Rotating electric machine control device and program

Abstract

To provide a rotating electric machine control device and a program capable of reducing a ripple current of a capacitor while reducing the amount of calculation.SOLUTION: A control device 40 sets the switching patterns of first and second inverters 20A and 20B in a prescribed cycle. The control device 40 sets a plurality of candidate timings for the switching timing of some of the voltage vectors constituting the switching pattern of the first inverter 20A, and calculates an evaluation function for evaluating a ripple current of a smoothing capacitor 22 when each candidate timing is set. The control device 40 determines the switching pattern of the first inverter 20A in a prescribed cycle on the basis of the evaluation function. The control device 40 sets, as the candidate timings, timings corresponding to switching timings of the voltage vectors forming the switching pattern of second inverter 20B.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Conventionally, as described in Patent Document 1, there is known a system including a rotating electric machine, a power conversion circuit electrically connected to the rotating electric machine, and a capacitor provided on the input side of the power conversion circuit. This system includes a control device that performs switching control of the power conversion circuit to control the control amount of the rotating electric machine to a command value.

[0003] In order to reduce the ripple current flowing through the capacitor, the control device determines a switching pattern to be adopted in the next control period based on model predictive control (MPC). More specifically, the control device sets multiple switching states of the power conversion circuit in each prediction period obtained by dividing the control period into multiple periods. This results in multiple switching patterns being set as combinations of the switching states.

[0004] When multiple switching patterns are set, the control device calculates an evaluation function having as input parameters the deviation between the controlled variable and the command value and the current flowing through the capacitor. The control device determines the switching pattern to be adopted in the next control cycle by selecting the switching pattern corresponding to the evaluation function with the smallest value among the evaluation functions corresponding to the set switching patterns. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-40423 [Non-patent literature]

[0006] [Non-Patent Document 1] “Capacitor current reducing control of the inverters for the dual winding motor”, IECON 2015- 41st Annual Conference of the IEEE Industrial Electronics Society, 2015, pp. 000499-000504 Summary of the Invention [Problem to be solved by the invention]

[0007] As a system for controlling the drive of a rotating electric machine, a system including a plurality of power conversion circuits electrically connected to the rotating electric machine and a capacitor provided on the input side of each power conversion circuit and common to each power conversion circuit is also known. When model predictive control is applied to a system including a plurality of power conversion circuits, it is necessary to set a plurality of switching patterns for each power conversion circuit. As a result, there is a concern that the number of candidates for switching patterns to be searched for in model predictive control will increase, and the amount of calculation of the control device will increase. In particular, there is a concern that the increase in the amount of calculation will be significant when the prediction period is set to be short.

[0008] It is possible to set the prediction period longer to suppress the increase in the amount of calculations, but in this case, there is a concern that the discretization error will increase and it will not be possible to set an optimal switching pattern that can reduce the ripple current of the capacitor.

[0009] A primary object of the present invention is to provide a control device and program for a rotating electrical machine that can reduce the amount of calculation while reducing the ripple current in a capacitor. [Means for solving the problem]

[0010] The present invention includes a rotating electric machine and a plurality of power conversion circuits electrically connected to the rotating electric machine; a capacitor provided on an input side of each of the power conversion circuits and common to each of the power conversion circuits, a setting unit that sets a switching pattern of each of the power conversion circuits in a specified period based on a command voltage vector to be applied to the rotating electric machine; a function calculation unit that, when a part of the power conversion circuits among the power conversion circuits is set as a calculation target circuit and a switching pattern of the calculation target circuit is set as a target pattern, sets a plurality of candidate timings for switching timings of a part of the voltage vectors among the voltage vectors constituting the target pattern set by the setting unit, and calculates an evaluation function for evaluating a ripple current of the capacitor when each of the candidate timings is set; a determination unit that determines the target pattern in the specified period based on each of the calculated evaluation functions; a switch control unit that, when a power conversion circuit other than the calculation target circuit among the power conversion circuits is set as a non-target circuit and a switching pattern of the non-target circuit is set as a reference pattern, performs switching control of the non-target circuit so that the switching pattern of the non-target circuit in the specified period becomes the reference pattern set by the setting unit, and performs switching control of the calculation target circuit so that the switching pattern of the calculation target circuit in the specified period becomes the target pattern determined by the determination unit, The function calculation unit sets a timing corresponding to a switching timing of a voltage vector constituting the reference pattern as the candidate timing.

[0011] In the present invention, a target pattern of a calculation target circuit is set by a setting unit, and a plurality of candidate timings are set by searching for switching timings of some voltage vectors constituting the target pattern. Then, an evaluation function for evaluating a ripple current of a capacitor when each candidate timing is set is calculated. Based on the evaluation function calculated corresponding to each candidate timing, a target pattern in a specified period is determined.

[0012] In the present invention, the timing corresponding to the switching timing of the voltage vector constituting the reference pattern in the non-target circuit among the power conversion circuits is set as the candidate timing in the calculation target circuit. Therefore, the number of candidate timings to be searched can be reduced. This makes it possible to reduce the amount of calculation and reduce the ripple current of the capacitor. [Brief description of the drawings]

