JP2016092946A - Electric power conversion system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric power conversion system capable of reducing loss.SOLUTION: A first inverter 20 of an electric power conversion system has first switching elements 21-26, and is connected to one-end sides 111, 121, and 131 of coils 11, 12, and 13 and a first power source 41. A second inverter 30 has second switching elements 31-36, and is connected to the other-end sides 112, 122, and 132 of the coils 11, 12, and 13 and a second power source 42. A control part 60 controls ON/OFF operations of the switching elements 21-26 and 31-36. The first switching elements 21-26 have small ON resistance in a small-current region than the second switching elements 31-36. Loss can be reduced by controlling the first inverters 20 and second inverter 30 according to a driving region of a motor generator 10.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power conversion device.

  Conventionally, the structure provided with two inverters with respect to one electric motor is known. For example, in Patent Document 1, all control switches of two inverters are the same type of element.

Japanese Patent No. 4933632

When all the switching elements of the two inverters are, for example, insulated gate bipolar transistors (hereinafter referred to as “IGBT”) as in Patent Document 1, they are referred to as metal oxide semiconductor field effect transistors (hereinafter referred to as “MOSFETs”). ), The loss in the small current region is large.
This invention is made | formed in view of the above-mentioned subject, The objective is to provide the power converter device which can reduce a loss.

The present invention is a power conversion device that converts electric power of a rotating electrical machine having a winding, and includes a first inverter, a second inverter, and a control unit.
The first inverter has a first switching element and is connected to one end of the winding and the first voltage source.
The second inverter has a second switching element and is connected to the other end of the winding and the second voltage source.

The control unit controls the on / off operation of the first switching element and the second switching element.
The first switching element has a smaller on-resistance than the second switching element in a small current region. Specifically, for example, the first switching element is a MOSFET and the second switching element is an IGBT.

  In the present invention, in a configuration in which two inverters are provided for one rotating electrical machine, elements having different characteristics are used for the first switching element and the second switching element. The loss can be reduced by controlling the first inverter and the second inverter so that the first switching element is switched in the small current region in accordance with the driving region of the rotating electrical machine.

It is a schematic block diagram which shows the power converter device by one Embodiment of this invention. It is explanatory drawing explaining the relationship between the both-ends voltage of MOSFET and IGBT by 1 embodiment of this invention, and element current. It is a schematic block diagram explaining the cooler by one Embodiment of this invention. It is explanatory drawing explaining the cooling water temperature by one Embodiment of this invention. It is explanatory drawing explaining the drive area | region of the motor generator by one Embodiment of this invention. It is explanatory drawing explaining the one-side drive operation | movement by one Embodiment of this invention. It is explanatory drawing explaining the inversion drive operation | movement by one Embodiment of this invention.

Hereinafter, a power converter according to the present invention will be described with reference to the drawings.
(One embodiment)
A power converter according to an embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 1, the power conversion device 1 of the present embodiment converts the power of the motor generator 10.
The motor generator 10 is a so-called “main motor” that is applied to an electric vehicle such as an electric vehicle or a hybrid vehicle and generates torque for driving drive wheels (not shown). The motor generator 10 has a function as an electric motor for driving the drive wheels, and a function as a generator that generates electric power by being driven by kinetic energy transmitted from an engine or drive wheels (not shown). In this embodiment, the case where the motor generator 10 functions as an electric motor will be mainly described.

  Motor generator 10 is a three-phase AC rotating machine, and includes U-phase coil 11, V-phase coil 12, and W-phase coil 13. The U-phase coil 11, the V-phase coil 12, and the W-phase coil 13 correspond to “windings”, and the U-phase coil 11, the V-phase coil 12, and the W-phase coil 13 are hereinafter appropriately referred to as “coils 11 to 13”.

The power converter 1 includes a first inverter 20, a second inverter 30, a cooler 50, a control unit 60, and the like.
The first inverter 20 is a three-phase inverter that switches energization to the coils 11 to 13, and includes U1 upper arm element 21, V1 upper arm element 22, W1 upper arm element 23, and U1 lower arm element 24 that are six switching elements. , V1 lower arm element 25, and W1 lower arm element 26. Hereinafter, the U1 upper arm element 21, the V1 upper arm element 22, the W1 upper arm element 23, the U1 lower arm element 24, the V1 lower arm element 25, and the W1 lower arm element 26 are appropriately referred to as “(first) switching elements 21 to 21”. 26 ".

