JP2003111203A - Drive gear for automotive dynamo-electric machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drive gear for an automotive dynamo-electric machine that can suppress voltage fluctuations of the power source caused by the operating condition of the power-fed automotive dynamo-electric machine being switched. SOLUTION: The duty ratio of the switching elements Q1, Q2 on the DC-DC converter is feedback controlled in order to make the voltage 200 of the high voltage power source system 200 converge within a prescribed target range. If switching occurs between power operation and regenerative operation in controlling the switching elements Q1, Q2, the sharp change of the circuit condition during switching may cause a sharp change in the voltage and current on the low voltage power source system 100, adversely affecting the battery 1 and other low voltage components of the low voltage power source system 100. Therefore, the power transmission direction of the DC-DC converter 2 is switched before and after switching, as well as the maximum duty ratio of the switching elements Q1, Q2 so that the voltage and the current of the low voltage power source system 100 stay within the tolerance of the battery 1 of the low voltage power source system 100.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle rotary electric machine drive device, and more particularly to a vehicle rotary electric machine drive device having a bidirectional DC-DC converter.

[0002]

2. Description of the Related Art In addition to a vehicle rotary electric machine that only generates and regenerates running power and a torque assist operation and a regenerative braking operation as those operations, an engine start operation and a power generation operation for vehicle electric load power supply are performed. A rotating electric machine for a vehicle is known. A brushless synchronous machine that is AC-driven by an inverter circuit is usually adopted as the vehicular rotary electric machine capable of appropriately switching between the electric operation and the power generation operation.

It is desirable that these rotary electric machines for vehicles have a high voltage specification as much as possible in order to reduce the size and improve the efficiency of the rotary electric machine and the inverter circuit that drives the rotary electric machine, but the on-vehicle battery has a predetermined low voltage. Since there is no choice but to use a rated one, it is necessary to interpose a DC-DC converter capable of bidirectional power transfer between the vehicle-mounted battery and the inverter circuit.

[0004]

However, in the vehicle rotary electric machine drive device having the above-described bidirectional DC-DC converter for supplying power to the vehicle rotary electric machine, when the vehicle rotary electric machine is switched between the electric operation and the power generation operation. Due to the sudden change in the circuit state, the voltage of the low-voltage power supply system or the high-voltage power supply system overshoots and becomes excessive, which may adversely affect the battery and electrical equipment connected thereto.

The present invention has been made in view of the above problems, and it is an object of the present invention to provide a vehicular rotary electric machine drive device capable of suppressing voltage fluctuations in a power supply system due to switching of operating states of a vehicular rotary electric machine to which power is supplied. Has an aim.

[0006]

According to a first aspect of the present invention, there is provided a vehicle rotary electric machine drive device for a vehicle, wherein bidirectional electric power is transmitted and received through a high voltage vehicle rotary electric machine which is in charge of at least part of generation and regeneration of traveling power and an inverter device. A high-voltage power supply system, a low-voltage power supply system having a low-voltage battery for generating a lower voltage than the high-voltage power supply system, and a low-voltage power supply system disposed between the both power supply systems DC-DC for controlling power transfer
In a vehicular rotary electric machine drive device including a converter and a control unit that performs PWM control of a switching element incorporated in the DC-DC converter, the control unit converges the voltage of the high-voltage power supply system within a predetermined target range. While performing feedback control of the duty ratio of the switching element so as to make the switching operation between the power running operation and the regenerative operation of the vehicle rotary electric machine, or in accordance with the voltage change of the high-voltage power supply system accompanying the switching. The maximum duty ratio of the switching element is switched in the voltage fluctuation suppressing direction of the low voltage power supply system.

That is, according to this configuration, the duty ratio of the switching element of the DC-DC converter is feedback-controlled so that the voltage of the high-voltage power supply system converges within a predetermined target range. In this case, when the control of the switching element is switched between the power running operation and the regenerative operation, the voltage and current of the low-voltage power supply system suddenly change due to a sudden change in the circuit state at the time of switching, which adversely affects the battery of the low-voltage power supply system.

