phase half-bridge circuit 19U, the V-phase half-bridge circuit 19V, and the W-phase half of the inverter circuit 28 are compared. A PWM signal to be a drive command signal of the bridge circuit 19W is generated and output.

The gate driver 37 is above the gate voltage of the upper arm switching element 18A and the lower arm switching element 18D of the U-phase half bridge circuit 19U and the V-phase half bridge circuit 19V based on the PWM signal output from the PWM signal generation unit 36. The gate voltage of the arm switching element 18B and the lower arm switching element 18E and the gate voltage of the upper arm switching element 18C and the lower arm switching element 18F of the W-phase half bridge circuit 19W are generated.

Then, each of the switching elements 18A to 18F of the inverter circuit 28 is ON / OFF driven based on the gate voltage output from the gate driver 37. That is, when the gate voltage is in the ON state (predetermined voltage value), the switching element is turned on, and when the gate voltage is in the OFF state (zero), the switching element is turned off. When the switching elements 18A to 18F are the above-mentioned IGBTs, the gate driver 37 is a circuit for applying a gate voltage to the IGBT based on the PWM signal, and is composed of a photocoupler, a logic IC, a transistor, and the like. NS.

Then, the voltage at the connection point between the upper arm switching element 18A and the lower arm switching element 18D of the U-phase half bridge circuit 19U is applied (output) to the U-phase armature coil 2 of the motor 8 as the U-phase voltage Vu (phase voltage). Then, the voltage at the connection point between the upper arm switching element 18B and the lower arm switching element 18E of the V-phase half bridge circuit 19V is applied (output) to the V-phase armature coil 3 of the motor 8 as the V-phase voltage Vv (phase voltage). Then, the voltage at the connection point between the upper arm switching element 18C and the lower arm switching element 18F of the W phase half bridge circuit 19W is applied (output) to the W phase armature coil 4 of the motor 8 as the W phase voltage Vw (phase voltage). Will be done.

(3) Operation of Control Device 21 Next, the actual control operation of the control device 21 will be described with reference to FIGS. 2 to 18. The PWM signal generation unit 36 constituting the control device 21 of the inverter device 1 of the embodiment calculates and outputs the U-phase voltage command value Vu'and the V-phase voltage command value Vv'by the phase voltage command calculation unit 33 as described above. , And the W-phase voltage command value Vw'(three-phase modulation voltage command value) is actually set from the dead time when switching the switching elements 18A to 18F and the command of the PWM signal generation unit 36. By correcting while considering the delay time until 18F switches (delay time of each switching element 18A to 18F), the U-phase voltage such that the fluctuation of the neutral point potential Vc of the motor 8 disappears (becomes zero). The command correction value Cu, the V-phase voltage command correction value Cv, and the W-phase voltage command correction value Cw (voltage command correction value) are calculated.

Then, by comparing the magnitudes of the U-phase voltage command correction value Cu, the V-phase voltage command correction value Cv, and the W-phase voltage command correction value Cw with the single carrier signals X1 to X4 described later, the inverter circuit 28 A PWM signal that serves as a drive command signal for the U-phase half-bridge circuit 19U, the V-phase half-bridge circuit 19V, and the W-phase half-bridge circuit 19W is generated to drive the motor 8.

The U-phase voltage command correction value Cu, the V-phase voltage command correction value Cv, and the W-phase voltage command correction value Cw (voltage command correction value) shown in each figure are used in the case of performing three-phase modulation control of the motor 8. It is a value after normalization of the voltage command correction value at the DC voltage Vdc (after correction to -1 to 1). Further, each phase voltage of the U-phase voltage Vu, the V-phase voltage Vv, and the W-phase voltage Vw is also a value after being normalized by the DC voltage Vdc.

(3-1) First change control executed by the PWM signal generation unit 36 of the control device 21 (No. 1)
Next, an example of the actual operation of the PWM signal generation unit 36 will be described with reference to FIGS. 2 and 3 in comparison with FIGS. 21 and 22. That is, here, an example of the first change control executed by the PWM signal generation unit 36 in order to solve the problems of FIGS. 21 and 22 described above will be outlined. Basically, as in the case of FIGS. 21 and 22, the PWM signal generation unit 36 of this embodiment also corrects the voltage command values Vu'and Vv'Vw'of each phase output by the phase voltage command calculation unit 33. In addition, the voltage command correction values are set to Cu, Cv, and Cw, the switching timings of the upper and lower arm switching elements 18A to 18F of each phase are synchronized, and the change in the phase voltage applied to the motor 8 is canceled by the change in the other phase voltage. Therefore, the neutral point potential Vc is controlled so as not to fluctuate. Note that FIG. 3 is an enlargement of two consecutive carrier cycles of the frame Z2 portion of FIG. Further, the conditions in this case are also the case where the carrier frequency is 20 kHz and the electric angular frequency is 800 Hz.

Similarly, in each figure, Cup is the start-up command value of the U-phase voltage command correction value Cu, and Cudown is the start-up command value of the U-phase voltage command correction value Cu. Similarly, Cvup is the start-up command value of the V-phase voltage command correction value Cv, Cvdown is the start-up command value of the V-phase voltage command correction value Cv, Cup is the start-up command value of the W-phase voltage command correction value Cw, and Cwdown is the start-up command value. It is a start-up command value of the W-phase voltage command correction value Cw, and the PWM signal generation unit 36 uses them (start-up command value Cup, start-up command value Cudown, start-up command value Cvup, start-up command value Cvdown, start-up command). By comparing the magnitude of the carrier signal with the value Cw (value Cw, start-up command value Voltage)), a PWM signal to be the drive command signal of the inverter circuit 28 is generated.

Then, also in this case, as shown in FIG. 19, the V-phase current iv is zero-crossed in the phase of 30 °, and is reversed from a negative value (direction flowing out from the motor) to a positive value (direction flowing into the motor). .. The PWM signal generation unit 36 of the embodiment predicts whether or not the phase currents (iu, iv, iw) cross zero within the carrier cycle each time the carrier cycle starts (the start of the specified switching section).

As shown in FIG. 19, when it is predicted that the V-phase current iv crosses zero and the direction is reversed, the PWM signal generation unit 36 has a V-phase upper and lower arm in the carrier cycle (carrier cycle on the left side when facing FIG. 3). The start-up command value Cvup and the start-up command value Cvdown of the V-phase voltage command correction value Cv are changed so as to stop the switching of the switching elements 18B and 18E.

