Control device for power conversion apparatus

Abstract

To control a voltage of an intermediate terminal into a desired value and suppress rotation of a rotary machine regardless of a stop angle of the rotary machine during charging for charging a power source.SOLUTION: A power conversion apparatus 1 comprises: capacitors 7a and 7b which are connected in series between a cathode and an anode of a battery 2; switch elements Q1 to Q12; a control device 9 which controls the switch elements Q1 to Q12; and a charging relay 13 which can connect a charging stand 14 for charging the battery 2 between a node Nm where the capacitors 7a and 7b are connected with each other, and an anode side terminal of the capacitor 7b. The control device 9 includes: a voltage control section 15 which controls a voltage of the node Nm within a range of an output voltage of the charging stand 14 by stepping down a voltage of the battery 2; and a phase current control section 16 which determines an input phase to electrify a motor 3 with a current of the charging stand 14 from among three phases and controls a current ratio that is a ratio of currents flowing to two phases other than the input phase in the three phases.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a control device for a power conversion device that converts electric power flowing between a power source and a rotating machine. [Background technology]

[0002] Currently, while 800V charging stations are beginning to be installed, their penetration rate is low, with 400V charging stations being the mainstream. BEV is an abbreviation for Battery Electric Vehicle. In order to charge a BEV equipped with an 800V battery at a 400V charging station, a voltage regulator such as a boost converter dedicated to charging that converts 400V to 800V is required.

[0003] Patent Document 1 discloses a technology for boosting the voltage of a charging stand by operating a three-level inverter and a motor as a boost converter. Hereinafter, the technology disclosed in Patent Document 1 will be simply referred to as the prior art. According to the prior art, it is possible to charge a battery, which is a power source, by adjusting the voltage of the charging stand, which is a charger, without providing a separate voltage adjustment device such as a boost converter. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2022-160202 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the conventional technology, the charging stand is considered as a voltage source, so the voltage of the intermediate terminal to which the charging stand is connected is stable and only the current is controlled. However, in actual charging stands, the current is controlled by a DC / DC converter and the current is output. Therefore, the control of the conventional technology cannot control the voltage of the intermediate terminal, and the voltage of multiple capacitors connected to the intermediate terminal fluctuates according to the current of the charging stand, which may result in problems such as the inability to charge or the application of a voltage exceeding the withstand voltage to the capacitors.

[0006] Furthermore, when performing control as in the conventional technology, current is applied to the motor during charging, i.e., while the vehicle is stopped, so it is necessary to suppress the motor torque so that the motor does not rotate. In the conventional technology, the input phase for applying the charger's current to the motor and the control phase that contributes to the boost operation are selected according to the stop angle of the motor, which is a rotating machine, to boost the voltage. Specifically, in the conventional technology, the controller detects the stop angle in the rotation direction of the motor, and selects as the input phase the coil that minimizes the amount of change in the rotation angle when the rotation angle of the motor changes by establishing a conductive state with the intermediate terminal.

[0007] According to such conventional technology, the direction of the resultant magnetic field created by the phase currents is not controlled, so as shown in Figure 28, depending on the stop angle during charging, the motor may rotate and the vehicle may move. That is, for example, when the stop angle is 0°, the resultant magnetic field is applied in the same direction as the magnet, so no torque, which is an attractive force, is generated. On the other hand, when the stop angle is 30°, for example, the magnet and the resultant magnetic field are misaligned, so torque is applied to the magnet, and the vehicle may move.

[0008] The present invention has been made in consideration of the above-mentioned circumstances, and an object of the present invention is to provide a control device for a power conversion device that can control the voltage of an intermediate terminal to a desired value and suppress the rotation of a rotating machine regardless of the stop angle of the rotating machine while charging a power source. [Means for solving the problem]

[0009] The control device of a power conversion device described in claim 1 is used in a power conversion device that converts electric power passing between a power source (2) and a rotating machine (3) having multiple phase coils (3u, 3v, 3w) and a neutral point (6) to which one terminal of the multiple phase coils is connected. The power conversion device includes a plurality of capacitors (7a, 7b) connected in series between the positive electrode of the power source and the negative electrode of the power source, a plurality of intermediate switch elements (Q7 to Q12, D1 to D6) provided between an intermediate terminal (Nm) to which the plurality of capacitors are connected and each of the coils of the multiple phases, a plurality of positive side switch elements (Q1, Q3, Q5) provided between each of the coils of the multiple phases and the positive electrode of the power source, a plurality of negative side switch elements (Q2, Q4, Q6) provided between each of the coils of the multiple phases and the negative electrode of the power source, a control device (9, 53, 63, 73) that controls the intermediate switch elements, the positive side switch elements, and the negative side switch elements, and a connection unit (13) that can connect a charger (14) for charging the power source between the intermediate terminal and the positive terminal or the negative terminal of the capacitor.

[0010] The control device includes a voltage control unit (15, 54) that controls the voltage of the intermediate terminal within the range of the output voltage of the charger by stepping down the voltage of the power source, and a phase current control unit (16) that determines an input phase from the multiple phases through which the current of the charger is passed to the rotating machine, and controls a current ratio that is a ratio of currents flowing through two phases other than the input phase among the multiple phases. In the above configuration, a three-level inverter is formed by a plurality of intermediate switch elements, a plurality of positive side switch elements, and a plurality of negative side switch elements. In such a configuration, the voltage control unit of the control device can control the voltage of the intermediate terminal within the range of the output voltage of the charger by stepping down the three-level inverter.

