JP5923386B2 - Converter device and motor driving device using the same - Google Patents

Description

  The present invention relates to a converter device and a motor driving device using the converter device, and particularly a rectifying operation for performing a rectifying operation of a three-phase AC power source and a boosting operation of a DC voltage for a motor driving device that drives a permanent magnet synchronous motor at a variable speed. It relates to the control of the circuit.

  Permanent magnet synchronous motors (hereinafter referred to as motors) have characteristics that are more efficient than induction motors, and thus have a wide range of applications from home appliances to industrial equipment or electric vehicle fields.

  In addition, the above devices are required to improve the efficiency in the normal operation area (high efficiency in the low and medium speed range) in accordance with the movement of global warming prevention and energy saving, but to improve the feeling of use of the device High output (expanding driving range in high speed range) is also required at the same time.

  For example, in the case of an air conditioner for home appliances, it is possible to improve both APF (year-round energy consumption efficiency), which is an energy-saving index, and to improve low-temperature heating capacity (heating capacity at an outside temperature of 2 ° C), which is an index for higher output Required.

  As a means of high efficiency (especially in the low and medium speed range) by the motor drive device, there is a low speed design of the motor (magnet amount and winding increase), but when the motor is designed at a low speed, the induced voltage generated in the high speed range is reduced. Therefore, it is difficult to achieve high-speed driving, and there is a concern that the efficiency may be greatly reduced.

  Therefore, as one of means for driving a low-speed designed motor at high speed, there is a method for boosting a DC voltage. In this method, a step-up chopper circuit is added to the rectifier circuit and high-speed switching operation is performed to boost the DC voltage, resulting in an increase in circuit loss.

  As means for solving this problem, Patent Document 1 has been proposed. Patent Document 1 has a configuration in which a full-wave rectification and a voltage doubler rectification are switched by adding a bidirectional switch, a diode, and a capacitor to a three-phase rectifier circuit, and the DC voltage is changed.

  Moreover, although viewpoints differ, patent document 2 is proposed as another system. Patent Document 2 adds three bidirectional switch circuits that short-circuit a power supply via a reactor to a three-phase rectifier circuit, and operates each bidirectional switch according to the phase of the power supply voltage, thereby reducing the power supply current. A method for suppressing harmonics is described.

JP-A-5-168243 JP 2004-166359 A

Kawabata et al. “Examination of position sensorless motor current sensorless permanent magnet synchronous motor” 2002 IEEJ Industrial Application Division Conference No.171 2002

  According to the method of Patent Document 1, since this method can change the DC voltage without using the switching operation, the switching loss does not increase. However, because the method switches between full-wave rectification and voltage doubler rectification, only two values of the full-wave rectification voltage and voltage doubler rectification voltage are selected as the DC voltage value. In other words, the DC voltage cannot be changed freely. Further, since one diode is added to each phase in the three-phase rectifier circuit, additional diode loss occurs during full-wave rectification.

  Moreover, according to the method of Patent Document 2, a short circuit operation is performed once or a plurality of times in a half cycle of the power supply before and after the phase where the voltages of adjacent phases of the power supply voltage coincide with each other, and harmonics can be suppressed. It is. However, there is a limit to boosting the DC voltage, and boosting up to the double voltage rectified voltage cannot be performed as in Patent Document 1.

  Therefore, the methods of Patent Documents 1 and 2 do not have a rectifier circuit that can freely control a wide range of voltage changes from a full-wave rectified voltage to a double voltage rectified voltage, and can be applied to a motor drive device that drives a variable speed at high efficiency over a wide range. Is not enough.

  Therefore, the object of the present invention is to propose a rectifier circuit system that can freely control a wide range of voltage changes from a full-wave rectified voltage to a double voltage rectified voltage in a rectifier circuit of a three-phase AC power supply. Furthermore, it is possible to achieve both higher efficiency and wider driving.