Therefore, in this configuration, before and after the switching, at the same time when the power transmission direction of the DC-DC converter is switched, the switching element is arranged so that the voltage and the current of the low voltage power system fall within the allowable range of the battery of the low voltage power system. The maximum duty ratio value is also switched at the same time. This gives D
Since the overshoot voltage superimposed on the power supply line of the low-voltage power supply system can be suppressed when the operating state (power transmission direction) of the C-DC converter is switched, the operation of the vehicular rotating electric machine can be suppressed while suppressing adverse effects on the battery. Mode switching can be performed.

According to a second aspect of the present invention, in the vehicular rotary electric machine driving apparatus according to the first aspect, the DC-DC converters are connected in series to each other and connected to both ends of the high-voltage power supply system on the high side. Of the switching element and the switching element on the low side, and a reactor connecting the connection point of both the switching elements and the high end of the low-voltage power supply system, the control unit, from the high-voltage power supply system During power transmission to the low-voltage power supply system, that is, during the regenerative operation, the high-side switching element is PWM-controlled within the range of the first maximum duty ratio to transmit power from the low-voltage power supply system to the high-voltage power supply system. At the time of the power running operation, the low-side switching element is PWM-controlled within the range of the second maximum duty ratio.

That is, according to this structure, the effect described in claim 1 can be realized with a simple structure.

According to a third aspect of the present invention, in the vehicular rotary electric machine driving apparatus according to the first aspect, the control unit changes the maximum duty ratio based on a detection signal related to the temperature or the current of the battery. It is characterized by doing.

According to this structure, the maximum voltage during charging of the battery is adjusted in accordance with the allowable voltage (maximum voltage during charging and minimum voltage during discharging) of the battery of the low-voltage power supply system varying according to the temperature and current. Since the duty ratio and the maximum duty ratio at the time of discharging the battery are changed, it is possible to avoid the adverse effect on the battery due to the switching even if the temperature or the current of the battery changes.

According to another aspect of the present invention, there is provided a rotary electric machine drive device for a vehicle, which has a high-voltage battery and is bidirectional through an inverter device and a high-voltage rotary electric machine for a vehicle which is in charge of at least a part of generation and regeneration of traveling power. A high-voltage power supply system that transfers power, a low-voltage power supply system that has a low-voltage battery and generates a lower voltage than the high-voltage power supply system, and a power supply system that is arranged between the two power supply systems. In a vehicular rotary electric machine drive device including a DC-DC converter for controlling bidirectional power transfer and a control unit for PWM control of a switching element built in the DC-DC converter, the control unit is for the vehicle. In response to a sudden change in the operating state of the rotating electric machine, or in response to a sudden change in the high-voltage power supply system accompanying the sudden change,
It is characterized in that its own power transmission state is controlled so as to suppress voltage fluctuations of the high-voltage power supply system within an allowable current range of the low-voltage battery.

That is, according to this configuration, in the dual power supply system in which the high-voltage power supply system and the low-voltage power supply system each have a battery, the battery of the low-voltage power supply system is used to suppress the voltage fluctuation of the battery of the high-voltage power supply system. DC-D within the allowable range of
Since the C converter is driven and controlled, it is possible to reduce the voltage fluctuation of the high voltage power supply system.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION A preferred embodiment of a vehicle rotary electric machine drive system according to the present invention will be described with reference to FIG.

(Overall Structure) 1 is a battery (low voltage battery) of the low voltage power supply system 100, 2 is a bidirectional DC-DC converter (DC-DC converter), 3 is a three-phase inverter circuit, and 4 is a DC-DC converter. A controller for control (control unit), 5 is a synchronous machine forming a vehicle running motor, 6, 7
Is a smoothing capacitor.