[0011] As will be described in detail later, in the above configuration, by skillfully adjusting the current ratio, the torque of the motor can be made zero and the rotation can be suppressed. In the above configuration, the phase current control unit of the control device controls the current ratio to a predetermined value that makes the torque zero, thereby suppressing the rotation of the motor. In this way, with the above configuration, it is possible to obtain the excellent effect of controlling the voltage of the intermediate terminal to a desired value and suppressing the rotation of the rotating machine regardless of the stop angle of the rotating machine during charging of the power source. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of a power conversion device according to a first embodiment; [Diagram 2] FIG. 11 is a waveform diagram showing the relationship between the electrical angle and the current ratio of the motor when stopped according to the first embodiment; [Diagram 3] FIG. 1 is a diagram showing a configuration example when the inverter according to the first embodiment is operated as a step-down converter. [Figure 4] FIG. 2 shows a configuration example when the inverter according to the first embodiment is operated as a step-down converter. [Diagram 5] FIG. 1 is a diagram showing an example of a specific configuration of a control device according to a first embodiment; [Figure 6] FIG. 13 is a diagram showing an example of a determination result by an input phase determination unit according to the first embodiment; [Figure 7] FIG. 1 is a diagram showing an example of a specific configuration of a current ratio calculation unit according to the first embodiment; [Figure 8] FIG. 13 is a diagram showing an example of a determination result of a maximum value determination unit and a current ratio calculation formula according to the first embodiment; [Figure 9] FIG. 1 is a diagram showing an example of a specific configuration of a switch signal selection unit according to a first embodiment; [Figure 10] FIG. 2 is a diagram showing a schematic flow of operations performed by each functional block in the control device according to the first embodiment; [Figure 11] FIG. 1 is a schematic diagram showing an example of an operational waveform of each part of the power conversion device according to the first embodiment. [Figure 12]FIG. 2 is a schematic diagram showing an example of an operational waveform of each part of the power conversion device according to the first embodiment. [Figure 13] FIG. 1 is a diagram showing an example of a relationship between the electrical angle of the motor and the time average torque of the motor when stopped according to the first embodiment; [Figure 14] FIG. 1 is a schematic diagram showing a configuration of a modified example of an inverter according to a first embodiment; [Figure 15] FIG. 13 is a diagram for explaining an example of a current path when an inverter according to a modified example is operated as a step-down converter. [Figure 16] FIG. 11 is a diagram showing an example of a determination result by an input phase determination unit according to the second embodiment; [Figure 17] FIG. 13 is a schematic diagram showing an example of waveforms of a U-phase current, a V-phase current, and a torque according to a comparative example; [Figure 18] FIG. 13 is a diagram showing an example of waveforms of a U-phase current, a V-phase current, and a torque according to a second embodiment; [Figure 19] FIG. 13 is a diagram illustrating a configuration added to a PWM modulation unit according to a third embodiment. [Figure 20] FIG. 13 is a schematic diagram illustrating an example of waveforms of a U-phase current, a V-phase current, an intermediate terminal voltage, a battery voltage, and a battery current according to the third embodiment and a comparative example. [Figure 21] FIG. 13 is a schematic diagram illustrating an example of waveforms of a U-phase current, a V-phase current, an intermediate terminal voltage, a battery voltage, and a battery current according to the fourth embodiment and a comparative example. [Figure 22] FIG. 13 is a diagram illustrating a configuration of a power conversion device according to a fifth embodiment. [Figure 23] FIG. 13 is a diagram showing an example of a specific configuration of a control device according to a fifth embodiment. [Figure 24] FIG. 13 is a diagram illustrating a configuration of a power conversion device according to a sixth embodiment. [Diagram 25] FIG. 13 is a diagram showing an example of a specific configuration of a control device according to a sixth embodiment. [Figure 26] FIG. 13 is a diagram illustrating a configuration of a power conversion device according to a seventh embodiment. [Figure 27] FIG. 23 is a diagram showing an example of a specific configuration of a control device according to a seventh embodiment. [Figure 28]FIG. 1 is a diagram for explaining a problem of a motor rotating depending on a stop angle of the motor according to the prior art; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, a number of embodiments will be described with reference to the drawings. Note that the same reference numerals are used to designate substantially the same components in the respective embodiments, and the description thereof will be omitted. (First embodiment) The first embodiment will be described below with reference to FIGS.

[0014] <Overall composition> As shown in FIG. 1, a power conversion device 1 of this embodiment is mounted on a vehicle such as a BEV, and converts power flowing between a battery 2 and a motor 3 also mounted on the vehicle. The battery 2 supplies DC voltage to the power conversion device 1 and corresponds to a power source. The battery 2 can be configured as a battery pack in which secondary batteries such as lithium ion batteries are connected in series in multiple stages. Each terminal of the battery 2 is connected to a pair of DC power supply lines 4, 5. Specifically, the positive electrode of the battery 2 is connected to the DC power supply line 4, and the negative electrode is connected to the DC power supply line 5.

[0015] The motor 3 corresponds to a rotating machine and has multiple phases, specifically, three-phase coils 3u, 3v, and 3w, and a neutral point 6 to which one terminal of the coils 3u, 3v, and 3w is connected. In other words, the motor 3 is a star-connected three-phase AC motor. The motor 3 serves as a drive source for running the vehicle. The power conversion device 1 includes multiple capacitors 7a, 7b, an inverter 8, a control device 9, current sensors 10a, 10b, voltage sensors 11a, 11b, a rotor position sensor 12, a charging relay 13, and the like.

[0016] The positive terminal of the capacitor 7a is connected to the DC power supply line 4, and the negative terminal is connected to the node Nm. The positive terminal of the capacitor 7b is connected to the node Nm, and the negative terminal is connected to the DC power supply line 5. That is, the multiple capacitors 7a, 7b are connected in series between the positive electrode of the battery 2 and the negative electrode of the battery 2. The node Nm is a node where the multiple capacitors 7a, 7b are connected to each other, and functions as an intermediate terminal.

[0017] The inverter 8 is a T-type NPC three-level inverter and includes switch elements Q1 to Q12. Each of the switch elements Q1 to Q12 is configured with an N-channel MOSFET. Each of the switch elements Q1 to Q12 includes a body diode connected between the drain and source with the source side serving as the anode. The switch elements Q1 to Q12 may also be configured with other semiconductor switching elements such as IGBTs. The switch elements Q1 to Q6 are connected between DC power supply lines 4 and 5 to form a three-phase full-bridge circuit.

[0018] That is, the drains of the switching elements Q1, Q3, and Q5 are connected to a DC power supply line 4, and the sources of the switching elements Q2, Q4, and Q6 are connected to a DC power supply line 5. The source of the switching element Q1 and the drain of the switching element Q2 are connected to a node Nu. The source of the switching element Q3 and the drain of the switching element Q4 are connected to a node Nv. The source of the switching element Q5 and the drain of the switching element Q6 are connected to a node Nw.

[0019] The node Nu functions as a U-phase output terminal of the inverter 3 and is connected to the other terminal of the U-phase coil 3u of the motor 3. The node Nv functions as a V-phase output terminal of the inverter 3 and is connected to the other terminal of the V-phase coil 3v of the motor 3. The node Nw functions as a W-phase output terminal of the inverter 3 and is connected to the other terminal of the W-phase coil 3w of the motor 3.

[0020] In the above configuration, the switch elements Q1, Q3, and Q5 are provided between the three-phase coils 3u, 3v, and 3w of the motor 3 and the positive electrode of the battery 2, and correspond to a plurality of positive-side switch elements. Also, in the above configuration, the switch elements Q2, Q4, and Q6 are provided between the three-phase coils 3u, 3v, and 3w of the motor 3 and the negative electrode of the battery 2, and correspond to a plurality of negative-side switch elements. In the following description, the switch elements Q1, Q3, and Q5 may be collectively referred to as the positive-side switch elements, and the switch elements Q2, Q4, and Q6 may be collectively referred to as the negative-side switch elements.

[0021] The switch elements Q7 and Q8 are provided so as to be able to open and close between the node Nm and the node Nu. Specifically, the sources of the switch elements Q7 and Q8 are connected in common. The drain of the switch element Q7 is connected to the node Nm, and the drain of the switch element Q8 is connected to the node Nu. The switch elements Q9 and Q10 are provided so as to be able to open and close between the node Nm and the node Nv. Specifically, the sources of the switch elements Q9 and Q10 are connected in common. The drain of the switch element Q9 is connected to the node Nm, and the drain of the switch element Q10 is connected to the node Nv.

[0022] The switch elements Q11 and Q12 are provided so as to be capable of opening and closing between the node Nm and the node Nw. Specifically, the sources of the switch elements Q11 and Q12 are commonly connected. The drain of the switch element Q11 is connected to the node Nm, and the drain of the switch element Q12 is connected to the node Nw. In the above configuration, the switch elements Q7 to Q12 are provided between the node Nm and each of the three-phase coils 3u, 3v, and 3w of the motor 3, and correspond to a plurality of intermediate switch elements. In the following description, the switch elements Q7 to Q12 may be collectively referred to as intermediate switch elements.

[0023] The control device 9 includes various functional blocks, and controls the intermediate switch elements, the positive side switch elements, and the negative side switch elements by the operation of these functional blocks. The control device 9 performs PWM control of the drive of the positive side switch elements and the negative side switch elements. Note that PWM is an abbreviation for Pulse Width Modulation. The control device 9 generates switch signals that drive each of the switch elements Q1 to Q12. The switch signals generated by the control device 9 are provided to the gates of the switch elements Q1 to Q12. In this way, the control device 9 controls the on / off of the switch elements Q1 to Q12.