[0013] [Figure 1] 1 is an overall configuration diagram of a control system according to a first embodiment. [Diagram 2] FIG. 4 is a functional block diagram showing the processing of the control device. [Diagram 3] A diagram showing voltage vectors. [Figure 4] FIG. 4 is a diagram showing the relationship between voltage vectors and the switching states of each phase. [Diagram 5] FIG. 4 is a diagram showing an example of voltage vectors that configure a switching pattern. [Figure 6] FIG. 4 is a diagram showing switching patterns of first and second inverters. [Figure 7] FIG. 13 is a diagram showing how a plurality of candidate timings are set for the end timing of the 0th voltage vector as a search target for model predictive control. [Figure 8] FIG. 4 is a diagram showing a switching pattern of a first inverter determined by model predictive control. [Figure 9] FIG. 13 is a diagram showing how a plurality of candidate timings are set for the end timing of a seventh voltage vector as a search target for model predictive control. [Figure 10] FIG. 4 is a diagram showing a switching pattern of a first inverter determined by model predictive control. [Figure 11] 4 is a time chart showing changes in a first inverter current, a second inverter current, and an inverter sum current; [Figure 12] 4 is a flowchart showing a procedure for torque control of a rotating electric machine based on model predictive control. [Figure 13]11 is a flowchart showing the procedure of an evaluation function calculation process. [Figure 14] 4 is a flowchart showing the procedure of a subroutine A. [Figure 15] 11 is a flowchart showing the procedure of a subroutine B. [Figure 16] FIG. 11 is a diagram showing a switching pattern of a first inverter determined by model predictive control according to a modified example of the first embodiment. [Figure 17] FIG. 11 is a diagram showing a switching pattern of a first inverter determined by model predictive control according to a modified example of the first embodiment. [Figure 18] 10 is a flowchart showing the procedure of an evaluation function calculation process according to a second embodiment. [Figure 19] 4 is a flowchart showing the procedure of a subroutine A. [Figure 20] 11 is a flowchart showing the procedure of a subroutine B. [Figure 21] FIG. 13 is a diagram showing an example of voltage vectors that configure a switching pattern according to the third embodiment. [Figure 22] FIG. 13 is a diagram showing how a plurality of candidate timings are set for the end timing of the 0th voltage vector as a search target for model predictive control. [Diagram 23] FIG. 4 is a diagram showing a switching pattern of a first inverter determined by model predictive control. [Figure 24] FIG. 13 is a diagram showing how a plurality of candidate timings are set for the end timing of a seventh voltage vector as a search target for model predictive control. [Diagram 25] FIG. 4 is a diagram showing a switching pattern of a first inverter determined by model predictive control. [Figure 26] FIG. 13 is a diagram showing an example of voltage vectors that configure a switching pattern according to the fourth embodiment. [Figure 27] FIG. 13 is a diagram showing how a plurality of candidate timings are set for the end timing of the 0th voltage vector as a search target for model predictive control. [Figure 28] FIG. 4 is a diagram showing a switching pattern of a first inverter determined by model predictive control. [Figure 29] FIG. 13 is a diagram showing how a plurality of candidate timings are set for the end timing of a seventh voltage vector as a search target for model predictive control. [Diagram 30] FIG. 4 is a diagram showing a switching pattern of a first inverter determined by model predictive control. [Diagram 31] FIG. 13 is a diagram showing an example of voltage vectors that configure a switching pattern according to the fifth embodiment. [Diagram 32] FIG. 13 is a diagram showing how a plurality of candidate timings are set for the end timing of a seventh voltage vector as a search target for model predictive control. [Diagram 33] FIG. 4 is a diagram showing a switching pattern of a first inverter determined by model predictive control. [Diagram 34] FIG. 13 is a diagram showing an example of voltage vectors that configure a switching pattern according to the sixth embodiment. [Diagram 35] 13 is a diagram showing how a plurality of candidate timings are set for the end timing of a first voltage vector as a search target for model predictive control. FIG. [Diagram 36] FIG. 4 is a diagram showing a switching pattern of a first inverter determined by model predictive control. [Figure 37] FIG. 13 is an overall configuration diagram of a control system according to a seventh embodiment. [Figure 38] FIG. 13 is a diagram showing how a plurality of candidate timings are set for the end timing of the 0th voltage vector as a search target for model predictive control. [Figure 39] FIG. 4 is a diagram showing a switching pattern of a first inverter determined by model predictive control. [Diagram 40] FIG. 13 is a diagram showing how a plurality of candidate timings are set for the end timing of a seventh voltage vector as a search target for model predictive control. [Diagram 41] FIG. 4 is a diagram showing a switching pattern of a first inverter determined by model predictive control. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] 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.

[0015] 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 having three-phase double windings. The rotating electric machine 10 of this embodiment is a permanent magnet type synchronous machine. The rotating electric machine 10 is a power source for running a vehicle and includes a rotor 12 capable of transmitting power to driving 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. Each of the first and second winding groups 10A and 10B is made up of a three-phase winding having a different neutral point. The first winding group 10A has U-, V-, and W-phase windings UA, VA, and WA that are offset from each other by 120 degrees in electrical angle, and the second winding group 10B has U-, V-, and W-phase windings UB, VB, and WB that are offset from each other by 120 degrees in electrical angle. 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 constitute 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 constitute the second winding group 10B.

[0016] 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.

[0017] The control system includes first and second inverters 20A, 20B corresponding to the first and second winding groups 10A, 10B, a DC power supply 21, and a smoothing capacitor 22. The first and second inverters 20A, 20B correspond to a power conversion circuit that converts an input DC voltage into an AC voltage and outputs 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.

[0018] The first inverter 20A includes a series connection 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 constituting the first winding group 10A are connected to the connection points of the series connection 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.

[0019] The second inverter 20B, like the first inverter 20A, includes a series connection 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 connection 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.

[0020] The switches included in each of the inverters 20A and 20B are not limited to N-channel MOSFETs, and may be IGBTs, for example. In this case, it is sufficient that a freewheel diode is connected in inverse parallel to the switch.

[0021] In the first inverter 20A, a first end of a smoothing capacitor 22 is connected to a drain which is a 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 a source which is a 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.

[0022] In the second inverter 20B, the drains of the upper arm switches SuBH, SvBH, and SwBH are connected to a middle portion 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 middle portion 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.

[0023] 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.

[0024] The control device 40 acquires the three-phase current flowing through the first winding group 10A and the three-phase current 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 current flowing through a conductive member (e.g., a bus bar) electrically connecting the first inverter 20A and the first winding group 10A, and detects at least two phases of the three-phase current flowing through the first winding group 10A. Also, for example, the first current detection unit 31A detects the current flowing on the first inverter 20A side of the connection point with the second high potential side path LHB in the first high potential side path LHA. 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.

[0025] The control device 40 is mainly composed of a microcomputer 40a, and the microcomputer 40a includes a CPU. The functions provided by the microcomputer 40a can be provided by software recorded in a substantial memory device and a computer that executes the software, by software alone, by hardware alone, or by a combination of these. For example, when the microcomputer 40a is provided by an electronic circuit that is hardware, it can be provided by a digital circuit including a large number of logic circuits, or an analog circuit. For example, the microcomputer 40a executes a program stored in a non-transitory tangible storage medium as a storage unit provided in the microcomputer 40a. The program includes, for example, programs for the processes shown in FIG. 2 and FIG. 12 to FIG. 15. By executing the program, a method corresponding to the program is executed. The storage unit is, for example, a non-volatile memory. The program stored in the storage unit can be updated via a network such as the Internet, such as OTA (Over The Air).

[0026] The control device 40 generates drive signals for turning 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 amount of the rotating electric machine 10 to a command value. The drive signals are input to the gates of the switches to turn the switches on and off. In each phase, the upper arm switch and the lower arm switch are alternately turned on with a dead time therebetween. The control amount in this embodiment is torque. The torque control of the rotating electric machine 10 executed by the control device 40 will be described with reference to FIG. 2.

[0027] 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 by, for example, minimum current maximum torque control (MTPA).

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] A model predictive control unit (hereinafter, predictive control unit 44) determines a switching pattern of the first inverter 20A for realizing a voltage vector applied from the first inverter 20A to the first winding group 10A and a switching pattern of the second inverter 20B for realizing a voltage vector applied from the second inverter 20B to the second winding group 10B based on the calculated values ​​VdA*, VqA*, IdAr, IqAr, VdB*, VqB*, IdBr, IqBr, and the electrical angle θe, etc. The predictive control unit 44 determines the switching patterns of the first and second inverters 20A and 20B in the next specified period in the current specified period so that the current ripple of the smoothing capacitor 22 in the next specified period is reduced.