Further, the PWM signal generation unit 36 has a U-phase voltage command correction value Cu start-up command value Cup and a start-up command value Cudown, and a W-phase voltage command correction value Cw start-up command value Cup and a start-up command value Cwdown. By changing the above, the switching of the U-phase upper and lower arm switching elements 18A and 18D and the W-phase upper and lower arm switching 18C and 18F is synchronized, and the change of the U-phase voltage Vu is canceled by the change of the W-phase voltage Vw.

By such a first change control, the other two-phase phases (U-phase voltage Vu, W) are not changed without changing the V-phase voltage Vv in which the direction of the current (V-phase current iv) flowing through the motor 8 is reversed. The upper and lower arm switching elements 18A, 18D, 18C, and 18F are switched synchronously so as to cancel the changes in the phase voltage Vw), and the neutral point potential Vc in the carrier cycle in which the direction of the V-phase current iv is reversed. It becomes possible to eliminate the fluctuation of (bottom of FIG. 3).

That is, in the present invention, it is possible to eliminate or significantly suppress the fluctuation of the neutral point potential Vc of the motor 8 by the switching timing of the upper and lower arm switching elements 18A to 18F. In particular, in the carrier cycle in which the direction of the current flowing through the motor 8 is reversed by the PWM signal generation unit 36, the variation of the neutral point potential Vc of the motor 8 occurs due to the dead time and the delay time of the switching element as shown in FIG. Since the switching operation is changed in the direction of eliminating or suppressing, the neutral point potential Vc fluctuates due to the error due to the dead time caused by reversing the direction of the current flowing through the motor 8 and the delay time of the switching element. It becomes possible to eliminate or suppress the inconvenience that occurs. As a result, it is possible to eliminate or suppress the generation of common mode noise extremely effectively.

Further, in the embodiment of FIG. 3, the specified switching section (carrier cycle) is started from the state where the U-phase lower arm switching element 18D is ON and the other two-phase upper arm switching elements 18B and 18C are ON. Therefore, the change in the U-phase voltage Vu can be smoothly canceled by the change in the W-phase voltage Vw.

Further, in the first change control, the PWM signal generation unit 36 has a carrier cycle in which the direction of the V-phase current iv is reversed (on the left side when facing FIG. 3) and a carrier cycle which is continuous therewith (on the right side when facing FIG. 3). The pulse widths of the phase voltages Vu, Vv, and Vw shown by the white arrows in FIG. 3 are the same as the pulse widths of the phase voltages Vu, Vv, and Vw shown by the white arrows in FIG. 22, respectively. , Control the switching so that they are substantially the same.

As a result, comparing FIGS. 22 and 3, the carrier cycle (on the left side when facing FIG. 3) in which the direction of the current (V-phase current iv) flowing through the motor 8 is reversed and the carrier cycle continuous therewith (toward FIG. 3) (Right side) Since the inconvenience of changing the line voltage as a whole can be eliminated or suppressed, the switching operation is changed in order to eliminate or suppress the fluctuation of the neutral point potential Vc. As a result, the inconvenience of changing the voltage applied to the motor 8 can be eliminated or suppressed, and stable operation control of the motor 8 can be realized.

(3-2) First change control executed by the PWM signal generation unit 36 of the control device 21 (No. 2)
Next, the first change control executed by the PWM signal generation unit 36 will be described in detail with reference to FIGS. 4 to 6 using another example.
(3-2-1) When the phase current (motor current) is not inverted FIG. 4 shows two consecutive carrier cycles, and the uppermost stage of FIG. 4 is generated by the PWM signal generation unit 36 of the control device 21. U-phase voltage command correction value Cu start-up command value Cup, start-up command value Cudown, V-phase voltage command correction value Cw start-up command value Cvup, Cvdown, and W-phase voltage command correction value Cw start-up command value Cup, start-up command value Voltage and carrier signals (saw wave carriers) X1 to X4 are shown. The second stage from the top is the ON / OFF state of the upper and lower arm switching elements 18A to 18F of each phase, and the second stage from the bottom is the motor. The U-phase voltage Vu, the V-phase voltage Vv, and the W-phase voltage Vw applied to No. 8 are shown, and the lowermost stage shows the neutral point potential Vc of the motor 8.

Further, the lower side of FIG. 4 shows the directions of the U-phase current iu, the V-phase current iv, and the W-phase current iwa flowing through the motor 8. The direction of each phase current is indicated by> 0 in the direction of inflow to the motor 8 and <0 in the direction of outflow from the motor 8. In the example of FIG. 4, the U-phase current iu and the W-phase current iu are in the direction of flowing into the motor 8, and the V-phase current iv is in the direction of flowing out of the motor 8. The case where the phase current does not zero-cross and does not reverse is shown.

In the embodiment, the single carrier signal (sawtooth carrier) in the present invention is composed of two downlinks X1 and X2 in order to create a dead time. The downlink X2 is a phase that advances from the downlink X1. Then, the PWM signal generation unit 36 compares the downlink X1 and X2 of the carrier signal with the startup command value Cup of the U-phase voltage command correction value Cu, and the lower arm switching element in the phase where the startup command value Cup crosses the downlink X1. A PWM signal is generated in which the 18D is turned off and the upper arm switching element 18A is turned on in a phase crossing the downlink X2. Further, a PWM signal is generated in which the upper arm switching element 18A is turned off in the phase where the fall command value Cudown crosses the downlink X1, and the lower arm switching element 18D is turned ON in the phase where the downlink X2 is crossed.

Further, the PWM signal generation unit 36 compares the downlink X1 and X2 of the carrier signal with the startup command value Cvup of the V-phase voltage command correction value Cv, and the lower arm switching element in the phase where the startup command value Cvup crosses the downlink X1. A PWM signal is generated in which 18E is turned off and the upper arm switching element 18B is turned on in a phase crossing the downlink X2. Further, a PWM signal is generated in which the upper arm switching element 18B is turned off in the phase where the fall command value Cvdown crosses the downlink X1, and the lower arm switching element 18E is turned ON in the phase where the downlink command value Cvdown crosses the downlink X2.

