Rotating electric machine control device and program

Abstract

To provide a control device for a rotary electrical machine and a program that are capable of reducing the ripple current flowing through a capacitor.SOLUTION: A control device 40 sets a drive command such that first and second inverters 20A and 20B alternatively output a reactive voltage vector and an effective voltage vector while causing the reactive voltage vectors of the first and second inverters 20A and 20B to appear sequentially, and performs switching controls of the first and second inverters 20A and 20B based on the set drive command. The control device 40 sets a drive command such that an effective voltage vector appears in which the magnitude of the direct current component flowing through a smoothing capacitor 22 is maximum in an intermediate period among the output periods of the effective voltage vector sandwiched between the output periods of the reactive vector, and, in the other periods, the effective voltage vector appears in which the magnitude of the direct current component is smaller in magnitude than the effective voltage vector appearing in the intermediate period.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a control device for a rotating electrical machine and a program. [Background technology]

[0002] As described in Patent Document 1, a conventional system is known that includes a rotating electric machine, two power conversion circuits electrically connected to the rotating electric machine, a capacitor provided on the input side of each power conversion circuit and common to the power conversion circuits, and a DC power supply connected in parallel to the capacitor. This system includes a control device that performs switching control of the power conversion circuits to control the control amount of the rotating electric machine to a command value. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-120296 Summary of the Invention [Problem to be solved by the invention]

[0004] In order to reduce the ripple current flowing through the capacitor, there is a technique for controlling the switching of each power conversion circuit so that each power conversion circuit alternately outputs a reactive voltage vector and an active voltage vector while sequentially generating a reactive voltage vector of each power conversion circuit. Despite the existence of such a technique, there is still room for improvement in reducing the ripple current flowing through the capacitor.

[0005] A primary object of the present invention is to provide a control device and program for a rotating electrical machine that can reduce ripple current flowing through a capacitor. [Means for solving the problem]

[0006] The present invention includes a rotating electric machine and a plurality of power conversion circuits electrically connected to the rotating electric machine; a capacitor electrically connected to the input side of each of the power conversion circuits and common to each of the power conversion circuits; a DC power supply connected in parallel to the capacitor, a setting unit that sets a drive command for each of the power conversion circuits such that each of the power conversion circuits alternately outputs a reactive voltage vector and an active voltage vector while sequentially causing a reactive voltage vector of each of the power conversion circuits to appear; a control unit that performs switching control of each of the power conversion circuits based on the drive command, The setting unit sets the drive command such that, in each of the power conversion circuits, an effective voltage vector having the maximum magnitude of the DC current component flowing through the capacitor appears in an intermediate period of an effective period, which is an output period of an effective voltage vector sandwiched between output periods of a reactive voltage vector, and in other periods, an effective voltage vector appears whose DC current component is smaller in magnitude than the effective voltage vector appearing in the intermediate period.

[0007] This makes it possible to prevent the output periods of the maximum effective voltage vectors from overlapping in the power conversion circuits, thereby effectively reducing the ripple current flowing through the capacitor. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is an overall configuration diagram of a control system according to a first embodiment. [Figure 2] FIG. 3 is a functional block diagram showing the processing of the control device. [Figure 3] A diagram showing voltage vectors. [Figure 4] FIG. 3 is a diagram showing the relationship between voltage vectors and the driving states of each phase. [Figure 5] FIG. 10 is a diagram showing an example of a 60-degree voltage vector. [Figure 6] FIG. 10 is a diagram showing an example of a 120-degree voltage vector. [Figure 7]4 is a flowchart showing the procedure for setting a drive command for each inverter. [Figure 8] FIG. 4 is a diagram for explaining a method for calculating a DC bus current. [Figure 9] 4 is a time chart showing the transition of a drive command, etc. [Figure 10] 6 is a time chart showing the transition of a drive command etc. according to Comparative Example 1. [Figure 11] 10 is a time chart showing the transition of a drive command etc. according to Comparative Example 2. [Figure 12] FIG. 10 is a diagram for explaining a method for calculating a current difference. [Figure 13] FIG. 10 is a diagram showing the effect of reducing ripple current in a smoothing capacitor. [Figure 14] 10 is a flowchart showing the procedure of a process for setting drive commands for each inverter according to a second embodiment. [Figure 15] 10 is a flowchart showing the procedure of a process for setting drive commands for each inverter according to a third embodiment. [Figure 16] FIG. 10 is an overall configuration diagram of a control system according to a fourth embodiment. [Figure 17] 4 is a time chart showing the transition of a drive command, etc. DETAILED DESCRIPTION OF THE INVENTION

[0009] First Embodiment DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of a control device according to the present invention will now be described with reference to the drawings. The control device of this embodiment constitutes a control system mounted on a vehicle.

[0010] As shown in FIG. 1, the control system includes a rotating electric machine 10. The rotating electric machine 10 is a permanent magnet field type synchronous machine with three-phase double windings. The rotating electric machine 10 of this embodiment is a permanent magnet type synchronous machine. The rotating electric machine 10 serves as a power source for running a vehicle and includes a rotor 12 capable of transmitting power to drive wheels, and a stator 13. The rotor 12 includes permanent magnets that serve as field poles. The stator 13 is provided with two armature winding groups, a first winding group 10A and a second winding group 10B. The rotor 12 is shared by the first and second winding groups 10A and 10B. The first and second winding groups 10A and 10B each include a three-phase winding with a different neutral point. The first winding group 10A includes U-, V-, and W-phase windings UA, VA, and WA, which are offset from one another by 120 electrical degrees, while the second winding group 10B includes U-, V-, and W-phase windings UB, VB, and WB, which are offset from one another by 120 electrical degrees. In this embodiment, the first winding group 10A and the second winding group 10B have the same configuration. Specifically, the number of turns of each of the U-, V-, and W-phase windings UA, VA, and WA that make up the first winding group 10A is equal to the number of turns of each of the U-, V-, and W-phase windings UB, VB, and WB that make up the second winding group 10B.