In order to solve the above problems, for example, the configuration described in the claims is adopted.
The present application includes a plurality of means for solving the above-mentioned problems. To give an example of the above, “a three-phase diode bridge connected to a three-phase AC power source, a DC side and a load side of the three-phase diode bridge” In a converter device for converting the AC voltage of the three-phase AC power source into a DC voltage, comprising a smoothing capacitor connected in series and a detecting means for detecting the voltage phase of the three-phase AC power source, Switch means provided between the AC side of the three-phase diode bridge and the midpoint of the series-connected smoothing capacitor, for switching so as to be conducted for each phase of the three-phase AC power supply, and controlling the switch means And a control unit that conducts the phase during a period in which the voltage of any phase of the three-phase AC power source detected by the detection means is maximum or minimum. And wherein the "controlling the switching means so that.

According to the present invention, in a rectifier circuit of a three-phase AC power supply, a wide voltage change from a full-wave rectified voltage to a double voltage rectified voltage can be freely controlled, and further higher efficiency can be achieved.
Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

1 is a basic configuration diagram of a motor drive device of Embodiment 1. FIG. FIG. 3 is a configuration diagram of a switch circuit according to the first embodiment. FIG. 6 is an explanatory diagram of conduction timing of the switch circuit according to the first embodiment. It is a simulation waveform at the time of the switch circuit stop of Example 1 (full wave rectification operation). It is a simulation waveform at the time of the switch circuit operation | movement (double voltage rectification operation | movement) of Example 1. FIG. It is a simulation waveform at the time of switch circuit operation | movement (conducting width change example 1) of Example 1. FIG. It is a simulation waveform at the time of the switch circuit operation | movement (conduction width change example 2) of Example 1. FIG. FIG. 3 is a configuration diagram 1 of a switch circuit according to a second embodiment. FIG. 3 is a configuration diagram of a switch circuit according to a second embodiment. FIG. 10 is an explanatory diagram of conduction timing of the switch circuit according to the second embodiment. It is a simulation waveform at the time of switch circuit operation | movement (double voltage rectification) of Example 2. FIG. FIG. 6 is an operation explanatory diagram 1 of a motor drive device according to a third embodiment. FIG. 6 is an operation explanatory diagram 2 of the motor drive device of Embodiment 3.

  Embodiments of the present invention will be described below with reference to the drawings.

  The first embodiment of the present invention will be described below with reference to FIGS. First, the basic circuit configuration and operation will be described with reference to FIGS. FIG. 1 is a basic configuration diagram of the motor drive device according to the first embodiment.

  FIG. 1 shows a three-phase AC reactor 2 connected to a three-phase AC power source 1, a three-phase diode bridge circuit 3, a DC side of the three-phase diode bridge circuit 3, and an inverter circuit 5 that drives a motor 6. A smoothing capacitor 4 connected in series, a bidirectional switch circuit 9 corresponding to each phase provided between the AC side of the three-phase diode bridge circuit 3 and the midpoint of the smoothing capacitor 4 connected in series; Voltage phase detection means 8 for detecting the voltage phase of the three-phase AC power supply 1, current detection means 7 for detecting a direct current flowing through the inverter circuit 5, and control for controlling the inverter circuit 5 and the bidirectional switch circuit 9 1 is a motor drive device including a circuit 10.

  In FIG. 1, when the inverter circuit 5 is referred to as an inverter device and the circuit on the left side of the inverter circuit 5 is referred to as a converter device, the motor driving device of the present embodiment converts the AC voltage of the three-phase AC power source into a DC voltage. And an inverter device that converts the DC voltage into a desired AC voltage and supplies the converted AC voltage to the motor.

  Here, the motor 6 is a permanent magnet synchronous motor, and the inverter circuit 5 is a circuit composed of a semiconductor element that generates an arbitrary AC voltage in accordance with the PWM signal 10A from the control circuit 10 and drives the motor 6. is there. The voltage phase detection means 8 is composed of a voltage dividing resistor, and the voltage detection values (Vrn, Vsn, Vtn) of the three-phase AC power supply are input to the control circuit 10.

