WO2018117084A1

WO2018117084A1 - Electric power conversion device

Info

Publication number: WO2018117084A1
Application number: PCT/JP2017/045478
Authority: WO
Inventors: 芳光高橋; 満孝伊藤; 浩史清水; 遠藤　剛
Original assignee: 株式会社デンソー
Priority date: 2016-12-21
Filing date: 2017-12-19
Publication date: 2018-06-28
Also published as: JP6636905B2; JP2018102070A

Abstract

The electric power conversion device (15) is provided with a first inverter (20), a second inverter (30), and a control part (65). One of the first inverter (20) and the second inverter (20) is a fixed output inverter, a power supply to be connected to the fixed output inverter is a fixed output power supply, the other of the first inverter (20) and the second inverter (30) is a variable output inverter, and a power supply to be connected to the variable output inverter is a variable output power supply. The control part (65) controls the fixed output inverter such that the output from the fixed output power supply has a fixed output value, and controls the variable output inverter such that electric power is supplied from the fixed output power supply and the variable output power supply to a rotary electric machine (10) when electric power required by the rotary electric machine (10) is higher than the fixed output value, or surplus electric power output from the fixed output power supply is supplied to the variable output power supply when the required electric power is higher than or equal to the fixed output value

Description

Power converter

Cross-reference of related applications

This application is based on patent application No. 2016-247628 filed on Dec. 21, 2016, the description of which is incorporated herein by reference.

The present disclosure relates to a power conversion device.

Conventionally, an inverter drive system that converts electric power of a motor by two inverters is known. For example, in Patent Document 1, the phase of the fundamental wave component of the pulse width modulation signal (hereinafter referred to as “PWM”) of the first inverter system and the second inverter system at a high voltage is 180 [°. By shifting, the two power supplies are electrically connected in series, and the motor is driven by the sum of the two power supply voltages. Further, in Patent Document 1, at the time of a low voltage, either one of the upper arm or the lower arm of the first inverter system or the second inverter system is simultaneously turned on for three phases, and the other is PWM driven.

JP 2006-238686 A

However, in Patent Document 1, no consideration is given to the deterioration of the power source accompanying the fluctuation of the motor output. An object of the present disclosure is to provide a power conversion device that can use a voltage source with high efficiency.

The power conversion device according to the present disclosure converts 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.

Here, one of the first inverter and the second inverter is a fixed output inverter, and a voltage source connected to the fixed output inverter is a fixed output voltage source. The other of the first inverter and the second inverter is a variable output inverter, and the voltage source connected to the variable output inverter is a variable output voltage source.

The control unit controls the fixed output inverter so that the output from the fixed output voltage source becomes a constant output value. In addition, the control unit supplies power to the rotating electrical machine from the fixed output voltage source and the variable output voltage source when the required power of the rotating electrical machine is greater than the constant output value. The variable output inverter is controlled such that surplus power output from the source is supplied to the variable output voltage source. Thereby, the output from the voltage source on the fixed output inverter side can be made constant, and the voltage source can be used with high efficiency. For example, if the voltage source on the fixed output inverter side is a battery, the duty cycle of the battery can be reduced and the life can be extended.

The above and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description with reference to the accompanying drawings. The drawing
FIG. 1 is a schematic configuration diagram showing the configuration of the power conversion device according to the first embodiment. FIG. 2 is an explanatory diagram illustrating the relationship between MG power and battery power according to the first embodiment. FIG. 3 is an explanatory diagram for explaining the operation when the MG power is larger than the constant output value in the first embodiment. FIG. 4A is an explanatory diagram illustrating an operation when the MG power is equal to or less than a constant output value and the first battery voltage is higher than the second battery voltage in the first embodiment. FIG. 4B is an explanatory diagram illustrating an operation when the MG power is equal to or lower than a constant output value and the first battery voltage is higher than the second battery voltage in the first embodiment. FIG. 5A is an explanatory diagram for explaining the operation when the MG power is equal to or lower than a constant output value and the first battery voltage is equal to or lower than the second battery voltage in the first embodiment. FIG. 5B is an explanatory diagram for explaining an operation when the MG power is equal to or lower than a constant output value and the first battery voltage is equal to or lower than the second battery voltage in the first embodiment. FIG. 5C is an explanatory diagram illustrating an operation when the MG power is equal to or lower than a constant output value and the first battery voltage is equal to or lower than the second battery voltage in the first embodiment. FIG. 6 is a time chart for explaining power transfer according to the first embodiment. FIG. 7 is a flowchart illustrating the drive control process according to the first embodiment. FIG. 8 is an explanatory diagram illustrating the relationship between MG power and battery power according to the second embodiment. FIG. 9 is a schematic configuration diagram illustrating a configuration of the power conversion device according to the third embodiment.

Hereinafter, a power change device according to the present disclosure will be described with reference to the drawings. Hereinafter, in a plurality of embodiments, the same numerals are given to the substantially same composition, and explanation is omitted.
(First embodiment)
A first embodiment is shown in FIGS. As shown in FIG. 1, the rotating electrical machine drive system 1 includes a motor generator 10 as a rotating electrical machine and a power conversion device 15. Motor generator 10 is mounted on a vehicle (not shown). The vehicle is an electric vehicle such as an electric vehicle or a hybrid vehicle, for example, and the motor generator 10 is a so-called “main motor” that 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).