[0011] Incidentally, the phase difference Δθ between the first winding group 10A and the second winding group 10B may be, for example, 0 electrical degrees or 30 electrical degrees.

[0012] The control system includes first and second inverters 20A and 20B corresponding to the first and second winding groups 10A and 10B, a DC power supply 21, and a smoothing capacitor 22. The first and second inverters 20A and 20B correspond to power conversion circuits that convert an input DC voltage into an AC voltage and output it. A common DC power supply 21 is connected to each of the first inverter 20A and the second inverter 20B. In this embodiment, the DC power supply 21 is a storage battery.

[0013] The first inverter 20A includes a series-connected assembly of first U-, V-, and W-phase upper-arm switches SuAH, SvAH, and SwAH and first U-, V-, and W-phase lower-arm switches SuAL, SvAL, and SwAL. U-, V-, and W-phase windings UA, VA, and WA that constitute the first winding group 10A are connected to the connection points of the above-mentioned series-connected assembly in the U-, V-, and W-phases. In this embodiment, each of the switches SuAH to SwAL is an N-channel MOSFET and includes a body diode.

[0014] Similar to the first inverter 20A, the second inverter 20B includes a series-connected assembly of second U-, V-, and W-phase upper-arm switches SuBH, SvBH, and SwBH and second U-, V-, and W-phase lower-arm switches SuBL, SvBL, and SwBL. U-, V-, and W-phase windings UB, VB, and WB constituting the second winding group 10B are connected to the connection points of the series-connected assembly in the U-, V-, and W-phases. In this embodiment, each of the switches SuBH to SwBL is an N-channel MOSFET and includes a body diode.

[0015] The switches provided in each of the inverters 20A and 20B are not limited to N-channel MOSFETs, but may be IGBTs, for example, in which case a freewheel diode may be connected in anti-parallel to the switch.

[0016] In the first inverter 20A, a first end of a smoothing capacitor 22 is connected to the drain, which is the high potential side terminal, of each of the upper arm switches SuAH, SvAH, and SwAH, via a first high potential side path LHA. In the first inverter 20A, a second end of the smoothing capacitor 22 is connected to the source, which is the low potential side terminal, of each of the lower arm switches SuAL, SvAL, and SwAL, via a first low potential side path LLA. A negative terminal of the DC power supply 21 is connected to the second end of the smoothing capacitor 22. A positive terminal of the DC power supply 21 is connected to the first end of the smoothing capacitor 22.

[0017] In the second inverter 20B, the drains of the upper arm switches SuBH, SvBH, and SwBH are connected to a midpoint of the first high potential side path LHA via a second high potential side path LHB. In the second inverter 20B, the sources of the lower arm switches SuBL, SvBL, and SwBL are connected to a midpoint of the first low potential side path LLA via a second low potential side path LLB. In other words, in this embodiment, the smoothing capacitor 22 is shared by the inverters 20A and 20B.

[0018] The control system includes a voltage detection unit 30, a first current detection unit 31A, a second current detection unit 31B, and an angle detection unit 32. The voltage detection unit 30 detects the terminal voltage of the smoothing capacitor 22 as a power supply voltage VDC. The angle detection unit 32 detects the rotation angle (electrical angle) of the rotating electric machine 10. The angle detection unit 32 is, for example, a resolver. The detection values ​​of the above detection units 30, 31A, 31B, 32 are input to a control device 40 provided in the control system.

[0019] The control device 40 acquires the three-phase currents flowing through the first winding group 10A and the three-phase currents flowing through the second winding group 10B based on the detection values ​​of the first and second current detection units 31A and 31B. For example, the first current detection unit 31A detects the currents flowing through a conductive member (e.g., a bus bar) electrically connecting the first inverter 20A and the first winding group 10A, and detects the currents for at least two phases of the three-phase currents flowing through the first winding group 10A. In this case, for example, a CT-type current sensor that directly detects phase currents may be used as the first current detection unit 30A. Furthermore, for example, the first current detection unit 31A detects the current flowing in the first high potential side path LHA closer to the first inverter 20A than the connection point with the second high potential side path LHB. In this case, the control device 40 acquires the phase current flowing through the first winding group 10A based on the detection value of the first current detection unit 31A and the relationship between the switching state of the first inverter 20A and the phase current shown in Fig. 4. The same applies to the second current detection unit 31B.

[0020] The control device 40 is primarily composed of a microcomputer 40a, which includes a CPU. The functions provided by the microcomputer 40a can be provided by software stored in a physical memory device and a computer executing the software, software alone, hardware alone, or a combination thereof. For example, if the microcomputer 40a is provided by a hardware electronic circuit, the function can be provided by a digital circuit including multiple logic circuits or an analog circuit. For example, the microcomputer 40a executes a program stored in a non-transitory tangible storage medium serving as a storage unit of the microcomputer 40a. The program includes, for example, programs for the processes shown in FIGS. 2 and 6. Execution of the program results in the execution of a method corresponding to the program. The storage unit is, for example, a non-volatile memory. The programs stored in the storage unit can be updated via a network such as the Internet, for example, via OTA (Over the Air) or other means.

[0021] The control device 40 generates drive commands to turn on and off each switch of the first and second inverters 20A, 20B based on the input detection values ​​in order to control the control variable of the rotating electric machine 10 to a command value. The switches are turned on and off by charging and discharging the gates of the switches based on the drive commands. In each phase, the upper arm switch and the lower arm switch are alternately turned on with a dead time therebetween. The control variable in this embodiment is torque. Using FIG. 2, the torque control of the rotating electric machine 10 executed by the control device 40 will be described.