  The control circuit 10 includes a semiconductor arithmetic element and a semiconductor circuit (analog circuit and digital circuit), and calculates the voltage phase of the three-phase AC power source 1 from the voltage detection values (Vrn, Vsn, Vtn) of the three-phase AC power source. Means, motor control means for controlling the motor 6 using the inverter circuit 5, and rectifier circuit control means for controlling the bidirectional switch circuit 9.

  Here, the motor control means is a control method for performing position sensorless / motor current sensorless vector control of the motor 6 based on current information from the current detection means 7, and details are described in Non-Patent Document 1.

  However, in this embodiment, the motor and the motor control method are not limited. In other words, the motor 6 can be an induction motor, a synchronous reluctance motor, a switched reluctance motor, or the like, and the motor control method can be a control method that matches the connected motor. Further, in this embodiment, sensorless control is described as an example, but the presence or absence of the sensor is not limited.

  FIG. 2 shows the configuration of the bidirectional switch circuit 9. This circuit is composed of a single-phase diode bridge circuit (91A, 91B, 91C) and a switch element (92A, 92B, 92C). When the switch element (92A, 92B, 92C) is made conductive, the terminal Pr (Ps , Pt) and the terminal Pc. Here, Gr, Gs, and Gt indicate gate signals (see FIG. 3) of the switch elements (92A, 92B, and 92C).

  FIG. 3 shows the power supply voltage waveform (phase voltage) and the conduction timing (gate signal) of the bidirectional switch circuit 9. In the present embodiment, as shown in FIG. 3, at least one bidirectional switch circuit 9 connected to the phase is made conductive during the period when the voltage of each phase of the three-phase AC power supply 1 is maximum or minimum. In this method, the DC voltage is controlled between the full-wave rectified voltage and the double voltage rectified voltage.

  More specifically, the switch element 92A of the switch circuit 90A connected to the R phase is made conductive (the gate signal Gr is turned on) during the period from the point A to the point B where the R phase voltage of the three-phase AC power supply 1 becomes maximum. . Then, since the power supply current flows from the R phase to the S and T phases, the smoothing capacitor on the low potential side of the smoothing capacitor 4 connected in series is charged from the R phase through the bidirectional switch 90A, and the three-phase diode bridge circuit A current returns to the power source through 3.

  On the contrary, the switch element 92A of the switch circuit 90A connected to the R phase is made conductive (the gate signal Gr is turned on) during the period from the point C to the point D where the R phase voltage of the three-phase AC power supply 1 is minimized. Then, since the power source current flows from the S and T phases to the R phase, the smoothing capacitors on the high potential side of the smoothing capacitors 4 connected in series from the S and T phases via the three-phase diode bridge circuit 3 are charged and bidirectionally supplied. A current returns to the power source through the switch 90A.

  As described above, the converter device of the present embodiment is provided between the midpoints of the smoothing capacitor 4 connected in series with the AC side of the three-phase diode bridge 3 so as to be conductive for each phase of the three-phase AC power source 1. Are provided with a bidirectional switch circuit 9 (switch means) for switching, and a control circuit 10 (control unit) for controlling the bidirectional switch circuit 9 (switch means). Then, the control circuit 10 (control unit) is bidirectional so that the phase is conducted during the period when the voltage of any phase of the three-phase AC power supply 1 detected by the voltage phase detection means 8 is maximum or minimum. Voltage rectification can be performed by controlling the switch circuit 9 (switch means).

  Here, although the voltage doubler rectification operation has been described with reference to FIG. 3, it is possible to control the DC voltage between the full-wave rectified voltage and the voltage doubler rectified voltage by adjusting the conduction time of the bidirectional switch circuit 9. is there. Specifically, a DC voltage control means for detecting a DC voltage and adjusting the conduction time with a proportional / integral controller or the like may be added.