[0033] The switching patterns are made up of combinations of voltage vectors shown in Fig. 3 and Fig. 4. In Fig. 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). Hereinafter, the sign of the voltage vector corresponding to the first inverter 20A may be given the subscript A, and the sign of the voltage vector corresponding to the second inverter 20B may be given the subscript B.

[0034] "Iinv" in FIG. 4 is a current flowing through the inverter. In this embodiment, as shown in FIG. 1, a current flowing through the first high potential side path LHA on the first inverter 20A side from the connection point with the first low potential side path LLA is referred to as a first inverter current IinvA. A current flowing through the second high potential side path LHB is referred to as a second inverter current IinvB. Each of the inverter currents IinvA and IinvB has a positive sign when it flows from the smoothing capacitor 22 side toward the inverter side. The sum of the first inverter current IinvA and the second inverter current IinvB is referred to as an inverter sum current Isum. The inverter sum current Isum has a positive sign when it flows from the smoothing capacitor 22 side toward the inverter side.

[0035] 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 effective voltage vectors of the V and W phases and the first inverter current IinvA is similar to that of the U phase.

[0036] The predictive control unit 44 determines a switching pattern in a prescribed period based on the second command voltage vector VtrB in the dq coordinate system determined by the second d- and q-axis command voltages VdB* and VqB*. In this embodiment, as shown in FIG. 5, a switching pattern is determined that is a combination of two effective voltage vectors, which sandwich the second command voltage vector VtrB and have a phase difference of 60 degrees, and two reactive voltage vectors V0 and V7, among six effective voltage vectors. FIG. 5 shows an example in which the first and second voltage vectors V1 and V2 are selected as the two effective voltage vectors sandwiching the second command voltage vector VtrB. In this embodiment, hereinafter, a case in which the first and second voltage vectors V1 and V2 and the zeroth and seventh voltage vectors V0 and V7 are selected in the second inverter 20B (corresponding to the "non-target circuit") will be described as an example.

[0037] FIG. 6(b) shows a switching pattern (corresponding to a "reference pattern") of the second inverter 20B. Note that FIG. 6(b) shows a switching pattern in two specified periods. Two specified periods correspond to one switching period of each switch constituting each of the inverters 20A, 20B. When a carrier signal is used, one switching period is one period of the carrier signal. Incidentally, the specified period may be set to, for example, a period longer than one switching period.

[0038] The length of one specified period is Ts / 2, and the total output period of two active voltage vectors having a phase difference of 60 degrees in the specified period is "TE1+TE2." The prediction control unit 44 sets the total output period Tz of two reactive voltage vectors V0 and V7 in the specified period to "Ts / 2-(TE1+TE2)."

[0039] The prediction control unit 44 performs switching control of the switches SuBH to SwBL constituting the second inverter 20B so that the switching pattern of the second inverter 20B becomes the switching pattern determined by the above-mentioned method.

[0040] The predictive control unit 44 determines a switching pattern (corresponding to a "target pattern") in a specified period based on the first command voltage vector VtrA in the dq coordinate system determined by the first d- and q-axis command voltages VdA* and VqA*. In this embodiment, as in the case of the second inverter 20B, a switching pattern consisting of a combination of two active voltage vectors and two reactive voltage vectors V0 and V7 having a phase difference of 60 degrees between them, sandwiching the first command voltage vector VtrA, is determined (see FIG. 5). FIG. 6(a) shows the switching pattern of the first inverter 20A. In this embodiment, hereinafter, a case where the first and second voltage vectors V1 and V2 and the zeroth and seventh voltage vectors V0 and V7 are selected in the first inverter 20A (corresponding to a "calculation target circuit") will be described as an example.

[0041] As shown in Fig. 6, the switching patterns VtA and VtB of the inverters 20A and 20B are switching patterns in which the reactive voltage vector of the first inverter 20A and the reactive voltage vector of the second inverter 20B appear alternately. Specifically, the start timings of the switching patterns VtA and VtB of the first and second inverters 20A and 20B are shifted by 1 / 2 a specified period. This is to reduce the current ripple of the smoothing capacitor 22. The current ripple is a value quantified by, for example, the difference between the maximum value and the minimum value of the current flowing through the smoothing capacitor 22 in a specified period.

[0042] In order to further reduce the current ripple, the predictive control unit 44 searches for the end timing tx of the reactive voltage vector that appears first in each specified period by model predictive control. In other words, the predictive control unit 44 searches for the output period of the reactive voltage vector that appears first. Explained with reference to FIG. 6(a), the predictive control unit 44 searches for the output period T0 of the zeroth voltage vector V0A that appears first in the first specified period, and searches for the output period of the seventh voltage vector V7A that appears first in the second specified period.

[0043] When the predictive control unit 44 completes the search for the end timing tx that can reduce the current ripple, it places the first and second voltage vectors V1A and V2A next to the zeroth voltage vector V0A without changing the output periods T1 and T2 of the first and second voltage vectors V1A and V2A that were set based on the first command voltage vector VtrA. The predictive control unit 44 places the seventh voltage vector V7A next to the second voltage vector V2A. The predictive control unit 44 sets the output period T7 of the seventh voltage vector V7A that appears last in the specified period to "Ts / 2-(T0+T1+T2)".

[0044] The prediction control unit 44 controls the switching of the switches SuAH to SwAL constituting the first inverter 20A so that the switching pattern of the first inverter 20A becomes the switching pattern determined by the above-mentioned method.

[0045] The process of searching for the end timing tx of the reactive voltage vector executed by the prediction control unit 44 will be further described with reference to FIGS.

[0046] First, the search process in the first specified period (0 to Ts / 2) shown in FIG. 6 will be described with reference to FIG. 6 to FIG.

[0047] As shown in FIG. 6(a), in the switching pattern of the first inverter 20A in the first specified period, the first maximum number of switching times SAmax of the voltage vector is three.

[0048] On the other hand, in the switching pattern of the second inverter 20B in the first specified period, a second maximum switching count SBmax of the voltage vector is expressed by the following equation (eq1).

[0049]

number

[0050] As shown in Figure 7, the predictive control unit 44 selects a candidate timing for the end timing tx of the 0th voltage vector V0A from among the four switching timings tB[1], tB[2], tB[3], and tB[4] of the voltage vectors that constitute the switching pattern VtB of the second inverter 20B.

[0051] In this embodiment, the predictive control unit 44 selects, as a candidate timing for the end timing tx, a switching timing that can maintain the total output period "T0+T7" of the 0th and 7th voltage vectors V0A and V7A set based on the first command voltage vector VtrA to be the same period before and after the adjustment of the end timing tx. In other words, the predictive control unit 44 performs an exclusion process to exclude, from the candidate timing for the end timing tx, switching timings that make the output period of the 0th voltage vector V0A longer than the total output period "T0+T7" of the 0th and 7th voltage vectors V0A and V7A shown in FIG. 6(a). This is to avoid a situation in which the voltage vector applied to the first winding group 10A cannot be the first command voltage vector VtrA. 7, among the four switching timings tB[1], tB[2], tB[3], and tB[4], the third and fourth switching timings tB[3] and tB[4] are excluded from the candidate timings of the end timing tx of the zeroth voltage vector V0A. This omits the calculation process of the evaluation function Jcr corresponding to the third and fourth switching timings tB[3] and tB[4], and the amount of calculation in the control device 40 can be reduced.

