JP4690151B2 - Power converter - Google Patents

Description

  The present invention relates to a boost converter that boosts the voltage of a DC power supply, a DC link capacitor connected to the boost converter, and AC power transfer (drive and regeneration) between the DC link capacitor and each load. More particularly, the present invention relates to a technique for suppressing an effective value of a pulse current flowing into the DC link capacitor.

  In the conventional power conversion device, in order to minimize the current of the DC link capacitor and miniaturize the device, the carrier signals for driving the two inverters are synchronized and the phase is set to 0 degree or 180 degrees. Is set so that the carrier signal of the boost converter is also synchronized with the carrier signal of the inverter and the pulse current from the two inverters cancels out the pulse current from the boost converter (for example, Patent Documents 1 and 2). reference).

Japanese Patent Publication No. 8-34695 (page 4, right column, line 23 to page 5, right column, line 21, lines 1 to 4) JP 2004-187468 A (paragraphs 0017 to 0076)

By the way, the PWM (Pulse Width Modulation) controlled inverter differs from the original PWM operation in which the pulse output operation is performed according to the cycle of the carrier signal, and the pulse output according to the cycle of the voltage command signal is performed for the purpose of increasing the voltage utilization rate. A rectangular wave output operation may be performed.
In such a power conversion device, when one inverter shifts from PWM driving to rectangular wave driving, the pulse current from the other inverter and the pulse current from the boost converter are intensified. Because of the phase relationship (which will be described in more detail in the embodiments described later), the current of the DC link capacitor increases, which requires a capacitor with a large capacity, or when the capacity of the DC link capacitor is small. There has been a problem that the fluctuation of the input voltage of the inverter becomes large and the motor driving current as a load cannot be stabilized.

In addition, the boost converter has a non-boosting operation mode in which, for example, when the induced voltage level of the motor as a load is low, the high-voltage side switch element of the boost converter is always turned on and the input / output terminals are always energized. May take.
As described above, when the boost converter shifts to the non-boosting operation mode, when both motors drive or regenerate simultaneously, the phase difference between the carrier signals of both inverters is set to 0 degree or 180 degrees, the DC link capacitor Current will increase (as will be described in more detail in the embodiments described later), and for this purpose, a capacitor with a large capacity is required, and when the capacity of the DC link capacitor is small, the fluctuation of the input voltage of the inverter increases. There was a problem that the motor drive current could not be stabilized.

  The present invention has been made to solve the above-described problems. Even when the inverter shifts to a rectangular wave output operation or when the boost converter shifts to a non-boosting operation, the DC link capacitor is supplied to the DC link capacitor. An object of the present invention is to obtain a small power conversion device in which an inflow current is suppressed and a stable motor drive can be realized with a small DC link capacitor.

The power converters according to the first and second inventions are a boost converter that boosts the voltage of a DC power supply by PWM operation of a switch element, a DC link capacitor connected to a boost side terminal of the boost converter, and the DC link capacitor And a plurality of inverters that exchange (drive and regenerate) AC power with each load in the PWM operation of the switch element, and synchronize the PWM carrier signal of the boost converter and the PWM carrier signal of the inverter In the power converter to operate,
When a part of the plurality of inverters shifts from the pulse output operation based on the carrier signal cycle to the rectangular wave output operation including the pulse output based on the voltage command signal cycle, the PWM carrier signal of the boost converter and the PWM carrier signal of the inverter By adjusting the phase difference, the effective value of the sum of pulse currents flowing into the DC link capacitor from the remainder of the plurality of inverters and the boost converter is suppressed , and each
In the first invention, the transition to the rectangular wave output operation in the inverter is determined under the condition of α> 1 when (the voltage command signal amplitude value / the carrier signal zero-peak value) is defined as the modulation factor α. Thus, the second invention is such that the frequency of the PWM carrier signal of the boost converter is twice the frequency of the PWM carrier signal of the inverter.

The power conversion devices according to the third and fourth inventions include a boost converter that boosts the voltage of a DC power supply by PWM operation of a switch element, a DC link capacitor connected to the boost side terminal of the boost converter, and the DC A plurality of inverters are connected to the link capacitor to exchange (drive and regenerate) AC power with each load in the PWM operation of the switch element. The PWM carrier signal of the boost converter and the PWM carrier signal of the inverter are synchronized. In the power conversion device operated by letting
When a part of the plurality of inverters shifts from the pulse output operation based on the carrier signal cycle to the rectangular wave output operation including the pulse output based on the voltage command signal cycle, the PWM carrier signal of the boost converter and the PWM carrier signal of the inverter By adjusting the phase difference, the effective value of the sum of pulse currents flowing into the DC link capacitor from the remainder of the plurality of inverters and the boost converter is suppressed, and each
In the third invention, the PWM carrier signals of the boost converter and the inverter are both triangular waves,
The step-up converter is a two-phase step-up converter composed of first and second converter units that are connected in parallel to each other and operate with PWM carrier signals that are 180 degrees out of phase with each other at the same frequency as the PWM carrier signal of the inverter. And
When at least one of the plurality of inverters is in a driving state and the other is in a regenerative state, one of the two inverters shifts to the rectangular wave output operation. When both the inverter that has shifted to the rectangular wave output operation and the boost converter are in the drive or regenerative state and the boost ratio β ≧ 2 of the boost converter,
The phase difference between the PWM carrier signal of the first converter unit and the PWM carrier signal of the inverter is 0 degree, and the phase difference between the PWM carrier signal of the second converter part and the PWM carrier signal of the inverter is 180 degrees. In the fourth invention, the PWM carrier signals of the boost converter and the inverter are both triangular waves,
The step-up converter is a two-phase step-up converter composed of first and second converter units that are connected in parallel to each other and operate with PWM carrier signals that are 180 degrees out of phase with each other at the same frequency as the PWM carrier signal of the inverter. And
When one of the plurality of inverters is in a driving state and the other is in a regenerative state, when one of the inverters shifts to the rectangular wave output operation, the rectangular wave When both the inverter that has shifted to the output operation and the boost converter are in the drive or regenerative state and the boost ratio β <2 of the boost converter,
The phase difference between the PWM carrier signal of the first converter unit and the PWM carrier signal of the inverter is 90 degrees, and the phase difference between the PWM carrier signal of the second converter unit and the PWM carrier signal of the inverter is 270 degrees. It is what.

In the power converters according to the first and second inventions, the effective value of the pulse current flowing into the DC link capacitor is effectively suppressed when a part of the inverter shifts to the rectangular wave output operation. Miniaturization is realized.
Furthermore, in the first invention, the transition to the rectangular wave output operation in the inverter is determined under the condition of α> 1 when (voltage command signal amplitude value / carrier signal zero-peak value) is defined as the modulation factor α. Therefore, the transition to the rectangular wave output operation of the inverter can be easily and reliably determined. In the second invention, the frequency of the PWM carrier signal of the boost converter is set to twice the frequency of the PWM carrier signal of the inverter. Control for suppressing the effective value of the pulse current sum flowing into the DC link capacitor can be easily performed.