Further, the PWM signal generation unit 36 compares the downlink X1 and X2 of the carrier signal with the startup command value Cup of the W phase voltage command correction value Cw, and the lower arm switching element in the phase where the startup command value Cup crosses the downlink X1. A PWM signal is generated in which the 18F is turned off and the upper arm switching element 18C is turned on in a phase crossing the downlink X2. Further, a PWM signal is generated in which the upper arm switching element 18C is turned off in the phase where the fall command value Cwdown crosses the downlink X1, and the lower arm switching element 18F is turned ON in the phase where the downlink command value Cwdown crosses the downlink X2.

Further, in the PWM signal generation unit 36, in the embodiment, the U-phase lower arm switching element 18D is turned on, the V-phase upper arm switching element 18B, and the W-phase upper arm switching element 18C are turned on. The specified switching section (1 carrier cycle) is started.

When the U-phase current iu and the W-phase current iwa flow into the motor 8 and the V-phase current iv flows out from the motor 8 as in the embodiment, the U-phase is operated by the upper arm switching element 18A. While the phase voltage Vu changes and the upper arm switching element 18A is ON, the U phase voltage Vu becomes "H", and even in the W phase, the W phase voltage Vw changes due to the operation of the upper arm switching element 18C, and the upper arm The W-phase voltage Vw becomes “H” while the switching element 18C is ON. On the other hand, in the V phase, the V-phase voltage Vv changes due to the operation of the lower arm switching element 18E, and the V-phase voltage Vv becomes “H” during the period when the lower arm switching element 18E is OFF. Then, the sum of the widths of the periods of "H" in FIG. 4 is the magnitude of each phase voltage (U-phase voltage Vu, V-phase voltage Vv, W-phase voltage Vw).

As is clear from this figure, the PWM signal generation unit 36 corrects the voltage command values Vu', Vv', and Vw' to obtain the voltage command correction values Cu, Cv, and Cw, so that the continuous two-carrier cycle of FIG. 4 is obtained. In the first half of the first carrier cycle (on the left side), the W-phase upper arm switching element 18C is ON, the lower arm switching element 18F is OFF, and the U-phase lower arm switching element is further turned off. The timing at which the 18D is turned off and the timing at which the V-phase upper arm switching element 18B is turned off are synchronized, and the timing at which the U-phase upper arm switching element 18A is turned on and the timing at which the V-phase lower arm switching element 18E is turned on are set. By synchronizing, the timing at which the U-phase voltage Vu becomes "H" and the V-phase voltage Vv becomes "L" is synchronized, and the change in the U-phase voltage Vu is canceled by the change in the V-phase voltage Vv.

Further, in the latter half of the first carrier cycle, the U-phase upper arm switching element 18A is turned on, the lower arm switching element 18D is fixed in the OFF state, and the V-phase lower arm switching element 18E is turned OFF. By synchronizing the timing with the timing at which the upper arm switching element 18C of the W phase is turned off, and the timing at which the upper arm switching element 18B of the V phase is turned on with the timing at which the lower arm switching element 18F of the W phase is turned on. , The timing at which the V-phase voltage Vv becomes “H” and the W-phase voltage Vw becomes “L” is synchronized, and the change in the V-phase voltage Vv is canceled by the change in the W-phase voltage Vw.

In the first half of the next carrier cycle (on the right side) of the two consecutive carrier cycles shown in FIG. 4, the U-phase upper arm switching element 18A is fixed to the ON state, the lower arm switching element 18D is fixed to the OFF state, and further. , The timing when the upper arm switching element 18B of the V phase is turned off and the timing when the lower arm switching element 18F of the W phase is turned off are synchronized, and the timing when the lower arm switching element 18E of the V phase is turned on and the upper arm of the W phase By synchronizing the timing at which the switching element 18C is turned on, the timing at which the V-phase voltage Vv becomes “L” and the W-phase voltage Vv becomes “H” is synchronized, and the change in the V-phase voltage Vv is changed to the W-phase voltage Vw. It is canceled by the change of.

Further, in the latter half of the next carrier cycle, the W-phase upper arm switching element 18C is turned on, the lower arm switching element 18F is fixed in the OFF state, and the U-phase upper arm switching element 18A is turned OFF. By synchronizing the timing with the timing at which the lower arm switching element 18E of the V phase is turned off, and the timing at which the lower arm switching element 18D of the U phase is turned on with the timing at which the upper arm switching element 18B of the V phase is turned on. , The timing at which the U-phase voltage Vu becomes “L” and the V-phase voltage Vv becomes “H” is synchronized, and the change in the U-phase voltage Vu is canceled by the change in the V-phase voltage Vv.

The correction operation of the PWM signal generation unit 36 as described above will be described in more detail as follows.
In a normal general inverter device, the PWM signal generation unit generates a PWM signal so as to realize the three-phase modulation voltage command value of the phase voltage command calculation unit within one carrier cycle. In the device 1, the PWM signal generation unit 36 makes the fluctuation of the neutral point potential Vc of the motor 8 zero within the plurality of continuous carrier cycles, and the U-phase-V phase in the entire continuous plurality of carrier cycles. Three-phase modulation voltage command values Vu', Vv', Vw' are corrected so that the line voltage, V-phase-W-phase line voltage, and W-phase-U-phase line voltage do not change. The values Cu, Cv, and Cw are calculated to generate a PWM signal.

That is, assuming that the continuous plurality of carrier cycles are two cycles as shown in FIG. 4, there are two three-phase modulation voltage command values for the two cycles of the phase voltage command calculation unit 33. The PWM signal generation unit 36 reproduces the value obtained by adding the two three-phase modulation voltage command values in two carrier cycles. Alternatively, the value received from the phase voltage command calculation unit 33 in the first carrier cycle may be doubled and reproduced in two carrier cycles.

Specifically, with reference to FIG. 4, when looking at the W phase, in two consecutive carrier cycles, the W phase voltage command correction value Cw = W phase voltage command value Vw'+ common addition value α in the entire two carrier cycles. become. This is a value that is added in common to all U-phase, V-phase, and W-phase, and is the line voltage between U-phase and V-phase, the line voltage between V-phase and W-phase, and the line between W-phase and U-phase. In terms of voltage, it is possible to apply a waveform close to the voltage as the original three-phase modulation voltage command value.