The motor generator 10 is a three-phase AC rotating machine, and includes a U-phase coil 11, a V-phase coil 12, and a W-phase coil 13. The U-phase coil 11, the V-phase coil 12 and the W-phase coil 13 correspond to “windings”. Hereinafter, the motor generator is appropriately “MG”, and the U-phase coil 11, the V-phase coil 12 and the W-phase coil 13 are “coils”. 11-13 ". In the present embodiment, the current flowing through the U-phase coil 11 is defined as a U-phase current Iu, the current flowing through the V-phase coil 12 is defined as a V-phase current Iv, and the current flowing through the W-phase coil 13 is defined as a W-phase current Iw. Further, the U-phase current Iu, the V-phase current Iv, and the W-phase current Iw are appropriately referred to as phase currents Iu, Iv, and Iw. In the present embodiment, the current flowing from the first inverter 20 side to the second inverter 30 side is positive, and the current flowing from the second inverter 30 side to the first inverter 20 side is negative.

The power conversion device 15 converts the power of the motor generator 10 and includes a first inverter 20, a second inverter 30, a control unit 65, and the like. The first inverter 20 is a three-phase inverter that switches energization of the coils 11 to 13 and includes switching elements 21 to 26. The second inverter 30 includes switching elements 31 to 36 for switching energization of the coils 11 to 13. The switching element 21 includes an element unit 211 and a free wheeling diode 221. Similarly, the other switching elements 22 to 26 and 31 to 36 have element units 212 to 216, 311 to 316, and free-wheeling diodes 222 to 226 and 321 to 326, respectively.

The element units 211 to 216 and 311 to 316 are IGBTs (insulated gate bipolar transistors), and the on / off operation is controlled by the control unit 65. The element portions 211 to 216 and 311 to 316 are allowed to be energized from the high potential side to the low potential side when turned on, and are de-energized when turned off. The element portions 211 to 216 and 311 to 316 are not limited to IGBTs but may be MOSFETs or the like.

The free-wheeling diodes 221 to 226 and 321 to 326 are connected in parallel with the element portions 211 to 216 and 311 to 316, respectively, and allow energization from the low potential side to the high potential side. For example, the free-wheeling diodes 221 to 226 and 321 to 326 may be built in, such as a parasitic diode of a MOSFET, or may be externally attached.

In the first inverter 20, switching elements 21 to 23 are connected to the high potential side, and switching elements 24 to 26 are connected to the low potential side. The first high potential side wiring 27 connecting the high potential side of the switching elements 21 to 23 is connected to the positive electrode of the first battery 41, and the first low potential side wiring connecting the low potential side of the switching elements 24 to 26 is connected. 28 is connected to the negative electrode of the first battery 41.

One end 111 of the U-phase coil 11 is connected to the connection point of the

U-phase switching elements

21, 24, and one end 121 of the V-phase coil 12 is connected to the connection point of the V-

phase switching elements

22, 25, One end 131 of the W-phase coil 13 is connected to a connection point between the switching

elements

23 and 26. That is, the first inverter 20 is connected between the

coils

11, 12, 13 and the first battery 41.

In the second inverter 30, the switching elements 31 to 33 are connected to the high potential side, and the switching elements 34 to 36 are connected to the low potential side. Further, the second high potential side wiring 37 that connects the high potential side of the switching elements 31 to 33 is connected to the positive electrode of the second battery 42, and the second low potential side wiring that connects the low potential side of the switching elements 34 to 36. 38 is connected to the negative electrode of the second battery 42.

The other end 112 of the U-phase coil 11 is connected to the connection point of the

U-phase switching elements

31 and 34, and the other end 122 of the V-phase coil 12 is connected to the connection point of the V-

phase switching elements

32 and 35. The other end 132 of the W-phase coil 13 is connected to a connection point between the W-

phase switching elements

33 and 36. That is, the second inverter 30 is connected between the

coils

11, 12, 13 and the second battery 42. Thus, in the present embodiment, the first inverter 20 and the second inverter 30 are connected to both sides of the coils 11 to 13. Hereinafter, the switching elements 21 to 23 and 31 to 33 connected to the high potential side are referred to as “upper arm elements”, and the switching elements 24 to 26 and 34 to 36 connected to the low potential side are referred to as “lower arm elements”.

The first battery 41 as the first voltage source is connected to the first inverter 20 and provided so as to be able to exchange electric power with the motor generator 10 via the first inverter 20. The second battery 42 as the second voltage source is connected to the second inverter 30 and is provided so as to be able to exchange power with the motor generator 10 via the second inverter 30.

In the present embodiment, the first battery 41 and the second battery 42 are chargeable / dischargeable DC power sources such as lithium ion batteries. Hereinafter, the voltage of the first battery 41 is referred to as a first battery voltage Vb1, and the voltage of the second battery 42 is referred to as a second battery voltage Vb2. Further, in the present embodiment, the capacity of the first battery 41 is a so-called “high capacity type” that is relatively larger than the capacity of the second battery 42, and the second battery 42 has a so-called “high capacity”. "Output type".