The DC-DC converter 2 is a reactor L.
And an IGB having flywheel diodes D respectively
It comprises a high-side switching element Q1 and a low-side switching element Q2. The reactor L connects the connection point of both switching elements Q1 and Q2 and the high potential end of the low voltage battery 1, and the other end of the high side switching element Q1 is connected to the high potential power supply line VH of the high voltage power supply system 200. The other end of the switching element Q2 on the low side is grounded. VL is a high-potential power supply line of the low-voltage power supply system 100, which connects the reactor L and the high-potential end of the low-voltage battery 1.

The inverter circuit 3 includes six IGBTs and six IGBTs.
This is a well-known three-phase inverter circuit in which one pair of flywheel diodes are connected in anti-parallel, and the DC high voltage of the high-voltage power supply system 200 is converted into a three-phase AC voltage, and the electric machine of the three-phase synchronous machine 5 is converted. It is applied to the child coil. The inverter circuit 3 is controlled by an inverter control controller (not shown) and applies a three-phase AC voltage of a predetermined phase to the armature winding of the synchronous machine 5 according to the rotor position of the synchronous machine 5. In addition,
The predetermined phase of the three-phase AC voltage differs between the power generation operation and the electric operation. That is, the inverter control controller changes the predetermined phase of the three-phase AC voltage with reference to the rotor position of the synchronous machine 5 in response to a vehicle request, thereby performing the power generation operation and the electric operation of the synchronous machine 5. Switch. Since these controls are already well known, further detailed description will be omitted.

The controller 4 uses the high potential power line VH.
It has a function of performing feedback control so that the voltage becomes a predetermined target value, and limiting the duty ratio to less than a predetermined maximum duty ratio when switching the operation mode of the bidirectional DC-DC converter 2.

(Basic Operation) Since the operation differs between the electric operation (power running operation) and the power generation operation (regeneration operation) of the vehicle rotary electric machine 5, both operations will be described in order.

First, DC in electric operation (powering operation)
The basics of DC converter control will be described below.

Low-voltage battery 1 for electric operation (powering operation)
Needs to supply the necessary power to the inverter circuit.

Therefore, the controller 4 PWM-switches the low-side switching element Q2 within the range of the first duty ratio. That is, when the switching element Q2 is turned on, the low voltage battery 1 causes the reactor L,
A current flows through the switching element Q2, electromagnetic energy is accumulated in the reactor L, and the switching element Q2
When the current is cut off, the reactor L tries to maintain the current state and causes a current to flow to the high potential power supply line VH through the flywheel diode D connected in antiparallel with the switching element Q1 on the high side. Hereinafter, the low voltage battery 1 continuously supplies DC power to the inverter circuit 3 by repeating this.

Further, the controller 4 reduces the duty ratio of the switching element Q2 by increasing the voltage of the high potential power source line VH, and increases the duty ratio of the switching element Q2 by decreasing the voltage of the high potential power source line VH. It is carried out.

As a result, when the voltage of the high-potential power supply line VH increases, the duty ratio of the switching element Q2 decreases and the electromagnetic energy stored in the reactor L decreases to D.
When the output voltage of the C-DC converter 2 decreases and conversely the voltage of the high potential power supply line VH decreases, the electromagnetic energy stored in the reactor L increases due to the increase of the duty ratio of the switching element Q2, and the output of the DC-DC converter 2 increases. The voltage increases and the voltage of the high potential power supply line VH is maintained within a predetermined range.

Therefore, an increase in the duty ratio of the switching element Q2 causes an increase in the discharge current of the low voltage battery 1. Therefore, the duty ratio of the switching element Q2 is limited to less than the predetermined maximum duty ratio so that the discharge current of the low voltage battery 1 becomes less than the maximum allowable discharge current value.
Note that the switching element Q1 may be intermittently (complementarily) intermittently in a pattern opposite to that of the switching element Q2.

Next, DC in power generation operation (regeneration operation)
The basics of controlling the DC converter will be described below.

During the power generation operation (regeneration operation), the low voltage battery 1 needs to absorb the required power from the inverter circuit.