The three-phase modulation voltage command value of this common addition value α is output for each of the U phase, V phase, and W phase, but this command is actually the command value of the line voltage, and the U phase-V phase. The line voltage of, V phase-W phase line voltage, and W phase-U phase line voltage may be set as instructed.
Expressed mathematically, the first U-phase voltage command value is Vu'1, the second U-phase voltage command value is Vu'2, and the voltage that can be applied to the motor 8 by the first U-phase PWM signal is PU1. Assuming that the voltage that can be applied to the motor 8 by the second U-phase PWM signal is PU2,
PU1 + PU2 + α = Vu'1 + Vu'2 ... (i)
Will be.

Similarly, considering the V phase and W phase,
PV1 + PV2 + α = Vv'1 + Vv'2 ... (ii)
PW1 + PW2 + α = Vw'1 + Vw'2 ... (iii)
Will be.
Vv'1 is the first V-phase voltage command value, Vv'2 is the second V-phase voltage command value, PV1 is the voltage that can be applied to the motor 8 with the first V-phase PWM signal, and PV2 is the second V-phase voltage command value. This is a voltage that can be applied to the motor 8 with a V-phase PWM signal. Vw'1 is the first W-phase voltage command value, Vw'2 is the second W-phase voltage command value, PW1 is the voltage that can be applied to the motor 8 with the first W-phase PWM signal, and PW2 is the second. This is a voltage that can be applied to the motor 8 with a W-phase PWM signal.

As described above, considering the case where the value received from the phase voltage command calculation unit 33 in the first carrier cycle is doubled and reproduced in two carrier cycles, the equation is as follows.
PU1 + PU2 + α = 2 × Vu'1 ・ ・ ・ (iv)
PV1 + PV2 + α = 2 × Vv'1 ... (v)
PW1 + PW2 + α = 2 × Vw'1 ... (vi)

Incidentally, in the general conventional method, the above equations (iv) to (vi) are as follows (the common addition value α is 0 when line-line modulation such as two-phase modulation is not performed).
PU1 + α = Vu'1 ... (vii)
PV1 + α = Vv'1 ... (viii)
PW1 + α = Vw'1 ... (ix)
Further, the above-mentioned method of the patent document can also be expressed by the same formula as the above formulas (vii) to (ix).

Considering the line voltage in the above equations (i) to (vi), the line voltage of the U phase-V phase is
PU1 + PU2 + α- (PV1 + PV2 + α) = Vu'1 + Vu'2- (Vv'1 + Vv'2) ... (x)
Then, this equation (x) becomes the following equation (xi).
PU1-PV1 + PU2-PV2 = Vu'1-Vv'1 + Vu'2-Vv'2 ... (xi)

Then, even in the conventional methods of the above formulas (vii) to (ix), the same value is obtained when two carrier cycles are taken into consideration. The two carrier cycles of U phase and V phase are as follows.
PU1 + α + PU2 + α = Vu'1 + Vu'2 ... (xii)
PV1 + α + PV2 + α = Vv'1 + Vv'2 ... (xiii)
When these equations (xii) and (xiii) are added in the same manner as in the case of equation (x), the same result is obtained as follows.
PU1 + α + PU2 + α- (PV1 + α + PV2 + α) = Vu'1 + Vu'2- (Vv'1 + Vv'2) ... (xiv)
Then, this equation (xiv) becomes the following equation (xv), which is the same as the equation (xi).
PU1-PV1 + PU2-PV2 = Vu'1-Vv'1 + Vu'2-Vv'2 ... (xv)

As described above, when considering the two carrier cycles according to the embodiment, the PWM signal generation unit 36 outputs the voltage (voltage command correction values Cu, Cv, Cw) according to the output of the phase voltage command calculation unit 33. It can be seen that there is (the width of the white arrow in FIG. 4).

As described above, the neutral point potential Vc, which is the average of each phase voltage Vu, Vv, and Vw, is always constant and does not change as shown in FIG. 4, so that common mode noise is effectively eliminated or suppressed. You will be able to do it. Further, in the embodiment, the PWM signal generation unit 36 fixes the upper arm switching element 18C of the W phase to the ON state and the lower arm switching element 18F to the OFF state in the first half of the first carrier cycle of FIG. 4, and lowers the U phase. Since the specified section of switching is started from the state where the arm switching element 18D is ON and the V-phase upper arm switching element 18B is ON, the change of the U-phase voltage Vu is changed by the change of the V-phase voltage Vv. You will be able to cancel it smoothly.

Further, in the first half of the next carrier cycle of FIG. 4, the U-phase upper arm switching element 18A is fixed to the ON state and the lower arm switching element 18D is fixed to the OFF state, and the V-phase upper arm switching element 18B is turned ON, and the W phase is turned on. The specified switching section is started from the state where the lower arm switching element 18F is ON, and the change in the V-phase voltage Vv can be smoothly canceled by the change in the W-phase voltage Vw. ..

(3-2-2) When the W-phase current iw is inverted However, as shown in FIG. 5, the W-phase current iw zero-crosses in the first carrier cycle, and the direction in which the W-phase current iw flows into the motor 8 (> 0) is reversed (> 0). In the case of inverting to <0), if switching control is performed at the same timing as in FIG. 4, the W-phase voltage Vw falls at the timing when the W-phase lower arm switching element 18F is turned on, so that the dead time and the switching element The neutral point potential Vc fluctuates in the direction of increasing in a pulse shape with a width corresponding to the delay time of.

Here, the PWM signal generation unit 36 of the embodiment predicts whether or not the phase currents (iu, iv, iw) cross zero within the carrier cycle each time the carrier cycle starts (the start of the specified switching section). do. When the PWM signal generation unit 36 of this embodiment predicts that the W-phase current iw zero-crosses in the latter half of the first carrier cycle and reverses from the direction of inflow to the motor 8 to the direction of outflow, the PWM signal generation unit 36 is shown in FIG. As shown in 6, in the first carrier cycle (carrier cycle on the left side when facing FIG. 6), the W-phase voltage command correction value Cw is started up so as to stop the switching of the W-phase upper and lower arm switching elements 18C and 18F. Change the command value Cup and the start-up command value Cwdown.

Further, the PWM signal generation unit 36 has a U-phase voltage command correction value Cu start-up command value Cup and a start-up command value Cudown, and a V-phase voltage command correction value Cv start-up command value Cvup and a start-up command value Cvdown. By changing the above, the switching of the U-phase upper and lower arm switching elements 18A and 18D and the V-phase upper and lower arm switching 18B and 18E is synchronized, and the change of the U-phase voltage Vu is canceled by the change of the V-phase voltage Vv.