  4 to 7 show the simulation results. 4 shows a state where the operation of the bidirectional switch circuit 9 is stopped (full-wave rectification state), and FIG. 5 shows a state where the bidirectional switch circuit 9 is operated (double voltage rectification state) as shown in FIG. 6 and 7 show a state in which the conduction time of the bidirectional switch circuit 9 is shorter than the time shown in FIG. The power supply voltage was 200 V and the load was 30 A as a direct current.

  As shown in the simulation results of FIGS. 4 to 7, the voltage at both ends of the smoothing capacitor 4 is changed from the full-wave rectified voltage to the double voltage rectified voltage by changing and controlling the conduction time for each phase of the bidirectional switch circuit 9. DC voltage can be controlled between the two.

  As described above, the control of the bidirectional switch circuit 9 of the present embodiment can realize a rectifier circuit that can freely control a wide voltage change from a full-wave rectified voltage to a double voltage rectified voltage in a rectifier circuit of a three-phase AC power supply. .

  Here, in the present embodiment (FIG. 3), the conduction timing of the bidirectional switch circuit 9 has been described with a focus on the voltage peak of the three-phase AC power supply 1, but the conduction timing is not limited to this phase. . In other words, the conduction timing (phase) of the bidirectional switch circuit 9 may be changed according to the magnitude of the load or the power supply current. The conduction time of the bidirectional switch circuit 9 can be divided into a plurality of pulses.

  Next, a second embodiment will be described with reference to FIGS. In this embodiment, the loss of the bidirectional switch circuit 9 described in the first embodiment is reduced. Since the entire circuit configuration and the like are the same as those of the first embodiment, description thereof will be omitted.

  8 and 9 show the circuit configuration of the bidirectional switch circuit 9 of this embodiment. FIG. 8 includes a switch element (95A1, 95A2, 95B1, 95B2, 95C1, 95C2) and a diode (94A1, 94A2, 94B1, 94B2, 94C1, 94C2), and two switch elements (for example, 95A1, 95A2). Do one action. In other words, the same operation as that of the switch element (for example, 92A) in FIG. 2 is performed by two switch elements (for example, 95A1 and 95A2).

  FIG. 9 shows a configuration in which the diodes (94A1, 94A2, 94B1, 94B2, 94C1, 94C2) of FIG. 8 are deleted, and the switching element (95A1, 95A2, 95B1, 95B2, 95C1, 95C2) can maintain the reverse breakdown voltage. In the conditions, the configuration of FIG. 9 can be applied. With this circuit configuration, the number of semiconductors through which current flows can be reduced as compared with the circuit configuration shown in FIG. 2, and the conduction loss of the bidirectional switch circuit can be reduced. Specifically, in the case of the circuit of FIG. 2, the number of conducting semiconductors is three (two diodes and one switch element). In the case of the circuit of FIG. 8, the number of conducting semiconductors is two (one diode and one switching element). In the case of the circuit of FIG. 9, the number of conducting semiconductors is one (one switching element), and the conduction loss of the semiconductor can be reduced.

  The conduction timing of the bidirectional switch circuit of this embodiment will be described with reference to FIG. FIG. 10 shows the power supply voltage waveform and the gate signal as in FIG. The difference from FIG. 3 is that there are six gate signals.

  As in FIG. 3, the switch element 95A1 of the switch circuit 93A (or 96A) connected to the R phase is turned on during the period from the point A to the point B where the R phase voltage of the three-phase AC power supply 1 is maximum (gate signal Grp On). Then, since the power supply current flows from the R phase to the S and T phases, the smoothing capacitor on the low potential side of the smoothing capacitor 4 connected in series passes from the R phase through the switch element 95A1 of the switch circuit 93A (or 96A). A current that charges and returns to the power supply through the three-phase diode bridge circuit 3 flows.

  On the contrary, the switch element 95A2 of the switch circuit 93A (or 96A) connected to the R phase is made conductive during the period from the point C to the point D where the R phase voltage of the three-phase AC power supply 1 is minimized (on the gate signal Grn). ) Then, since the power source current flows from the S and T phases to the R phase, the smoothing capacitor on the high potential side of the smoothing capacitor 4 connected in series from the S and T phases via the three-phase diode bridge circuit 3 is charged, A current that returns to the power source flows through the switch element 95A2 of the switch circuit 93A (or 96A). As described above, the same operation as in the first embodiment can be performed.