[0024] The current sensor 10a detects the U-phase current of the motor 3, and outputs a detection signal corresponding to the detection value Iu to the control device 9. In FIG. 1 and other figures, each signal may be indicated with a symbol corresponding to the value represented by the signal. The current sensor 10b detects the V-phase current of the motor 3, and outputs a detection signal corresponding to the detection value Iv to the control device 9. In this embodiment, the U-phase current and the V-phase current of the three-phase current of the motor 3 are detected, but it is sufficient to detect the currents of any two phases of the three-phase current. Alternatively, a configuration in which all three-phase currents are detected may be used.

[0025] The voltage sensor 11a functions as a first voltage sensor that detects a first voltage, which is the voltage of the battery 2. The voltage sensor 11a outputs a detection signal corresponding to a detection value VH of the first voltage to the control device 9. The voltage sensor 11b functions as a second voltage sensor that detects a second voltage, which is a voltage between the node Nm and the negative electrode of the battery 2, that is, a terminal-to-terminal voltage of the capacitor 7b. The voltage sensor 11b outputs a detection signal corresponding to a detection value VL of the second voltage to the control device 9. In the following description, the first voltage may be referred to as a battery voltage, and the second voltage may be referred to as an intermediate terminal voltage.

[0026] The rotor position sensor 12 detects the rotation angle of the motor 3, specifically the mechanical angle, and outputs a detection signal corresponding to the detected value θm to the control device 9. The power conversion device 1 is configured to be connected to a current output charging stand 14, which is equipment provided outside the vehicle, and to charge the battery 2 by stepping down the voltage of the battery 2 and regenerating the current of the charging stand 14. The charging relay 13 is provided to connect the charging stand 14 to the power conversion device 1. The contact 13a of the charging relay 13 is provided so as to be able to open and close between one output terminal of the charging stand 14 and the node Nm. The contact 13b of the charging relay 13 is provided so as to be able to open and close between the other output terminal of the charging stand 14 and the DC power supply line 5.

[0027] In the above configuration, the charging stand 14 functions as a charger for charging the battery 2. Also, in the above configuration, the charging relay 13 functions as a connection unit that can connect the charging stand 14 for charging the battery 2 between the node Nm and the negative terminal of the capacitor 7b. The power conversion device 1 configured as above is configured such that when the charging stand 14 is connected, the contacts 13a, 13b of the charging relay 13 are closed.

[0028] The control device 9 includes a voltage control unit 15 and a phase current control unit 16 as part of its functional blocks. The voltage control unit 15 controls the voltage of the node Nm to be within the range of the output voltage of the charging stand 14 by stepping down the voltage of the battery 2. An intermediate terminal voltage command representing an intermediate terminal voltage command value VL* transmitted from a higher-level ECU (not shown) is input to the control device 9. The voltage control unit 15 controls the voltage of the node Nm, i.e., the intermediate terminal voltage, based on the intermediate terminal voltage command. The phase current control unit 16 determines an input phase from among the three phases for passing the current of the charging stand 14 to the motor 3, and controls a current ratio that is a ratio of currents flowing through the two phases other than the input phase among the three phases.

[0029] The voltage control unit 15 is adapted to perform calculations for controlling the voltage of the node Nm within the range of the output voltage of the charging stand 14. The phase current control unit 16 obtains three-phase currents by performing coordinate conversion using the electrical angle when the rotation of the motor 3 is stopped and the d-axis current value and the q-axis current value at which the torque of the motor 3 is equal to or less than a predetermined threshold torque. The phase current control unit 16 determines, as an input phase, a phase corresponding to a maximum current value, which is the maximum absolute value among the calculated current values, which are the values ​​of the currents of the three phases obtained. In the following description, the phase corresponding to the maximum current value among the calculated current values ​​may be referred to as the absolute maximum phase.

[0030] The phase current control unit 16 determines the current ratio of the two phases other than the input phase as the absolute value of the value obtained by dividing each of the calculated current values ​​of the three phases by the maximum current value, and multiplies the current ratio by the calculation result of the voltage control unit 15 to obtain the current command for the three phases. In this case, the threshold torque is set to a value lower than the holding force of the parking brake provided on the vehicle. In addition, in this case, the phase current control unit 16 performs coordinate conversion with the value of the q-axis current set to 0.

[0031] The principle by which the torque of the motor 3 becomes 0 in the above configuration will be described below. First, the torque T of the motor 3 is expressed by the torque formula such as the following formula (1). Here, p is the number of pole pairs, id is the d-axis current, iq is the q-axis current, φm is the permanent magnet flux linkage, Ld is the d-axis inductance, and Lq is the q-axis inductance.

[0032]

number

[0033] According to (1) above, if the value of the q-axis current is 0, in other words, "iq = 0", the torque T will be 0. Therefore, the three-phase currents for which "iq = 0" are found. The U-phase current Iu, V-phase current Iv, and W-phase current Iw are expressed by the uvw / dq coordinate transformation equation such as the following equation (2).

[0034]

number

[0035] When the above formula (2) is expanded, it becomes the following formulas (3), (4), and (5). Note that in each of the following formulas, √(2 / 3) represents the square root of 2 / 3, √3 represents the square root of 3, and * represents multiplication.

[0036] Iu=√(2 / 3)*{Id*cosΘ+Iq*sinΘ} …(3) Iv=√(2 / 3)*{Id*cos(Θ-2π / 3)+Iq*sin(Θ-2π / 3)} =√(2 / 3)*[Id*{cosΘcos(2π / 3)+sinΘsin(2π / 3)}+Iq*{sinΘcos(2π / 3)-cosΘsin(2π / 3)}] =√(2 / 3)*{Id*(-1 / 2*cosΘ+√3 / 2*sinΘ)+Iq*(-1 / 2*sinΘ-√3 / 2*cosΘ)} …(4) Iw=√(2 / 3)*{Id*cos(Θ+2π / 3)+Iq*sin(Θ+2π / 3)} =√(2 / 3)*[Id*{cosΘcos(2π / 3)-sinΘsin(2π / 3)}+Iq*{sinΘcos(2π / 3)+cosΘsin(2π / 3)}] =√(2 / 3)*{Id*(-1 / 2*cosΘ-√3 / 2*sinΘ)+Iq*(-1 / 2*sinΘ+√3 / 2*cosΘ)} …(5)

[0037] By substituting "Iq = 0" into equations (3), (4), and (5), and using the addition theorem (cos(Θ-α)=cosΘcosα+sinΘsinα), the three-phase currents are expressed by the following equations (6), (7), and (8).

[0038] Iu = √(2 / 3) * Id * cosΘ … (6) Iv=√(2 / 3)*Id*(-1 / 2cosΘ+√3 / 2sinΘ) =√(2 / 3)*Id*cos(Θ-2π / 3) …(7) Iw=√(2 / 3)*Id*(-1 / 2*cosΘ-√3 / 2*sinΘ) =√(2 / 3)*Id*cos(Θ-4π / 3) …(8)

[0039] In equations (6) to (8), the terms before cos represent coefficients, and the terms after cos represent current ratios. The coefficients are proportional to the current of the charging stand 14, that is, "coefficient ∝ current of the charging stand 14". In this way, the three-phase currents Iu, Iv, and Iw for which "Iq = 0" can be expressed as cosine waves with a phase shift of 2π / 3. That is, the current ratio of the three-phase currents Iu, Iv, and Iw can be expressed as a waveform as shown in FIG. 2. In FIG. 2, the horizontal axis represents the electrical angle [deg] of the motor 3 when stopped, and the vertical axis represents the current ratio. In this way, the torque of the motor 3 can be made zero by controlling the three-phase currents Iu, Iv, and Iw to have a current ratio as shown in FIG. 2 according to the electrical angle when stopped.