[0052] The prediction control unit 44 determines a switching pattern VtA when the end timing tx is set to the first switching timing tB[1], and calculates an evaluation function Jcr when this switching pattern VtA is adopted. The evaluation function Jcr is a function for evaluating the ripple current of the smoothing capacitor 22, and the smaller the value, the smaller the ripple current. A method for calculating the evaluation function Jcr will be described in detail later.

[0053] The prediction control unit 44 determines a switching pattern VtA in the case where the end timing tx is set to the second switching timing tB[2], and calculates an evaluation function Jcr in the case where this switching pattern VtA is adopted.

[0054] The prediction control unit 44 determines the switching pattern VtA corresponding to the evaluation function having the smaller value of the two evaluation functions Jcr as the switching pattern of the first inverter 20A. FIG. 8 shows an example in which the first switching timing tB[1] is set to the end timing tA[1] of the 0th voltage vector V0A of the first inverter 20A. The output period (tA[1] to tA[2]) of the first voltage vector V1A in FIG. 8(a) is the same length as T1 in FIG. 6(a), and the output period (tA[2] to tA[3]) of the second voltage vector V2A in FIG. 8(a) is the same length as T2 in FIG. 6(a). In addition, the total output period of the 0th and 7th voltage vectors V0A and V7A in FIG. 8(a) is the same length as the total output period of the 0th and 7th voltage vectors V0A and V7A in FIG. 6(a).

[0055] Next, the search process in the second specified period (Ts / 2 to Ts) shown in FIG. 6 will be described with reference to FIG. 6, FIG. 9, and FIG.

[0056] As shown in FIG. 6(a), in the switching pattern of the first inverter 20A in the second specified period, the first maximum number of switching times SAmax of the voltage vector is three.

[0057] On the other hand, in the switching pattern of the second inverter 20B in the second specified period, a second maximum switching count SBmax of the voltage vector is expressed by the following equation (eq2).

[0058]

number

[0059] As shown in Figure 9, the predictive control unit 44 selects a candidate timing for the end timing tx of the seventh voltage vector V7A from the two switching timings tB[1], tB[2] of the voltage vectors that constitute the switching pattern VtB of the second inverter 20B.

[0060] By performing the above-mentioned exclusion process, the prediction control unit 44 excludes the second switching timing tB[2] from the candidate timings, and selects the first switching timing tB[1] as the candidate timing tx.

[0061] The predictive control unit 44 determines a switching pattern VtA when the end timing tx is set to the first switching timing tB[1], and calculates an evaluation function Jcr when this switching pattern VtA is adopted. Incidentally, when there is only one candidate timing tx, the predictive control unit 44 may determine a switching pattern of the second inverter 20B that adopts the only candidate timing without calculating the evaluation function Jcr. FIG. 10 shows an example in which the first switching timing tB[1] is set to the end timing tA[1] of the seventh voltage vector V7A of the first inverter 20A.

[0062] Next, the calculation process of the evaluation function Jcr executed by the prediction control unit 44 will be described with reference to Fig. 11. Fig. 11 shows the transitions of the first inverter current IinvA, the second inverter current IinvB, and the inverter sum current Isum.

[0063] In this embodiment, the candidate timing tx coincides with the switching timing of the voltage vector of the second inverter 20B. However, as a modified example of this embodiment, a configuration in which the candidate timing tx is shifted from the switching timing of the voltage vector can also be adopted. In order to explain the calculation method of the evaluation function Jcr in each of the configuration in which the candidate timing tx coincides with the switching timing and the configuration in which the candidate timing tx is shifted from the switching timing, FIG. 11 shows the transition when the candidate timing tx is shifted from the switching timing.

[0064] The effective value Icrms of the current flowing through the smoothing capacitor 22 in the specified period (0 to Ts / 2) is expressed by the following equation (eq3). The effective value Icrms of the capacitor current is a correlation value of the current ripple of the smoothing capacitor 22. In the following equation (eq3), Isrms represents the effective value of the inverter sum current Isum in the specified period (0 to Ts / 2). Isave represents the average value of the inverter sum current Isum in the specified period (0 to Ts / 2) (hereinafter referred to as the sum current average value). The effective value Isrms of the inverter sum current Isum is expressed by the following equation (eq4).

[0065]

number

[0066]

number

[0067]

number

[0068] In this embodiment, the prediction control unit 44 calculates the sum current average value Isave using the following equation (eq6). In the following equation (eq6), mA indicates a first modulation factor of the output voltage of the first inverter 20A, and mB indicates a second modulation factor of the output voltage of the second inverter 20B. IA indicates a maximum value of the output phase current of the first inverter 20A, and IB indicates a maximum value of the output phase current of the second inverter 20B. φA indicates a phase difference (i.e., power factor) of the output phase current of the first inverter 20A with respect to the output phase voltage of the first inverter 20A. φB indicates a phase difference of the output phase current of the first inverter 20A with respect to the output phase voltage of the second inverter 20B.

[0069]

number

[0070] The prediction control unit 44 predicts the first and second inverter currents IinvA and IinvB at each Δts in order to calculate the inverter sum current Isum at each Δts in the above formula (eq5). For this prediction method, the current prediction method described in the above Patent Document 1 may be used. Taking the first inverter current IinvA as an example, the prediction control unit 44 predicts the first inverter current IinvA[1] at ts[1], which is future than ts[0], based on the first inverter current IinvA[0] at ts[0] grasped based on the detection value of the first current detection unit 31A, the voltage vectors at ts[0] and ts[1], and the motor model. Then, the prediction control unit 44 predicts the first inverter current IinvA[2] at ts[2], which is future than ts[1], based on the first inverter current IinvA[1] at ts[1], the voltage vectors at ts[1] and ts[2], and the motor model. By repeating this, the prediction control unit 44 predicts the first inverter current IinvA at each Δts in one specified period (0 to Ts / 2). The prediction control unit 44 calculates the inverter sum current Isum at each Δts based on the predicted first and second inverter currents IinvA and IinvB at each Δts. Note that the process of acquiring the currents IinvA, IinvB, and Isum by the prediction and calculation process corresponds to a "current acquisition unit."

[0071] The first and second inverter currents IinvA and IinvB at each Δts may be predicted, for example, by the following method instead of the above-mentioned method. The prediction control unit 44 obtains the phase currents grasped based on the detection values ​​of the first and second current detection units 31A and 31B, and predicts the first and second inverter currents IinvA and IinvB at each future Δts by shifting the phase of the obtained phase currents. This makes it possible to perform current prediction without using a motor model.