In the power converters according to the third and fourth inventions, the effective value of the pulse current flowing into the DC link capacitor is effectively suppressed when a part of the inverter shifts to the rectangular wave output operation. Capacitor miniaturization is realized.
Further, in the third invention, the PWM carrier signals of the boost converter and the inverter are both triangular waves, and the boost converters are connected in parallel to each other and are PWM carriers whose phases are 180 degrees out of phase with each other at the same frequency as the PWM carrier signal of the inverter. A two-phase boost converter composed of first and second converter units that operate with a signal, and at least one of a plurality of inverters is in a driving state and the other is in a regenerative state Sometimes when one of the two inverters shifts to a rectangular wave output operation, the inverter that has shifted to the rectangular wave output operation and the boost converter are both driven or in a regenerative state, and the boost ratio β of the boost converter When ≧ 2, the PWM carrier signal of the first converter unit and the PWM carrier of the inverter The phase difference between the PWM carrier signal of the second converter unit and the PWM carrier signal of the inverter is 180 degrees, so that the DC link capacitor can be used even when a two-phase boost converter is employed. In the fourth aspect of the invention, the PWM carrier signals of the boost converter and the inverter are both triangular waves, and the boost converters are connected in parallel to each other, and the PWM carrier signal of the inverter A two-phase boost converter composed of first and second converter units that operate with PWM carrier signals that are 180 degrees out of phase with each other at the same frequency, and one of at least two of the plurality of inverters One of the inverters is square wave when one is in the drive state and the other is in the regenerative state When the transition to the output operation is performed and both the inverter and the boost converter that have transitioned to the rectangular wave output operation are in a driving or regenerative state and the boost ratio β <2 of the boost converter, The phase difference between the PWM carrier signal and the PWM carrier signal of the inverter is 90 degrees, and the phase difference between the PWM carrier signal of the second converter section and the PWM carrier signal of the inverter is 270 degrees. Even in this case, the effective value of the sum of pulse currents flowing into the DC link capacitor is reliably suppressed.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a configuration of a power conversion device according to Embodiment 1 of the present invention. A high voltage terminal of the battery 1 which is a direct current power supply and the terminal DCbh of the boost converter 2 are connected, and a low voltage terminal and the terminal DCbl of the boost converter 2 are connected. One terminal of the DC link capacitor 3 is connected to the terminal DCp of the boost converter 2, the DC voltage terminal INV1p of the first inverter 4, and the terminal INV2p of the second inverter 5, and the other terminal is connected to the boost converter 2 Terminal DCn, a DC voltage terminal INV1n of the first inverter 4, and a terminal INV2n of the second inverter 5.
The first motor generator 6 which is a load operates as a generator or a drive motor, and the three-phase cable of the first motor generator 6 is connected to the AC terminals INV1u, INV1v and INV1w of the first inverter 4, respectively. The three-phase cable of the second motor generator 7 is connected to the AC terminals INV2u, INV2v, INV2w of the second inverter 5, respectively.
Boost converter 2, first inverter 4, and second inverter 5 are each operated by a gate signal formed by control unit 8, and respectively boost DC voltage and exchange (drive and regenerate) AC power. Do.

  FIG. 2 shows a circuit configuration of the boost converter 2. A series body of switch elements SH and SL arranged between the DC voltage terminals DCp and DCn, a capacitor Cin arranged between the battery voltage terminals DCbh and DCbl, for smoothing the input voltage, and a switch element And a choke coil L provided between the voltage node DCbh and the voltage terminal DCbh. The series of switch elements controls the connection between the voltage terminal DCp and the connection point of the switch element and the connection between the voltage terminal DCn and the connection point by a gate signal input from the control unit 8. Each switch element includes a semiconductor switch element (IGBT) and a parallel connection body of a diode.

  FIG. 3 shows the circuit configuration of the first and second inverters 4 and 5. In the figure, k represents 1 or 2, and in the case of 1, the first inverter 4 and in the case of 2, the component of the second inverter 5 is shown. A low voltage that controls the connection between each AC terminal INVku, INVkv, INVkw and the high-voltage side DC voltage terminal INVkp, and that controls the connection between the high-voltage side switching elements SuHk, SvHk, SwHk and the low-voltage side DC voltage terminal INVkn. The side switch elements SuLk, SvLk, and SwLk are included. The switch element is a parallel connection body of a semiconductor switch element (IGBT) and a diode. Each switch element is driven by a gate signal input from the control unit 8.

  Here, operations of inverters 4 and 5 and boost converter 2 will be described. FIG. 4 shows operation waveforms of the inverter using the PWM method. In the figure, based on the carrier signal waveform of the inverter, the fundamental wave signal (voltage instruction signal) waveform of each of the U phase, V phase, and W phase ((a) in the figure), the comparison calculation of the carrier signal and the fundamental wave signal. Generated in the U-phase, V-phase, and W-phase of the motor generators 6 and 7 (FIG. (C)). ), And an input current waveform to the inverters 4 and 5 ((d) in the figure). The gate signal of the DC low voltage side switch element is an inverted signal of the gate signal of the high voltage side switch element.

Then, each switch element is turned on / off based on the gate signal formed by comparing the carrier signal and the fundamental wave signal, and the AC voltage terminal is similar to the fundamental wave signal by utilizing the change in the applied voltage time. The shape is the same as the state where an alternating voltage is applied (when the alternating voltage terminal is viewed, it is a pulsed voltage, but a smooth alternating voltage is applied as an average voltage). Furthermore, by changing the amplitude and phase of the fundamental wave signal, the magnitude and direction of the current flowing through the motor generators 6 and 7 can be freely changed. As a result, the current flowing into and out of the DC voltage terminals of the inverters 4 and 5 becomes a pulsed current as shown in the figure.
The ratio of the carrier signal zero-peak value of the inverters 4 and 5 and the amplitude value of the fundamental wave signal (fundamental wave amplitude value / inverter carrier zero-peak value) is referred to as a modulation rate. Further, cos φ when the phase difference between the phase current and the fundamental wave signal is φ is called a power factor.

  FIG. 5 shows an operation waveform of the inverter by the rectangular wave method. In this method, since the connection time between the AC terminal and the DC terminal per cycle is longer than that in the PWM method described above, the average applied voltage to the motor generators 6 and 7 can be increased. There are benefits. This is an effective method when it is desired to increase the current mainly in a region where the motor induced voltage in the high speed rotation region of the motor generators 6 and 7 is large.