[0022] The command current setting unit 41 sets first d- and q-axis command currents IdA* and IqA* corresponding to the first inverter 20A and second d- and q-axis command currents IdB* and IqB* corresponding to the second inverter 20B based on the command torque Trq*. The command currents IdA*, IqA*, IdB*, and IqB* may be calculated, for example, by minimum current maximum torque per amplitude (MTPA) control.

[0023] The first conversion unit 42A converts the U-, V-, and W-phase currents of the first winding group 10A in the three-phase fixed coordinate system into a first d-axis current IdAr and a first q-axis current IqAr in a two-phase rotating coordinate system (dq coordinate system) based on the detection value of the first current detection unit 31A and the electrical angle θe detected by the angle detection unit 32.

[0024] The first current control unit 43A calculates a first d-axis command voltage VdA* as a manipulated variable for feedback-controlling the first d-axis current IdAr to the first d-axis command current IdA*. The first current control unit 43A calculates a first q-axis command voltage VqA* as a manipulated variable for feedback-controlling the first q-axis current IqAr to the first q-axis command current IqA*. The feedback control used by the first current control unit 43A is, for example, proportional-integral control.

[0025] The second conversion unit 42B converts the U-, V-, and W-phase currents of the second winding group 10B in the three-phase fixed coordinate system into a second d-axis current IdBr and a second q-axis current IqBr in the dq coordinate system based on the detection value of the second current detection unit 31B and the electrical angle θe.

[0026] The second current control unit 43B calculates a second d-axis command voltage VdB* as a manipulated variable for feedback-controlling the second d-axis current IdBr to the second d-axis command current IdB*. The second current control unit 43B calculates a second q-axis command voltage VqB* as a manipulated variable for feedback-controlling the second q-axis current IqBr to the second q-axis command current IqB*. The feedback control used by the second current control unit 43B is, for example, proportional-integral control.

[0027] Based on the calculated values ​​VdA*, VqA*, IdAr, IqAr, VdB*, VqB*, IdBr, and IqBr, as well as the electrical angle θe, the switch control unit 44 determines a drive command for the first inverter 20A to realize a voltage vector applied from the first inverter 20A to the first winding group 10A and a drive command for the second inverter 20B to realize a voltage vector applied from the second inverter 20B to the second winding group 10B. The switch control unit 44 sets drive commands for the first and second inverters 20A and 20B in the next specified period, in the current specified period, so that the current ripple in the smoothing capacitor 22 in the next specified period Tsw is reduced. In this embodiment, the specified period Tsw is the switching period of the upper and lower arm switches constituting the inverters. The switching period corresponds to one period of the carrier signal in PWM control using a carrier signal.

[0028] The drive command is composed of a combination of voltage vectors shown in Figures 3 and 4. In Figure 4, "H" indicates that the upper arm switch is on, and "L" indicates that the lower arm switch is on. The first to sixth voltage vectors V1 to V6 are active voltage vectors (non-zero voltage vectors), and the zeroth and seventh voltage vectors V0 and V7 are reactive voltage vectors (zero voltage vectors). The first, third, and fifth voltage vectors V1, V3, and V5 are odd-numbered voltage vectors, and the second, fourth, and sixth voltage vectors V2, V4, and V6 are even-numbered voltage vectors.

[0029] In FIG. 4, "Iinv" denotes a current flowing through the inverter. In this embodiment, as shown in FIG. 1, the current flowing through the first high potential side path LHA on the first inverter 20A side relative to the connection point with the second high potential side path LHB is referred to as the first inverter current IinvA. The current flowing through the second high potential side path LHB is referred to as the second inverter current IinvB. The sign of each of the inverter currents IinvA and IinvB is positive when it flows from the smoothing capacitor 22 side toward the inverter side.

[0030] The inverter current Iinv in FIG. 4 will be described using the first inverter 20A as an example. When the voltage vectors output from the first inverter 20A are the 0th and 7th voltage vectors V0 and V7, the first inverter current IinvA is 0. When the voltage vector output from the first inverter 20A is the first voltage vector V1, the first inverter current IinvA is equal to the U-phase current of the first winding group 10A. When the voltage vector output from the first inverter 20A is the fourth voltage vector V4, the first inverter current IinvA is equal in magnitude to the U-phase current of the first winding group 10A and flows in the opposite direction to the U-phase current. The relationship between the active voltage vectors of the V and W phases and the first inverter current IinvA is similar to that of the U phase.

[0031] A method for setting the inverter drive command will be described.

[0032] First, the first inverter 20A will be described. The switch control unit 44 calculates a first command voltage vector VtrA in a three-phase fixed coordinate system based on the first d-axis command voltage VdA*, the first q-axis command voltage VqA*, and the electrical angle θe. The switch control unit 44 selects a 60-degree voltage vector or a 120-degree voltage vector as two active voltage vectors sandwiching the first command voltage vector VtrA.

[0033] The 60-degree voltage vectors are two effective voltage vectors that sandwich the first command voltage vector VtrA and have a phase difference of 60 degrees, as shown in Fig. 5. Fig. 5 shows an example in which the first and second voltage vectors V1 and V2 are selected as effective voltage vectors.

[0034] The 120-degree voltage vectors are two effective voltage vectors that sandwich the first command voltage vector VtrA and have a phase difference of 120 degrees, as shown in Fig. 6. Fig. 6 shows an example in which the second and sixth voltage vectors V2 and V6, which are even-numbered voltage vectors, are selected as the effective voltage vectors.