The first capacitor 43 is connected to the first high potential side wiring 27 and the first low potential side wiring 28. The first capacitor 43 is a smoothing capacitor that smoothes the current from the first battery 41 to the first inverter 20 side or the current from the first inverter 20 to the first battery 41 side. The second capacitor 44 is connected to the second high potential side wiring 37 and the second low potential side wiring 38. The second capacitor 44 is a smoothing capacitor that smoothes the current from the second battery 42 to the second inverter 30 or the current from the second inverter 30 to the second battery 42.

The control signal generation unit 60 includes a first driver circuit 61, a second driver circuit 62, and a control unit 65. The control unit 65 is mainly composed of a microcomputer and performs various arithmetic processes. Each processing in the control unit 65 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 65 controls the first inverter 20 and the second inverter 30. Specifically, based on command values relating to driving of the motor generator 10 such as the torque command value trq ^* and the current command values Iu ^* , Iv ^* , Iw ^* , the element units 211 to 26 of the switching elements 21 to 26, 31 to 36. A control signal for controlling the on / off operation of 216, 311 to 316 is generated and output to the

driver circuits

61, 62. Hereinafter, appropriately controlling the on / off operation of the element portions 211 to 216 and 311 to 316 of the switching elements 21 to 26 and 31 to 36 is simply referred to as controlling the on / off operations of the switching elements 21 to 26 and 31 to 36.

The on / off operation of the switching elements 21 to 26 is controlled based on, for example, the first fundamental wave F1 and the carrier wave. Further, the on / off operation of the switching elements 31 to 36 is controlled based on, for example, the second fundamental wave F1 and the carrier wave. Control according to the fundamental waves F1 and F2 is, for example, sinusoidal PWM control in which the amplitudes of the fundamental waves F1 and F2 are equal to or smaller than the amplitude of the carrier wave, that is, the modulation factor is 1 or less. Alternatively, overmodulation PWM control may be used in which the amplitudes of the fundamental waves F1 and F2 are larger than the amplitude of the carrier wave, that is, the modulation rate is larger than 1. Furthermore, it may be a rectangular wave control in which the amplitude is infinite and each element is switched on and off every half cycle of the fundamental waves F1 and F2. The rectangular wave control can be regarded as 180 ° energization control in which each element is turned on and off every 180 ° of electrical angle. Further, the energization phase in the rectangular wave control may be other than 180 °, for example, 120 ° energization. The amplitudes of the fundamental waves F1 and F2 may be the same or different.

The first driver circuit 61 generates and outputs a gate signal for controlling the on / off operation of the element units 211 to 216 in response to a control signal from the control unit 65. The second driver circuit 62 generates and outputs a gate signal for controlling the on / off operation of the element units 311 to 316 in accordance with a control signal from the control unit 65. The element units 211 to 216 and 311 to 316 are turned on / off according to the control signal, whereby the DC power of the

batteries

41 and 42 is converted into AC power and supplied to the motor generator 10. Thereby, driving of motor generator 10 is controlled by control unit 65 via first inverter 20 and second inverter 30.

FIG. 2 is a diagram for explaining the relationship between MG power and battery power, where the horizontal axis represents MG power Pmg and the vertical axis represents battery power Pb1 and Pb2. Here, the MG power Pmg is power required to output a desired torque and rotation speed, and corresponds to “required power”. In the present embodiment, motor generator 10 is in a power running state when MG power Pmg is positive, and is in a regenerative state when negative. The first battery 41 is in a discharged state when the first battery power Pb1 is positive, and is in a charged state when negative. The second battery 42 is in a discharged state when the second battery power Pb2 is positive, and is in a charged state when negative.

2, the MG power Pmg is indicated by a solid line, the first battery power Pb1 is indicated by a one-dot chain line, and the second battery power Pb2 is indicated by a two-dot chain line. Further, when the values are the same, the values are slightly shifted for explanation. Hereinafter, the first inverter 20 is a “fixed output inverter”, the second inverter 30 is a “variable output inverter”, the first battery 41 is a “fixed output voltage source”, and the second battery 42 is a “variable output voltage source”. However, the control of the

inverters

20 and 30 may be interchanged so that the first inverter 20 may be a variable output inverter and the second inverter 30 may be a fixed output inverter. Further, the fixed output inverter and the variable output inverter may be appropriately switched according to the SOC (State Of Charge) of the

batteries

41 and 42. The same applies to the second embodiment.

As shown in FIG. 2, when the motor generator 10 is in the regenerative state, all the switching elements 21 to 26 of the first inverter 20 are turned off, and the first battery power Pb1 is set to zero. At this time, power input / output to / from the first battery 41 is not performed. Further, second inverter 30 is controlled in accordance with MG power Pmg, and second battery 42 is charged with power generated by regenerative driving of motor generator 10.

When the MG power Pmg is larger than the fixed upper limit value Pmg_h, the

inverters

20 and 30 are controlled so that the motor generator 10 outputs the desired MG power Pmg. In this case, the first battery power Pb1 is set larger than the constant output value Pfix. When the first battery power Pb1 cannot be increased above the constant output value Pfix, such as when the first inverter 20 is controlled in a rectangular wave in the power fixed region Rfix, a region where the MG power Pmg is greater than the fixed upper limit value Pmg_h. There is no need.