In the figure, U-phase, V-phase, and W-phase gate signals (gate signals of DC high-voltage side switching elements) (the figure (a)), U-phase, V-phase, and W-phase of motor generators 6 and 7 are shown. The waveform of the current flowing through the inverter 4 (FIG. 2B) and the waveform of the input current to the inverters 4 and 5 (FIG. 2C) are shown. The gate signal of the DC low voltage side switch element is an inverted signal of the gate signal of the high voltage side switch element.
As shown in the figure, a voltage based on the gate signal is applied to each AC voltage terminal, and the currents of the motor generators 6 and 7 are controlled. As a result, the current flowing into the DC voltage terminals of the inverters 4 and 5 becomes a DC current as shown in the figure.

FIG. 6 shows operation waveforms of the inverters 4 and 5 under conditions different from those in FIG. This is a case where the modulation rate is set to 2 (> 1) in the PWM method described above. In the figure, U-phase, V-phase, and W-phase fundamental wave signals and inverter carrier signal waveforms (FIG. 1A), gate signals of each phase (DC high-voltage side switching element gate signal) waveforms (FIG. 2B). )), Current waveforms flowing in the U-phase, V-phase and W-phase of the motor generators 6 and 7 (FIG. (C)), and input current waveforms to the inverters 4 and 5 (FIG. (D)) are shown. Yes.
Compared with the rectangular wave method (FIG. 5), it can be seen that the gate signal is changed from one pulse to three pulses. This rectangular wave method is effective when it is desired to reduce the average applied voltage to the motor generators 6 and 7 and suppress the current more than the rectangular wave method. Although the current flowing into the DC voltage terminals of the inverters 4 and 5 is somewhat disturbed as compared with the rectangular wave system, it is a DC current.

As described above, the waveform shown in FIG. 5 is an operation waveform in the case of one pulse of a rectangular wave, and the waveform shown in FIG. 6 is an operation waveform in the case of a PWM overmodulation rectangular wave. Further, under the condition equal to or higher than the modulation factor shown in FIG. 6, the larger the modulation factor, the closer the input / output current of the DC voltage terminals of the inverters 4 and 5 is to the shape of one pulse of the rectangular wave shown in FIG. It becomes the direct current form. In addition, even when the modulation factor is 1 or more and less than 2, the disturbance is increased, but a direct current is generated. In addition to the multi-pulse rectangular wave system on the extension line of the PWM system, there is a multi-pulse rectangular wave system that operates with a predetermined gate signal pattern.
In the specification of the present application, the operation including the rectangular wave pulse output with the period of the voltage command signal (fundamental wave signal) longer than the carrier signal period of the PWM operation is included. Therefore, the operation including the cases of FIGS. Or a square wave output operation.

FIG. 7 shows operation waveforms in the PWM system of the drive (step-up) operation and the regeneration (step-down) operation of the step-up converter 2. In the figure, carrier signal and voltage instruction signal waveforms ((a)), gate signal waveforms of each switch element ((b) (c)), current waveforms at DCp and DCn terminals ((d)). Indicates. By comparing the voltage instruction signal and the carrier signal, the gate signal of the low-voltage side switching element is formed. The gate signal of the high voltage side switch element is its inverted signal.
When the voltage instruction signal is increased, the ON time of the low-voltage side switch element is increased, and the voltage between the DC terminals DCp-DCn is increased. When the switch element is turned on and off, the energy is repeatedly accumulated and released in the choke coil L, and the energy is transferred from the battery 1 to the inverters 4 and 5 or from the inverters 4 and 5 to the battery 1. As shown in the figure, the current flowing through the DC voltage terminals DCp and DCn is pulsed.

Next, the operation of Embodiment 1 of the present invention will be described. In the present invention, the relationship between the carrier signals for driving the first and second inverters 4 and 5 and the boost converter 2 consists of three modes A, B and C as shown in FIG. Each mode is selected according to the operation states of inverters 4 and 5 and boost converter 2 shown in Table 1. In Table 1, the drive state of the inverter is a state where energy is transferred from the DC link capacitor 3 to the motor generators 6 and 7, and the regenerative state is transfer from the motor generators 6 and 7 to the DC link capacitor 3. It is in a state of being.
Further, the drive state of boost converter 2 is a state in which energy is transferred from battery 1 to DC link capacitor 3, and the regenerative state is the opposite.

The relationship between carrier signals will be described. Mode A is the same as that in the case of the one-arm boost converter described in Patent Document 2. The carrier signals of the first and second inverters 4 and 5 are the same, and the carrier signal of the boost converter 2 has a frequency that is twice that of the inverter carrier signal and is synchronized with each other so that the valley of the triangular wave coincides with the peak and valley of the inverter carrier. The relationship is established (FIG. 8A).
Further, as will be described later (FIG. 10B), the center of the zero current period (carrier valley) of the current from the boost converter 2 and the center of the zero current period (carrier peak) of the current from the inverter 5 are The phase relationship is in agreement.

In mode B, the carrier signals of the first and second inverters 4 and 5 are the same, the carrier signal of the boost converter 2 is synchronized with each other by setting the frequency to twice that of the inverter carrier signal, and the peaks of the triangular wave are (FIG. 8B).
As will be described later (FIG. 10C), the center of the pulse current output period of the current from the boost converter 2 (the peak of the carrier) and the center of the zero current period of the current from the inverter 5 (the peak of the carrier) The phase relationship is in agreement.

Mode C is a case where the high-voltage side switching element of the boost converter 2 is in an always-on operation state and a non-boosting operation is performed, and the carrier signal of the first inverter 4 and the carrier signal of the second inverter 5 are The relationship is such that the frequencies are the same and the phase difference is 90 degrees (FIG. 8C).
Further, as will be described later (FIG. 11B), the center of the zero current period of the current from the first inverter 4 (carrier valley) and the center of the pulse current output period of the current from the second inverter 5 ( The phase relationship matches the center of the carrier.

  When mode B is selected, as shown in Table 1, the boost converter 2 is driven by the PWM method, only one of the first and second inverters 4 and 5 is driven by the rectangular wave method, and the other is driven by the PWM method. In the operation state where one of the inverters is driven and the other is regenerative, and mode C is selected, the high-voltage side switching element of the boost converter 2 is always on, and the first and second inverters 4 and 5 Both are in the PWM mode when driving or regenerating. The same mode A as in the prior art is selected when the operating state is other than the above.

  Next, the effect when mode B is employed in the present invention will be described. An explanation will be given by taking as an example an operation state (1 in Table 1) in which the first inverter 4 is driven by a motor using a rectangular wave method, the second inverter 5 is regenerated by a PWM method, and the boost converter 2 is driven (boosted) by a PWM method. To do. Description will be made assuming that the direction of current flow shown in FIG. 9 is positive.