[0035] The switch control unit 44 sets a drive command, which is a command switching pattern such that the two selected active voltage vectors Vα and Vβ and the reactive voltage vector appear in the specified period Tsw. The switch control unit 44 calculates output periods Tα and Tβ of the active voltage vectors Vα and Vβ in the specified period Tsw based on the first command voltage vector VtrA. The switch control unit 44 calculates the output period Tz of the reactive voltage vector in the specified period Tsw by "Tz = Tsw - (Tα + Tβ)".

[0036] The drive command for the second inverter 20B is set in the same manner as for the first inverter 20A. The switch control unit 44 calculates a second command voltage vector VtrB based on the second d-axis command voltage VdB*, the second q-axis command voltage VqB*, and the electrical angle θe. The switch control unit 44 selects a 60-degree voltage vector or a 120-degree voltage vector as two active voltage vectors sandwiching the second command voltage vector VtrB. The switch control unit 44 sets a drive command such that the two selected active voltage vectors and the reactive voltage vector appear in the specified cycle Tsw. In this embodiment, the switch control unit 44 sets the drive command by space vector modulation (SVM). In this embodiment, the switch control unit 44 corresponds to the "setting unit" and the "control unit."

[0037] The drive command setting process executed by the switch control unit 44 will be described with reference to Fig. 7. The following describes an example in which the first command voltage vector VtrA and the second command voltage vector VtrB are set to the same voltage vector. However, this setting is not limiting, and the first command voltage vector VtrA and the second command voltage vector VtrB may be set to different voltage vectors.

[0038] In step S10, the modulation factor Mr is calculated. The modulation factor Mr is a value obtained by normalizing the magnitude of the command voltage vector with the power supply voltage VDC, for example, a value obtained by dividing the magnitude of the command voltage vector by the power supply voltage VDC. When the first command voltage vector VtrA and the second command voltage vector VtrB are set to the same voltage vector, the modulation factor Mr can be calculated using either the first or second command voltage vector VtrA, VtrB. The processing in step S10 corresponds to the "modulation factor calculation unit."

[0039] In step S11, it is determined whether the calculated modulation factor Mr exceeds a threshold value Mth (for example, 0.6). The process of step S11 is a process for determining whether to select a 60-degree voltage vector or a 120-degree voltage vector. The process of step S11 corresponds to the "selection unit."

[0040] If it is determined in step S11 that the modulation factor Mr exceeds the threshold value Mth, the process proceeds to step S12, where 60-degree voltage vectors sandwiching the first command voltage vector VtrA are selected as effective voltage vectors for setting the drive command for the first inverter 20A, and 60-degree voltage vectors sandwiching the second command voltage vector VtrB are selected as effective voltage vectors for setting the drive command for the second inverter 20B.

[0041] In step S12, the DC bus current Idc when one of the 60-degree voltage vectors sandwiching the first command voltage vector VtrA is selected and the DC bus current Idc when the other is selected are calculated. The DC bus current Idc is the above-mentioned first inverter current IinvA. Then, the magnitude (specifically, for example, absolute value) of the two calculated DC bus currents Idc is determined. An example will be described with reference to FIG. 8, where first and second voltage vectors V1 and V2 are selected as 60-degree voltage vectors. In FIG. 8, Idc(i) indicates the DC bus current Idc that flows when the ith voltage vector Vi is selected. The DC bus current Idc can be calculated, for example, by the following two methods.

[0042] The first method will be described. DC current information, which is map information or formula information correlating the DC bus current Idc(i) and the electrical angle θe, is stored in the storage unit of the control device 40. The switch control unit 44 calculates the DC bus current Idc(1) when the first voltage vector V1 is selected and the DC bus current Idc(2) when the second voltage vector V2 is selected, based on the DC current information and the current electrical angle θe. The second method will be described. The control device 40 knows the voltage vector (V1, V2) to be used next. Therefore, the switch control unit 44 calculates the DC bus current Idc(1) when the first voltage vector V1 is selected and the DC bus current Idc(2) when the second voltage vector V2 is selected, based on the voltage vector to be used next and the relationship between the voltage vector and the inverter current Iinv shown in FIG. 4.

[0043] Then, the calculated DC bus currents Idc(1) and Idc(2) are compared, and it is determined that the magnitude of the DC bus current Idc(1) is greater than the magnitude of the DC bus current Idc(2). This determination result is used to determine the order of the active voltage vectors sandwiched between reactive voltage vectors during the output period of the active voltage vectors.

[0044] 9(b) and 9(e), the drive command for the first inverter 20A is set so that two active voltage vectors are sandwiched between reactive voltage vectors. Specifically, the drive command is set so that an active voltage vector (V1) having the maximum magnitude (|IU|) of the DC bus current Idc appears in an intermediate period (specifically, a central period) among the active periods, which are output periods of active voltage vectors (V1, V2) sandwiched between output periods of a reactive voltage vector (V7), and an active voltage vector (V2) having a smaller magnitude (|-IW|) of the DC bus current Idc than the active voltage vector appearing in the intermediate period appears in other periods.

[0045] More specifically, the drive commands are set so that an effective voltage vector (V2, V1) appears such that the magnitude of the DC bus current Idc gradually increases (|-IW|→|IU|) from the start of the valid period to the intermediate period, and an effective voltage vector (V1, V2) appears such that the magnitude of the DC bus current Idc gradually decreases (|IU|→|-IW|) from the intermediate period to the end of the valid period. In the example shown in Fig. 9(b), the second voltage vector V2, the first voltage vector V1, and the second voltage vector V2 appear in this order during the valid period sandwiched between the seventh voltage vector.