In the example of FIG. 2, when the MG power Pmg is higher than the fixed upper limit value Pmg_h, the first battery power Pb1 and the second battery power Pb2 are described as matching, but may be different. In the example of FIG. 2, the first battery power Pb1 and the second battery power Pb2 coincide with each other at the fixed upper limit value Pmg_h, but the first battery power Pb1 and the second battery power Pb2 are different from each other. The fixed upper limit Pmg_h may be set so that

When the motor generator 10 is in a power running state and the MG power Pmg is in the power fixed region Rfix where the fixed upper limit value Pmg_h is not more than the first inverter 41 so that the output from the first battery 41 becomes constant at the constant output value Pfix. 20 is controlled. At this time, the modulation factor of the first fundamental wave F1 is constant. The constant output value Pfix is appropriately set to a value that allows the first battery 41 to output power with high efficiency. In other words, the constant output value Pfix is a value that is not affected by fluctuations in the MG power Pmg. The first inverter 20 is controlled based on the first fundamental wave F1 having a modulation rate corresponding to the constant output value Pfix. For example, if the first inverter 20 is rectangular wave controlled, the switching loss of the first switching elements 21 to 26 can be reduced.

When the MG power Pmg is in the power fixed region Rfix, the second inverter 20 is controlled based on the MG power Pmg and the constant output value Pfix. In the fixed power region Rfix, a region where the MG power Pmg is larger than the constant output value Pfix is a double-sided discharge region Rd, and a region where the MG power Pmg is smaller than the constant output value Pfix is a one-side charging region Rc.

When the MG power Pmg is the double-sided discharge region Rd, the control unit 65 sets the phase of the second fundamental wave F2 to be opposite to that of the first fundamental wave F1. In other words, in the case of the double-sided discharge region Rd, the first fundamental wave F1 and the second fundamental wave F2 are out of phase with each other by approximately 180 [°]. In this embodiment, the phase difference between the fundamental waves F1 and F2 is set to 180 [°], but a deviation that allows the application of a voltage corresponding to the sum of the first battery voltage Vb1 and the second battery voltage Vb2 is allowed. The When MG power Pmg is in both-side discharge region Rd, control unit 65 sets the modulation factor of second fundamental wave F2 according to the difference between MG power Pmg and constant output value Pfix. Specifically, the modulation rate of the second fundamental wave F2 is increased as the MG power Pmg increases.

By controlling the

inverters

20 and 30 using the fundamental waves F1 and F2 having opposite phases, it can be considered that the first battery 41 and the second battery 42 are electrically connected in series. A voltage corresponding to the sum of the voltage Vb1 and the second battery voltage Vb2 (ie, Vb1 + Vb2) can be applied to the motor generator 10. For example, as shown in FIG. 3, when the switching

elements

21, 25, 26, 32, 33, and 34 are turned on, current flows as indicated by an arrow Y 1, and the motor generator 10 includes the first battery 41 and the second battery. It is driven using 42 electric power. In FIG. 3 and the like, elements that are on are indicated by solid lines, and elements that are off are indicated by broken lines.

When the MG power Pmg is equal to the constant output value Pfix, the control unit 65 sets the second battery power Pb2 to 0. That is, the input / output of the second battery 42 is set to zero. Specifically, the second inverter 30 is turned on by turning on one of all the phases of the upper arm elements 31 to 33 of the second inverter 30 or all the phases of the lower arm elements 34 to 36 and turning off the other. It becomes a sex point.

FIG. 4A shows an example in which the second inverter 30 is neutralized by turning off the upper arm elements 31 to 33 and turning on the lower arm elements 34 to 36 and switching the first inverter 20 to the neutral point. If the

elements

21, 25, and 26 are on, a current flows as indicated by an arrow Y2. By making the second inverter 30 neutral, the power input / output of the second battery 42 becomes zero. In the present embodiment, the case where the MG power Pmg is equal to the constant output value Pfix is included in the one-side charging region Rc, and the modulation factor of the second fundamental wave F2 is regarded as 0. Note that a case where the MG power Pmg is equal to the constant output value Pfix is included in the both-side discharge region Rd, and the modulation factor of the second fundamental wave F2 may be regarded as zero.

As shown in FIG. 2, when the MG power Pmg is in the one-side charging region Rc, the constant output value Pfix is larger than the MG power Pmg, so that the control unit 65 charges the second battery 42 with surplus power. The second inverter 30 is controlled. When the MG power Pmg is the one-side charging region Rc and the first battery voltage Vb1 is greater than the second battery voltage Vb2, that is, when Vb1> Vb2, the control unit 65 changes the phase of the second fundamental wave F2 to the first The phase is the same as that of the fundamental wave F1. In other words, the phase difference between the first fundamental wave F1 and the second fundamental wave F2 is substantially 0 [°]. By controlling the

inverters

20 and 30 using the fundamental waves F1 and F2 having the same phase, a voltage corresponding to the difference between the first battery voltage Vb1 and the second battery voltage Vb2 (ie, Vb1−Vb2) is supplied to the motor generator 10. Can be applied. In the present embodiment, the phase difference between the fundamental waves F1 and F2 is set to 0 [°], but a deviation that allows application of a voltage corresponding to the difference between the first battery voltage Vb1 and the second battery voltage Vb2 is allowed. The

As shown in FIG. 4B, for example, when the switching

elements

21, 25, 26, 31, 35, and 36 are turned on, current flows as indicated by an arrow Y 3, and the motor generator 10 uses the power of the first battery 41. Driven. Further, the second battery 42 is charged with surplus power.