FIG. 10 shows the mode A when the first and second inverters 4 and 5 are operated by PWM and the boost converter 2 is operated by PWM (when the operation region of mode A is operated by mode A (a)). When the first inverter 4 is operated by a rectangular wave, the second inverter 5 is operated by PWM, and the boost converter 2 is operated by PWM (when the operation region of mode B is operated by mode A (b)), Operation waveforms when the first inverter 4 is operated by a rectangular wave, the second inverter 5 is operated by PWM, and the boost converter 2 is operated by PWM (when the operation region of mode B is operated by mode B (c)) are shown.
In the figure, carrier signals, fundamental wave signals, voltage instruction signals of the first and second inverters 4 and 5 and the boost converter 2, the input current to each DC link unit, and the current of the DC link capacitor are shown.

From the figure, if the first and second inverters 4 and 5 are in the PWM operation state, the pulse current of the first inverter 4, the pulse current of the second inverter 5, and the boost converter can be driven by driving with the carrier signal of mode A. The sum of the two pulse currents cancels out the phase relationship, and the effective current value of the DC link capacitor 3 becomes small ((a) in the figure), which is the same as that described in Patent Document 2.
When the first inverter 4 shifts to the rectangular wave system in this state, the relationship that the three pulse currents cancel each other does not hold as shown in FIG. Will get bigger. When the carrier signal is switched to mode B in this state, the pulse currents of the second inverter 5 and the boost converter 2 are alternately generated, and the direct current of the first inverter 4 is canceled out. The effective current value of the DC link capacitor 3 becomes small ((c) in the figure).

  From the above description, the effective current value of the DC link capacitor 3 is increased by the method disclosed in Patent Document 2 depending on the operation states of the first and second inverters 4 and 5 and the boost converter 2. By changing the carrier signal so that the center of the pulse current output period of the current from (the peak of the carrier) and the center of the zero current period of the current from the inverter 5 (the peak of the carrier) coincide with each other. It can be seen that the effective current value of the DC link capacitor 3 can be reduced.

  As described above, the effect of the present invention is that the first inverter 4 is motor-driven by the rectangular wave system, the second inverter 5 is regenerated by the PWM system, and the boost converter 2 is driven (boosted) by the PWM system (Table). 1 of 1) as an example, but the operation state (2 in Table 1) in which the operations of the first inverter 4 and the second inverter 5 are interchanged, the first inverter 4 is regenerated in a rectangular wave system, The operation state (3 in Table 1) in which the second inverter 5 is motor-driven by the PWM method, and the boost converter 2 is regenerated (step-down) by the PWM method, and the first inverter for the three operation states in Table 1 Even in the operation state (4 in Table 1) in which the operations of 4 and the second inverter 5 are interchanged, the DC current of either one is canceled by the pulse current of the other inverter and the pulse current of the boost converter. It works , It is possible to obtain the same effect as described above.

  In addition, in the power conversion device including the third, fourth,... And a plurality of arbitrary number of inverters, the relation described above relates to the operating states of at least two inverters and the boost converter. If so, the center of the pulse current output period of the current from the boost converter (carrier peak) and the center of the zero current period of the inverter (carrier peak) of the inverter and boost converter should match. By setting the carrier signal so as to have a correct phase, the effective current value of the DC link capacitor 3 can be reduced.

Next, effects when the mode C of the present invention is employed will be described. A case will be described as an example where the high-voltage side switching element of the boost converter 2 is always on and the first and second inverters 4 and 5 are in the driving operation state by the PWM method (6 in Table 1). Description will be made assuming that the direction of current flow shown in FIG. 9 is positive.
In FIG. 11, in mode A, the first and second inverters 4 and 5 are driven by the PWM method, and the boost converter 2 is in an operating state in which the high-voltage side switching element is always on (the carrier signal is not related). The operation waveforms in (a)) in the figure and when the first and second inverters 4 and 5 are driven in mode C in that state ((b) in the figure) are shown. In the figure, carrier signals and fundamental wave signals of the first and second inverters 4 and 5, input currents to the respective DC link units, and currents of the DC link capacitor 3 are shown.

  When both inverters 4 and 5 are driven in mode A under these operating conditions, the pulse current of the first inverter 4 and the pulse current of the second inverter 5 strengthen each other as shown in FIG. 3 becomes large ((a) in the figure). When the carrier signal is switched to mode C in this state, the pulse currents of the first inverter 4 and the second inverter 5 are alternately generated, and the direct current supplied from the boost converter 2 to the DC link unit is canceled. Because of this relationship, the effective current value of the DC link capacitor 3 is small ((b) in the figure).

  When the high-voltage side switching element of the boost converter 2 is always on and the first and second inverters 4 and 5 are in the drive operation state by the PWM method, the method disclosed in Patent Documents 1 and 2 uses a DC link capacitor. However, instead of this, the center of the zero current period of the current from the first inverter 4 (the peak of the carrier) and the center of the pulse current output period of the current from the second inverter 5 (of the carrier) It can be seen that the current of the DC link capacitor 3 can be reduced by setting the phase relationship so that the center) matches.

  As described above, the effects of the present invention have been described by taking the first and second inverters 4 and 5 as an example of the driving operation state. However, both the first inverter 4 and the second inverter 5 are in the regenerative operation state (see Table 1). Even in 5), since the pulse currents of the inverters 4 and 5 are alternately generated and operate so as to cancel the DC current of the boost converter 2, the same effect can be obtained.

  In addition, in the power conversion device including the third, fourth,... And a plurality of arbitrary number of inverters, the relation described above relates to the operating states of at least two inverters and the boost converter. If there is, the center of the zero current period of the current from one inverter (carrier valley) matches the center of the pulse current output period of the current from the other inverter (carrier center). With such a phase relationship, the effective current value of the DC link capacitor 3 can be reduced.

Next, in the power conversion device including the two inverters 4 and 5 and the boost converter 2, the above-described effective current value of the DC link capacitor 3 is reduced by determining the various operation states of each inverter and the boost converter. A control flow for selecting one of the control modes A, B, or C will be described with reference to FIG.
First, as shown in Table 2, the status type of each model is symbolized.

Whether the operation of the inverter is a rectangular wave method or a PWM method is determined by the modulation rate of PWM control. The former corresponds to the condition of modulation factor> 1, and the latter corresponds to the condition of modulation factor ≦ 1. And And, as shown in Table 2 (a), this modulation rate> 1 state is expressed as “1”, the modulation rate ≦ 1 state is expressed as “0”, and the modulation rates of the first and second inverters are expressed as follows: It shall be expressed by “A” and “B”, respectively.
Next, as shown in Table 2 (b), the drive and regeneration operation states of the inverter and the boost converter are expressed as “1” for drive and “0” for regeneration, and the first and second inverters and The operation state of the boost converter is expressed by “a”, “b”, and “c”, respectively.
Further, whether or not the high voltage side switching element of the boost converter is always on is determined based on whether the boost ratio α of the boost converter is 1 or less or greater than 1.