  The U1 upper arm element 21 is connected to the high potential side of the U1 lower arm element 24, the V1 upper arm element is connected to the high potential side of the V1 lower arm element 25, and the W1 upper arm element 23 is connected to the W1 lower arm element 26. Connected to the high potential side. The U1 upper arm element 21, the V1 upper arm element 22, and the W1 upper arm element 23 connected to the high potential side are hereinafter referred to as “first upper arm elements 21 to 23”, and the lower U1 connected to the low potential side. The arm element 24, the V1 lower arm element 25, and the W1 lower arm element 26 are referred to as “first lower arm elements 24-26”.

  The first inverter 20 is connected between one end 111, 121, 131 of the coils 11, 12, 13 and a first power supply 41 as a first voltage source. Specifically, a connection point 27 between the U1 upper arm element 21 and the U1 lower arm element 24 is connected to one end 111 of the U-phase coil 11, and a connection point 28 between the V1 upper arm element 22 and the V1 lower arm element 25 is V. The connection point 29 between the W1 upper arm element 23 and the W1 lower arm element 26 is connected to one end 131 of the W phase coil 13. Further, the high potential side wiring that connects the high potential side of the first upper arm elements 21 to 23 is connected to the positive electrode of the first power supply 41, and the low potential side that connects the low potential side of the first lower arm elements 24 to 26. The wiring is connected to the negative electrode of the first power supply 41.

  The second inverter 30 is a three-phase inverter that switches energization to the coils 11 to 13, and is a U2 upper arm element 31, a V2 upper arm element 32, a W2 upper arm element 33, and a U2 lower arm element 34 that are six switching elements. , V2 lower arm element 35, and W2 lower arm element 36. Hereinafter, the U2 upper arm element 31, the V2 upper arm element 32, the W2 upper arm element 33, the U2 lower arm element 34, the V2 lower arm element 35, and the W2 lower arm element 36 are appropriately referred to as “(second) switching elements 31 to 31”. 36 ".

  The U2 upper arm element 31 is connected to the high potential side of the U2 lower arm element 34, the V2 upper arm element 32 is connected to the high potential side of the V2 lower arm element 35, and the W2 upper arm element 33 is connected to the W2 lower arm element 36. Connected to the high potential side. The U2 upper arm element 31, the V2 upper arm element 32, and the W2 upper arm element connected to the high potential side are hereinafter referred to as “second upper arm elements 31 to 33”, and the U2 lower arm element 34 connected to the low potential side as appropriate. , V2 lower arm element 35 and W2 lower arm element 36 are referred to as “second lower arm elements 34 to 36”.

The second inverter 30 is connected between the other ends 112, 122, 132 of the coils 11, 12, 13, and the second power source 42 as a second voltage source. Specifically, a connection point 37 between the U2 upper arm element 31 and the U2 lower arm element 34 is connected to the other end 112 of the U-phase coil 11, and a connection point 38 between the V2 upper arm element 32 and the V2 lower arm element 35. Is connected to the other end 122 of the V-phase coil 12, and a connection point 39 between the W2 upper arm element 33 and the W2 lower arm element 36 is connected to the other end 132 of the W-phase coil 13. Further, the high potential side wiring that connects the high potential side of the second upper arm elements 31 to 33 is connected to the positive electrode of the second power source 42, and the low potential side that connects the low potential side of the second lower arm elements 34 to 36. The wiring is connected to the negative electrode of the second power supply 42.
Thus, in this embodiment, the 1st inverter 20 and the 2nd inverter 30 are connected to the both sides of the coils 11-13.

The first switching elements 21 to 26 are MOSFETs of unipolar semiconductor elements, and the second switching elements 31 to 36 are IGBTs of bipolar semiconductor elements.
When mentioning the characteristics of the MOSFET and the IGBT, the MOSFET has a smaller switching loss than the IGBT. In addition, MOSFETs tend to increase the element temperature in a large current region where the current is relatively large as compared to IGBTs. Therefore, if the element area is increased in order to suppress an increase in element temperature, the size of the device increases.