[0040] The power conversion device 1 configured as described above can operate the inverter 8 as a step-down converter that steps down the voltage of the battery 2. When the control device 9 operates the inverter 8 as a step-down converter, the control device 9 controls each switch element of the input phase, which is one of the three phases, and the control phase, which is two phases other than the input phase, as follows. That is, the control device 9 fixes the middle switch element of the input phase to ON, fixes the middle switch element of the control phase, the positive side switch element of the input phase, and the negative side switch element of the input phase to OFF, and then PWM controls the ON / OFF of the positive side switch element and the negative side switch element of the control phase, thereby stepping down the voltage of the battery 2.

[0041] For example, as shown in Figures 3 and 4, when the input phase is the W phase and the control phases are the U phase and the V phase, switch elements Q11 and Q12 are fixed ON and switch elements Q5 to Q10 are fixed OFF, and then the ON / OFF of switch elements Q1 to Q4 is PWM controlled to step down the voltage of battery 2 and regenerate the current of charging stand 14. Note that, compared to Figure 3, Figure 4 omits the illustration of configuration that does not directly contribute to the operation as a step-down converter.

[0042] <Control device configuration> A specific configuration of the control device 9 is, for example, as shown in Fig. 5. The voltage control unit 15 includes a subtractor 17 that subtracts the detection value VL of the voltage sensor 11b from the command value VL* of the intermediate terminal voltage, and a PI controller 18 that outputs a signal corresponding to the current command IL* by performing PI control on the output signal of the subtractor 17. In this way, the voltage control unit 15 performs PI control from the command value VL* of the intermediate terminal voltage and the detection value VL of the voltage sensor 11b to calculate the current command IL*.

[0043] The electrical angle calculation unit 19 converts the detection value θm of the rotor position sensor 12 into an electrical angle θe. Such a conversion can be performed as "electrical angle θe = detection value θm of mechanical angle × number of pole pairs of the motor 3". The phase current control unit 16 includes an input phase determination unit 20, a current ratio calculation unit 21, a phase current command calculation unit 22, a W-phase current calculation unit 23, and a PI control unit 24. The input phase determination unit 20 performs ON / OFF fixation determination of each of the switch elements Q1 to Q12 from the electrical angle θe.

[0044] Based on the result of the ON / OFF fixation determination, the input phase determination unit 20 outputs positive and negative switch signals Su2, Sv2, and Sw2, which are switch signals corresponding to the positive and negative switch elements, and intermediate switch signals Snu, Snv, and Snw, which are switch signals corresponding to the intermediate switch elements. In the following description, the positive and negative switch signals and intermediate switch signals may be simply referred to as switch signals. Each switch signal is a binary signal, with a high level corresponding to a level that turns on the switch element and a low level corresponding to a level that turns off the switch element.

[0045] In this specification, the high level of a binary signal may be referred to as "1," and its low level may be referred to as "0." For each switch signal, the input phase determination unit 20 regards the signal as "0" when the corresponding switch element is fixed to OFF, and as "1" when the corresponding switch element is fixed to ON, or when the corresponding switch element is not fixed to ON or OFF.

[0046] The result of the ON / OFF fixation determination by the input phase determination unit 20 is as shown in Fig. 6. Fig. 6 corresponds to a table in which the current ratios of the three-phase currents shown in Fig. 2 are quantified. For example, when the electrical angle θe is "0 to less than 30°", the phase with the maximum absolute value is the "U phase", the switch signal Su2 is "0", the switch signals Sv2 and Sw2 are "1", the switch signal Snu is "1", and the switch signals Snv and Snw are "0". When the electrical angle θe is "30 to less than 90°", the phase with the maximum absolute value is the "W phase", the switch signal Sw2 is "0", the switch signals Su2 and Sv2 are "1", the switch signal Snw is "1", and the switch signals Snu and Snv are "0".

[0047] At the boundary of the electrical angle θe, that is, when the electrical angle θe is "30°+60°×n", there are two maximum absolute value phases, and either of these two phases may be set as the maximum absolute value phase, where n is an integer. When the electrical angle θe is 30°, there are two maximum absolute value phases, the U phase and the W phase, but in this embodiment, the W phase is set as the maximum absolute value phase.

[0048] The current ratio calculation unit 21 calculates current ratios Ru, Rv, and Rw representing the respective ratios of the U-phase current, the V-phase current, and the W-phase current of the motor 3 from the electrical angle θe. The phase current command calculation unit 22 includes a multiplier 22u that multiplies the current command IL* by the current ratio Ru to output a signal corresponding to the phase current command Iu* of the U-phase, a multiplier 22v that multiplies the current command IL* by the current ratio Rv to output a signal corresponding to the phase current command Iv* of the V-phase, and a multiplier 22w that multiplies the current command IL* by the current ratio Rw to output a signal corresponding to the phase current command Iw* of the W-phase. In this way, the phase current command calculation unit 22 multiplies the current command IL* by the current ratios Ru, Rv, and Rw to calculate the phase current commands Iu*, Iv*, and Iw*.

[0049] The W-phase current calculation unit 23 is composed of a subtractor that subtracts the detection value Iv of the current sensor 10b from a value obtained by inverting the sign of the detection value Iu of the current sensor 10a and outputs a signal corresponding to the calculated value Iw of the W-phase current. In this manner, the W-phase current calculation unit 23 calculates the W-phase current from the U-phase current and the V-phase current. Specifically, the W-phase current calculation unit 23 calculates the W-phase current as "Iw=-Iu-Iv".

[0050] The PI control unit 24 includes a subtractor 25u that subtracts the detection value Iu from the phase current command Iu*, and a PI controller 26u that outputs a signal corresponding to a phase voltage command Vu* of the U phase by performing PI control on the output signal of the subtractor 25u. The PI control unit 24 also includes a subtractor 25v that subtracts the detection value Iv from the phase current command Iv*, and a PI controller 26v that outputs a signal corresponding to a phase voltage command Vv* of the V phase by performing PI control on the output signal of the subtractor 25v.

[0051] Furthermore, the PI control unit 24 includes a subtractor 25w that subtracts a calculated value Iw from the phase current command Iw*, and a PI controller 26w that outputs a signal corresponding to a phase voltage command Vw* of the W phase by performing PI control on an output signal of the subtractor 25w. In this manner, the PI control unit 24 performs PI control on the phase current commands Iu*, Iv*, Iw*, the detection values ​​Iu, Iv of the current sensors 10a, 10b, and the calculated value Iw obtained as a result of the calculation by the W-phase current calculation unit 23, to calculate the phase voltage commands Vu*, Vv*, Vw*.

[0052] The PWM modulation units 27u, 27v, and 27w calculate duties from the phase voltage commands Vu*, Vv*, and Vw* and the detection value VH of the voltage sensor 11a. The PWM modulation units 27u, 27v, and 27w PWM-modulate the calculated duties to calculate positive and negative switch signals Su1, Sv1, and Sw1 that are switch signals corresponding to the positive and negative switch elements.

[0053] The switch signal selection unit 28 transmits to the inverter 8 a signal obtained by calculating the logical product, that is, AND, of the positive and negative switch signals Su1, Sv1, Sw1 transmitted from the PWM modulation units 27u, 27v, 27w and the positive and negative switch signals Su2, Sv2, Sw2 transmitted from the input phase determination unit 20. In addition, the switch signal selection unit 28 transmits the intermediate switch signals Snu, Snv, Snw transmitted from the input phase determination unit 20 to the inverter 8 as they are.