Hereinafter, the control flow will be described with reference to the steps of FIG. In step S1, a step-up ratio α is input, and in step 2, it is determined whether α> 1. In the case of NO in step S2, that is, when the boost ratio α is 1 or less and corresponds to a non-boosting operation state in which the high-voltage side switch element of the boost converter is always on, in step S3, the operating state a of both inverters , B.
Next, it is determined whether or not the addition value shown in step S4 obtained by multiplying and adding each of a and b and the inverted ones (1 → 0 or 0 → 1) is zero. In the case of NO in step S4, this corresponds to one of the inverters being driven and the other being in the regenerative operation state, and mode A is selected as usual (step S5).
If “YES” in the step S4, this corresponds to both the inverters being in a driving or regenerative operation state, corresponding to the previous FIG. 11B, and selecting the mode C (step S6).

Returning to step S2, if this determination is YES, that is, if the boost converter corresponds to a PWM pulse output operation, the modulation rate states A and B of both inverters are input in step S7.
Next, it is determined whether or not the addition value shown in step S8 obtained by multiplying and adding each of A and B and the inverted one (1 → 0 or 0 → 1) is 1 or not. If NO in step S8, this corresponds to both inverters being of the PWM system or rectangular wave system, and mode A is selected as before (step S9).
If YES in step S8, if either one of the inverters is a PWM system and the other is a rectangular wave system, the operation states a and b of both inverters are input in step S10.

Next, it is determined whether or not the addition value shown in step S11 is 1. If NO in step S11, this corresponds to both the inverters being in the drive or regenerative operation state, and mode A is selected as usual (step S12).
If YES in step S11, that is, if either one of the inverters is driven and the other is in a regenerative operation state, the modulation rate state A of the first inverter is input in step S13.
In step S14, it is determined whether A is 1. If NO, that is, if the first inverter has a modulation factor ≦ 1, and therefore the PWM method and the second inverter are a rectangular wave method, step S15. In step S16, it is determined whether or not b = c. If YES in step S16, that is, if both the rectangular-wave second inverter and the boost converter are in the drive or regenerative operation state, this corresponds to the case equivalent to FIG. 10C. Mode B is selected (step S17).

Returning to step S14, if this determination is YES, that is, if the first inverter has a modulation factor> 1, and therefore, the rectangular wave method and the second inverter are in the PWM method, the operation state c of the boost converter in step S18. In step S19, it is determined whether a = c. If YES in step S19, that is, if both the rectangular wave type first inverter and the boost converter are in the drive or regenerative operation state, this corresponds to FIG. Select (step S20).
In the case of NO in step S16 or S19, therefore, if the operation state of the rectangular wave type inverter and the boost converter are different, the mode A is selected as in the conventional case (step S21).

  By applying the control flow described above, it is possible to ensure control that always reduces the effective current value of the DC link capacitor.

Embodiment 2. FIG.
The second embodiment of the present invention differs from the first embodiment in the configuration of the boost converter. FIG. 13 shows the configuration of the boost converter. This boost converter 2 is called a two-phase boost converter. The boost converter shown in FIG. 2 has a configuration in which a second converter unit including a series body of switch elements SH2 and SL2 and a choke coil L2 connected to a connection point of the series body is added.
The other end of the choke coil L2 is connected to the voltage terminal DCbh, and the series of switch elements is similarly connected to the voltage terminals DCp and DCn.
The first converter unit and the second converter unit operate alternately in a state where the phase is shifted by 180 degrees due to the gate signal from the control unit 8. The current flowing through the voltage terminals DCp and DCn is a pulse current having a frequency twice the frequency of the gate signal pulse for driving each converter unit.

Next, the operation of the second embodiment of the present invention will be described. The relationship between the operating state and the mode is as shown in Table 1 above. In mode C, boost converter 2 has only the switch element always turned on, so the operation is the same in the second embodiment.
On the other hand, the relationship between the carrier signals in mode A and mode B is different from that in form 1. Although details are omitted, as introduced in Patent Document 2, the step-up ratio of the boost converter (ratio of the battery voltage to the voltage of the DC link unit) is used in order to avoid interference of the pulse current between the two converter units. The carrier signal relationship differs depending on whether the value is 2 or more and less than 2.
FIG. 14 shows the carrier signal relationship when the step-up ratio is 2 or more, and FIG. 15 shows the case where the step-up ratio is less than 2.

Next, the relationship between carrier signals will be described. Mode A is the same as that in the case of the two-arm boost converter described in Patent Document 2. The carrier signals of the first and second inverters 4 and 5 are the same, and the carrier signal of the boost converter 2 is synchronized with the same frequency as the inverter carrier signal.
When the step-up ratio is 2 or more (FIG. 14A), the carrier signal of the first converter has a phase difference of 90 degrees from the carrier signal of the inverter, and the carrier signal of the second converter is the carrier signal of the inverter. And a phase difference of 270 degrees.
When the step-up ratio is less than 2 (FIG. 15A), the carrier signal of the first converter has a phase difference of 0 degrees from the carrier signal of the inverter, and the carrier signal of the second converter is the carrier signal of the inverter. And a phase difference of 180 degrees.

In mode B, the carrier signals of the first and second inverters 4 and 5 are the same, and the carrier signal of the boost converter 2 is synchronized with the same frequency as the inverter carrier signal.
When the step-up ratio is 2 or more (FIG. 14B), the carrier signal of the first converter has a phase difference of 0 degrees from the carrier signal of the inverter, and the carrier signal of the second converter is the carrier signal of the inverter. And a phase difference of 180 degrees.
When the step-up ratio is less than 2 (FIG. 15B), the carrier signal of the first converter has a phase difference of 90 degrees from the carrier signal of the inverter, and the carrier signal of the second converter is the carrier signal of the inverter. And a phase difference of 270 degrees.

Next, the effect when mode B is adopted in the second embodiment of the present invention will be described. Under conditions where the step-up ratio is 2 or more, the first inverter 4 is motor-driven by the rectangular wave system, the second inverter 5 is regenerated by the PWM system, and the boost converter 2 is driven (boosted) by the PWM system (table) A description will be given taking 1) 1) as an example. As in the previous case, the current flowing direction shown in FIG. 9 will be described as positive.
In FIG. 16, when the first and second inverters 4 and 5 are operated in PWM and the boost converter 2 is operated in PWM in mode A (when the operation region of mode A is operated in mode A (a)), mode A When the first inverter 4 is operated by a rectangular wave, the second inverter 5 is operated by PWM, and the boost converter 2 is operated by PWM (when the operation region of mode B is operated by mode A (b)), Operation waveforms when the first inverter 4 is operated by a rectangular wave, the second inverter 5 is operated by PWM, and the boost converter 2 is operated by PWM (when the operation region of mode B is operated by mode B (c)) are shown.
In the figure, carrier signals, fundamental wave signals, voltage instruction signals of the first and second inverters 4 and 5 and the boost converter 2, the input current to each DC link unit, and the current of the DC link capacitor are shown.