  FIG. 11 shows an operation simulation result similar to FIG. FIG. 11 shows the result of operating the bidirectional switch circuit 9 (double voltage rectification state) as shown in FIG. The power supply voltage and load conditions are the same as in FIG. Although the configuration of the bidirectional switch circuit is different, FIGS. 5 and 11 have the same DC voltage and power supply current waveforms.

  That is, in the converter device of the present embodiment, the control circuit 10 (control unit) is on the low potential side of the smoothing capacitor 4 connected in series during the period when the voltage of the three-phase AC power source 1 detected by the voltage phase detecting means 8 is high. The bidirectional switch circuit 9 (switch means) is controlled so as to charge the smoothing capacitor of the three-phase AC power supply 1 and the smoothing capacitor on the high potential side of the smoothing capacitor 4 connected in series is charged when the power supply voltage of the three-phase AC power supply 1 is low. Thus, the bidirectional switch circuit 9 (switch means) is controlled.

  As described above, the conduction loss of the bidirectional switch circuit can be reduced by using the configuration of the bidirectional switch circuit of FIG. 8 or FIG. 9 and the conduction timing shown in FIG. In addition, since the number of semiconductors used can be reduced, the circuit scale and cost can also be reduced.

  Hereinafter, the present embodiment will be described with reference to the drawings. In the first and second embodiments, the operation of the rectifier circuit has been described. In this embodiment, the operation of the motor driving in these embodiments will be described.

  12 and 13 show a change image of the total efficiency of the motor drive device including the motor rotation speed or load on the horizontal axis and the DC voltage and the motor on the vertical axis. Here, the total efficiency is shown when the motor is driven by a full-wave rectified voltage (switch circuit stopped state) (solid line) and when the motor is driven by changing the DC voltage (switch circuit operating state) (dotted line). .

  FIG. 12 is an operation explanatory diagram in the case where the DC voltage is controlled by adjusting the conduction time of the bidirectional switch circuit 9 as described in the first embodiment, and FIG. 13 is the conduction time of the bidirectional switch circuit 9. It is operation | movement explanatory drawing in the case of switching a full wave rectified voltage and a double voltage rectified voltage, without adjusting this.

  In the case of FIG. 12, the operation of the bidirectional switch circuit is stopped at the time of low rotation and used as a full-wave rectifier circuit. Then, the DC voltage becomes a full-wave rectified voltage, and the motor can be driven with a low DC voltage, so that the overall efficiency is improved (the loss of the bidirectional switch circuit does not occur). That is, the control circuit 10 (control unit) controls the bidirectional switch circuit 9 (switch means) so that no phase is conducted when the load state is smaller than a predetermined value. However, when the rotation speed is high, driving cannot be performed with a low DC voltage, and it is necessary to drive using a field-weakening control (control that causes a large amount of reactive current to flow).

  Therefore, by operating the bidirectional switch circuit 9 and controlling to a desired DC voltage, the motor can be driven without using field-weakening control, so that efficient driving is possible (the efficiency of the dotted line is achieved).

  In addition, since this circuit is not boosted by a high-speed switching operation unlike the boost chopper circuit, the switching loss is small, and the overall efficiency can be improved as compared with the method using the boost chopper circuit.

  Here, in this embodiment, since the two-phase switch circuit is described in a state in which the two phases are not simultaneously conducted, the DC voltage does not exceed the double voltage rectified voltage. The DC voltage can be increased. However, the power supply current waveform is a waveform containing a large amount of harmonics.

  In FIG. 13, the conduction time is not varied as shown in FIG. 12, and the full-wave rectification operation (bidirectional switch circuit operation stop) and the double voltage rectification operation (bidirectional switch circuit operation) are switched under a predetermined load condition. An example is shown. In the case of this method, since there is no control of the conduction time, the DC voltage cannot be controlled, but the control configuration can be simplified. Therefore, it is preferable to apply to an application (for example, a refrigerator, etc.) that is usually driven at a light load and needs to be activated at a high load.