[0054] <Configuration of current ratio calculation section> As a specific configuration of the current ratio calculation unit 21, for example, a configuration example as shown in Fig. 7 can be adopted. The current ratio calculation unit 21 of the configuration example shown in Fig. 7 includes a dq / uvw coordinate conversion unit 31, an absolute value conversion unit 32, and a maximum value determination unit 33. The dq / uvw coordinate conversion unit 31 performs dq / uvw coordinate conversion using the electrical angle θe, the d-axis current Id, and the q-axis current Iq. At this time, the value of the d-axis current Id is set to 1, that is, "Id=1", and the value of the q-axis current Iq is set to 0, that is, "Iq=0". Note that as long as "Iq=0", the value of the d-axis current Id may be any value.

[0055] An absolute value conversion unit 32 converts the calculated current value Iru of the U phase, the calculated current value Irv of the V phase, and the calculated current value Irw of the W phase, which are the calculation results of the dq / uvw coordinate transformation, into absolute values ​​|Iru|, |Irv|, and |Irw|, respectively. A maximum value determination unit 33 determines, from the electrical angle θe, the phase having the maximum absolute value among the calculated current values ​​Iru, Irv, and Irw, which are the calculation results of the dq / uvw coordinate transformation, and calculates the current ratios Ru, Rv, and Rw from a current ratio calculation formula.

[0056] The result of the determination by maximum value determination unit 33 and the current ratio calculation formula are as shown in Fig. 8. The current ratio calculation formula used in this case is expressed by division with the absolute value corresponding to the maximum absolute value phase as the denominator and the absolute values ​​corresponding to each of the phases as the numerator. For example, when the electrical angle θe is 15°, the phase with the maximum absolute value is the "U phase", so the current ratio calculation formula is expressed by division with the absolute value |Iru| as the denominator and the absolute values ​​|Iru|, |Irv|, |Irw| corresponding to each of the phases as the numerators, as shown in the following formulas (9), (10), and (11). Ru = |Iru| / |Iru| …(9) Rv = |Irv| / |Iru| …(10) Rw = |Irw| / |Iru| …(11)

[0057] In this case, as in the case of fixed ON / OFF judgment, when the electrical angle θe is at the boundary between the electrical angles θe, that is, when the electrical angle θe is "30° + 60° × n", there will be two phases with maximum absolute values, and either of these two phases may be determined to be the phase with maximum absolute value.

[0058] <Configuration of switch signal selection section> As a specific configuration of the switch signal selection unit 28, for example, a configuration example as shown in Fig. 9 can be adopted. The switch signal selection unit 28 of the configuration example shown in Fig. 9 includes AND circuits 34, 35, and 36. The AND circuit 34 receives the switch signal Su1 output from the PWM modulation unit 27u and the switch signal Su2 output from the input phase determination unit 20, and outputs a signal representing the logical product of these input signals.

[0059] The AND circuit 35 receives the switch signal Sv1 provided by the PWM modulation unit 27v and the switch signal Sv2 provided by the input phase determination unit 20, and outputs a signal representing the logical product of these input signals. The AND circuit 36 ​​receives the switch signal Sw1 provided by the PWM modulation unit 27w and the switch signal Sw2 provided by the input phase determination unit 20, and outputs a signal representing the logical product of these input signals. The switch signal selection unit 28 outputs the output signals of the AND circuits 34 to 36 to the positive and negative switch elements of the inverter 8. The switch signal selection unit 28 also outputs the switch signals Snu, Snv, and Snw provided by the input phase determination unit 20 to the middle switch elements of the inverter 8.

[0060] Next, the operation of the above configuration will be described. The flow of operations by each functional block in the control device 9 is shown in a flowchart in Fig. 10. As shown in Fig. 10, in step S101, an electrical angle θe is calculated from a detection value θm of the rotor position sensor 12 and output. After execution of step S101, the process proceeds by splitting into two systems, a first system and a second system. Then, the process proceeds by splitting into both systems, step S102 and step S103.

[0061] In the first system, the process proceeds to step S102, where current ratios Ru, Rv, and Rw are calculated from the electrical angle θe and output. In the second system, the process proceeds to step S103, where the input phase is determined from the electrical angle θe and switch signals Su2, Sv2, Sw2, Snu, Snv, and Snw are output. After executing step S103, the second system waits until step S109 is started. On the other hand, after executing step S102, the first system proceeds to step S104. In step S104, PI control is performed based on the command value VL* of the intermediate terminal voltage and the detection value VL of the voltage sensor 11b, and a current command IL* is output.

[0062] After executing step S104, the process proceeds to step S105, where phase current commands Iu*, Iv*, Iw* are calculated and output from the current ratios Ru, Rv, Rw and the current command IL*. After executing step S105, the process proceeds to step S106, where PI control is performed from the phase current commands Iu*, Iv*, Iw*, the detection values ​​Iu, Iw of the current sensors 10a, 10b, and the calculated value Iw of the W-phase current, and phase voltage commands Vu*, Vv*, Vw* are output. After executing step S106, the process proceeds to step S107, where a duty is calculated and output from the phase voltage commands Vu*, Vv*, Vw* and the detection value VH of the voltage sensor 11a.

[0063] After step S107 is executed, the process proceeds to step S108, where PWM modulation is performed and switch signals Su1, Sv1, and Sw1 are output. After step S108 is executed, the process proceeds to step S109, where a switch signal is selected. After step S109 is executed, the process proceeds to step S110, where a switch signal is output to the inverter 8. After step S110 is executed, this series of operations is completed.

[0064] Next, an example of the operating waveforms of each part of the power conversion device 1 having the above configuration will be described with reference to Fig. 11. In Fig. 11, the positive switch element is called the upper arm, the negative switch element is called the lower arm, and the middle switch element is called the middle SW. Fig. 11 shows the simulation results under the following conditions.

[0065] <Condition> Battery voltage → 800V Intermediate terminal voltage command value → 400V Motor 3 electrical angle when stopped → 45° Current ratio Ru:Rv → 0.732:0.268

[0066] 11, the above configuration allows the intermediate terminal voltage to be controlled according to the command value. Also, with the above configuration, the average torque of the motor 3 is 0 [Nm], and the rotation of the motor 3 can be suppressed regardless of the stop angle.

[0067] According to the present embodiment described above, the following effects can be obtained. In the power conversion device 1 configured as above, the inverter 8, which is a three-level inverter, is configured by a plurality of intermediate switch elements, a plurality of positive pole side switch elements, and a plurality of negative pole side switch elements. In such a configuration, the voltage control unit 15 of the control device 9 can control the intermediate terminal voltage to be within the range of the output voltage of the charging stand 14 by stepping down the inverter 8. As described above, according to the present embodiment, since it is possible to control the intermediate terminal voltage to a desired value, even when the charging stand 14 with a current output is connected, there is no risk of a malfunction such as the voltage of the capacitors 7a, 7b fluctuating and making it impossible to charge, or a malfunction such as a voltage exceeding the withstand voltage being applied to the capacitors 7a, 7b.

[0068] In the above configuration, the torque of the motor 3 can be made zero and the rotation can be suppressed by appropriately adjusting the current ratio. Therefore, in the above configuration, the phase current control unit 16 of the control device 9 can suppress the rotation of the motor 3 by controlling the current ratio to a predetermined value that makes the torque zero. Therefore, according to this embodiment, the rotation of the motor 3 can be suppressed regardless of the stop angle of the motor 3 during charging of the battery 2, and as a result, it is possible to prevent the occurrence of a situation in which the vehicle moves during charging.