[0072] 12 to 15, the procedure of torque control of the rotating electric machine 10 executed by the prediction control unit 44 will be described. This control process is repeatedly executed at a predetermined processing period, for example. The processing period is sufficiently shorter than Ts / 4. In order to explain the torque control in each of a configuration in which the candidate timing tx coincides with the switching timing and a configuration in which the candidate timing tx is shifted from the switching timing, FIGS. 12 to 15 show a processing procedure taking into account a configuration in which the candidate timing tx is shifted from the switching timing.

[0073] In step S10, a switching pattern in a specified period of the first inverter 20A is selected. More specifically, a switching pattern consisting of a combination of two active voltage vectors and two reactive voltage vectors V0A and V7A having a phase difference of 60 degrees on either side of the first command voltage vector VtrA determined by the first d- and q-axis command voltages VdA* and VqA* is selected.

[0074] In step S11, a switching pattern in a specified period of the second inverter 20B is determined. More specifically, a switching pattern consisting of a combination of two active voltage vectors and two reactive voltage vectors V0B, V7B, which are sandwiched between the second command voltage vector VtrB determined by the second d, q-axis command voltages VdB*, VqB* and have a phase difference of 60 degrees, is determined. The processes in steps S10 and S11 correspond to a "setting unit."

[0075] In steps S12 to S19, a search is made for an output period of the reactive voltage vector of the first inverter 20A that appears first in the specified period and that minimizes the value of the evaluation function Jcr.

[0076] More specifically, in step S12, candidate timings for the end timing tx of the output period of the reactive voltage vector are determined. At this time, the number of candidate timings is narrowed down by the above-mentioned elimination process.

[0077] In step S13, the evaluation function minimum value Jcmin is initialized. The initialized value may be set to a value that is sufficiently larger than the maximum value assumed as the evaluation function Jcr.

[0078] In step S14, one of the candidate timings determined in step S12 is selected, and the switching pattern in the specified period of the first inverter 20A is set.

[0079] In step S15, an evaluation function calculation process is performed, the details of which will be described later.

[0080] In step S16, it is determined whether the evaluation function Jcr calculated in step S15 is smaller than the evaluation function minimum value Jcmin.

[0081] If it is determined in step S16 that the evaluation function Jcr is smaller than the evaluation function minimum value Jcmin, the process proceeds to step S17, where the evaluation function Jcr calculated in the current processing cycle is set as the evaluation function minimum value Jcmin, and the evaluation function minimum value Jcmin is updated, and then the process proceeds to step S18.

[0082] When the process of step S17 is completed, or when the result of the determination in step S16 is negative, the process proceeds to step S18, where it is determined whether or not the calculation of the evaluation function Jcr for all the candidate timings determined in step S12 is completed. The processes of steps S12 to S18 correspond to a "function calculation unit."

[0083] If it is determined in step S18 that the process is not completed, the process returns to step S14. On the other hand, if it is determined in step S18 that the process is completed, the process proceeds to step S19. In step S19, the candidate timing associated with the smallest evaluation function among the evaluation functions Jcr associated with the candidate timings is adopted. Then, the switching pattern in which the adopted candidate timing becomes the output end timing of the reactive voltage vector is determined as the switching pattern of the first inverter 20A. The process of step S19 corresponds to the "determination unit."

[0084] In step S20, the switching control of each of the switches SuAH-SwAL constituting the first inverter 20A is performed so that the switching pattern of the first inverter 20A becomes the switching pattern determined in step S19. Also, the switching control of each of the switches SuBH-SwBL constituting the second inverter 20B is performed so that the switching pattern of the second inverter 20B becomes the switching pattern determined in step S11. The process of step S20 corresponds to a "switch control unit."

[0085] The evaluation function calculation process in step S15 will be described with reference to Fig. 13. In the description of this process, please refer to the time chart in Fig. 11.

[0086] In step S30, the first counter SA, the second counter SB, the order parameter S, and the evaluation function Jcr are set to their initial values ​​(0).

[0087] In step S31, calculation processing of the initial state is performed, for example, processing of calculating the first and second inverter currents IinvA and IinvB at each Δts described above, and the inverter sum current Isum at each Δts described above, etc.

[0088] In step S32, it is determined whether or not both a first condition that the first counter SA is equal to or smaller than a first maximum number of switching times SAmax and a second condition that the second counter SB is equal to or smaller than a second maximum number of switching times SBmax are satisfied. In the example shown in FIG. 11, the first maximum number of switching times SAmax is 4, and the second maximum number of switching times SBmax is 5.

[0089] If the judgment in step S32 is positive, proceed to step S33 and determine whether the voltage vector switching timing tA[SA] of the first inverter 20A is earlier than the voltage vector switching timing tB[SB] of the second inverter 20B or is the same as the voltage vector switching timing tB[SB] of the second inverter 20B.

[0090] If the determination in step S33 is affirmative, the process proceeds to subroutine A in step S34, and if the determination in step S33 is negative, the process proceeds to subroutine B in step S35. After the process in step S34 or S35 is completed, the process proceeds to step S32.

[0091] FIG. 14 shows the procedure of the subroutine A.

[0092] In step S50, ts[S] indicating the switching timing of the voltage vectors of the first and second inverters 20A and 20B is set to tA[SA], the switching timing of the voltage vector of the first inverter 20A. Note that S in [ ] is the sequence parameter described above.

[0093] In step S51, the first inverter current IinvA[SA] and the second inverter current IinvB[SB-1] are added together to calculate the inverter sum current Isum[S].

[0094] In step S52, the time interval Δts[S] is calculated by subtracting the switching timing ts[S−1] one step before from the switching timing ts[S].

[0095] In step S53, the inverter sum current Isum[S-1] minus the sum current average value Isave is squared. The squared value is then multiplied by the time interval Δts in step S52 to calculate the area of ​​the region defined by the sum current average value Isave and the inverter sum current Isum[S-1] in one section (ts[S]-ts[S-1]). With reference to FIG. 11, this area is, for example, the area of ​​the region indicated by hatching in the one section from ts[1] to ts[2]. The evaluation function Jcr is updated by adding this area to the evaluation function Jcr calculated up to the previous time.

[0096] In step S54, the first counter SA and the order parameter S are incremented by one.

[0097] FIG. 15 shows the procedure of the subroutine B.

[0098] In step S60, ts [s] indicating the switching timing of the voltage vectors of the first and second inverters 20A, 20B is set to the switching timing tB [SB] of the voltage vector of the second inverter 20B.

[0099] In step S61, the first inverter current IinvA[SA-1] and the second inverter current IinvB[SB] are added together to calculate the inverter sum current Isum[S].

[0100] In step S62, the time interval Δts[S] is calculated by subtracting the switching timing ts[S−1] one step before from the switching timing ts[S].