FIG. 2 shows the relationship between the both-end voltage of each element of the MOSFET and the IGBT and the element current, the solid line D1 shows the characteristics of the MOSFET, and the solid line D2 shows the characteristics of the IGBT. As shown in FIG. 2, when the device current is smaller than the current value Ic that is a current that is passed when the voltage across the device is Vc, the on-resistance of the MOSFET is small and the conduction loss is small compared to the IGBT. On the other hand, when the device current is larger than the current value Ic, the on-resistance of the IGBT is small and the conduction loss is small compared to the MSOFET.
Therefore, a MOSFET having excellent DC characteristics and AC characteristics is advantageous in driving in a small current region where the current is relatively small, and IGBT is advantageous in driving in a large current region where the current is relatively large.

As shown in FIG. 1, the first power supply 41 is a DC power supply that can be charged / discharged, such as a lithium ion battery, and is connected to the first inverter 20 and exchanges power with the motor generator 10 via the first inverter 20. Provided possible.
The second power supply 42 is a chargeable / dischargeable DC power supply such as a lithium ion battery, and is connected to the second inverter 30 so as to be able to exchange power with the motor generator 10 via the second inverter 30.

  The first power supply 41 of the present embodiment is an “output type” having a smaller internal resistance and a larger output than the second power supply 42, and is less deteriorated due to repeated charge / discharge than the second power supply 42. The second power source 42 is a “capacitance type” having a larger capacity than the first power source 41 and can output for a long time. In the present embodiment, the first power supply voltage Vb1 that is the voltage of the first power supply 41 and the second power supply voltage Vb2 that is the voltage of the second power supply 42 are equal, for example, 300 [V].

The first capacitor 43 is a smoothing capacitor that smoothes the current from the first power supply 41 to the first inverter 20 side or the current from the first inverter 20 to the first power supply 41 side.
The second capacitor 44 is a smoothing capacitor that smoothes the current from the second power source 42 to the second inverter 30 side or the current from the second inverter 30 side to the second power source 42 side.

As shown in FIGS. 1 and 3, the cooler 50 cools the first inverter 20 and the second inverter 30 and includes a main body 51, an inflow pipe 55, and an outflow pipe 57. In FIG. 3, the description of the motor generator 10 and the control unit 60 is omitted. The main body 51 is formed with a cooling passage 52 through which cooling water flows. The cooling passage 52 is provided with a plurality of fins 53. Thereby, heat dissipation efficiency improves.
The cooling passage 52 communicates with an inflow passage 56 formed in the inflow piping 55 and an outflow passage 58 formed in the outflow piping 57. As indicated by the block arrow W, the cooling water flows from the inflow passage 56 into the cooling passage 52 and is discharged from the outflow passage 58.

  In the present embodiment, MOSFETs having a large temperature rise when energizing a large current are used for the first switching elements 21 to 26, so that the cooling performance on the first inverter 20 side is higher than that on the second inverter 30 side. In addition, the inflow pipe 55 side is disposed on the first inverter 20 side, and the outflow pipe 57 is disposed on the second inverter 30 side.

In the cooler 50, an area mainly related to the cooling of the first inverter 20 is the first cooling area C1, and an area mainly related to the cooling of the second inverter 30 is the second cooling area C2, the first cooling area C1, and the second cooling. An intermediate area C3 is defined between the area C2.
In FIG. 4, the end portion on the inflow pipe 55 side of the main body 51 of the cooler 50 is set to zero, the cooling position that is the distance from the end portion on the inflow pipe 55 side is taken as the horizontal axis, and the cooling water temperature is taken as the vertical axis. As shown in FIG. 4, the cooling water temperature rises by flowing through the first cooling region C1, becomes substantially level in the intermediate region C3, and further rises by flowing through the second cooling region C2. That is, the temperature of the cooling water in the first cooling region C1 is lower than the temperature of the cooling water in the second cooling region C2, and in the cooler 50, the cooling performance on the first inverter 20 side is higher than the second inverter 30 side. It can be said.