From the figure, if the first and second inverters 4 and 5 are in the PWM operation state, the pulse current of the first inverter 4, the pulse current of the second inverter 5, and the boost are driven by driving with the carrier signal of mode A. The sum of the pulse current of the converter 2 cancels out the phase relationship, and the effective current value of the DC link capacitor 3 becomes small ((a) in the figure), which is the same as the contents described in Patent Document 2. .
When the first inverter 4 shifts to the rectangular wave system in this state, the relationship that the three pulse currents cancel each other does not hold as shown in FIG. Will get bigger. When the carrier signal is switched to mode B in this state, the pulse currents of the second inverter 5 and the boost converter 2 are alternately generated, and the direct current of the first inverter 4 is canceled out. The effective current value of the DC link capacitor 3 becomes small ((c) in the figure).

Next, a case where the boost ratio is less than 2 will be described. An explanation will be given by taking as an example an operation state (1 in Table 1) in which the first inverter 4 is driven by a motor using a rectangular wave method, the second inverter 5 is regenerated by a PWM method, and the boost converter 2 is driven (boosted) by a PWM method. To do.
In FIG. 17, when the first and second inverters 4 and 5 are operated in PWM and the boost converter 2 is operated in PWM in mode A (when the operation region of mode A is operated in mode A (a)), mode A When the first inverter 4 is operated by a rectangular wave, the second inverter 5 is operated by PWM, and the boost converter 2 is operated by PWM (when the operation region of mode B is operated by mode A (b)), Operation waveforms when the first inverter 4 is operated by a rectangular wave, the second inverter 5 is operated by PWM, and the boost converter 2 is operated by PWM (when the operation region of mode B is operated by mode B (c)) are shown.
In the figure, carrier signals, fundamental wave signals, voltage instruction signals of the first and second inverters 4 and 5 and the boost converter 2, the input current to each DC link unit, and the current of the DC link capacitor are shown.

From the figure, if the first and second inverters 4 and 5 are in the PWM operation state, the pulse current of the first inverter 4, the pulse current of the second inverter 5, and the boost are driven by driving with the carrier signal of mode A. The sum of the pulse current of the converter 2 cancels out the phase relationship, and the effective current value of the DC link capacitor 3 becomes small ((a) in the figure), which is the same as the contents described in Patent Document 2. .
When the first inverter 4 shifts to the rectangular wave system in this state, the relationship that the three pulse currents cancel each other does not hold as shown in FIG. Will get bigger. When the carrier signal is switched to mode B in this state, the pulse currents of the second inverter 5 and the boost converter 2 are alternately generated, and the direct current of the first inverter 4 is canceled out. The effective current value of the DC link capacitor 3 becomes small ((c) in the figure).

  From the above description, depending on the operating states of the first and second inverters 4 and 5 and the boost converter 2, the current disclosed value of the DC link capacitor 3 can be obtained by the method disclosed in Patent Document 2 as in the first embodiment. However, by changing the phase relationship so that the center of the pulse current output period of the current from the boost converter 2 coincides with the center of the zero current period of the current from the inverter 5, the current effective of the DC link capacitor 3 is changed. It can be seen that the value can be reduced.

  As described above, the effect of the present invention is that the first inverter 4 is motor-driven by the rectangular wave system, the second inverter 5 is regenerated by the PWM system, and the boost converter 2 is driven (boosted) by the PWM system (Table). Although 1) 1) has been described as an example, the same effect can be obtained for the other operations shown in Table 1.

  In addition, in the power conversion device including the third, fourth,... And a plurality of arbitrary number of inverters, the relation described above relates to the operating states of at least two inverters and the boost converter. If there is, the center of the zero current period of the current from one inverter (carrier valley) matches the center of the pulse current output period of the current from the other inverter (carrier center). With such a phase relationship, the effective current value of the DC link capacitor 3 can be reduced.

  Although the description of the control flow is omitted, for example, after selecting the mode B in the one shown in FIG. 12 described above, specific phase relationships will be described with reference to FIGS. What is necessary is just to set it as the control operation which switches to the content which carried out.

Embodiment 3 FIG.
In the previous embodiment, the case where both the carrier signal of the inverter and the carrier signal of the boost converter are triangular waves has been described. In the third embodiment, a case will be described in which the shape of the carrier signal of the inverter is left unchanged and the shape of the carrier signal of the boost converter is a sawtooth waveform. The configuration of the power converter is the same as that of the first embodiment.
FIG. 18 shows the shapes of both carrier signals. As in the first embodiment, the frequency of the carrier signal of the boost converter is twice the frequency of the carrier signal of the inverter. One cycle of the carrier signal of the inverter is set to 100 steps, and the phase difference between both carrier signals is expressed by the number of steps.

In the previous embodiment, since both the carrier signal of the inverter and the carrier signal of the boost converter have a triangular wave shape, the pulse between the inverter 4 and the 5-DC link capacitor 3 is obtained by matching the peaks and valleys between the triangular wave signals. The timing at which the current flows and the timing at which the pulse current between the boost converter 2 and the DC link capacitor 3 flows can be easily matched, and the current of the DC link capacitor 3 can be reduced by the above-described method.
However, when the carrier signal of the boost converter has a sawtooth waveform as in this embodiment, the timing of both pulse currents varies depending on the boost ratio (voltage command value of the boost converter). It is necessary to adjust the phase difference.

In FIG. 19, the first inverter 4 is driven by a rectangular wave method (PWM method and modulation factor is 1 or more), the second inverter 5 is regenerated by the PWM method, and the boost converter 2 is driven by the PWM method. The relationship between the phase difference between the carrier signal of the converter and the carrier signal of the inverter and the current effective value (current ripple) (relative value) of the DC link capacitor 3 is shown.
In the figure, the boost ratio of the boost converter 2 is 1.5 and 2.5, the modulation rate of the first inverter 4 is infinite (rectangular wave 1 pulse), 1.5, 1, and the modulation of the second inverter 5 The calculation results under the condition where the rate is 0.2 to 1 are shown. The power factor of the first inverter 4 is 1, and the power factor of the second inverter 5 is -1.
From the figure, except for the conditions of the boost ratio 2.5, the modulation factor 1 of the first inverter 4 and the modulation factor 0.2 to 0.3 of the second inverter 5, the optimum phase when the boost ratio is 2.5 Is 10 steps regardless of the modulation rate of the second inverter 5, and 16 steps when the step-up ratio is 1.5. When other conditions are examined, the same thing can be said, and there exists a relationship between the step-up ratio and the optimum phase difference as shown in FIG.
Therefore, in the third embodiment, the control unit 8 adjusts the phase difference between the carrier signal of the boost converter and the carrier signal of the inverter according to the condition of the boost ratio.