[0069] The effect obtained by this embodiment is also clear from the simulation results shown in Figs. 12 and 13. The conditions for these simulations are the same as those described above. As shown in Fig. 12, according to this embodiment, the average value of the intermediate terminal voltage is 400 [V] and the average value of the torque of the motor 3 is 0 [Nm], so that the intermediate terminal voltage can be controlled according to the command value and the battery 2 can be charged without generating torque. Also, as shown in Fig. 13, according to this embodiment, the time average torque of the motor 3 when the electrical angle of the motor 3 at the time of stopping changes within the range of 0 to 360° is suppressed to 0 [Nm], so that the torque of the motor 3 can be suppressed regardless of the electrical angle.

[0070] The phase current control unit 16 of the control device 9 can also control the current ratio so that the torque becomes equal to or less than a threshold torque set to a value lower than the holding force of a parking brake provided on the vehicle, thereby suppressing the rotation of the motor 3. Even in this case, as long as the parking brake is activated during charging, it is possible to prevent the vehicle from moving in the same way as in the case where the current ratio is controlled so that the torque becomes zero.

[0071] <Modifications of the inverter circuit configuration> The circuit configuration of the inverter is not limited to a T-type NPC three-level inverter, but may be an NPC three-level inverter, such as inverter 8A shown in Fig. 14. Inverter 8A differs from inverter 8 shown in Fig. 1 in the connection form of switch elements Q7 to Q12 and in the addition of diodes D1 to D6. In this case, switch elements Q7 to Q12 and diodes D1 to D6 form an intermediate switch element.

[0072] The source of the switching element Q7 is connected to the node Nu, and its drain is connected to the source of the switching element Q1. The drain of the switching element Q8 is connected to the node Nu, and its source is connected to the drain of the switching element Q2. The anode of the diode D1 is connected to the node Nm, and its cathode is connected to the drain of the switching element Q7. The cathode of the diode D2 is connected to the node Nm, and its anode is connected to the source of the switching element Q8.

[0073] The source of the switching element Q9 is connected to the node Nv, and its drain is connected to the source of the switching element Q3. The drain of the switching element Q10 is connected to the node Nv, and its source is connected to the drain of the switching element Q4. The anode of the diode D3 is connected to the node Nm, and its cathode is connected to the drain of the switching element Q9. The cathode of the diode D4 is connected to the node Nm, and its anode is connected to the source of the switching element Q10.

[0074] The source of the switching element Q11 is connected to the node Nw, and its drain is connected to the source of the switching element Q5. The drain of the switching element Q12 is connected to the node Nw, and its source is connected to the drain of the switching element Q6. The anode of the diode D5 is connected to the node Nm, and its cathode is connected to the drain of the switching element Q11. The cathode of the diode D6 is connected to the node Nm, and its anode is connected to the source of the switching element Q12.

[0075] When the inverter 8A having the above configuration is used, the inverter 8A can function as a step-down converter by turning on the middle switch element of the input phase and synchronously switching the positive switch element, negative switch element and middle switch element of the control phase, which are two phases other than the input phase. In this case, the current flows through the path shown by the thick arrow in FIG. 15.

[0076] The inverter 8, which is a T-type NPC three-level inverter, and the inverter 8A, which is an NPC three-level inverter, each have the following features. First, the inverter 8 has the advantage that the number of elements can be reduced by six compared to the inverter 8A, although only the elements connected to the neutral point can use low-voltage elements with a relatively low withstand voltage, while the elements constituting the bridge must use high-voltage elements with a relatively high withstand voltage. In contrast, the inverter 8A has a greater number of elements than the inverter 8, but has the advantage that all elements can be low-voltage elements.

[0077] Second embodiment The second embodiment will be described below with reference to FIGS. In this embodiment, the content of the control by the control device 9 is different from that in the first embodiment. In this case, the control device 9 controls so that the positive and negative switch elements connected to the phase with the smallest current ratio are turned off when it is determined that the electrical angle when the motor 3 is stopped matches an angle that satisfies the following formula (12), where n is an integer. Electrical angle = 30 degrees + 60 degrees × n … (12)

[0078] It should be noted that "when it is determined that the angles match" in this case does not necessarily mean that the angles match perfectly, but also means that a deviation within a range that achieves the desired level of effect obtained by this embodiment, which will be described later, is acceptable.

[0079] As shown in FIG. 2, when the electrical angle is an angle that satisfies the formula (12), there exists a phase in which the current ratio is 0. Therefore, the control device 9 of this embodiment controls the positive and negative switch elements of the phase in which the current ratio is 0 to be turned off when there is a phase in which the current ratio is 0. In this case, the determination result by the input phase determination unit 20 is as shown in FIG. 16. As shown in FIG. 16, when the electrical angle θe is "30°", "90°", "150°", "210°", "270°" and "330°", the positive and negative switch signals of the phase in which the current ratio is the smallest, more specifically, the current ratio is 0, are set to "0".

[0080] Next, the effects obtained by this embodiment will be described with reference to Fig. 17 and Fig. 18. In addition, the effects obtained by this embodiment will be described below while comparing with a comparative example in which the positive and negative switch elements of the phases in which the current ratio is 0 are switched. Note that Fig. 17 and Fig. 18 show the results of a simulation under the following conditions.

[0081] <Condition> Battery voltage → 800V Intermediate terminal voltage command value → 400V Motor 3 electrical angle when stopped → 30° Switching phases → U phase and V phase

[0082] As shown in Fig. 17, in the comparative example, although the average current is 0, a current ripple occurs. Therefore, in the comparative example, a deviation occurs in the current ratio due to the current ripple, and as a result, a torque ripple occurs due to the current ripple. In contrast, as shown in Fig. 18, in the present embodiment, the positive and negative switch elements of the phases in which the current ratio is 0 are fixed to off, so that the occurrence of torque ripple can be suppressed.

[0083] Third embodiment The third embodiment will be described below with reference to FIGS. This embodiment is different from the first embodiment in the contents of the control by the control device 9. In this case, the control device 9 controls the switching phases of the positive and negative switch elements connected to the two phases other than the input phase among the three phases to be different from each other, that is, performs an interleaving operation.

[0084] In order to realize such control, the control device 9 adds a configuration as shown in Fig. 19 to the PWM modulation units 27u, 27v, and 27w. The divider 41 divides the U-phase phase voltage command Vu* by the detection value VH of the voltage sensor 11a. The output signal of the divider 41 is input to the non-inverting input terminal of the comparator 42. The divider 43 divides the V-phase phase voltage command Vv* by the detection value VH of the voltage sensor 11a. The output signal of the divider 43 is input to the non-inverting input terminal of the comparator 44.

[0085] The carrier generator 45 generates and outputs a carrier which is a triangular wave. The carrier output from the carrier generator 45 is input to the inverting input terminal of the comparator 42 and the inverting amplifier circuit 46. The inverting amplifier circuit 46 inverts and amplifies the input signal and outputs it. The output signal of the inverting amplifier circuit 46 is 180° out of phase with the carrier output from the carrier generator 45 and is input to the inverting input terminal of the comparator 44.

[0086] In the above configuration, the output signal of the comparator 42 becomes the switch signal Su1, and the output signal of the comparator 44 becomes the switch signal Sv1. According to the above configuration, the control device 9 can generate the switch signal Su1 corresponding to one of the two phases other than the input phase based on the carrier output from the carrier generator 45, and generate the switch signal Sv1 corresponding to the other of the two phases other than the input phase based on a signal obtained by inverting and amplifying the carrier output from the carrier generator 45.