As shown in FIG. 1, the control unit 60 is configured as a normal computer, and includes a CPU, a ROM, a RAM, an I / O, a bus line connecting these configurations, and the like. Each processing in the control unit 60 may be software processing by executing a program stored in advance by the CPU, or may be hardware processing by a dedicated electronic circuit.
The control unit 60 generates a control signal for controlling the on / off operation of the switching elements 21 to 26, 31 to 36, and outputs the generated control signal to the gates of the switching elements 21 to 26, 31 to 36.

  In the present embodiment, the driving operation is switched according to the rotation speed and torque of the motor generator 10. As shown in FIG. 5, the region where the rotation speed and torque of the motor generator 10 are less than the first threshold value L1 is a low load region R11, and the region where the rotation number and torque is greater than or equal to the first threshold value L1, and less than the second threshold value L2 Region R12, a region where the rotation speed and torque are equal to or higher than the second threshold L2 and less than the third threshold L3, which is the output upper limit, is defined as a high load region R13. The first threshold L1 is set so that the current supplied to the first inverter 20 is less than or equal to a predetermined value in consideration of the on-resistance, switching loss, element temperature, and the like of the switching elements 21-26, 31-36. The The second threshold L2 is the maximum value that can be output with the power of the second power source 42.

In the low load region R11, a first one-side drive operation for driving the motor generator 10 by the electric power of the first power supply 41 is used. The first one-side driving operation and the second one-side driving operation, which will be described later, can also be regarded as one power source driving operation.
In the first one-side drive operation, either one of all phases of the second upper arm elements 31 to 33 or all phases of the second lower arm elements 34 to 36 is turned on, and the other is turned off. Neutralized. Further, the first inverter 20 is controlled by PWM control or the like according to the drive request of the motor generator 10.

  In the example shown in FIG. 6A, all the phases of the second upper arm elements 31 to 33 are turned on, and all the phases of the second lower arm elements 34 to 36 are turned off, so that the second inverter 30 is neutral. It becomes. In the first inverter 20, when the U1 upper arm element 21, the V1 lower arm element 25, and the W1 lower arm element 26 are turned on, a current in a path indicated by an arrow Y1 in FIG. 6A flows. In addition, in the second inverter 30, the second upper arm elements 31 to 33 are turned on and the second lower arm elements 34 to 36 are turned on to reduce the bias of heat loss of the second switching elements 31 to 36. The state to be performed may be switched as appropriate. The same applies to the second one-side drive operation described later.

In the middle load region R12, the second one-side drive operation is performed in which the motor generator 10 is driven by the electric power of the second power source 42. In the second one-side driving operation, one of the all phases of the first upper arm elements 21 to 23 or the all phases of the first lower arm elements 24 to 26 is turned on, and the other is turned off. Neutralized. Further, the second inverter 30 is controlled by PWM control or the like in response to the drive request of the motor generator 10.
In the example shown in FIG. 6B, all phases of the first upper arm elements 21 to 23 are turned on and all phases of the first lower arm elements 24 to 26 are turned off, so that the first inverter 20 is neutral. It becomes. In the second inverter 30, when the U2 upper arm element 31, the V2 lower arm element 35, and the W2 lower arm element 36 are turned on, a current in a path indicated by an arrow Y2 in FIG. 6B flows.

  In the present embodiment, since the first power supply voltage Vb1 and the second power supply voltage Vb2 are equal, the voltage applied to the motor generator 10 in the region below the second threshold L2 (that is, the low load region R1 and the medium load region R2). Is substantially constant, the smaller the rotation speed and torque, the smaller the current, and the closer to the second threshold L2, the larger the current. That is, in the low load region R1 and the medium load region R2, it is relatively understood that the low load region R1 is a “small current region” and the medium load region R2 is a “large current region”.

In the present embodiment, since the first switching elements 21 to 26 that perform the first one-side driving operation and perform the switching operation in the low load region R1 are MOSFETs, it is possible to reduce the loss compared to the case of the IGBT. .
In the first one-side drive operation, the first power supply 41 is charged / discharged. When the motor generator 10 is a main motor and is in a traveling state in which frequent deceleration energy is generated, the drive region of the motor generator 10 is a low load region R1. In the present embodiment, a high-output power source that is relatively small in internal resistance and deterioration due to repeated charge / discharge is adopted as the first power source 41, and the first power source 41 side is charged / discharged in the low load region R1. Since the one-side drive operation is used, the deterioration of the first power supply 41 can be suppressed as compared with the case where a capacitive power supply is used.