[0101] In step S63, the inverter sum current Isum[S-1] minus the sum current average value Isave is squared. The squared value is then multiplied by the time interval Δts in step S62 to calculate the area of ​​the region defined by the sum current average value Isave and the inverter sum current Isum[S-1] in one section (ts[S]-ts[S-1]). The evaluation function Jcr is updated by adding this area to the evaluation function Jcr calculated up to the previous time.

[0102] In step S64, the second counter SB and the order parameter S are incremented by one.

[0103] Returning to the explanation of FIG. 13, if it is determined in step S32 that the first counter SA is greater than the first maximum switching number SAmax, or if it is determined that the second counter SB is greater than the second maximum switching number SBmax, the process proceeds to step S36.

[0104] In step S36, it is determined whether the first counter SA is equal to or smaller than the first maximum switching number SAmax. Until it is determined in step S36 that the first counter SA is greater than the first maximum switching number SAmax, subroutine A is executed in step S37. Subroutine A is the process shown in FIG.

[0105] After step S36, in step S38, it is determined whether the second counter SB is equal to or smaller than the second maximum switching number SBmax. Until it is determined in step S38 that the second counter SB is greater than the second maximum switching number SBmax, subroutine B is executed in step S39. Subroutine B is the process shown in FIG.

[0106] As described above, in this embodiment, the end timing of the reactive voltage vector that appears first in the specified period in the switching pattern of the first inverter 20A is searched for. From among multiple candidate timings, the candidate timing that minimizes the evaluation function Jcr is selected as the end timing by this search process. At this time, the switching timing of each voltage vector of the second inverter 20B is selected as the candidate timing. Therefore, the number of candidate timings to be searched can be reduced. This makes it possible to reduce the amount of calculation of the control device 40 while reducing the ripple current of the smoothing capacitor 22.

[0107] The elimination process eliminates candidate timings that prevent the output voltage vector of the first inverter 20A from becoming the first command voltage vector VtrA. As a result, the number of candidate timings can be narrowed down, and the number of evaluation functions Jcr to be calculated can be reduced. This makes it possible to more suitably reduce the amount of calculation of the control device 40.

[0108] <Modification of the first embodiment> As shown in Figs. 16 and 17, the predictive control unit 44 may use first and second carrier signals SigA and SigB (triangular wave signals) to switch the voltage vector. The first carrier signal SigA is used to switch the voltage vector of the first inverter 20A, and the second carrier signal SigB is used to switch the voltage vector of the second inverter 20B. The phase of the second carrier signal SigB is shifted by 1 / 2 the specified period from the first carrier signal SigA. This is to shift the start timings of the switching patterns VtA and VtB of the first and second inverters 20A and 20B by 1 / 2 the specified period. Note that Cmax indicates the maximum value of each carrier signal SigA and SigB, and Cmin indicates the minimum value of each carrier signal SigA and SigB.

[0109] <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 evaluation function calculation process shown in Figs. 18 to 20 is devised to further reduce the amount of calculation. Figs. 18 to 20 correspond to Figs. 13 to 15 above. In Figs. 18 to 20, the same processes as those shown in Figs. 13 to 15 are denoted by the same reference numerals for convenience.

[0110] The procedure for the evaluation function calculation process is shown in Fig. 18. In this embodiment, a flag F is initialized to 0 in step S30.

[0111] After completing step S34 or S35, the process proceeds to step S41, where it is determined whether or not the flag F is 1. The flag F indicates that the calculation of the evaluation function Jcr is to be continued when it is 0, and indicates that the calculation of the evaluation function Jcr is to be stopped when it is 1.

[0112] If it is determined in step S41 that flag F is 1, the process shown in Fig. 18 is temporarily terminated, and the process proceeds to step S18 in Fig. 12. On the other hand, if it is determined in step S41 that flag F is 0, the process proceeds to step S32. In this embodiment, if the process of step S40 is completed with flag F remaining at 0, the process proceeds to step S16 in Fig. 12.

[0113] FIG. 19 shows the procedure of the subroutine A in step S34 shown in FIG.

[0114] After the process of step S53 is completed, the process proceeds to step S55, where it is determined whether the evaluation function Jcr calculated in step S53 is equal to or less than the evaluation function minimum value Jcmin. If it is determined in step S55 that the evaluation function Jcr is equal to or less than the evaluation function minimum value Jcmin, the process proceeds to step S41 in FIG. 18 via step S54.

[0115] On the other hand, if it is determined in step S55 that the evaluation function Jcr is greater than the evaluation function minimum value Jcmin, the process proceeds to step S56, where the flag F is switched to 1. After that, the process proceeds to step S41 in FIG.

[0116] FIG. 20 shows the procedure of the subroutine B in step S35 shown in FIG.

[0117] After the process of step S63 is completed, the process proceeds to step S65, where it is determined whether the evaluation function Jcr calculated in step S63 is equal to or less than the evaluation function minimum value Jcmin. If it is determined in step S65 that the evaluation function Jcr is equal to or less than the evaluation function minimum value Jcmin, the process proceeds to step S41 in FIG. 18 via step S64.

[0118] On the other hand, if it is determined in step S65 that the evaluation function Jcr is greater than the evaluation function minimum value Jcmin, the process proceeds to step S66, where the flag F is switched to 1. After that, the process proceeds to step S41 in FIG.

[0119] It should be noted that the subroutine A in step S37 in Fig. 18 is the same as the subroutine A in Fig. 14. Moreover, the subroutine B in step S39 in Fig. 18 is the same as the subroutine B in Fig. 15.

[0120] According to the present embodiment described above, in the evaluation function calculation process, it is possible to discontinue the calculation of the evaluation function Jcr corresponding to the candidate timing at which the effect of reducing the ripple current of the smoothing capacitor 22 is small. This makes it possible to further suitably reduce the amount of calculation of the control device 40.

[0121] <Third embodiment> The third embodiment will be described below with reference to the drawings, focusing on differences from the first embodiment. In this embodiment, as shown in FIG. 21, the predictive control unit 44 determines a switching pattern consisting of a combination of two active voltage vectors having a phase difference of 60 degrees between them and the first command voltage vector VtrA, one other active voltage vector, and two reactive voltage vectors V0 and V7 among six active voltage vectors. The other active voltage vector is a voltage vector different from the active voltage vector having a phase difference of 60 degrees among two active voltage vectors having a phase difference of 120 degrees between them and the first command voltage vector VtrA. FIG. 21 shows an example in which the first, second, and sixth voltage vectors V1, V2, and V6 are selected as the three active voltage vectors. In this embodiment, hereinafter, a case in which the first, second, and sixth voltage vectors V1, V2, and V6 and the zeroth and seventh voltage vectors V0 and V7 are selected in the first inverter 20A will be described as an example.