[0046] For the 60-degree voltage vectors sandwiching the second command voltage vector VtrB, the DC bus current Idc is calculated in the same manner as for the first command voltage vector VtrA. In this case, the DC bus current Idc in step S12 is the second inverter current IinvB. Then, a drive command is set so that an effective voltage vector (V1) whose magnitude of the DC bus current Idc is maximum appears in an intermediate period (specifically, a central period) among the output periods of the effective voltage vectors (V1, V2) sandwiched between the output periods of the reactive voltage vector (V7), and an effective voltage vector (V2) whose magnitude of the DC bus current Idc is smaller than that of the effective voltage vector appearing in the intermediate period appears in the other periods.

[0047] As shown in FIGS. 9(d) and 9(f), the drive command for the second inverter 20B is shifted in phase from the drive command for the first inverter 20A by 1 / 2 (180 degrees) of the specified period Tsw. This prevents the output periods of the reactive voltage vectors (V7) of the first and second inverters 20A and 20B from overlapping, resulting in a drive command that causes the first and second inverters 20A and 20B to alternately output reactive and active voltage vectors. This effectively reduces the ripple current flowing through the smoothing capacitor 22. The current ripple is quantified, for example, by the difference between the maximum and minimum values ​​of the current flowing through the smoothing capacitor 22 during the specified period Tsw. FIG. 9(g) shows the transition of the total current It, which is the sum of the first inverter current IinvA and the second inverter current IinvB. The fluctuation ΔI of the total current It correlates with the ripple current flowing through the smoothing capacitor 22.

[0048] 9, the drive commands for the first and second inverters 20A and 20B are set so that the output periods of the effective voltage vector (V1) in which the DC bus current Idc is maximized in the first and second inverters 20A and 20B do not overlap, thereby further enhancing the effect of reducing the ripple current.

[0049] Note that when the 60-degree voltage vector is selected, if the modulation factor Mr increases further, the output period of the active voltage vector (V1) at which the DC bus current Idc is maximized becomes longer. As a result, a drive command may be set such that the output period of the active voltage vector (V1) at which the DC bus current Idc is maximized in the first inverter 20A partially overlaps with the output period of the active voltage vector (V1) at which the DC bus current Idc is maximized in the second inverter 20B. On the other hand, if the modulation factor Mr decreases, the output period of the reactive voltage vector (V7) becomes longer. As a result, a drive command may be set such that the output period of the reactive voltage vector (V7) at the first inverter 20A partially overlaps with the output period of the reactive voltage vector (V7) at the second inverter 20B.

[0050] 9(a) and (c) show the transitions of the carrier signals SgA and SgB and the U-, V-, and W-phase command time ratios DUA, DVA, DWA, DUB, DVB, and DWB. The carrier signals and command time ratios are used when drive commands are set by PWM control based on a comparison of the magnitudes of the carrier signals and command time ratios, rather than by space vector modulation. The U-, V-, and W-phase command time ratios are calculated by dividing the U-, V-, and W-phase command voltages VU, VV, and VW, which are calculated based on the d- and q-axis command voltages and electrical angle θe in the d-q coordinate system, by the power supply voltage VDC.

[0051] As examples for comparison with this embodiment, Comparative Example 1 is shown in Fig. 10 and Comparative Example 2 is shown in Fig. 11. Comparative Example 1 is configured such that the drive commands for first and second inverters 20A and 20B are synchronized. In Comparative Example 1, the ripple current of smoothing capacitor 22 is significantly larger than in this embodiment.

[0052] In Comparative Example 2, the first and second inverters 20A and 20B are provided with drive commands that alternately output reactive voltage vectors and active voltage vectors without overlapping the output periods of the reactive voltage vectors (V0, V7) of the first and second inverters 20A and 20B. However, in Comparative Example 2, the active voltage vectors are not arranged such that the magnitude of the DC bus current Idc gradually increases and then gradually decreases during the output periods of the active voltage vectors sandwiched between the reactive voltage vectors. Therefore, in Comparative Example 2, the ripple current of the smoothing capacitor 22 is larger than in this embodiment.

[0053] Returning to the explanation of FIG. 7, in step S13, if the selected 60-degree voltage vector with the larger DC bus current Idc is an odd-numbered voltage vector, top-flat control is performed. Top-flat control is a control in which the upper arm switches are fixed to ON and the lower arm switches are fixed to OFF for one of the three phases. The drive command shown in FIG. 9 is a drive command for top-flat control.

[0054] On the other hand, if the selected 60-degree voltage vector with the larger DC bus current Idc is an even voltage vector, bottom flat control is performed. Bottom flat control is a control that continues to fix the upper arm switch to OFF and the lower arm switch to ON for one of the three phases.

[0055] If it is determined in step S11 that the modulation factor Mr is equal to or less than the threshold value Mth, the process proceeds to step S14, where the 120-degree voltage vectors are selected as the two effective voltage vectors. The following description will be given taking the first command voltage vector VtrA as an example.

[0056] In step S14, when two odd-numbered voltage vectors are selected as 120-degree voltage vectors sandwiching the first command voltage vector VtrA, the respective DC bus currents Idc are calculated, and when two even-numbered voltage vectors are selected, the respective DC bus currents Idc are calculated. This calculation may be performed by a method using the current electrical angle θe and the above-described DC current information, as described in step S12, or a method using a voltage vector to be used next and the relationship between the voltage vectors and the inverter current Iinv shown in FIG.

[0057] In step S15, an odd current difference ΔIodd, which is the difference between the DC bus currents Idc when two odd voltage vectors are selected, and an even current difference ΔIeven, which is the difference between the DC bus currents Idc when two even voltage vectors are selected, are calculated. Fig. 12 shows an example in which the odd current difference ΔIodd is calculated as the difference between Idc(1) and Idc(3), and an example in which the even current difference ΔIeven is calculated as the difference between Idc(2) and Idc(4).