Therefore, the controller 4 PWM-switches the high-side switching element Q1 within the range of the second duty ratio. That is, when the switching element Q1 is turned on, a current flows from the high potential power supply line VH to the low voltage battery 1 through the reactor L, electromagnetic energy is accumulated in the reactor L, and the switching element Q1
When the reactor L is shut off, the reactor L tries to maintain the current state and the low voltage battery 1 is connected through the flywheel diode D connected in anti-parallel with the low side switching element Q2.
Apply current to. Hereinafter, the low voltage battery 1 is continuously supplied with DC power from the inverter circuit 3 by repeating this process.

The controller 4 also increases the voltage of the high-potential power supply line VH to increase the duty ratio of the switching element Q1 and decreases the voltage of the high-potential power supply line VH to reduce the duty ratio of the switching element Q2. It is carried out.

As a result, when the voltage of the high-potential power supply line VH increases, the electromagnetic energy stored in the reactor L and the battery charging current increase due to the increase of the duty ratio of the switching element Q1, and the voltage of the high-potential power supply line VH decreases. When the voltage of the high-potential power supply line VH decreases, the duty ratio of the switching element Q1 decreases, so that the stored electromagnetic energy of the reactor L and the battery charging current decrease and the voltage of the high-potential power supply line VH increases. Is maintained within a predetermined range.

Therefore, an increase in the duty ratio of the switching element Q1 causes an increase in the charging current of the low voltage battery 1. Therefore, the duty ratio of the switching element Q1 is limited to less than a predetermined maximum duty ratio so that the charging current of the low voltage battery 1 becomes less than the maximum allowable charging current value.
The switching element Q2 may be intermittently (complementarily) intermittently in a pattern opposite to the intermittent pattern of the switching element Q1.

Explaining further, the voltage of the high-potential power supply line VL of the low-voltage power supply system 100 changes between charging and discharging. This is because the applied voltage at the time of charging the low-voltage battery 1 cannot be charged unless it is set higher than the open-circuit voltage, but the terminal voltage at the time of discharging the low-voltage battery 1 is lower than the open-circuit voltage due to the voltage drop due to its internal resistance. This is because it must be lowered. The voltage change of the high potential power supply line VL of the low voltage power supply system 100 during the electric operation (power running operation) and the power generation operation (regeneration operation) may be forced, but the high potential power supply line VH may be changed. It can be implemented naturally only by giving feedback control to make it constant.

That is, if the low-voltage battery 1 is not charged properly during the regenerative operation, the voltage of the high-potential power supply line VH rapidly increases, and accordingly, the duty ratio of the switching element Q1 rapidly increases to a low level. The voltage of the high-potential power supply line VL of the voltage power supply system 100 rises, and the battery 1 can be charged smoothly. On the contrary, if charging of the low voltage battery 1 is not successful in the power running operation, the voltage of the high-potential power supply line VH rapidly decreases, and accordingly, the duty ratio of the switching element Q2 rapidly increases, and the low voltage power supply is increased. The voltage of the high-potential power supply line VL of the system 100 decreases, and the battery 1 can be discharged smoothly.

In addition, the duty ratio of the switching element Q2 is forcibly set to a predetermined value for a predetermined short time when switching from the regenerative operation to the electric operation without relying on the above feedback control, whereby the low-voltage battery 1 quickly becomes high. Power is supplied to the potential power supply line VH to prevent the voltage drop on the high potential power supply line VH, and conversely, when switching from the electric operation to the regenerative operation, the switching element Q
It is also possible to forcibly set the duty ratio of 1 to a predetermined value for a predetermined short time, thereby quickly supplying power from the high-potential power supply line VH to the low-voltage battery 1 and preventing an increase in the voltage of the high-potential power supply line VH. . Of course, in this case, it is necessary to return to the normal feedback control after the lapse of the predetermined short time.

(Description of Controller 4) Next, the controller 4 for controlling the above DC-DC converter will be described in more detail with reference to FIG.