[0087] Next, the effects obtained by this embodiment will be described with reference to Fig. 20. In addition, the effects obtained by this embodiment will be described below while comparing with a comparative example in which the switching phases of the positive and negative switch elements connected to the two phases other than the input phase out of the three phases are controlled to be in the same phase. Note that Fig. 20 shows the simulation results under the following conditions.

[0088] <Condition> Battery voltage → 800V Intermediate terminal voltage command value → 400V Motor 3 electrical angle when stopped → 60° Switching phases → U phase and V phase

[0089] As shown in Fig. 20, in the comparative example, the phases of the switching of the two phases are the same, so the peak of the U-phase current and the peak of the V-phase current overlap, and as a result, relatively large ripples are generated in the intermediate terminal voltage, the battery voltage, and the battery current, which is the current of battery 2. In contrast, as shown in Fig. 20, in the present embodiment, the phases of the switching of the two phases are shifted by 180°, that is, there is a phase difference of 180° between the phases of the switching of the two phases. Therefore, according to the present embodiment, the ripples are offset in the two phases, and as a result, the ripples in the intermediate terminal voltage, the battery voltage, and the battery current can be significantly reduced.

[0090] (Fourth embodiment) The fourth embodiment will be described below with reference to FIG. This embodiment is different from the first embodiment in the content of the control by the control device 9. In this case, the voltage control unit 15 of the control device 9 controls the voltage of the intermediate terminal to be equal to the intermediate voltage of the voltage of the battery 2, specifically, 1 / 2 the voltage of the battery 2.

[0091] Next, the effects obtained by this embodiment will be described with reference to Fig. 21. In addition, the effects obtained by this embodiment will be described below while comparing with a comparative example in which the intermediate terminal voltage is controlled to be equal to 1 / 4 of the battery voltage. Note that Fig. 21 shows the simulation results under the following conditions.

[0092] <Condition> Battery voltage → 800V Motor 3 electrical angle when stopped → 60° Switching phases → U phase and V phase Phase difference of switching phase: 180° (same as the third embodiment)

[0093] As shown in Fig. 21, in the comparative example, the gradients of the increase and decrease of the ripple are different for the U-phase current and the V-phase current, so the ripple reduction effect achieved by setting the phase difference of the switching phase to 180° is not sufficiently achieved. In contrast, as shown in Fig. 21, in the present embodiment, the duty is 0.5, so the gradients of the increase and decrease of the ripple are equal for the U-phase current and the V-phase current, and as a result, the ripple reduction effect achieved by setting the phase difference of the switching phase to 180° can be maximized.

[0094] Fifth embodiment The fifth embodiment will be described below with reference to FIGS. 22, a power conversion device 51 of the present embodiment differs from the power conversion device 1 of the first embodiment shown in FIG 1 in that a charging stand communication unit 52 is added and a control device 53 is provided instead of the control device 9. The charging stand communication unit 52 functions as a communication unit that receives a maximum voltage value that indicates the maximum value of the output voltage of the charging stand 14 and is transmitted by the control device 53 from the charging stand 14.

[0095] The maximum voltage value data received by control device 53 may be any data capable of determining the maximum voltage value, such as data indicative of the maximum voltage value itself or a signal capable of identifying the specifications of charging stand 14. Control device 53 differs from control device 9 in that it includes a voltage control unit 54 instead of voltage control unit 15. Voltage control unit 54 has the same functions as voltage control unit 15. However, voltage control unit 54 controls the voltage of the intermediate terminal to be the maximum value of the output voltage of charging stand 14, based on the maximum voltage value provided via charging stand communication unit 52.

[0096] As a specific configuration of the control device 53, for example, a configuration example as shown in Fig. 23 can be adopted. In Fig. 23, the PWM modulation units 27u, 27v, and 27w are collectively shown as the PWM modulation unit 27. The control device 53 of the configuration example shown in Fig. 23 sets the maximum voltage value provided by the charging stand communication unit 52 to the command value VL* of the intermediate terminal voltage. Therefore, the voltage control unit 54 performs PI control based on the command value VL*, which is the maximum voltage value, and the detection value VL of the voltage sensor 11b, to calculate the current command IL*.

[0097] According to the present embodiment described above, the control device 53 receives the maximum voltage value from the charging stand communication unit 52, and sets the maximum voltage value as the command value VL* of the intermediate terminal voltage to control the intermediate terminal voltage. According to this embodiment, the charging power can be maximized, and therefore the charging time can be shortened. Furthermore, according to this embodiment, when charging with the same power, the current of the charging stand 14 is smaller when the voltage of the charging stand 14 is higher, and therefore the loss due to the resistance of the current path can be reduced.

[0098] Sixth embodiment The sixth embodiment will be described below with reference to FIGS. As shown in Fig. 24, a power conversion device 61 of the present embodiment differs from the power conversion device 1 of the first embodiment shown in Fig. 1 in that a charging stand communication unit 62 is added and a control device 63 is provided instead of the control device 9. The charging stand communication unit 62 functions as a communication unit that transmits a charger current command representing a command value for the output current of the charging stand 14 from the control device 63 to the charging stand 14.

[0099] In this case, a power supply current command indicating a command value for the current of the battery 3, transmitted from a higher-level ECU (not shown), is input to the control device 63. Note that the higher-level ECU is assumed to be, for example, a battery ECU that monitors the battery 3. The control device 63 determines a charger current command by multiplying the power supply current command given from the outside by the detection value VH of the voltage sensor 11a and dividing the result by the detection value VL of the voltage sensor 11b.

[0100] 25 may be used as a specific configuration of the control device 63. The control device 63 of the configuration example shown in Fig. 25 includes a divider 64 that divides the detection value VH of the voltage sensor 11a by the detection value VL of the voltage sensor 11b, and a multiplier 65 that multiplies the power supply current command by the output signal of the divider 64. In the above configuration, the output signal of the multiplier 65 becomes a charger current command and is transmitted to the charging stand communication unit 62.

[0101] According to the present embodiment described above, the following effects can be obtained. That is, an ideal converter satisfies the relationship of "input voltage x input current = output voltage x output current". In the above configuration, therefore, when controlling the current of the battery 2, that is, the output current, it is necessary to convert it into an input current, so the power supply current command is multiplied by the ratio of the detected value VH of the battery voltage, which is the output voltage, to the detected value VL of the intermediate terminal voltage, which is the input voltage, to obtain the input current, which is then transmitted to the charging stand 14 as a charger current command. In this way, when the power conversion device 61 is made to function as a converter, the current of the battery 3 can be controlled with high precision.

[0102] Seventh embodiment The seventh embodiment will be described below with reference to FIGS. As shown in FIG. 26, the power conversion device 71 of this embodiment differs from the power conversion device 1 of the first embodiment shown in FIG. 1 in that a charging stand communication unit 72 is added and that a control device 73 is provided instead of the control device 9.

[0103] Similar to the charging stand communication unit 62 in the sixth embodiment, the charging stand communication unit 72 functions as a communication unit that transmits a charger current command representing a command value of the output current of the charging stand 14 from the control device 73 to the charging stand 14. In this case, similar to the control device 63 in the sixth embodiment, a power supply current command is input to the control device 73. The control device 73 calculates the duties of two phases other than the input phase, obtains a duty average value which is the average value of the calculated duties, and obtains the charger current command by performing a calculation to divide the power supply current command by the duty average value.