[0122] The predictive control unit 44 determines a switching pattern consisting of a combination of three active voltage vectors sandwiching the second command voltage vector VtrB and two reactive voltage vectors V0 and V7, similarly to the case of the first inverter 20A. In the present embodiment, hereinafter, a case will be described in which the first, second, and sixth voltage vectors V1, V2, and V6 and the zeroth and seventh voltage vectors V0 and V7 are selected in the second inverter 20B.

[0123] The process of searching for the end timing tx of the reactive voltage vector, which is executed by the prediction control unit 44, will be described with reference to FIGS.

[0124] First, the search process in the first specified period (0 to Ts / 2) will be described with reference to FIGS.

[0125] As shown in FIG. 23(a), in the switching pattern of the first inverter 20A in the first specified period, the first maximum number of switching times SAmax of the voltage vector is four.

[0126] On the other hand, in the switching pattern of the second inverter 20B in the first specified period, a second maximum switching count SBmax of the voltage vector is expressed by the following equation (eq7).

[0127]

number

[0128] 22, the prediction control unit 44 selects a candidate timing for the end timing tx of the zeroth voltage vector V0A from among six switching timings tB[1] to tB[6] of the voltage vectors constituting the switching pattern VtB of the second inverter 20B. The prediction control unit 44 may perform the above-mentioned exclusion process.

[0129] FIG. 23 shows an example in which the first switching timing tB[1] is set to the end timing tA[1] of the zeroth voltage vector V0A of the first inverter 20A.

[0130] Next, the search process in the second specified period (Ts / 2 to Ts) will be described with reference to FIGS.

[0131] As shown in FIG. 25(a), in the switching pattern of the first inverter 20A in the second specified period, the first maximum number of switching times SAmax of the voltage vector is four.

[0132] On the other hand, in the switching pattern of the second inverter 20B in the second specified period, the second maximum switching count SBmax of the voltage vector is expressed by the above equation (eq7).

[0133] 24, the predictive control unit 44 selects a candidate timing for the end timing tx of the seventh voltage vector V7A from two switching timings tB[1] and tB[2] of the voltage vectors constituting the switching pattern VtB of the second inverter 20B. The predictive control unit 44 may perform the above-mentioned exclusion process.

[0134] FIG. 25 shows an example in which the first switching timing tB[1] is set to the end timing tA[1] of the seventh voltage vector V7A of the first inverter 20A.

[0135] According to the present embodiment described above, it is possible to obtain the same effects as those of the first embodiment.

[0136] <Fourth embodiment> The fourth embodiment will be described below with reference to the drawings, focusing on differences from the first embodiment. In this embodiment, as shown in FIG. 26, the predictive control unit 44 determines a switching pattern consisting of a combination of two active voltage vectors, which are sandwiched between the first command voltage vector VtrA and have a phase difference of 120 degrees, and two reactive voltage vectors V0 and V7, among six active voltage vectors. This determination method is used, for example, when the modulation factor is low. FIG. 26 shows an example in which the second and sixth voltage vectors V2 and V6 are selected as the two active voltage vectors. In this embodiment, hereinafter, a case in which the second and sixth voltage vectors V2 and V6 and the zeroth and seventh voltage vectors V0 and V7 are selected in the first inverter 20A will be described as an example.

[0137] The predictive control unit 44 determines a switching pattern consisting of a combination of two active voltage vectors sandwiching the second command voltage vector VtrB and two reactive voltage vectors V0 and V7, similarly to the case of the first inverter 20A. In the present embodiment, hereinafter, a case where the second and sixth voltage vectors V2 and V6 and the zeroth and seventh voltage vectors V0 and V7 are selected in the second inverter 20B will be described as an example.

[0138] The process of searching for the end timing tx of the reactive voltage vector, which is executed by the prediction control unit 44, will be described with reference to Figs.

[0139] First, the search process in the first specified period (0 to Ts / 2) will be described with reference to FIGS.

[0140] As shown in FIG. 28(a), in the switching pattern of the first inverter 20A in the first specified period, the first maximum number of switching times SAmax of the voltage vector is three.

[0141] On the other hand, in the switching pattern of the second inverter 20B in the first specified period, a second maximum switching count SBmax of the voltage vector is expressed by the following equation (eq8).

[0142]

number

[0143] 27, the prediction control unit 44 selects a candidate timing for the end timing tx of the zeroth voltage vector V0A from among the four switching timings tB[1] to tB[4] of the voltage vectors constituting the switching pattern VtB of the second inverter 20B. The prediction control unit 44 may perform the above-mentioned exclusion process.

[0144] FIG. 28 shows an example in which the first switching timing tB[1] is set to the end timing tA[1] of the zeroth voltage vector V0A of the first inverter 20A.

[0145] Next, the search process in the second specified period (Ts / 2 to Ts) will be described with reference to FIGS.

[0146] As shown in FIG. 30(a), in the switching pattern of the first inverter 20A in the second specified period, the first maximum number of switching times SAmax of the voltage vector is three.

[0147] On the other hand, in the switching pattern of the second inverter 20B in the second specified period, the second maximum switching count SBmax of the voltage vector is expressed by the above equation (eq8).

[0148] 29, the predictive control unit 44 selects a candidate timing for the end timing tx of the seventh voltage vector V7A from two switching timings tB[1] and tB[2] of the voltage vectors constituting the switching pattern VtB of the second inverter 20B. The predictive control unit 44 may perform the above-mentioned exclusion process.

[0149] FIG. 30 shows an example in which the first switching timing tB[1] is set to the end timing tA[1] of the seventh voltage vector V7A of the first inverter 20A.

[0150] According to the present embodiment described above, it is possible to obtain the same effects as those of the first embodiment.

[0151] <Fifth embodiment> The fifth embodiment will be described below with reference to the drawings, focusing on the differences from the fourth embodiment. In this embodiment, as shown in FIG. 31, the prediction control unit 44 determines a switching pattern consisting of a combination of two active voltage vectors having a phase difference of 120 degrees and one reactive voltage vector. By reducing the number of reactive voltage vectors by one, the number of switching operations in a specified period of the inverter can be reduced. FIG. 31 shows an example in which the second and sixth voltage vectors V2 and V6 are selected as two active voltage vectors, and the seventh voltage vector V7 is selected as one reactive voltage vector. In this embodiment, hereinafter, a case in which the second and sixth voltage vectors V2 and V6 and the seventh voltage vector V7 are selected in the first inverter 20A will be described as an example.

[0152] The predictive control unit 44 determines a switching pattern for the second inverter 20B consisting of a combination of two active voltage vectors having a phase difference of 120 degrees and one reactive voltage vector, similar to the case of the first inverter 20A. In the present embodiment, hereinafter, a case in which the second and sixth voltage vectors V2 and V6 and the seventh voltage vector V7 are selected in the second inverter 20B will be described as an example.

[0153] 32 and 33, a description will be given of a search process for the end timing tx of a reactive voltage vector executed by the prediction control unit 44. In this embodiment, the length of the prescribed period is set to Ts, which corresponds to one switching period.