Reference numeral 40 is a microcomputer for analog threshold voltage, 41 to 45 are comparators, 46 and 47 are AND circuits, and 48 is a switching circuit.

The microcomputer 40 is a microcomputer for setting the maximum duty ratio of the switching element Q2 during the power running operation and the maximum duty ratio of the switching element Q1 during the regenerative operation. An analog signal voltage proportional to the temperature and current of the low voltage battery 1 is input to the microcomputer 40 from a sensor (not shown), and these analog signal voltages are converted into digital signals by an A / D converter built in the microcomputer 40.

The microcomputer 40 corrects the maximum duty ratio of the switching element Q2 during the power running operation and the maximum duty ratio of the switching element Q1 during the regenerative operation according to the input temperature and current of the low voltage battery 1. More specifically, the microcomputer 40 holds a map showing the relationship between the temperature and current of the low voltage battery 1 and the maximum duty ratio correction amount, and the maximum duty ratio of the maximum duty ratio is calculated from the map according to the input temperature and current. Calculate the correction amount. To explain further,
If the temperature of the low-voltage battery 1 is high, the correction amount is changed to decrease the maximum duty ratio, and if the current of the low-voltage battery 1 is large, the correction amount is changed to decrease the maximum duty ratio. Accordingly, when the temperature of the low voltage battery 1 is high or the current is large, the maximum duty ratio is reduced to reduce the maximum current of the low voltage battery 1, and the additional heat generation or the increase of the additional current causes the specifications of the low voltage battery 1. It is possible to prevent the deterioration of conditions.

The maximum duty ratio of the switching element Q2 during the powering operation and the maximum duty ratio of the switching element Q1 during the regenerative operation, which are obtained by the microcomputer 40, are D / A converted in the microcomputer 40 and the comparators 43 and 45 are used.
Are individually output to. Note that Vref1 is an analog threshold voltage corresponding to the maximum duty ratio of the switching element Q2 during the powering operation, and Vref2 is an analog threshold voltage corresponding to the maximum duty ratio of the switching element Q1 during the regenerative operation.

The comparator 41 is a circuit for discriminating between the power running operation and the regenerative operation. It is omitted to receive a signal for distinguishing the power running operation and the regenerative operation from the controller for controlling the inverter circuit 3 described above. Good.

To further explain, the voltage of the high-potential power supply line VH of the high-voltage power supply system 200 is considerably different between the power running operation and the regenerative operation, which is low during the power running operation and high during the regenerative operation. , Outputs high level during regenerative operation, and outputs low level during powering operation.

The comparator 41 includes the signal switching circuit 4
8 is controlled to output the output signal of the AND circuit 46 to the switching element Q2 during the powering operation, and cut off the output signal transmission from the AND circuit 47 to the switching element Q1. On the contrary, the comparator 41 includes the signal switching circuit 4
8 is controlled to output the output signal of the AND circuit 47 to the switching element Q1 during the regenerative operation, and cut off the output signal transmission from the AND circuit 46 to the switching element Q2.

During the powering operation, the comparator 42 has the voltage VH of the high-potential power supply line VH (the same sign is used here).
Is compared with the triangular wave voltage, and the comparison result is calculated by the AND circuit 46.
To enter. Note that the pulse width (that is, the PWM duty ratio) of the pulse voltage (high level period) output by the comparator 42 decreases as the voltage VH of the high potential power supply line VH increases. As a result, when the voltage VH of the high potential power supply line VH increases, the ON time of the switching element Q2 decreases and the voltage VH of the high potential power supply line VH decreases.

Since the AND circuit 46 permits the high level output of the comparator 42 only during the period when the comparator 43 outputs the high level, the maximum duty ratio of the switching element Q2 during the power running operation is the above analog for power running operation. It can be seen that it is defined by the threshold voltage Vref1.