  The IGBT has a relatively small on-resistance in a large current region, and an increase in element temperature is small compared to the MOS, so that the second inverter 30 is switched during one-side driving with a relatively large current. Thereby, the heat generation at the time of driving in the middle load region R12 can be suppressed. Further, since the second power source 42 is of a capacitive type, long-term output is possible, and the cruising distance by the first power source 41 and the second power source 42 can be extended.

  That is, a combination of a MOSFET (first switching elements 21 to 26) and an output type power supply (first power supply 41) is used in a low load region R1 where powering and regeneration are frequently switched, and an IGBT (second switching elements 31 to 31) is used. 36) and a capacitive power source (second power source 42) are preferably used in the medium load region R2 in terms of switching loss, element heat generation, battery deterioration, and the like.

In the high load region R13, an inversion driving operation is performed in which the motor generator 10 is driven by the electric power of the first power supply 41 and the second power supply 42. The inversion driving operation can also be regarded as a two-power supply driving operation.
In the reverse drive operation, the first inverter 20 is controlled based on the first fundamental wave F1 corresponding to the drive request of the motor generator 10, and the second inverter 30 is controlled based on the second fundamental wave F2 corresponding to the drive request. .

  For example, the control unit 60 generates a first control signal by PWM control by comparing the first fundamental wave F1 and the carrier wave, and generates a second control signal by PWM control by comparing the second fundamental wave F2 and the carrier wave. Generate. The PWM control includes “sine wave PWM control” in which the amplitudes of the fundamental waves F1 and F2 are smaller than the amplitude of the carrier wave, and “overmodulation PWM control” in which the amplitudes of the fundamental waves F1 and F2 are larger than the carrier wave. Further, instead of the PWM control, rectangular wave control may be performed in which the switching elements 21 to 26 and 31 to 36 are switched on and off for each half cycle of the fundamental waves F1 and F2.

  In the inversion driving operation, the phases of the first fundamental wave F1 and the second fundamental wave F2 are inverted. In other words, the first fundamental wave F1 and the second fundamental wave F2 are out of phase by approximately 180 [°]. The phase difference between the first fundamental wave F1 and the second fundamental wave F2 is 180 [°], but a voltage corresponding to the sum of the voltage of the first power supply 41 and the voltage of the second power supply 42 is set to the motor generator 10. Deviations that can be applied to are allowed.

  Further, the first fundamental wave F1 and the second fundamental wave F2 may have the same waveform as in the case where both are sine waves. For example, one of the first inverter 20 and the second inverter 30 may be a sine wave. Different waveforms may be used, as in the case of PWM control and the other overmodulation PWM control. Alternatively, rectangular wave control may be performed in which the amplitude is infinite and the on / off state is switched every half cycle of the fundamental wave.

  In the inversion driving operation, when the amplitude and waveform of the first fundamental wave F1 and the second fundamental wave F2 are equal, the elements that are turned on in each phase are upside down in the first inverter 20 and the second inverter 30. In the example shown in FIG. 7, the U1 upper arm element 21, the V1 lower arm element 25, the W1 lower arm element 26, the V2 upper arm element 32, the W2 upper arm element 33, and the U2 lower arm element 34 are turned on. , A current in a path indicated by an arrow Y3 flows. Note that, when the amplitudes or waveforms of the first fundamental wave F1 and the second fundamental wave F2 are different, the elements that are turned on in each phase are not necessarily upside down in the first inverter 20 and the second inverter 30.

By performing the inversion driving operation, it can be considered that the first power supply 41 and the second power supply 42 are connected in series, and a voltage corresponding to the sum of the first power supply voltage Vb1 and the second power supply voltage Vb2 is obtained as a motor generator. 10, the output of the motor generator 10 can be increased.
6 and 7, the description of the control unit 60 is omitted, and elements that are on are indicated by solid lines and elements that are off are indicated by broken lines.