Needless to say, this method is applied to the operation mode of mode B described in the previous embodiment. Mode C is originally the case where the current of the boost converter becomes a direct current, and is the same as in the previous embodiment.
In the operation mode of mode A, the optimum phase of both carriers is found and operated, or the frequency of the carrier signal of the inverter and the frequency of the carrier signal of the boost converter are shifted slightly to operate asynchronously. . By operating asynchronously, the current of the DC link capacitor 3 becomes an intermediate value between the maximum value and the minimum value when the phase is synchronized and the phase is changed.

  In the above description, the one-phase boost converter has been described. However, in the two-phase boost converter described in the second embodiment, when the carrier signal has a sawtooth waveform, the conditions for the boost ratio are similarly set. The optimum phase may be determined according to the above.

  In the above description, the operation by the rectangular wave method is regarded as an extension line of the PWM method, and the modulation rate is described as an area of 1 or more (overmodulation PWM operation). However, the operation by this rectangular wave method is based on the information on the alternating current flowing from the current sensor to the motor generator and the frequency and phase information from the rotational position sensor of the motor generator in addition to the overmodulation PWM operation. This can also be realized by a method of controlling the gate of the switch element by determining the number of times the switch element is turned on / off, the length, and the output timing.

Further, in each modification of the present invention, when one of at least two of the plurality of inverters is in a driving state and the other is in a regenerative state, one of the two inverters outputs a rectangular wave. When the inverter and the boost converter that have shifted to the rectangular wave output operation are in the drive or regenerative state, the center of the period in which the pulse current of the inverter that performs the pulse output operation becomes zero, and the boost converter Since the phase difference is adjusted so as to coincide with the center of the pulse current output period, the effective value of the pulse current sum flowing into the DC link capacitor is reliably suppressed.

  In addition, when both the PWM carrier signal of the boost converter and the inverter are triangular waves, the apex that coincides with the center of the pulse current output period in the PWM carrier signal of the boost converter and the apex of the peak and valley of the PWM carrier signal of the inverter coincide. Since the phase difference is adjusted, the effective value of the pulse current sum flowing into the DC link capacitor is more reliably suppressed.

  In addition, when the PWM carrier signal of the inverter is a triangular wave and the PWM carrier signal of the boost converter is a sawtooth wave, the boost converter in which the effective value of the boost ratio of the boost converter and the sum of pulse currents flowing into the DC link capacitor is minimized in advance. Since the relational characteristic between the PWM carrier signal and the phase difference between the PWM carrier signal of the inverter is obtained and the relational characteristic is applied to obtain the phase difference based on the actual boost ratio, the sawtooth is applied to the PWM carrier signal of the boost converter. Even when a wavy signal is used, control for suppressing the effective value of the sum of pulse currents flowing into the DC link capacitor is possible.

It is a figure which shows the structure of the power converter device of this invention. It is a circuit diagram which shows the boost converter 2 which comprises the power converter device by Embodiment 1 of this invention. It is a circuit diagram which shows the inverters 4 and 5 which comprise the power converter device of this invention. It is a figure which shows the waveform at the time of the PWM system operation | movement of an inverter. It is a figure which shows the waveform at the time of the rectangular wave system operation | movement of an inverter. It is a figure which shows the waveform at the time of the rectangular wave system operation | movement of an inverter when a modulation factor is set to 2. FIG. It is a figure which shows the waveform at the time of the PWM system operation | movement of the step-up converter. It is a figure which shows the relationship of the carrier signal in Embodiment 1 of this invention. It is a figure which shows the direction of the electric current of the inverters 4 and 5 and the boost converter 2. FIG. It is a figure which shows the relationship between the carrier signal of mode A and B in Embodiment 1 of this invention, and the relationship of a DC link capacitor current. It is a figure which shows the relationship between the carrier signal of mode A and C in Embodiment 1 of this invention, and the relationship of a DC link capacitor current. It is a figure which shows the control flow in Embodiment 1 of this invention. It is a circuit diagram which shows the boost converter 2 which comprises the power converter device by Embodiment 2 of this invention. It is a figure which shows the relationship of the carrier signal in the case of boosting ratio 2 or more in Embodiment 2 of this invention. It is a figure which shows the relationship of the carrier signal in case the boost ratio is less than 2 in Embodiment 2 of this invention. It is a figure which shows the relationship between the carrier signal of mode A and B, and the relationship of a DC link capacitor current in case the step-up ratio of Embodiment 2 of this invention is 2 or more. It is a figure which shows the relationship between the carrier signal of mode A and B, and the relationship of a DC link capacitor current in case the step-up ratio of Embodiment 2 of this invention is less than 2. It is a figure which shows the shape and relationship of a carrier signal in Embodiment 3 of this invention. It is a figure which shows the relationship between the phase difference between the carrier signals in Embodiment 3 of this invention, and the current effective value (ripple) (relative value) of a DC link capacitor. It is a figure which shows the relationship between the pressure | voltage rise ratio and optimal phase difference in Embodiment 3 of this invention.

Explanation of symbols

1 battery, 2 boost converter, 3 DC link capacitor,
4 first inverter, 5 second inverter, 6 first motor generator,
7 Second motor generator, 8 control unit.

Claims (10)