[0058] In step S16, it is determined whether the odd current difference ΔIodd is smaller than the even current difference ΔIeven. If it is determined in step S16 that they are smaller, the process proceeds to step S17, where two odd voltage vectors sandwiching the first command voltage vector VtrA are selected as 120-degree voltage vectors used to set the drive command. On the other hand, if it is determined in step S16 that the even current difference ΔIeven is smaller than the odd current difference ΔIodd, the process proceeds to step S18, where two even voltage vectors sandwiching the first command voltage vector VtrA are selected as 120-degree voltage vectors used to set the drive command. The process of step S16 can enhance the effect of reducing the ripple current flowing through the smoothing capacitor 22.

[0059] In step S19, drive commands for the first and second inverters 20A and 20B are set based on the two active voltage vectors selected in step S17 or S18 and the reactive voltage vector, similarly to step S13.

[0060] According to the present embodiment described above, the effective value of the ripple current flowing through the smoothing capacitor 22 can be suitably reduced, as shown in FIG.

[0061] Second Embodiment The second embodiment will be described below with reference to the drawings, focusing on the differences from the first embodiment. In this embodiment, the method of selecting an effective voltage vector used to set a drive command is changed.

[0062] Fig. 14 shows the procedure of the drive command setting process executed by the switch control unit 44. In Fig. 14, the same processes as those shown in Fig. 7 are denoted by the same reference numerals.

[0063] In step S20, the first invalid period Tv1 is calculated by subtracting the output period of the 60-degree voltage vectors that sandwich the first command voltage vector VtrA in the specified period Tsw from the specified period Tsw. Note that the output period of the 60-degree voltage vector may be calculated based on the first command voltage vector VtrA.

[0064] Thereafter, a first time difference ΔT1, which is the difference between the output period in the specified cycle Tsw of the 60-degree voltage vector and the first invalid period Tv1, is calculated.

[0065] In step S21, the second odd invalid period Tv2odd is calculated by subtracting the output periods of the 120-degree voltage vectors that sandwich the first command voltage vector VtrA in the specified period Tsw from the specified period Tsw. Here, the 120-degree voltage vectors used in step S21 are two odd voltage vectors. Note that the output periods of the 120-degree voltage vectors may be calculated based on the first command voltage vector VtrA.

[0066] Thereafter, a second odd time difference ΔT2odd, which is the difference between the output period in the specified cycle Tsw of the 120-degree voltage vector and the second odd invalid period Tv2odd, is calculated.

[0067] In step S22, the second even invalid period Tv2even is calculated by subtracting the output periods of the 120-degree voltage vectors that sandwich the first command voltage vector VtrA in the specified period Tsw from the specified period Tsw. Here, the 120-degree voltage vectors used in step S21 are two even voltage vectors.

[0068] Thereafter, the second even time difference ΔT2even, which is the difference between the output period in the specified cycle Tsw of the 120-degree voltage vector and the second even invalid period Tv2even, is calculated.

[0069] In step S23, the smaller of the second odd number time difference ΔT2odd and the second even number time difference ΔT2even is selected as the second time difference ΔT2.

[0070] In step S24, it is determined whether the first time difference ΔT1 is smaller than the second time difference ΔT2. If it is determined in step S24 that the first time difference ΔT1 is smaller than the second time difference ΔT2, the 60-degree voltage vector is selected from the 60-degree voltage vector and the 120-degree voltage vector, and the process proceeds to step S12. The processing in steps S20 to S24 corresponds to the "selection unit."

[0071] On the other hand, if it is determined in step S24 that the second time difference ΔT2 is smaller than the first time difference ΔT1, the 120-degree voltage vector is selected from the 60-degree voltage vector and the 120-degree voltage vector, and the process proceeds to step S25. In step S25, when two active voltage vectors are selected, the respective DC bus currents Idc are calculated. The two active voltage vectors used in step S25 are the 120-degree voltage vector corresponding to the second time difference ΔT2 selected in step S23 from the second odd time difference ΔT2odd and the second even time difference ΔT2even. In this embodiment, whether to use the even voltage vector or the odd voltage vector has already been determined in step S23, and therefore the processes corresponding to steps S15 to S18 in FIG. 7 are not required.

[0072] In steps S20 to S24, the selection of the effective voltage vector used to set the drive command for the second inverter 20B is also performed in the same manner as for the first inverter 20A.

[0073] After the process of step S25 is completed, in step S19, drive commands for the first and second inverters 20A, 20B are set based on the two active voltage vectors and the reactive voltage vector used in step S25, similarly to step S13.

[0074] The processing of steps S20 to S24 allows the output period of the active voltage vector and the output period of the reactive voltage vector to be brought closer together in the specified cycle Tsw. This effectively prevents the output period of the active voltage vector in which the DC bus current Idc in the first inverter 20A is maximized from overlapping with the output period of the active voltage vector in which the DC bus current Idc in the second inverter 20B is maximized. As a result, the ripple current flowing through the smoothing capacitor 22 can be effectively reduced.

[0075] <Third embodiment> The third embodiment will be described below with reference to the drawings, focusing on the differences from the first embodiment. In this embodiment, even if a 120-degree voltage vector is selected, if the ripple of the phase current is larger than a predetermined value Ith, a 60-degree voltage vector is selected.

[0076] Fig. 15 shows the procedure of the drive command setting process executed by the switch control unit 44. In Fig. 15, the same processes as those shown in Fig. 7 are denoted by the same reference numerals.