During the regenerative operation, the comparator 45 causes the voltage VH of the high potential power supply line VH (the same sign is used here).
And the triangular wave voltage are compared, and the comparison result is AND circuit 47.
To enter. Note that the pulse width (that is, the PWM duty ratio) of the pulse voltage (high level period) output from the comparator 45 increases as the voltage VH of the high potential power supply line VH increases. As a result, when the voltage VH of the high-potential power supply line VH increases, the ON time of the switching element Q1 increases and a large current flows into the low-voltage power supply system 100, and the voltage VH of the high-potential power supply line VH can be lowered.

Since the AND circuit 46 permits the high level output of the comparator 45 only during the period when the comparator 44 outputs the high level, the maximum duty ratio of the switching element Q1 during the regenerative operation is the analog for regenerative operation described above. It can be seen that it is defined by the threshold voltage Vref2.

(Effects of Embodiment) As described above, in this embodiment, different maximum duty ratios are set for the power running operation and the regenerative operation, and the PWM operation and the regenerative operation of the switching element Q2 during the power running operation are performed. Since the PWM operation of the switching element Q1 at this time is limited to the range of each maximum duty ratio, even if the power running operation is switched to the regenerative operation, it is possible to prevent an excessive charging current from flowing into the low voltage battery 1. it can. Further, thereby, the surge voltage is not applied to other components (for example, a DC-DC converter for charging the auxiliary battery) connected to the low-voltage power supply line even when the power running / regeneration is switched.

(Modification) In the above embodiment, the switching element Q2 is PWM-controlled during the power running operation and the switching element Q1 is PWM-controlled during the regenerative operation. However, the remaining switching elements are reverse-operated (complementary) to the PWM-controlled switching elements. It is also possible to reduce the loss of the diode by performing the operation.

(Modification) Although the reactor chopper type bidirectional DC-DC converter is used in the above embodiment, a bidirectional DC-DC converter using a pair of single-phase bridge type inverter circuits and a transformer is adopted. You can also

In this case, the maximum duty ratio of the first single-phase bridge type inverter circuit is limited to the first predetermined value or less during the power running operation, and the maximum duty ratio of the remaining single phase bridge type inverter circuit remains during the regenerative operation. The duty ratio may be limited to the second predetermined value or less.

(Modification) In the above embodiment, the high potential power supply line V before and after the switching between the power running operation and the regenerative operation is performed.
Although the voltage VH of H was feedback-controlled to the predetermined target value, the switching element Q1 is forcibly executed at a predetermined duty ratio suitable for the regenerative operation from the moment when the power running operation is switched to the regenerative operation or immediately before that. May be.

(Modification) In the above embodiment, the traveling motor is assumed as the rotary electric machine 5 for a vehicle. However, electric power is supplied to the electric load for the vehicle and a generator motor for generating engine starting power is used for torque assist or regenerative braking. It can also be applied when used.

[0054]

Second Embodiment Another embodiment will be described below with reference to FIG.

In this embodiment, a high voltage battery 8 is provided between the high potential power supply line VH and the ground line of the circuit diagram of FIG. 1 to provide a dual power supply type power supply device for a vehicle.

In this case, the bidirectional DC-DC converter 2 exchanges electric power between the high-voltage battery 8 and the low-voltage battery 1, more specifically, maintains the voltage of the low-voltage battery 1 at a predetermined value. The bidirectional DC-DC converter is operated as described above. At this time, if the voltage of the high-potential power supply line VH shown in FIG. 2 deviates from the predetermined range, the voltage of the high-potential power supply line VH converges to the predetermined range. So that the switching elements Q1, Q2 of the bidirectional DC-DC converter 2
Can be operated.

By doing so, it is possible to obtain an effect that the low voltage battery 1 can partially bear the charge and discharge load of the high voltage battery 8 within the allowable range of the low voltage battery 1.

Since the specific control operation of the bidirectional DC-DC converter itself is the same as that of the first embodiment shown in FIG. 2, detailed description thereof will be omitted.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a vehicular rotary electric machine drive device of the present invention.

FIG. 2 is a circuit diagram showing an example of the controller of FIG.