Further, when the MG power Pmg is in the one-side charging region Rc, the control unit 65 sets the modulation factor of the second fundamental wave F2 according to the MG power Pmg. Specifically, the modulation factor of the second fundamental wave F2 is increased as the difference between the constant output value Pfix and the MG power Pmg increases. By changing the modulation factor of the second fundamental wave F2, the ratio between the state where the second inverter 30 shown in FIG. 4A is neutralized and the state where the second battery 42 shown in FIG. 4B is charged is controlled. It can also be understood as being. As a result, the amount of power transfer that is the amount of power transferred from the first battery 41 to the second battery 42 is controlled according to the MG power Pmg.

When the MG power Pmg is the one-side charging region Rc and the first battery voltage Vb1 is equal to or lower than the second battery voltage Vb2, that is, when Vb1 ≦ Vb2, the control unit 65 reduces the power of the first battery 41 by the chopper operation. Move to second battery 42. In the chopper operation, a non-charging period in which the power of the first battery 41 is not moved to the second battery 42 and a charging period in which the power of the first battery 41 is moved to the second battery 42 are periodically switched. The ratio between the non-charging period and the charging period is set according to the voltage difference between the first battery voltage Vb1 and the second battery voltage Vb2 and the difference between the constant output value Pfix and the MG power Pmg.

During the non-charging period, the second inverter 30 is controlled to be in the neutral point state shown in FIG. 5A. 5A is the same as FIG. 4A, in which one of the upper arm elements 31 to 33 or the lower arm elements 34 to 36 of the second inverter 30 is turned on for all phases and the other is turned off for all phases.

During the charging period, the second inverter 30 is controlled to be in the all-off state shown in FIG. 5B or the in-phase switch state shown in FIG. 5C. As shown in FIG. 5B, in the fully off state, the switching elements 31 to 36 of the second inverter 30 are all turned off. When switching between the neutral point state and the all-off state, the arm that is fully turned on may be switched between the neutral point state before the all-off state and the subsequent neutral point state. In this case, the entire off period can be regarded as a dead time accompanying switching of the arm to be turned on.

As shown in FIG. 5C, in the in-phase switching state,

inverters

20 and 30 are controlled using in-phase fundamental waves F1 and F2. If the amplitudes of the fundamental waves F1 and F2 are equal, the switching state of each phase is the same in the first inverter 20 and the second inverter 30. 5C, in the first inverter 20 and the second inverter 30, the U-phase

upper arm elements

21, 31 are turned on, and the V-phase and W-phase

lower arm elements

25, 26, 35, 36 are turned on. Show.

In the chopper operation, the coils 11 to 13 function as inductors in the boost converter, and energy is stored in the coils 11 to 13 by neutralizing the second inverter 30 during the non-charging period. When the charging period is switched, the energy stored in the coils 11 to 13 is released, and the second battery 42 is charged. Thereby, the power of the first battery 41 moves to the second battery 42.

Specifically, when the second inverter 30 is neutralized, the energization path is switched by turning off the switching element in which current flows from the high potential side to the low potential side via the element portion. The power of one battery 41 can be transferred to the second battery 42. For example, as shown in FIG. 5A, when the lower arm elements 34 to 36 are on, the U-phase current Iu is positive, the V-phase current Iv and the W-phase current Iw are negative, in the U-phase, the element unit 314, the V-phase and the W-phase Then, current flows through the

freewheeling diodes

325 and 326. When the U-phase lower arm element 34 is turned off from this state, the U-phase current Iu is energized through the free-wheeling diode 321 and flows into the positive electrode of the second battery 42 as shown in FIGS. 5B and 5C. Thereby, the 2nd battery 42 is charged. Similarly, when the second inverter 30 is neutralized by turning on the upper arm elements 31 to 33, when the switching element of the phase in which the current flows through the element portion is turned off, The second battery 42 is charged by switching the energization path at.

Here, when the charging period is set to the in-phase switching state and the on / off state of the one-phase or two-phase switching elements is switched, the number of elements for switching the switching state is smaller than when all the switching elements 31 to 36 are turned off. Switching loss can be reduced. Further, when the charging period is set to the all-off state and all the switching elements 31 to 36 are turned off, the control is easy.

零 Zero-phase current, which is the current that flows through the coils 11 to 13 during the charging period in chopper operation, does not affect the torque. As shown in FIG. 6, the phase currents Iu, Iv, and Iw have waveforms in which the zero-phase current is offset. The electric power according to the offset current moves from the first battery 41 to the second battery 42. The amount of power transferred from the first battery 41 to the second battery 42 can be adjusted by the ratio between the non-charging period and the charging period.

The drive control process of this embodiment will be described based on the flowchart of FIG. This process is executed by the control unit 65 at a predetermined cycle when a start switch such as an ignition switch is turned on. Hereinafter, “step” in step S101 is omitted, and is simply referred to as “S”. The other steps are the same. In first S101, the control unit 65 determines whether or not the MG power Pmg is 0 or more. When it is determined that the MG power Pmg is 0 or more (S101: YES), the process proceeds to S103. When it is determined that the MG power PMG is less than 0 (S101: NO), the process proceeds to S102.