By changing the switching operation of each of the switching elements 18A to 18E by such a first change control, the direction of the current (W-phase current iw) flowing through the motor 8 is not changed without changing the W-phase voltage Vw. The upper and lower arm switching elements 18A, 18D, 18B, and 18E are synchronously switched so as to cancel the changes in the other two-phase phases (U-phase voltage Vu, V-phase voltage Vv), and the W-phase current iwa It becomes possible to eliminate the fluctuation of the neutral point potential Vc in the carrier cycle (first carrier cycle) in which the direction of the current is reversed (lowermost part of FIG. 6). This makes it possible to eliminate or suppress the generation of common mode noise extremely effectively.

Also in this case (FIG. 6), the specified switching section (carrier cycle) is started from the state where the U-phase lower arm switching element 18D is ON and the other two-phase upper arm switching elements 18B and 18C are ON. Therefore, the change in the U-phase voltage Vu can be smoothly canceled by the change in the V-phase voltage Vv.

Further, also in this case, in the first change control, the PWM signal generation unit 36 has a carrier period in which the direction of the W-phase current iw is reversed (on the left side when facing FIG. 6) and a carrier period continuous to the carrier period (direction in FIG. 6). The pulse width of each phase voltage Vu, Vv, Vw shown by the white arrow in FIG. 6 is the pulse width of each phase voltage Vu, Vv, Vw shown by the white arrow in FIGS. 4 and 5. Switching is controlled so that they are the same as or substantially the same as the width.

As a result, the line voltage changes over the carrier cycle (on the left side when facing FIG. 6) in which the direction of the current (W phase current iw) flowing through the motor 8 is reversed and the carrier cycle (on the right side when facing FIG. 6) which is continuous with the carrier cycle. The voltage applied to the motor 8 can be eliminated or suppressed by changing the switching operation in order to eliminate or suppress the fluctuation of the neutral point potential Vc. It becomes possible to eliminate or suppress the inconvenience of changing the motor 8 and realize stable operation control of the motor 8.

(3-3) Second change control executed by the PWM signal generation unit 36 of the control device 21 Next, an example of the second change control executed by the PWM signal generation unit 36 using FIGS. 7 to 8 will be described in detail. Describe.
For example, as shown in FIG. 7, the U-phase current iu zero-crosses in the first carrier cycle of two consecutive carrier cycles, and is reversed from the direction in which the U-phase current iu flows into the motor 8 (> 0) to the direction in which it flows out (<0). The U-phase voltage Vu rises at the timing when the U-phase lower arm switching element 18D is turned off, the phase is delayed by the dead time and the delay time of the switching element, and the V-phase is turned on at the timing when the V-phase lower arm switching element 18E is turned on. Even when the voltage Vv drops, the neutral point potential Vc fluctuates in the direction of rising in a pulse shape with a width corresponding to the dead time and the delay time of the switching element.

Therefore, in this embodiment, when the PWM signal generation unit 36 predicts that the U-phase current iu crosses zero in the latter half of the first carrier cycle and reverses from the direction of inflow to the motor 8 to the direction of outflow, as shown in FIG. In the first carrier cycle (carrier cycle on the left side when facing FIG. 8), the U-phase voltage is such that the switching of the upper and lower arm switching elements 18A to 18F of all the phases (U-phase, V-phase, W-phase) is stopped. Command correction value Cu start-up command value Cup and start-up command value Cudown, V-phase voltage command correction value Cv start-up command value Cvup and start-up command value Cvdown, W-phase voltage command correction value Cw start-up command value Cup And change the down command value Cwdown.

By changing the switching operation of each of the switching elements 18A to 18E by such a second change control, in addition to the U-phase voltage Vu in which the direction of the current (U-phase current iu) flowing through the motor 8 is reversed, the other two Since the phase voltage (V-phase voltage Vv, W-phase voltage Vw) w of the phase does not change, the change of the neutral point potential Vc in the carrier cycle (first carrier cycle) in which the direction of the U-phase current iu is reversed. Can be resolved (bottom of FIG. 8). This makes it possible to eliminate or suppress the generation of common mode noise extremely effectively.

Further, even in the second change control, the PWM signal generation unit 36 has a carrier cycle in which the direction of the U-phase current iu is reversed (on the left side when facing FIG. 8) and a carrier cycle which is continuous therewith (on the right side when facing FIG. 8). The pulse widths of the phase voltages Vu, Vv, and Vw shown by the white arrows in FIG. 8 are the same as the pulse widths of the phase voltages Vu, Vv, and Vw shown by the white arrows in FIG. 7, respectively. , Control the switching so that they are substantially the same.

As a result, the line voltage changes over the carrier cycle (on the left side when facing FIG. 8) in which the direction of the current (U-phase current iu) flowing through the motor 8 is reversed and the carrier cycle (on the right side when facing FIG. 8) which is continuous therewith. The voltage applied to the motor 8 can be eliminated or suppressed by changing the switching operation in order to eliminate or suppress the fluctuation of the neutral point potential Vc. It becomes possible to eliminate or suppress the inconvenience of changing the motor 8 and realize stable operation control of the motor 8.

(3-4) Selection of First Change Control and Second Change Control In addition, the PWM signal generation unit 36 has the first change control (FIGS. 3 and 6) described above and the second change control. Of (FIG. 8), the one that approximates the switching operation before changing the switching operation of the upper and lower arm switching elements 18A to 18F of each phase (FIG. 5 in the case of FIG. 6; FIG. 7 in the case of FIG. 8). Select and execute. This makes it possible to minimize the adverse effect of the change in switching operation on the operation of the motor 8.

(3-5) Third change control executed by the PWM signal generation unit 36 of the control device 21 Next, an example of the third change control executed by the PWM signal generation unit 36 using FIGS. 9 to 10 will be described in detail. Describe.
For example, as shown in FIG. 9, in the state where the U-phase and V-phase lower arm switching elements 19D and 19E are turned on and the W-phase upper arm switching element 18C is turned on in the first carrier cycle of two consecutive carrier cycles. When the specified switching section starts (carrier cycle starts), the V-phase current iv crosses zero and reverses from the direction (> 0) inflow to the motor 8 to the direction (<0) outflow (<0). The V-phase voltage Vv rises at the timing when the lower arm switching element 18E turns off, the phase is delayed by the dead time and the delay time of the switching element, and the U-phase voltage Vu rises at the timing when the U-phase upper arm switching element 18A turns off. Even if it falls, the neutral point potential Vc rises in a pulse shape with a width corresponding to the dead time and the delay time of the switching element. That is, since the neutral point potential Vc rises and then falls, the neutral point potential Vc fluctuates twice.