A boost converter that boosts the voltage of the DC power supply by the PWM operation of the switch element, a DC link capacitor connected to the boost side terminal of the boost converter, and each load in the PWM operation of the switch element connected to the DC link capacitor A power converter that includes a plurality of inverters that exchange (drive and regenerate) AC power between them, and that operates by synchronizing the PWM carrier signal of the boost converter and the PWM carrier signal of the inverter,
When a part of the plurality of inverters shifts from a pulse output operation based on the period of the carrier signal to a rectangular wave output operation including a pulse output based on the period of the voltage command signal, the PWM carrier signal of the boost converter and the PWM of the inverter By adjusting the phase difference with the carrier signal, the effective value of the sum of pulse currents flowing into the DC link capacitor from the remainder of the plurality of inverters and the boost converter is suppressed ,
The transition to the rectangular wave output operation in the inverter is determined under the condition of α> 1 when (the voltage command signal amplitude value / the carrier signal zero-peak value) is defined as the modulation factor α. A power converter. A boost converter that boosts the voltage of the DC power supply by the PWM operation of the switch element, a DC link capacitor connected to the boost side terminal of the boost converter, and each load in the PWM operation of the switch element connected to the DC link capacitor A power converter that includes a plurality of inverters that exchange (drive and regenerate) AC power between them, and that operates by synchronizing the PWM carrier signal of the boost converter and the PWM carrier signal of the inverter,
When a part of the plurality of inverters shifts from a pulse output operation based on the period of the carrier signal to a rectangular wave output operation including a pulse output based on the period of the voltage command signal, the PWM carrier signal of the boost converter and the PWM of the inverter By adjusting the phase difference with the carrier signal, the effective value of the sum of pulse currents flowing into the DC link capacitor from the remainder of the plurality of inverters and the boost converter is suppressed,
The power conversion device according to claim 1, wherein the frequency of the PWM carrier signal of the boost converter is twice the frequency of the PWM carrier signal of the inverter . 2. The power conversion apparatus according to claim 1 , wherein the frequency of the PWM carrier signal of the boost converter is twice the frequency of the PWM carrier signal of the inverter. When at least one of the plurality of inverters is in a driving state and the other is in a regenerative state, one of the two inverters shifts to the rectangular wave output operation. When both the inverter that has shifted to the rectangular wave output operation and the boost converter are in the driving or regenerative state,
Claims, characterized in that the pulsed current of the inverter for performing the pulse output operation and the center of the period during which the zero and to adjust the phase difference as the center of the pulse current output period of the boost converter are identical Item 4. The power conversion device according to Item 2 or 3 . When the PWM carrier signals of the boost converter and the inverter are both triangular waves, the vertex that coincides with the center of the pulse current output period in the PWM carrier signal of the boost converter and the peak and valley of the PWM carrier signal of the inverter coincide with each other. The power converter according to claim 4, wherein the phase difference is adjusted. When the PWM carrier signal of the inverter is a triangular wave and the PWM carrier signal of the boost converter is a sawtooth wave, the boost value of the boost converter and the effective value of the pulse current sum flowing into the DC link capacitor are minimized in advance. The relationship characteristic between the phase difference between the PWM carrier signal of the boost converter and the PWM carrier signal of the inverter is obtained, and the phase difference is obtained based on the actual step-up ratio by applying the relationship characteristic. The power converter according to claim 2 or 3 . A boost converter that boosts the voltage of the DC power supply by the PWM operation of the switch element, a DC link capacitor connected to the boost side terminal of the boost converter, and each load in the PWM operation of the switch element connected to the DC link capacitor A power converter that includes a plurality of inverters that exchange (drive and regenerate) AC power between them, and that operates by synchronizing the PWM carrier signal of the boost converter and the PWM carrier signal of the inverter,
When a part of the plurality of inverters shifts from a pulse output operation based on the period of the carrier signal to a rectangular wave output operation including a pulse output based on the period of the voltage command signal, the PWM carrier signal of the boost converter and the PWM of the inverter By adjusting the phase difference with the carrier signal, the effective value of the sum of pulse currents flowing into the DC link capacitor from the remainder of the plurality of inverters and the boost converter is suppressed,
Both the PWM converter signal of the boost converter and the inverter are triangular waves,
The step-up converter is a two-phase step-up converter composed of first and second converter units that are connected in parallel to each other and operate with PWM carrier signals that are 180 degrees out of phase with each other at the same frequency as the PWM carrier signal of the inverter. And
When at least one of the plurality of inverters is in a driving state and the other is in a regenerative state, one of the two inverters shifts to the rectangular wave output operation. When both the inverter that has shifted to the rectangular wave output operation and the boost converter are in the drive or regenerative state and the boost ratio β ≧ 2 of the boost converter,
The phase difference between the PWM carrier signal of the first converter unit and the PWM carrier signal of the inverter is 0 degree, and the phase difference between the PWM carrier signal of the second converter part and the PWM carrier signal of the inverter is 180 degrees. it characterized in that the the power converter. Both the PWM converter signal of the boost converter and the inverter are triangular waves,
The step-up converter is a two-phase step-up converter composed of first and second converter units that are connected in parallel to each other and operate with PWM carrier signals that are 180 degrees out of phase with each other at the same frequency as the PWM carrier signal of the inverter. And
When at least one of the plurality of inverters is in a driving state and the other is in a regenerative state, one of the two inverters shifts to the rectangular wave output operation. When both the inverter that has shifted to the rectangular wave output operation and the boost converter are in the drive or regenerative state and the boost ratio β ≧ 2 of the boost converter,
The phase difference between the PWM carrier signal of the first converter unit and the PWM carrier signal of the inverter is 0 degree, and the phase difference between the PWM carrier signal of the second converter part and the PWM carrier signal of the inverter is 180 degrees. The power conversion device according to claim 1, wherein: A boost converter that boosts the voltage of the DC power supply by the PWM operation of the switch element, a DC link capacitor connected to the boost side terminal of the boost converter, and each load in the PWM operation of the switch element connected to the DC link capacitor A power converter that includes a plurality of inverters that exchange (drive and regenerate) AC power between them, and that operates by synchronizing the PWM carrier signal of the boost converter and the PWM carrier signal of the inverter,
When a part of the plurality of inverters shifts from a pulse output operation based on the period of the carrier signal to a rectangular wave output operation including a pulse output based on the period of the voltage command signal, the PWM carrier signal of the boost converter and the PWM of the inverter By adjusting the phase difference with the carrier signal, the effective value of the sum of pulse currents flowing into the DC link capacitor from the remainder of the plurality of inverters and the boost converter is suppressed,
Both the PWM converter signal of the boost converter and the inverter are triangular waves,
The step-up converter is a two-phase step-up converter composed of first and second converter units that are connected in parallel to each other and operate with PWM carrier signals that are 180 degrees out of phase with each other at the same frequency as the PWM carrier signal of the inverter. And
When one of the plurality of inverters is in a driving state and the other is in a regenerative state, when one of the inverters shifts to the rectangular wave output operation, the rectangular wave When both the inverter that has shifted to the output operation and the boost converter are in the drive or regenerative state and the boost ratio β <2 of the boost converter,
The phase difference between the PWM carrier signal of the first converter unit and the PWM carrier signal of the inverter is 90 degrees, and the phase difference between the PWM carrier signal of the second converter unit and the PWM carrier signal of the inverter is 270 degrees. A power conversion device characterized by that . Both the PWM converter signal of the boost converter and the inverter are triangular waves,
The step-up converter is a two-phase step-up converter composed of first and second converter units that are connected in parallel to each other and operate with PWM carrier signals that are 180 degrees out of phase with each other at the same frequency as the PWM carrier signal of the inverter. And
When one of the plurality of inverters is in a driving state and the other is in a regenerative state, when one of the inverters shifts to the rectangular wave output operation, the rectangular wave When both the inverter that has shifted to the output operation and the boost converter are in the drive or regenerative state and the boost ratio β <2 of the boost converter,
The phase difference between the PWM carrier signal of the first converter unit and the PWM carrier signal of the inverter is 90 degrees, and the phase difference between the PWM carrier signal of the second converter unit and the PWM carrier signal of the inverter is 270 degrees. The power conversion device according to claim 1, wherein:

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