In S102, the control unit 65 turns off all the switching elements 21 to 26 and stops the first inverter 20. Further, the control unit 65 regeneratively drives the second inverter 30 according to the MG power Pmg, and charges the second battery 42. Note that the first battery 41 may be charged instead of the second battery 42 or the

batteries

41 and 42 may be charged according to the SOC of the

batteries

41 and 42.

When it is determined that the MG power Pmg is equal to or greater than 0 (S101: YES), the control unit 65 determines whether the MG power Pmg is equal to or less than the fixed upper limit value Pmg_h. When it is determined that the MG power Pmg is equal to or less than the fixed upper limit value Pmg_h (S103: YES), the process proceeds to S105. When it is determined that the MG power Pmg is larger than the fixed upper limit value Pmg_h (S103: NO), the process proceeds to S104. In S104, control unit 65

controls inverters

20 and 30 according to MG power Pmg. If there is no higher output area than the fixed power area Rfix, the processes of S103 and S104 can be omitted.

When it is determined that the MG power Pmg is greater than or equal to 0 and less than or equal to the fixed upper limit value Pmg_h (S101: YES and S103: YES), that is, when the MG power Pmg is in the power fixed region Rfix, S105 The output value Pfix is set, and the process proceeds to S106. The constant output value Pfix may be a predetermined value, or may be variable according to at least one of the SOC of the

batteries

41 and 42, the environmental condition, and the operation history information. The environmental conditions include at least one of temperature, humidity, and atmospheric pressure, which is an external environment of the vehicle on which the rotating electrical machine drive system 1 is mounted. Moreover, you may make it transfer to S104 according to environmental conditions etc., when not performing constant output control from a fixed output inverter at the time of low temperature.

In S106, the control unit 65 determines whether or not the MG power Pmg is larger than the constant output value Pfix. When it is determined that the MG power Pmg is equal to or less than the constant output value Pfix (S106: NO), the process proceeds to S108. When it is determined that the MG power Pmg is larger than the constant output value Pfix (S106: YES), the process proceeds to S107.

In S107, the control unit 65 controls the first inverter 20 based on the first fundamental wave F1 having a constant modulation rate so that the output of the first battery 41 becomes the constant output value Pfix. Further, the control unit 65 controls the second inverter 30 based on the second fundamental wave F2 having the opposite phase to the first fundamental wave F1 so that the difference between the MG power Pmg and the constant output value Pfix is output ( (See FIG. 3). The modulation factor of the second fundamental wave F2 is set so as to become smaller as the MG power Pmg is closer to the constant output value Pfix. That is, the modulation factors of the fundamental waves F1 and F2 are larger as the difference between the MG power Pmg and the constant output value Pfix is smaller. The same applies when the fundamental waves F1 and F2 have the same phase in S109.

When it is determined that the MG power Pmg is equal to or less than the constant output value Pfix (S106: NO), the control unit 65 determines whether or not the first battery voltage Vb1 is greater than the second battery voltage Vb2. To do. When it is determined that the first battery voltage Vb1 is equal to or lower than the second battery voltage Vb2 (S108: NO), the process proceeds to S110. When it is determined that the first battery voltage Vb1 is greater than the second battery voltage Vb2 (S108: YES), the process proceeds to S109.

In S109, the control unit 65 controls the first inverter 20 at a constant modulation rate so that the output of the first battery 41 becomes the constant output value Pfix. Further, the control unit 65 is based on the second fundamental wave F2 having the same phase as the first fundamental wave F1 so that the surplus power obtained by removing the MG power Pmg from the constant output value Pfix is charged in the second battery 42. The second inverter 30 is controlled (see FIG. 4).

In S110, when the first battery voltage Vb1 is determined to be equal to or lower than the second battery voltage Vb2 (S108: NO), the control unit 65 causes the output of the first battery 41 to become the constant output value Pfix. The first inverter 20 is controlled at a constant modulation rate. Further, the control unit 65 performs the second chopper operation so as to switch between the non-charging period and the charging period in order to charge the second battery 42 with the surplus power obtained by subtracting the MG power Pmg from the constant output value Pfix. The inverter 30 is controlled (see FIG. 5).

In the present embodiment, in the configuration in which the

inverters

20 and 30 are connected to both sides of the motor generator 10, the output of the first battery 41 provided on the first inverter 20 side that is a fixed output inverter when the MG power is within a predetermined range. Is constant. Further, the second inverter 30 that is a variable output inverter is controlled based on the required power of the motor generator 10 and the output from the first inverter 20 side. By making the output of the first battery 41 constant, the battery duty cycle can be reduced and the battery life can be extended.

As described above, the power conversion device 15 of the present embodiment 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 65. And comprising. 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 battery 41. The second inverter 30 has 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 battery 42. The controller 65 controls the on / off operation of the first switching elements 21 to 26 and the second switching elements 31 to 36.