  In this method, since current does not flow to the bidirectional switch circuit during full-wave rectification, the same loss occurs in a normal full-wave rectifier circuit. In other words, when the bidirectional switch circuit operates, the loss of the bidirectional switch circuit increases. Therefore, as shown in the second embodiment, the loss of the bidirectional switch circuit can be reduced by devising the conduction timing of the switch element.

  As described above, by applying the rectifier circuit (converter device) according to the first to third embodiments to a motor drive device and changing the operation according to the load state of the motor, it is possible to achieve both high efficiency and wide range drive. A driving device and an apparatus using the same can be realized.

  It is particularly effective for the following reasons that the motor drive device to which the rectifier circuit (converter device) of these embodiments is applied is applied to the drive of a ferrite motor employing a ferrite magnet. Ferrite motors have less magnetic flux than motors using neodymium magnets, so it is necessary to wind more windings, but doing so increases the L component of the windings and narrows the drive range in the high-speed, high-load region. Problem arises. On the other hand, since the rectifier circuit (converter device) can be boosted by applying the rectifier circuits (converter device) 1 to 3 to the motor drive device, the ferrite motor has a higher speed and higher load region than the conventional one. A driving range can be secured.

DESCRIPTION OF SYMBOLS 1 Three-phase alternating current power supply 2 Three-phase alternating current reactor 3 Three-phase diode bridge 4 Smoothing capacitor 5 Inverter circuit 6 Motor 7 Current detection means 8 Voltage phase detection means 9 Bidirectional switch circuit 10 Control circuit

Claims (7)

A three-phase diode bridge connected to a three-phase AC power source;
A smoothing capacitor provided between the DC side and the load side of the three-phase diode bridge and connected in series;
Detecting means for detecting a voltage phase of the three-phase AC power supply, and a converter device for converting an AC voltage of the three-phase AC power supply into a DC voltage,
Switch means provided between the AC side of the three-phase diode bridge and the midpoint of the smoothing capacitor connected in series, and performing switching so as to be conducted for each phase of the three-phase AC power supply;
A control unit for controlling the switch means,
The control unit
The converter device, wherein the switch means is controlled so that a phase of the three-phase AC power source detected by the detecting means becomes maximum or minimum during a period of time. The converter device according to claim 1,
The controller is
During the period when the voltage of the three-phase AC power source detected by the detection unit is high, the switch unit is controlled to charge the smoothing capacitor on the low potential side of the smoothing capacitor connected in series, and the three-phase AC power source A converter device characterized by controlling the switch means so as to charge the smoothing capacitor on the high potential side of the smoothing capacitors connected in series during a period when the power supply voltage is low. The converter device according to claim 1 or 2,
The controller is
By changing the conduction time for each phase of the three-phase AC power supply by the switch means, the voltage across the smoothing capacitors connected in series is controlled between the full-wave rectified voltage and the double voltage rectified voltage. The converter device characterized. The converter device according to claim 1 or 2,
The switch means is configured by connecting in series a switch element that can conduct in only one direction, and connects the midpoint of the switch element to the midpoint of the smoothing capacitor connected in series, and the other of the switch elements Is connected to the AC side of the three-phase diode bridge. The converter device according to claim 1 or 2,
The controller is
When the load state is smaller than a predetermined value, the switch means is controlled so that no phase is conducted. In a motor drive device provided with a converter device that converts an alternating voltage of a three-phase alternating current power supply into a direct current voltage, an inverter device that converts the direct current voltage into a desired alternating voltage and supplies the motor to the motor,
5. A motor drive device, wherein the converter device according to claim 1 is employed as the converter device, and the load is the inverter device or the motor. In the motor drive device according to claim 6,
The controller is
A motor driving device that controls the switch means so that any phase is not conducted when the state of the load is smaller than a predetermined value.