[0077] After completing the process of step S17 or S18, the process proceeds to step S30, where a phase current ripple ΔIr when two active voltage vectors are used is calculated based on the two selected active voltage vectors. The phase current ripple is a value quantified by, for example, the difference between the maximum and minimum values ​​of the phase current in the specified period Tsw. An example of a method for calculating the phase current ripple will be described below.

[0078] The voltage equation in the rotating electrical machine 10 is expressed as the following equation (eq1).

[0079]

number

[0080]

number

[0081]

number

[0082] If it is determined in step S31 that the phase current ripple ΔIr is equal to or smaller than the predetermined value Ith, the process proceeds to step S19, where the 120-degree voltage vector is used to set the drive command. On the other hand, if it is determined in step S31 that the phase current ripple ΔIr is greater than the predetermined value Ith, the process proceeds to step S13, where the 60-degree voltage vector is used to set the drive command.

[0083] According to the present embodiment described above, it is possible to reduce the ripple current flowing through the smoothing capacitor 22 while suppressing an increase in the ripple of the phase current.

[0084] <Fourth embodiment> The fourth embodiment will be described below with reference to the drawings, focusing on the differences from the first embodiment. In this embodiment, as shown in Fig. 16, the rotating electric machine 10 further includes a third winding group 10C. In Fig. 16, the same components as those shown in Fig. 1 are denoted by the same reference numerals for convenience.

[0085] The control system includes a third inverter 20C electrically connected to the third winding group 10C. The configuration of the third inverter 20C is similar to the configurations of the first and second inverters 20A and 20B.

[0086] In the third inverter 20C, the drain of the upper arm switch of each phase is connected to a midpoint of the second high potential side path LHB via a third high potential side path LHC. In the third inverter 20C, the source of the lower arm switch of each phase is connected to a midpoint of the second low potential side path LLB via a third low potential side path LLC. In other words, in this embodiment, the smoothing capacitor 22 is shared by each of the inverters 20A to 20C.

[0087] The control system includes a third current detection unit. Similar to the first and second current detection units 31A and 31B, the control device 40 acquires three-phase currents flowing through the third winding group 10C based on the detection values ​​of the third current detection unit.

[0088] The control device 40 generates drive commands to turn on and off the switches of the first to third inverters 20A to 20C based on the input detection values ​​in order to control the torque of the rotating electric machine 10 to the command torque Trq*. Note that IinvC shown in Fig. 16 denotes the third inverter current flowing through the third high potential side path LHC. In this case, the total current It is "IinvA + InvB + InvC".

[0089] Fig. 17 shows an example of drive commands for the first to third inverters 20A to 20C of this embodiment. Note that the subscript C in the symbols shown in Fig. 17 indicates a parameter corresponding to the third inverter 20C. Fig. 17 also shows a case where the third command voltage vector VtrC of the third inverter 20C is the same as the first and second command voltage vectors VtrA and VtrB.

[0090] In this embodiment, in each of the inverters 20A to 20C, a drive command is set so that, among the output periods of the effective voltage vectors (V1, V2) sandwiched between the output periods of the reactive voltage vector (V7), an effective voltage vector (V1) whose magnitude of the DC bus current Idc is maximum appears in the central period, and in other periods, an effective voltage vector (V2) whose magnitude of the DC bus current Idc is smaller than that of the effective voltage vector appearing in the central period appears.

[0091] 17, the drive command for the second inverter 20B is a command obtained by shifting the phase of the drive command for the first inverter 20A by 1 / 3 (120 degrees) of the specified period Tsw. Also, the drive command for the third inverter 20C is a command obtained by shifting the phase of the drive command for the second inverter 20B by 1 / 3 of the specified period Tsw. This results in drive commands such that the output periods of the reactive voltage vector (V7) of each of the inverters 20A to 20C do not overlap, and each of the inverters 20A to 20C alternately outputs a reactive voltage vector and an active voltage vector.

[0092] According to this embodiment, it is possible to achieve the same effects as in the first embodiment.

[0093] <Other embodiments> The above-described embodiments may be modified as follows.

[0094] The control system may include the same number of rotating electric machines as the number of inverters. For example, in the control system shown in Fig. 1, the first inverter 20A is electrically connected to the first rotating electric machine, and the second inverter 20B is electrically connected to the second rotating electric machine.

[0095] The number of inverters may be four or more. When the number of inverters is N, the drive commands for each inverter may be shifted by, for example, 1 / N × specified period Tsw.

[0096] The number of phases of the inverter is not limited to three, but may be four or more (for example, five).

[0097] The rotating electric machine may be, for example, an in-wheel motor integrally mounted on a drive wheel of a vehicle, or an on-board motor mounted on the body of the vehicle. The rotating electric machine and inverter may be integrated with a transmission. The rotating electric machine is not limited to a main motor that serves as a power source for driving a vehicle, but may also be an auxiliary motor used in an electric power steering device, an electric fan, a pump, or the like.

[0098] The rotating electrical machine is not limited to a star-connected one, but may be a delta-connected one.

[0099] The control system is not limited to being applied to vehicles, but may also be applied to aircraft, ships, or railway vehicles.Furthermore, the control system is not limited to being applied to moving objects such as vehicles, but may also be applied to robots (for example, industrial robots), generators, or elevators.