Therefore, in this embodiment, as shown in FIG. 10, the PWM signal generation unit 36 has a V-phase upper and lower arm in the carrier period (on the left side when facing FIG. 10) in which the V-phase current iv is inverted, as in the case of FIG. Switching elements 18B and 18E are switched. On the other hand, the timing when the lower arm switching element 18A of the U phase is turned off and the timing when the upper arm switching element 18C of the W phase is turned off are synchronized, and the timing when the upper arm switching element 18A of the U phase is turned on and the lower side of the W phase. U-phase voltage command correction value Cu start-up command value Cup and start-up command value Cudown, W-phase voltage command correction value Cw start-up command value Cup and start-up command so as to synchronize the timing when the arm switching element 18F is turned on. By changing the value Cwdown, the timing at which the U-phase voltage Vu rises to "H" and the W-phase voltage Vw falls to "L" is synchronized, and the change in the U-phase voltage Vu is changed by the change in the W-phase voltage Vw. Cancel.

The neutral point potential Vc rises at the timing when the lower arm switching element 18E of the V phase is turned off, and then remains raised and does not fluctuate (lowermost stage of FIG. 10). By such a third change control, the fluctuation of the neutral point potential Vc is changed only once by switching the V-phase upper and lower arm switching elements 18B and 18E in which the direction of the current flowing through the motor 8 is reversed (only when the motor 8 starts up). It is possible to reduce to.

By changing the switching operation of each of the switching elements 18A to 18E by such a third change control, the change of the neutral point potential Vc in the carrier period (on the left side when facing FIG. 10) in which the direction of the current is reversed. Can be suppressed as compared with the case shown in FIG. In particular, in this case, since it becomes possible to correspond to a higher modulation rate than the first change control and the second change control described above, it is advantageous when an operating state in which the rotation speed of the motor 8 is high is required.

Further, in the third change control, the PWM signal generation unit 36 uniformly applies a voltage having a pulse width indicated by a broken line white arrow in FIG. 10 to all phases in the entire two consecutive carrier cycles of FIG. Adding to the phase. Since the voltage applied to the motor 8 is the difference between the phase voltages, the direction of the current (V-phase current iv) flowing through the motor 8 is reversed even if the same pulse width (broken white arrow) is added to all phases. The line voltage does not change over the entire carrier cycle (on the left side when facing FIG. 10) and the carrier cycle (on the right side when facing FIG. 10) continuous thereto. As a result, by changing the switching operation in order to eliminate or suppress the fluctuation of the neutral point potential Vc, the inconvenience that the voltage applied to the motor 8 changes is suppressed, and the motor 8 is stabilized. It becomes possible to realize operation control.

(3-6) Fourth change control executed by the PWM signal generation unit 36 of the control device 21 Next, an example of the fourth change control executed by the PWM signal generation unit 36 using FIGS. 11 to 12 will be described in detail. Describe.
For example, as shown in FIG. 11, in a state where the U-phase and V-phase lower arm switching elements 19D and 19E are turned on and the W-phase upper arm switching element 18C is turned on in the first carrier cycle of two consecutive carrier cycles. It is predicted that when the specified switching section starts (carrier cycle starts), the W-phase current iw crosses zero and the direction of flow into the motor 8 is reversed, but the direction of the W-phase current iw is unknown and U. The U-phase voltage Vu rises at the timing when the upper arm switching element 18A of the phase is turned on, the phase is delayed by the dead time and the delay time of the switching element, the lower arm switching element 18F of the W phase is turned on, and the W phase voltage Vw Even if the voltage falls, the neutral point potential Vc rises in a pulse shape with a width corresponding to the dead time and the delay time of the switching element. That is, since the neutral point potential Vc rises and then falls, the neutral point potential Vc fluctuates twice.

On the other hand, in the case of this embodiment, the U and V phases other than the W phase in which the direction of the current (iw) flowing through the motor 8 is reversed are defined sections for switching when the lower arm switching elements 18D and 18E are in the ON state. Therefore, the changes in the U-phase voltage Vu and the V-phase voltage Vv cannot cancel each other out.

Therefore, in this embodiment, the PWM signal generation unit 36 does not know the direction of the W-phase current iw to be inverted. Therefore, as shown in FIG. 12, in the carrier cycle in which the W-phase current iw is inverted (on the left side when facing FIG. 11). , The w-phase upper and lower arm switching elements 18C and 18F are switched in the same manner as in FIG. On the other hand, in the U-phase upper arm switching element 18A whose direction of the current is known to flow into the motor 8, the W-phase voltage Vw is the direction (<0) when the W-phase current iw flows out of the motor 8. Synchronize so that it turns on according to the timing of falling. Further, the V-phase lower arm switching element 18E, whose direction of the current is known to flow out from the motor 8, has a W-phase voltage Vw when the W-phase current iw flows into the motor 8 (> 0). U-phase voltage command correction value Cu start-up command value Cup and start-up command value Cudown, V-phase voltage command correction value Cv start-up command value Cvup and start-up so as to synchronize so as to turn off according to the fall timing. By changing the command value Cvdown, the timing at which the U-phase voltage Vu rises to "H" and the timing at which the V-phase voltage Vv rises to "H" are changed by the influence of the dead time and the delay time of the switching element. It synchronizes with the timing at which Vw falls, and cancels the change in W-phase voltage Vw by either of them.

In the example of FIG. 12, the W-phase current iw is actually reversed from the direction of inflow (> 0) into the motor 8 to the direction of outflow (<0), so that the timing at which the lower arm switching element 18F of the W-phase is turned on is turned on. Then, the W-phase voltage Vw drops. Therefore, the neutral point potential Vc rises at the timing when the lower arm switching element 18E of the V phase is turned off, and then remains raised and does not fluctuate (lowermost stage of FIG. 12). By such a fourth change control, in the embodiment, it is possible to reduce the fluctuation of the neutral point potential Vc to only once (only when rising) due to the switching of the V-phase lower arm switching element 18E.