As described in detail above, the power conversion device 1 converts the power of the motor generator 10 having the coils 11 to 13, and includes the first inverter 20, the second inverter 30, and the control unit 60. Prepare.
The first inverter 20 includes first switching elements 21 to 26 and is connected to one ends 111, 121, 131 of the coils 11, 12, 13 and the first power supply 41.
The second inverter 30 includes second switching elements 31 to 36 and is connected to the other ends 112, 122, 132 of the coils 11, 12, 13 and the second power supply 42.
The controller 60 controls the on / off operation of the first switching elements 21 to 26 and the second switching elements 31 to 36.

The first switching elements 21 to 26 have lower on-resistance than the second switching elements 31 to 36 in the small current region. The second switching elements 31 to 36 have lower on-resistance than the first switching elements 21 to 26 in the large current region.
In the present embodiment, in a configuration in which two inverters 20 and 30 are provided for one motor generator 10, elements having different characteristics are used in the first switching elements 21 to 26 and the second switching elements 31 to 36. ing. By controlling the first inverter 20 and the second inverter 30 so that the first switching elements 21 to 26 are switched in the small current region in accordance with the drive region of the motor generator 10, the loss can be reduced.

  Specifically, the first switching elements 21 to 26 are metal oxide semiconductor field effect transistors (MOSFETs), and the second switching elements 31 to 36 are insulated gate bipolar transistors (IGBT). Since the MOSFET has excellent DC characteristics and AC characteristics in a small current region, loss at a small current can be reduced. Also, since the amount of heat generated when the current is relatively large is smaller than that of the MOSFET, the IGBT can suppress heat generation at a large current compared to the case where all the switching elements are MOSFETs. Contribute.

When the rotational speed and torque of motor generator 10 are in low load region R1 that is smaller than first threshold value L1, control unit 60 neutralizes second inverter 30 and responds to the drive request of motor generator 10 with the first inverter. 20 is controlled.
When the rotational speed and torque of motor generator 10 are equal to or higher than first threshold value L1 and smaller than second threshold value L2, medium control region 60 neutralizes first inverter 20 and responds to the drive request. To control the second inverter 30.
Control unit 60 controls first inverter 20 and second inverter 30 according to the drive request when the rotational speed and torque of motor generator 10 are in high load region R3 that is equal to or greater than second threshold value L2.

  Thereby, compared with the case where the element switched in low load area | region R1 with a comparatively small electric current is IGBT, a loss can be reduced. Moreover, compared with the case where the element switched in the medium load region R12 where the current is relatively large is a MOSFET, heat generation in the region can be suppressed. Furthermore, in the high load region R3, high output can be realized by switching the first inverter 20 and the second inverter 30 and driving the motor generator 10 with the power of the first power supply 41 and the second power supply 42. .

The internal resistance of the first power supply 41 is smaller than the internal resistance of the second power supply 42. In the low load region R1, regeneration and power running are frequently switched according to the traveling state. In the present embodiment, as the first power source 41 connected to the first inverter 20 side switched in the low load region R1, an output type power source having a small internal resistance and a small deterioration due to charging / discharging is used. Thereby, compared with the case where a capacitive type power supply is used, deterioration of a power supply can be suppressed.
Further, the capacity of the second power supply 42 is larger than the capacity of the first power supply 41. Thereby, long-term output is possible.

  The power conversion device 1 includes a cooler 50 that cools the first inverter 20 and the second inverter 30. The cooling performance for cooling the first inverter 20 side of the cooler 50 is higher than the cooling performance for cooling the second inverter 30 side. Thereby, the 1st switching elements 21-26 which are MOSFETs with the larger calorific value in a large current region than IGBT can be cooled with high efficiency.

(Other embodiments)
(A) Inverter In the above embodiment, the first switching element is a MOSFET and the second switching element is an IGBT. In other embodiments, the first switching element may be a semiconductor element other than a MOSFET having a smaller on-resistance than the second switching element in a small current region. Further, the second switching element may be a semiconductor element other than the IGBT different from the first switching element.
In the above-described embodiment, the example in which the first inverter and the second inverter are PWM controlled has been mainly described. In other embodiments, at least one of the first inverter and the second inverter may be controlled by a control method other than PWM control.