[0100] The control unit and the method described herein may be implemented by a special-purpose computer configured by configuring a processor and memory programmed to perform one or more functions embodied in a computer program. Alternatively, the control unit and the method described herein may be implemented by a special-purpose computer configured by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the control unit and the method described herein may be implemented by one or more special-purpose computers configured by combining a processor and memory programmed to perform one or more functions with a processor configured with one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by a computer on a computer-readable non-transitory tangible storage medium. [Explanation of symbols]

[0101] 10... rotating electric machine, 20A, 20B... first and second inverters, 22... smoothing capacitor, 40... control device

Claims

1. A rotating electric machine (10), a plurality of power conversion circuits (20A to 20C) electrically connected to the rotating electric machine; a capacitor (22) electrically connected to the input side of each of the power conversion circuits and common to each of the power conversion circuits; a DC power supply (21) connected in parallel to the capacitor, and a control device (40) for a rotating electric machine that performs switching control of each of the power conversion circuits, a setting unit (44) that sets a drive command for each of the power conversion circuits such that each of the power conversion circuits alternately outputs a reactive voltage vector and an active voltage vector while sequentially causing a reactive voltage vector of each of the power conversion circuits to appear; a control unit (44) that performs switching control of each of the power conversion circuits based on the drive command, The setting unit sets the drive command in each of the power conversion circuits so that an effective voltage vector having the maximum magnitude of the DC current component flowing through the capacitor appears in an intermediate period of an effective period, which is an output period of an effective voltage vector sandwiched between output periods of a reactive voltage vector, and so that an effective voltage vector having a DC current component smaller in magnitude than the effective voltage vector appearing in the intermediate period appears in other periods.

2. 2. The control device for a rotating electric machine according to claim 1, wherein the setting unit sets the drive command such that an effective voltage vector appears in which the magnitude of the DC current component gradually increases from the start timing of the effective period to the intermediate period, and an effective voltage vector appears in which the magnitude of the DC current component gradually decreases from the intermediate period to the end timing of the effective period.

3. The control device for a rotating electric machine according to claim 1 , wherein the setting unit sets the drive command such that output periods of the maximum effective voltage vectors in the power conversion circuits do not overlap.

4. a modulation factor calculation unit that calculates a modulation factor based on a command voltage vector for controlling a control amount of the rotary electric machine to a command value and the voltage of the DC power supply; a selection unit that selects whether to use 60-degree voltage vectors, which are two effective voltage vectors sandwiching the command voltage vector and having a phase difference of 60 degrees, or 120-degree voltage vectors, which are two effective voltage vectors sandwiching the command voltage vector and having a phase difference of 120 degrees, the setting unit sets the drive command based on the selected 60-degree voltage vector or the selected 120-degree voltage vector; The selection unit If the modulation rate exceeds a threshold, the 60-degree voltage vector is selected; 4. The control device for a rotating electric machine according to claim 1, wherein the 120-degree voltage vector is selected when the modulation factor is equal to or less than the threshold value.

5. a selection unit that selects whether to use 60-degree voltage vectors, which are two effective voltage vectors sandwiching a command voltage vector for controlling a control amount of the rotary electric machine to a command value and having a phase difference of 60 degrees, or 120-degree voltage vectors, which are two effective voltage vectors sandwiching the command voltage vector and having a phase difference of 120 degrees, the setting unit sets the drive command for a specified period for each specified period based on the selected 60-degree voltage vector or the selected 120-degree voltage vector; The selection unit calculating a first invalid period by subtracting an output period of the 60-degree voltage vector included in the specified period from the specified period; calculating a first time difference that is a difference between an output period of the 60-degree voltage vector and the first invalid period; calculating a second invalid period by subtracting an output period of the 120-degree voltage vector included in the specified period from the specified period; calculating a second time difference that is the difference between the output period of the 120-degree voltage vector and the second invalid period; If the first time difference is less than the second time difference, selecting the 60 degree voltage vector; 4. The control device for a rotating electric machine according to claim 1, wherein the 120-degree voltage vector is selected when the second time difference is smaller than the first time difference.

6. 5. The control device for a rotating electric machine according to claim 4, wherein, when the 120-degree voltage vector is selected by the selection unit, the setting unit uses, for setting the drive command, one of two even voltage vectors that are on either side of the command voltage vector and have a phase difference of 120 degrees, or two odd voltage vectors that are on either side of the command voltage vector and have a phase difference of 120 degrees, the vector having a smaller magnitude of the DC current component.

7. 7. The control device for a rotating electric machine according to claim 4, wherein when the 60-degree voltage vector is selected by the selection unit, the setting unit fixes a drive state of one of the upper and lower arm switches (SuAH to SwBL) of each phase constituting the power conversion circuit.

8. The setting unit When the 120-degree voltage vector is selected by the selection unit, a ripple of a phase current flowing through the rotating electric machine is calculated; The control device for a rotating electric machine according to any one of claims 4 to 7, wherein when the calculated ripple of the phase current is larger than a predetermined amount, the 60 degree voltage vector is used to set the drive command instead of the 120 degree voltage vector.

9. A rotating electric machine (10), a plurality of power conversion circuits (20A to 20C) electrically connected to the rotating electric machine; a capacitor (22) electrically connected to the input side of each of the power conversion circuits and common to each of the power conversion circuits; a DC power supply (21) connected in parallel to the capacitor; A program applied to a system including a computer (40a), The computer a setting unit that sets a drive command such that each of the power conversion circuits alternately outputs a reactive voltage vector and an active voltage vector while sequentially causing a reactive voltage vector of each of the power conversion circuits to appear; a control unit that controls the switching of each of the power conversion circuits based on the drive command; The setting unit sets the drive command in each of the power conversion circuits so that an effective voltage vector having the maximum magnitude of the DC current component flowing through the capacitor appears in an intermediate period of an effective period, which is an output period of an effective voltage vector sandwiched between output periods of a reactive voltage vector, and so that an effective voltage vector having a smaller magnitude of the DC current component flowing through the capacitor than the effective voltage vector appearing in the intermediate period appears in other periods.

Images