By changing the switching operation of each of the switching elements 18A to 18E by such a fourth change control, the fluctuation of the neutral point potential Vc in the carrier period (on the left side when facing FIG. 12) in which the direction of the current is reversed can be changed. , It becomes possible to suppress more than the case shown in FIG. In particular, also in this case, since it becomes possible to correspond to a higher modulation rate than the first change control and the second change control described above, it is advantageous when an operating state in which the rotation speed of the motor 8 is high is required.

Further, even in the fourth change control, the PWM signal generation unit 36 uniformly applies the voltage of the pulse width indicated by the broken white arrow in FIG. 12 to all phases in the entire two consecutive carrier cycles of FIG. Since it is added to the phase, the voltage applied to the motor 8 is the difference between the phase voltages. Therefore, even if the same pulse width (broken white arrow) is added to all phases, the current (W phase) flowing through the motor 8 The line voltage does not change in the entire carrier cycle (on the left side when facing FIG. 12) in which the direction of the current iw) is reversed and the carrier cycle (on the right side when facing FIG. 12) which is continuous therewith. As a result, by changing the switching operation in order to eliminate or suppress the fluctuation of the neutral point potential Vc, the inconvenience that the voltage applied to the motor 8 changes is suppressed, and the motor 8 is stabilized. It becomes possible to realize operation control.

(3-7) Comparison of Fluctuation of Neutral Point Potential Vc Here, FIG. 13 shows a comparison of the fluctuation of the neutral point potential Vc of the motor 8 by each change control described in detail above and the conventional control. The top row in the figure shows the neutral point potential Vc in the case of the conventional three-phase modulation method described in FIG. 20, and the second row from the top shows the phase voltage as described in FIGS. 21 and 22. The neutral point potential Vc is shown when the voltage command value is corrected so that the change is canceled by the change of the other phase voltage, but the inversion (zero cross) of the phase current (motor current) is not taken into consideration.

The third stage from the top shows the neutral point potential Vc when the above-mentioned first change control and the second change control are performed, and the lowermost stage performs the third change control and the fourth change control. It shows the neutral point potential Vc in the case of. The conditions in this case are a carrier frequency of 20 kHz and an electric angular frequency of 200 Hz.

From this figure, it can be seen that by executing the first change control and the second change control, the fluctuation of the neutral point potential Vc of the motor 8 is suppressed as shown in the third stage from the top. Further, also by the third change control and the fourth change control, the number of times the neutral point potential Vc rises and falls as shown in the lowermost stage is compared with the fluctuations shown in the uppermost stage and the second stage from the top. It can be seen that there is a significant decrease in the same motor current phase.

(3-8) Summary of Line Voltages FIG. 14 shows the line voltage of the motor by the conventional three-phase modulation method described with reference to FIG. 20, and FIG. 15 shows the phase currents described with reference to FIGS. 21 and 22. The line voltage of the motor when the inversion (zero cross) of is not taken into consideration is shown. And FIG. 16 shows the line voltage of the motor by each change control described above.

The conditions in this case are also the case where the carrier frequency is 20 kHz and the electric angular frequency is 200 Hz. As is clear from these figures, it can be seen that each line voltage is an acceptable sine wave, although distortion is more likely to occur in the case of FIG. 16 as compared with FIGS. 14 and 15.

(3-9) Switching between First Change Control and Second Change Control, Third Change Control and Fourth Change Control Next, FIG. 17 shows the first change control and the second change control described above. The phase voltages Vu, Vv, and Vw at the time of the maximum phase voltage according to the above, and the line voltages of the U phase-V phase, the V phase-W phase, and the W phase-U phase are shown. Further, FIG. 18 shows the phase voltages Vu, Vv, Vw at the time of the maximum phase voltage by the third change control and the fourth change control described above, and the U phase-V phase, the V phase-W phase, and the W phase-U phase. The voltage between each line of is shown. All of these are values corrected to -1 to 1 and normalized.

As is clear from this figure, in the first change control and the second change control (FIG. 17), the modulation factor is 2/3 at the maximum, but the third change control and the fourth change control (FIG. 18). ), The modulation factor can be increased up to 4√3 / 9. That is, the maximum phase voltage of the third change control and the fourth change control is larger than that of the first change control and the second change control, and the line voltage that can be applied to the motor 8 is larger. It turns out to be.

Therefore, the PWM signal generation unit 36 of the control device 21 switches between the first change control and the second change control, the third change control, and the fourth change control described above according to the operating state of the motor 8. .. Specifically, in this embodiment, in the first region where the rotation speed of the motor 8 is lower than a predetermined threshold value (the region where a low modulation factor is sufficient), the first change control or the second change control is selected and executed. Then, in a predetermined second region (a region requiring a high modulation speed) higher than the first region, a third change control or a fourth change control is selected and executed. As a result, it is possible to appropriately eliminate or suppress the fluctuation of the neutral point potential Vc according to the operating state of the motor 8.

In the embodiment, the PWM signal generation unit 36 outputs the U-phase voltage command value Vu', the V-phase voltage command value Vv', and the W-phase voltage command value Vw'(three-phase modulation) output by the phase voltage command calculation unit 33. By correcting the voltage command value) while considering the dead time when switching each of the switching elements 18A to 18F and the delay time of the switching element, the fluctuation of the neutral point potential Vc of the motor 8 is eliminated (zero). The U-phase voltage command correction value Cu, the V-phase voltage command correction value Cv, and the W-phase voltage command correction value Cw (voltage command correction value) are calculated, and the phase current is changed by changing them. The fluctuation of the neutral point potential Vc due to zero cross is eliminated or suppressed, but the phase voltage command calculation unit 33 itself generates and changes the voltage command correction values Cu, Cv, and Cw, and outputs the voltage command correction values to the PWM signal generation unit 36. You may try to do it.

Further, in each of the above embodiments, the carrier signal of the sawtooth wave is used, but the present invention is not limited to this, and a triangular wave may be used, and the shape thereof is not limited. Further, in the examples, the case where two carrier cycles are taken into consideration is shown, but similarly, three carrier cycles or more may be taken into consideration. Further, in the embodiment, each of the above change controls is switched according to the rotation speed of the motor 8, but the invention of claim 9 is not limited to this, and another index indicating the load of the motor 8 may be adopted. Furthermore, in the examples, the present invention has been applied to an inverter device that drives and controls the motor of an electric compressor, but the present invention is not limited to this, and the present invention is effective for driving control of motors of various devices.