FIG. 3 is a circuit diagram showing another embodiment of the vehicle rotary electric machine driving device of the invention.

[Explanation of symbols]

1 is a low-voltage battery (battery), 2 is a DC-DC converter, 3 is an inverter circuit, 4 is a controller (control unit), 5 is a synchronous machine (rotary electric machine for vehicle), Q1 is a high-side switching element, and Q2 is Low side switching element, D is flywheel diode.

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 5H115 PG04 PI16 PU02 PV03 QN06                       RB22 SE03 SE06 TI06 TI09                       TR19 TU01 TU11                 5H590 AA01 AA24 AB02 AB03 AB20                       CC01 CC24 CD01 CD03 CD10                       CE05 DD32 EA10 EB00 FA08                       FB02 FC12 FC17 FC22 GA04                       HA04 HA18 JA03 JB04 JB13                 5H730 AA01 AS01 AS13 AS17 BB06                       BB57 BB82 CC25 DD02 EE07                       EE59 FD41 FD61 FF02 FG05                       FG11 FG12 FG23 XX02 XX03                       XX15 XX19 XX22 XX23 XX35                       XX38 XX41

Claims (4)

[Claims] 1. A high-voltage power supply system for bidirectional power supply / reception through a high-voltage vehicular rotating electrical machine, which is in charge of at least a part of generation and regeneration of traveling power, and an inverter device, and a low-voltage battery. A low-voltage power supply system that generates a lower voltage than the voltage power supply system; a DC-DC converter that is arranged between the both power supply systems and controls bidirectional power transfer between the both power supply systems; and the DC-DC converter. In a vehicular rotary electric machine drive device, comprising: a control unit for PWM-controlling a switching element built in the control unit, the control unit controls the switching element so that the voltage of the high-voltage power supply system converges to a predetermined target range. The duty ratio is feedback-controlled, and the high-voltage power supply is operated in response to the switching between the power running operation and the regenerative operation of the vehicle rotary electric machine, or in association with the switching. In response to a voltage change, the maximum duty ratio bidirectional DC-DC converter for a vehicle, characterized in that the switching to the voltage change suppression direction of the low-voltage power supply system of the switching element. 2. The vehicular rotary electric machine drive device according to claim 1, wherein the DC-DC converters are connected in series with each other and are connected to both ends of the high-voltage power supply system on the high-side switching element and the low-side. The switching element on the side, and a reactor that connects the connection point of both the switching elements and the high-level end of the low-voltage power supply system, the control unit, from the high-voltage power supply system to the low-voltage power supply system During power transmission, that is, during the regenerative operation, the high-side switching element is PWM-controlled within the range of the first maximum duty ratio, during power transmission from the low-voltage power supply system to the high-voltage power supply system, that is, during the power running operation. A rotary electric machine drive device for a vehicle, wherein the switching element on the low side is PWM-controlled within a range of a second maximum duty ratio. 3. The vehicular rotary electric machine driving device according to claim 1, wherein the control unit changes the maximum duty ratio based on a detection signal related to a temperature or a current of the battery. Rotating electric machine drive device for vehicle. 4. A high-voltage power supply system having a high-voltage battery for bidirectional power supply / reception through an inverter device and a high-voltage rotating electric machine for a vehicle, which is in charge of at least part of generation and regeneration of traveling power, and a low voltage. A low-voltage power supply system that has a battery for generating a lower voltage than the high-voltage power supply system, and a DC-DC that is disposed between the both power supply systems and controls bidirectional power transfer between the both power supply systems. In a vehicle rotary electric machine drive device comprising: a converter; and a control section for performing PWM control of a switching element incorporated in the DC-DC converter, the control section is configured to respond to a sudden change in an operating state of the vehicle rotary electric machine. Or, in response to a sudden change in the high-voltage power supply system due to the sudden change, it controls its own power transmission state so as to suppress voltage fluctuations in the high-voltage power supply system within the allowable current range of the low-voltage battery. Automotive rotary electrical drive device, characterized in that.