Suppose that one of the first inverter 20 and the second inverter 30 is a fixed output inverter, and a voltage source connected to the fixed output inverter is a fixed output voltage source. The other of the first inverter 20 and the second inverter 30 is a variable output inverter, and the voltage source connected to the variable output inverter is a variable output voltage source. Subsequently, the first inverter 20 will be described as a fixed output inverter, the first battery 41 as a fixed output voltage source, the second inverter 30 as a variable output inverter, and the second battery 42 as a variable output voltage source.

The control unit 65 controls the first inverter 20 so that the output from the first battery 41 becomes the constant output value Pfix. When the MG power Pmg, which is the required power of the motor generator 10, is greater than the constant output value Pfix, the control unit 65 supplies power to the motor generator 10 from the first battery 41 and the second battery 42, and the MG power Pmg is constant output. When the value is less than or equal to the value Pfix, the second inverter 30 is controlled such that the surplus power output from the first battery 41 is supplied to the second battery 42.

In this embodiment, since the output from the fixed output voltage source is constant, the fixed output voltage source can be used with high efficiency. If the fixed output inverter is the first inverter 20, the output of the first battery 41 is constant, so that the battery duty cycle is reduced and the life of the first battery 41 can be extended. The same applies to the case where the fixed output inverter is the second inverter 30.

When the MG power Pmg is larger than the constant output value Pfix, the control unit 65 causes the second switching elements 31 to 36 to be based on the modulation wave having the opposite phase to the modulation wave used for controlling the first switching elements 21 to 26. Control. As a result, the first battery 41 and the second battery 42 can be regarded as being connected in series, and in addition to the constant output value Pfix from the fixed output inverter side, the shortage can be output from the variable output inverter side. The desired power can be obtained.

The switching elements 21 to 26 and 31 to 36 are element units 211 to 216, 311 to 316, respectively, which can switch between allowing and blocking energization from the high potential side to the low potential side, and the high potential from the low potential side. Diodes 221 to 226 and 321 to 326 that allow energization to the side are included. When the MG power Pmg is smaller than the constant output value Pfix and the first battery voltage Vb1 is higher than the second battery voltage Vb2, the control unit 65 causes the first switching elements 21 to 26 and the second switching elements 31 to 36 to have the same phase. Control based on the modulated wave. Thereby, the surplus of the output from the first inverter 20 with respect to the MG power Pmg can be appropriately moved to the second battery 42.

When the MG power Pmg is smaller than the constant output value Pfix and the first battery voltage Vb1 is equal to or lower than the second battery voltage Vb2, the control unit 65 includes a non-charging period in which power transfer to the second battery 42 is not performed, The charging period during which power is transferred to the battery 42 is periodically switched. During the non-charging period, one of the upper arm elements 31 to 33 connected to the high potential side in the second inverter 30 or the lower arm elements 34 to 36 connected to the low potential side is turned on for all phases, and the other is The neutral point state is set to phase-off. In the charging period, the all-off state in which all the switching elements 31 to 36 of the second inverter 30 are turned off, or the in-phase switching state in which the first inverter 20 and the second inverter 30 are controlled based on the in-phase modulation wave And

By switching between the non-charging period in which the second inverter 30 is in the neutral point state and the charging period in which the second inverter 30 is in the all-off state or in-phase switching state, the chopper operation in which the coils 11 to 13 are regarded as inductors can be performed. Thereby, even if the 1st battery voltage Vb1 is the 2nd battery voltage Vb2 or less, the surplus of the output from the 1st battery 41 with respect to MG electric power Pmg can be moved to the 2nd battery 42 appropriately. . Therefore, the surplus power can be appropriately moved to the second battery 42 regardless of the battery voltages Vb1 and Vb2.

The modulation factor of the second fundamental wave F2, which is a modulation wave used for control of the second inverter 30 that is a variable output inverter, increases as the difference between the MG power Pmg and the constant output value Pfix increases. Thereby, desired MG power Pmg and power transfer can be realized.

The constant output value Pfix is variable in accordance with at least one of the SOC of the

batteries

41 and 42, environmental conditions, and driving history information of a vehicle using the motor generator 10 as a main motor. Thereby, the constant output value Pfix can be set appropriately.

(Second Embodiment)
A second embodiment is shown in FIG. As shown in FIG. 8, in this embodiment, the constant output value from the 1st battery 41 is made into two steps. Specifically, when motor generator 10 is in a power running state and MG power Pgm is in first power fixed region Rfix1, control unit 65 causes output from first battery 41 to become first constant output value Pfix1. Then, the first inverter 20 is controlled. Further, when the MG power Pmg is in the second power fixed region Rfix2, the control unit 65 controls the first inverter 20 so that the output from the first battery 41 becomes the second constant output value Pfix2. Control unit 65 controls second inverter 30 based on MG power Pmg and constant output values Pfix1 and Pfix2. Details of the control are the same as in the first embodiment.

The constant output values Pfix1, Pfix2, etc. can be set as appropriate. In the present embodiment, when the motor generator 10 is in the power running state, the output from the first battery 41 is fixed at two constant output values, but may be three or more stages. Even if comprised in this way, there exists an effect similar to the said embodiment. Moreover, the one side charge area | region Rc can be made small by switching the output from a fixed output inverter in steps.