[0104] As a specific configuration of the control device 73, for example, a configuration example as shown in FIG. 27 can be adopted. The control device 73 of the configuration example shown in FIG. 27 includes an average value calculation unit 74 and a divider 75. In this case, the PWM modulation units 27u and 27v corresponding to two phases other than the input phase, for example, the U phase and the V phase, output signals Du and Dv representing the results of calculating the respective duties to the average value calculation unit 74. The average value calculation unit 74 calculates a duty average value that is the average value of the duties of the U phase and the V phase based on the signals Du and Dv, and outputs a signal Da representing the calculated value. The divider 75 divides the power supply current command by the duty average value. In the above configuration, the output signal of the divider 75 becomes a charger current command and is transmitted to the charging stand communication unit 72.

[0105] According to the present embodiment described above, the following effects can be obtained. That is, an ideal converter satisfies the relationship "output current = duty x input current". Therefore, in the above configuration, when controlling the current of the battery 2, that is, the output current, it is necessary to convert it into an input current, so the power supply current command is divided by the average duty of the two phases to be switched to obtain the input current, and is transmitted to the charging stand 14 as a charger current command. In this way, when the power conversion device 71 is made to function as a converter, the current of the battery 3 can be controlled with high precision.

[0106] (Other embodiments) The present invention is not limited to the embodiments described above and illustrated in the drawings, and can be modified, combined, or expanded in any manner without departing from the spirit and scope of the present invention. The numerical values ​​and the like shown in the above embodiments are merely examples and are not intended to be limiting.

[0107] The positive side capacitor, which is a capacitor connected between the positive electrode of the battery 2 and the node Nm, is not limited to being composed of one capacitor 7a, and may be composed of, for example, two or more capacitors connected in parallel. Also, the negative side capacitor, which is a capacitor connected between the node Nm and the negative electrode of the battery 2, is not limited to being composed of one capacitor 7b, and may be composed of, for example, two or more capacitors connected in parallel.

[0108] Although the present disclosure has been described based on the embodiment, it is understood that the present disclosure is not limited to the embodiment or structure. The present disclosure also includes various modifications and modifications within the equivalent range. In addition, various combinations and forms, and other combinations and forms including only one element, more than one element, or less than one element, are also within the scope and concept of the present disclosure. [Explanation of symbols]

[0109] 1, 51, 61, 71...power conversion device, 2...battery, 3...motor, 3u, 3v, 3w...coil, 6...neutral point, 7a, 7b...capacitor, 9, 53, 63, 73...control device, 11a...voltage sensor, 11b...voltage sensor, 13...charging relay, 14...charging stand, 15, 54...voltage control unit, 16...phase current control unit, 52, 62, 72...charging stand communication unit, D1 to D6...diode, Nm...node, Q1, Q3, Q5...positive side switching element, Q2, Q4, Q6...negative side switching element, Q7 to Q12...intermediate switching element.

Claims

1. A control device used in a power conversion device that converts electric power passing between a power source (2) and a rotating machine (3) having multiple phase coils and a neutral point (6) to which one terminal of each of the multiple phase coils (3u, 3v, 3w) is connected, comprising: The power conversion device is A plurality of capacitors (7a, 7b) connected in series between the positive terminal of the power supply and the negative terminal of the power supply; a plurality of intermediate switch elements (Q7 to Q12, D1 to D6) provided between an intermediate terminal (Nm) to which the plurality of capacitors are connected and each of the coils of the plurality of phases; A plurality of positive pole side switch elements (Q1, Q3, Q5) provided between each of the coils of the plurality of phases and a positive pole of the power source; A plurality of negative pole side switch elements (Q2, Q4, Q6) provided between each of the coils of the plurality of phases and the negative pole of the power source; A control device (9, 53, 63, 73) for controlling the intermediate switch element, the positive switch element, and the negative switch element; a connection portion (13) capable of connecting a charger (14) for charging the power source between the intermediate terminal and the positive terminal or the negative terminal of the capacitor; Equipped with The control device includes: a voltage control unit (15, 54) that controls the voltage of the intermediate terminal to be within a range of an output voltage of the charger by stepping down the voltage of the power source; a phase current control unit (16) that determines an input phase for passing a current of the charger to the rotating machine from among the multiple phases, and controls a current ratio that is a ratio of currents flowing through two phases other than the input phase among the multiple phases; A control device for a power conversion device comprising:

2. the voltage control unit is configured to perform a calculation for controlling the voltage of the intermediate terminal within a range of an output voltage of the charger, The phase current control unit is determining the currents of the multiple phases by performing coordinate transformation using an electrical angle when the rotation of the rotating machine has stopped and a d-axis current value and a q-axis current value at which the torque of the rotating machine is equal to or less than a predetermined threshold torque; determining, as the input phase, a phase corresponding to a maximum current value, which is a maximum absolute value among the calculated current values, which are the current values ​​of the multiple phases; the current ratio of the two phases other than the input phase is set to an absolute value of a value obtained by dividing each of the calculated current values ​​of the plurality of phases by the maximum current value; The control device for a power conversion device according to claim 1 , wherein a result of multiplying the current ratio by a calculation result of the voltage control unit is set as a current command for the multiple phases.

3. The rotating machine serves as a drive source for running a vehicle, The control device for a power conversion device according to claim 2 , wherein the threshold torque is set to a value lower than a holding force of a parking brake provided on the vehicle.

4. The control device for a power conversion device according to claim 2 or 3, wherein the phase current control unit performs the coordinate transformation with a value of the q-axis current set to 0.

5. The control device includes: When n is an integer, The electrical angle when the rotating machine is stopped is expressed by the following formula: Electrical angle = 30 degrees + 60 degrees x n 3. The control device for a power conversion device according to claim 2, wherein when it is determined that the angle matches an angle that satisfies the above, the positive side switching element and the negative side switching element connected to a phase in which the current ratio is smallest are controlled to be turned off.

6. The control device includes:

3. The control device for a power conversion device according to claim 1, wherein the positive side switching element and the negative side switching element connected to two phases other than the input phase among the multiple phases are controlled so that their switching phases are different from each other.

7. The control device for a power conversion device according to claim 6 , wherein the voltage control unit controls the voltage at the intermediate terminal to coincide with an intermediate voltage of the voltages of the power sources.

8. Further, a communication unit (52) is provided for receiving a maximum voltage value representing a maximum value of an output voltage of the charger from the charger to the control device (53), 3. The control device for a power conversion device according to claim 1, wherein the voltage control unit (54) controls the voltage at the intermediate terminal to be a maximum value of an output voltage of the charger, based on the maximum voltage value.

9. moreover, a communication unit (62) that transmits a charger current command representing a command value of an output current of the charger from the control device (63) to the charger; a first voltage sensor (11a) for detecting a first voltage which is a voltage of the power supply; a second voltage sensor (11b) for detecting a second voltage between the intermediate terminal and a negative electrode of the power source; Equipped with 3. The control device for a power conversion device according to claim 1 or 2, wherein the control device (63) is configured to obtain the charger current command by performing a calculation of multiplying a power supply current command representing a command value of the current of the power supply given from outside by the detection value of the first voltage sensor and dividing the power supply current command by the detection value of the second voltage sensor.

10. Further, a communication unit (72) is provided for transmitting a charger current command representing a command value of an output current of the charger from the control device (73) to the charger, The control device (73) The driving of the positive side switch element and the negative side switch element is PWM controlled, The duties of two phases other than the input phase are calculated, and an average duty ratio is calculated as an average of the calculated duties.

3. The control device for a power conversion device according to claim 1, wherein the charger current command is determined by performing a calculation of dividing a power supply current command, which indicates a command value of a current of the power supply given from the outside, by the duty average value.

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