1 Inverter device 8 Motor 10 Upper arm power supply line 15 Lower arm power supply line 18A to 18F Upper and lower arm switching elements 19U U-phase half-bridge circuit 19V V-phase half-bridge circuit 19W W-phase half-bridge circuit 21 Controller 26A, 26B Current sensor 28 Inverter Circuit 33 Phase voltage command calculation unit 36 PWM signal generation unit 37 Gate driver

Claims (11)

An upper arm switching element and a lower arm switching element are connected in series for each phase between the upper arm power supply line and the lower arm power supply line, and the voltage at the connection point of the upper and lower arm switching elements of each phase is used as a three-phase AC output for the motor. Inverter circuit applied to
In an inverter device provided with a control device that controls switching of the upper and lower arm switching elements of each phase of the inverter circuit.
The control device is
A change in the phase voltage applied to the motor by synchronizing the switching timing of the upper and lower arm switching elements of each phase in consideration of the dead time when switching the upper and lower arm switching elements of each phase and the delay time of the switching element. Is executed as a switching operation that cancels out with changes in other phase voltages.
In the carrier cycle in which the direction of the current flowing through the motor is reversed, the switching operation is changed in the direction of eliminating or suppressing the fluctuation of the neutral point potential of the motor caused by the dead time and the delay time of the switching element. Inverter device characterized by The control device is characterized in that the specified section of switching is started from a state in which the lower arm switching element of any one phase is turned on and the upper arm switching element of the other two phases is turned on. The inverter device according to 1. The control device is characterized in that the specified section of switching is started from a state in which the lower arm switching element of any two phases is turned on and the upper arm switching element of the other one phase is turned on. The inverter device according to 1. In the carrier cycle in which the direction of the current flowing through the motor is reversed, the control device stops switching of the upper and lower arm switching elements in the phase in which the direction of the current is reversed, and the other two phases of the upper and lower arm switching elements. Any of claims 1 to 3, wherein by synchronizing the switching, the first change control for canceling the change in the phase voltage applied to the motor by the change in the other phase voltage is executed. Inverter device described in Crab. The control device is characterized in that, in a carrier cycle in which the direction of the current flowing through the motor is reversed, the second change control for stopping the switching of the upper and lower arm switching elements in all phases is executed. The inverter device according to any one of claims 3. The control device is
In the carrier cycle in which the direction of the current flowing through the motor is reversed, the switching of the upper and lower arm switching elements in the phase in which the direction of the current is reversed is stopped, and the switching of the other two phases of the upper and lower arm switching elements is synchronized. The first change control that cancels the change of the phase voltage applied to the motor by the change of the other phase voltage, and
It has a second change control that stops switching of the upper and lower arm switching elements of all phases in a carrier cycle in which the direction of the current flowing through the motor is reversed.
Any of claims 1 to 3, wherein one of the first change control and the second change control that approximates the switching operation before the switching operation is changed is selected and executed. Inverter device described in Crab. In the carrier cycle in which the direction of the current flowing through the motor is reversed, the control device sets a specified switching section in an ON state in which the two-phase upper and lower arm switching elements other than the phase in which the direction of the current flowing through the motor is reversed are vertically different. When starting, the change in the phase voltage of the two phases is changed by switching the upper and lower arm switching elements of the phase in which the direction of the current is reversed and synchronizing the switching of the upper and lower arm switching elements of the other two phases. The inverter device according to any one of claims 1 to 3, wherein a third change control that cancels each other is executed. In the carrier cycle in which the direction of the current flowing through the motor is reversed, the control device has a specified switching section in which the two-phase upper and lower arm switching elements other than the phase in which the direction of the current flowing through the motor is reversed are in the same ON state. When switching the upper and lower arm switching elements in the phase in which the direction of the current is reversed, the timing of the change in the phase voltage of the phase that changes due to the influence of the dead time and the delay time of the switching element is changed. By synchronizing the switching of the upper and lower arm switching elements of the two phases, the change in the phase voltage of the phase in which the direction of the current flowing through the motor is reversed is changed by the change in the phase voltage of any of the other two phases. The inverter device according to any one of claims 1 to 3, wherein the fourth change control for canceling is executed. The control device is
In the carrier cycle in which the direction of the current flowing through the motor is reversed, the switching of the upper and lower arm switching elements in the phase in which the direction of the current is reversed is stopped, and the switching of the other two phases of the upper and lower arm switching elements is synchronized. The first change control that cancels the change of the phase voltage applied to the motor by the change of the other phase voltage, and
A second change control that stops switching of the upper and lower arm switching elements of all phases in a carrier cycle in which the direction of the current flowing through the motor is reversed.
In the carrier cycle in which the direction of the current flowing through the motor is reversed, when the two-phase upper and lower arm switching elements other than the phase in which the direction of the current flowing through the motor is reversed start the specified switching section in the ON state where the upper and lower sides are different, the current A third phase in which changes in the phase voltage of the two phases are mutually canceled by switching the upper and lower arm switching elements of the phase in which the directions of the two phases are reversed and synchronizing the switching of the upper and lower arm switching elements of the other two phases. Change control and
In the carrier cycle in which the direction of the current flowing through the motor is reversed, when the two-phase upper and lower arm switching elements other than the phase in which the direction of the current flowing through the motor is reversed start the specified switching section in the same ON state. The upper and lower arm switching elements of the phase in which the direction of the current is reversed are switched, and at the timing of the change in the phase voltage of the phase that changes due to the influence of the dead time and the delay time of the switching element, the upper and lower sides of the other two phases are changed. A fourth change in which the change in the phase voltage of the phase in which the direction of the current flowing through the motor is reversed by synchronizing the switching of the arm switching elements is canceled by the change in the phase voltage of any of the other two phases. Have control,
The inverter device according to any one of claims 1 to 3, wherein each change control is selectively executed based on the operating state of the motor. The control device executes the first change control or the second change control in the first region where the rotation speed of the motor is low, and the second region where the rotation speed of the motor is higher than the first change control. The inverter device according to claim 9, wherein in the region, the third change control or the fourth change control is executed. The control device changes the switching operation in the continuous carrier cycle in the direction of eliminating or suppressing the change in the line voltage over the carrier cycle in which the direction of the current flowing through the motor is reversed and the entire carrier cycle continuous thereto. The inverter device according to any one of claims 1 to 10, wherein the inverter device is used.

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