(Third embodiment)
A third embodiment will be described with reference to FIG. As shown in FIG. 9, an engine 80 is connected to the first inverter 20 of the present embodiment via a third inverter 90 and a generator 85. The engine 80 is controlled by an engine control unit (not shown). The generator 85 has coils 86 to 88. The third inverter 90 is a three-phase inverter having switching elements 91-96. As the engine 80, the generator 85, and the third inverter 90, known ones may be used.

In this embodiment, an engine 80 is connected instead of the first battery 41 of the above embodiment. In this case, the first inverter 20 is a fixed output inverter, and the output from the first inverter 20 side is made constant by driving the engine 80 constant in the high efficiency region. In addition, the second inverter 30 is a variable output inverter, and the output from the second inverter 30 side is variable, thereby realizing a desired MG power Pmg.

In this embodiment, the engine 80 and the generator 85 are the first voltage source. In this case, the first inverter 20 is a fixed output inverter, and the second inverter 30 is a variable output inverter. Since the inverter on the engine 80 side is a fixed output inverter, the engine 80 can be driven in a constant high efficiency region, so that the overall efficiency can be increased.

(Other embodiments)
(1) Voltage source In the said embodiment, the lithium ion battery etc. were illustrated as a voltage source. In other embodiments, the voltage source may be a lead storage battery other than a lithium ion battery, a fuel cell, or an electric double layer capacitor. In the first embodiment, the first battery is a high capacity type and the second battery is a high output type. In other embodiment, what kind of thing may be used as a 1st battery and a 2nd battery, for example, it is good also as an equivalent.

(2) Rotating electrical machine In the above embodiment, the rotating electrical machine is a motor generator. In another embodiment, the rotating electrical machine may be an electric motor that does not have a function of a generator, or may be a generator that does not have a function of an electric motor. Further, the rotating electrical machine of the above embodiment has three phases. In other embodiments, the rotating electrical machine may have four or more phases. In the above embodiment, the rotating electrical machine is a main motor of an electric vehicle. In another embodiment, the rotating electrical machine is not limited to the main motor, but may be 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 described above, the present disclosure is not limited to the above-described embodiment, and can be implemented in various forms without departing from the spirit of the disclosure.

This disclosure has been described in accordance with the embodiment. However, the present disclosure is not limited to the embodiments and structures. The present disclosure also includes various modifications and modifications within the equivalent scope. Also, various combinations and forms, as well as other combinations and forms including only one element, more or less, are within the scope and spirit of the present disclosure.

Claims

A power conversion device for converting electric 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, 80, 85);
A second inverter (30) having a second switching element (31-36) and connected to the other end (112, 122, 132) of the winding and a second voltage source (42);
A controller (65) for controlling on / off operation of the first switching element and the second switching element;
With
One of the first inverter and the second inverter is a fixed output inverter, a voltage source connected to the fixed output inverter is a fixed output voltage source,
The other of the first inverter and the second inverter is a variable output inverter, and a voltage source connected to the variable output inverter is a variable output voltage source,
The controller is
Controlling the fixed output inverter so that the output from the fixed output voltage source becomes a constant output value;
When the required power of the rotating electrical machine is larger than the constant output value, power is supplied to the rotating electrical machine from the fixed output voltage source and the variable output voltage source, and when the required power is less than the constant output value, the fixed power value is supplied. A power converter that controls the variable output inverter so that surplus power output from an output voltage source is supplied to the variable output voltage source.
When the required power is greater than the constant output value, the control unit causes the switching element of the variable output inverter to be based on a modulation wave having a phase opposite to that of the modulation wave used for controlling the switching element of the fixed output inverter. The power conversion device according to claim 1 to be controlled.
The first switching element and the second switching element each have an element portion (211 to 216, 311 to 316) capable of switching between allowing and blocking energization from a high potential side to a low potential side, and a low potential Having diodes (221 to 226, 321 to 326) that allow energization from the side to the high potential side,
The controller is
When the required power is smaller than the constant output value and the voltage of the fixed output voltage source is higher than the voltage of the variable output voltage source, the switching elements of the fixed output inverter and the variable output inverter are based on a modulated wave having the same phase. Control
When the required power is smaller than the constant output value and the voltage of the fixed output voltage source is less than or equal to the voltage of the variable output voltage source, a non-charge period during which no power is transferred to the variable output voltage source, and the variable The charging period in which power is transferred to the output voltage source is periodically switched,
During the non-charging period, the variable output inverter has a neutral point where one of the upper arm element connected to the high potential side or the lower arm element connected to the low potential side is turned on for all phases and the other is turned off for all phases. State and
In the charging period, all the switching elements of the variable output inverter are all turned off, or the fixed output inverter and the variable output inverter are controlled based on the modulated wave having the same phase. The power converter according to claim 1 or 2.
The power conversion device according to any one of claims 1 to 3, wherein a modulation rate of a modulation wave used for controlling the variable output inverter increases as a difference between the required power and the constant output value increases.
The constant output value corresponds to at least one of a charging state of at least one of the first voltage source and the second voltage source, environmental conditions, and driving history information of a vehicle using the rotating electrical machine as a main motor. The power converter according to any one of claims 1 to 4, wherein the power converter is variable.
When the first voltage source is an engine (80) and a generator (85),
The first inverter is the fixed output inverter,
The power conversion device according to any one of claims 1 to 5, wherein the second inverter is the variable output inverter.