(B) Power supply In the above embodiment, the first voltage source is an output type lithium ion battery, and the second voltage source is a capacity type lithium ion battery. In other embodiments, the first voltage source may be other than a lithium ion battery such as a capacitor, the second voltage source is driven by a lead storage battery, a fuel cell, or a drive source such as an engine, and the like. It is good also as other than a lithium ion battery.
As the first voltage source, it is preferable to use an “output type” that is small in deterioration due to charge and discharge, and as the second voltage source, it is preferable to use a “capacitance type” to enable long-term output. Not limited to. That is, in other embodiments, the internal resistance of the first voltage source may be greater than or equal to the internal resistance of the second voltage source, and the capacity of the second voltage source may be less than or equal to the capacity of the first voltage source. . The first voltage source and the second voltage source may have equivalent characteristics. Further, the first power supply voltage and the second power supply voltage may be different.

(C) Cooler In the above embodiment, the first inverter and the second inverter are cooled by the same cooler. In another embodiment, the configuration of the cooler is not limited to the configuration of the above-described embodiment, and any configuration may be used, and a cooler may be provided for each inverter, or the cooler may be omitted. Further, the cooling performance on the first inverter side may be equal to or lower than the cooling performance on the second inverter side.

(D) Motor generator In the above embodiment, in the above embodiment, the motor generator is a three-phase rotating electric machine, but in other embodiments, it is not limited to a three-phase rotating electric machine and may be any type. .
The motor generator is the main motor of the electric vehicle. In another embodiment, the motor generator is not limited to the main motor, and may be, for example, a so-called ISG (Integrated Starter Generator) having both a starter function and an alternator function or an auxiliary motor. Moreover, you may apply a power converter device to apparatuses other than a vehicle.
As mentioned above, this invention is not limited to the said embodiment at all, In the range which does not deviate from the meaning of invention, it can implement with a various form.

DESCRIPTION OF SYMBOLS 1 ... Power converter 10 ... Motor generator (rotary electric machine)
11-13 ... Coil (winding)
DESCRIPTION OF SYMBOLS 20 ... 1st inverter 21-26 ... 1st switching element 30 ... 2nd inverter 31-36 ... 2nd switching element 41 ... 1st power supply (1st voltage source) 42 ...・ Second power supply (second voltage source)
50 ... Cooler 60 ... Control unit

Claims (6)

A power converter (1) for converting the power of a rotating electrical machine (10) having windings (11, 12, 13),
A first inverter (20) having a first switching element (21-26) and connected to one end (111, 121, 131) of the winding and a first voltage source (41);
A second inverter (30) having a second switching element (31-36) and connected to the other end (112, 122, 132) of the winding and the second voltage source (42);
A controller (60) for controlling on / off operation of the first switching element and the second switching element;
With
The first switching element has a smaller on-resistance than the second switching element in a small current region. The first switching element is a metal oxide semiconductor field effect transistor;
The power converter according to claim 1, wherein the second switching element is an insulated gate bipolar transistor. The controller is
When the rotational speed and torque of the rotating electrical machine are in a low load region smaller than a first threshold value, the second inverter is neutralized, and the first inverter is controlled according to the driving request of the rotating electrical machine,
When the rotational speed and torque of the rotating electrical machine are in the middle load region that is equal to or larger than the first threshold and smaller than the second threshold, the first inverter is neutralized, and the second inverter is turned on in response to the drive request. Control
3. The first inverter and the second inverter are controlled according to the drive request when the rotational speed and torque of the rotating electrical machine are in a high load region that is equal to or greater than the second threshold value. The power converter device described in 1.   The power converter according to claim 1, wherein an internal resistance of the first voltage source is smaller than an internal resistance of the second voltage source.   The capacity | capacitance of a said 2nd voltage source is larger than the capacity | capacitance of a said 1st voltage source, The power converter device as described in any one of Claims 1-4 characterized by the above-mentioned. A cooler (50) for cooling the first inverter and the second inverter;
The power conversion device according to any one of claims 1 to 5, wherein a cooling performance for cooling the first inverter side of the cooler is higher than a cooling performance for cooling the second inverter side. .

Images