[0154] 33(a), in the switching pattern of the first inverter 20A in the specified period (0 to Ts), the first maximum number of switching times SAmax of the voltage vector is 4. In addition, in the switching pattern of the second inverter 20B in the specified period, the second maximum number of switching times SBmax of the voltage vector is 4.

[0155] 32, the prediction control unit 44 selects candidate timings for the end timing tx of the seventh voltage vector V7A from among the four switching timings tB[1] to tB[4] of the voltage vectors constituting the switching pattern VtB of the second inverter 20B. The prediction control unit 44 may perform the above-mentioned exclusion process.

[0156] FIG. 33 shows an example in which the first switching timing tB[1] is set to the end timing tA[1] of the seventh voltage vector V7A of the first inverter 20A.

[0157] According to the present embodiment described above, it is possible to reduce the number of switching operations of the inverter and to reduce the ripple current of the smoothing capacitor 22. It is possible.

[0158] Sixth embodiment The sixth embodiment will be described below with reference to the drawings, focusing on the differences from the third embodiment. In this embodiment, as shown in FIG. 34, the prediction control unit 44 determines a switching pattern consisting of a combination of the three effective voltage vectors described in the third embodiment. The switching pattern does not include a reactive voltage vector. FIG. 34 shows an example in which the first, second, and sixth voltage vectors V1, V2, and V6 are selected as the three effective voltage vectors. In this embodiment, hereinafter, a case in which the first, second, and sixth voltage vectors V1, V2, and V6 are selected in the first inverter 20A will be described as an example.

[0159] The predictive control unit 44 determines a switching pattern for the second inverter 20B consisting of a combination of three effective voltage vectors, similar to the case of the first inverter 20A. In the present embodiment, hereinafter, a case where the first, second, and sixth voltage vectors V1, V2, and V6 are selected in the second inverter 20B will be described as an example.

[0160] In this embodiment, the length of the specified period is Ts, which corresponds to one switching period. The prediction control unit 44 searches for the end timing tx of the effective voltage vector (first voltage vector V1A) that appears first in the specified period. The search process for the end timing tx of the first voltage vector V1A executed by the prediction control unit 44 will be described with reference to Figs. 35 and 36.

[0161] 36(a), in the switching pattern of the first inverter 20A in the specified period (0 to Ts), the first maximum number of switching times SAmax of the voltage vector is 4. In addition, in the switching pattern of the second inverter 20B in the specified period, the second maximum number of switching times SBmax of the voltage vector is 4.

[0162] 35, the prediction control unit 44 selects candidate timings for the end timing tx of the first voltage vector V1A from among the four switching timings tB[1] to tB[4] of the voltage vectors constituting the switching pattern VtB of the second inverter 20B. The prediction control unit 44 may perform the above-mentioned exclusion process.

[0163] When the predictive control unit 44 completes the search for the end timing tx that can reduce the current ripple, it places the second, sixth, and second voltage vectors V2A, V6A, and V2A next to the first voltage vector V1A without changing the output periods of the second, sixth, and second voltage vectors V2A, V6A, and V2A that are set based on the first command voltage vector VtrA. The predictive control unit 44 places the first voltage vector V1A next to the arrangement of the second, sixth, and second voltage vectors V2A, V6A, and V2A. The predictive control unit 44 sets the output period of the first voltage vector V1A that appears last in the specified period to "Ts-TK". TK is the sum of the output period of the first voltage vector V1A that appears first in the specified period and the total output period of the second, sixth, and second voltage vectors V2A, V6A, and V2A. FIG. 36 shows an example in which the first switching timing tB[1] is set to the end timing tA[1] of the first voltage vector V1A of the first inverter 20A.

[0164] As described above, in this embodiment, the ripple current of the smoothing capacitor 22 can be reduced by the process of searching for the end timing of the effective voltage vector.

[0165] Seventh embodiment The seventh 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. 37, the rotating electric machine 10 further includes a third winding group 10C. In Fig. 37, the same components as those shown in Fig. 1 are denoted by the same reference numerals for convenience.

[0166] 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.

[0167] In the third inverter 20C, the drain of the upper arm switch of each phase is connected to a middle portion 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 middle portion 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.

[0168] The control system includes a third current detection unit. The control device 40 obtains three-phase currents flowing through the third winding group 10C based on the detection values ​​of the third current detection unit, similarly to the first and second current detection units 31A and 31B.

[0169] The control device 40 generates drive signals for turning 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 rotary electric machine 10 to the command torque Trq*.

[0170] 37, the current flowing through the third high potential side path LHC is referred to as the third inverter current IinvC. The third inverter current IinvC has a positive sign when it flows in the direction from the smoothing capacitor 22 side to the third inverter 20C side. The sum of the first to third inverter currents IinvA to IinvC is referred to as the inverter sum current Isum.

[0171] The predictive control unit 44 calculates the first to third command voltage vectors VtrA to VtrC for the first to third inverters 20A to 20C in the same manner as in the first embodiment. Then, the predictive control unit 44 determines a switching pattern for each of the inverters 20A to 20C, which is a combination of two active voltage vectors, which are sandwiched between the command voltage vector Vtr and have a phase difference of 60 degrees, and two reactive voltage vectors V0 and V7, among the six active voltage vectors. In the present embodiment, hereinafter, a case will be described in which the first and second voltage vectors V1 and V2 and the zeroth and seventh voltage vectors V0 and V7 are selected in each of the inverters 20A to 20C.

[0172] The start timings of the switching patterns VtA, VtB, and VtC of the first, second, and third inverters 20A, 20B, and 20C are shifted by ⅓ of a prescribed period in order to reduce current ripples in the smoothing capacitor 22.

[0173] The process of searching for the end timing tx of the reactive voltage vector, which is executed by the prediction control unit 44, will be described with reference to Figs.

[0174] First, the search process in the first specified period (0 to Ts / 2) will be described with reference to FIGS.

[0175] 39(a), in the switching pattern of the first and second inverters 20A and 20B in the first specified period, the first and second maximum switching numbers SAmax and SBmax are 3. In addition, in the switching pattern of the third inverter 20C in the first specified period, the third maximum switching number SCmax of the voltage vector is 3.

[0176] 38, the prediction control unit 44 selects candidate timings for the end timing tx of the zeroth voltage vector V0A of the first inverter 20A from three switching timings tB[1] to tB[3] of the voltage vectors constituting the switching pattern VtB of the second inverter 20B and three switching timings tC[1] to tC[3] of the voltage vectors constituting the switching pattern VtC of the third inverter 20C. The prediction control unit 44 may perform the above-mentioned exclusion process.

[0177] The candidate timings may be selected from either the group of switching timings tB[1] to tB[3] of the second inverter 20B or the group of switching timings tC[1] to tC[3] of the third inverter 20C.

[0178] FIG. 39 shows an example in which the second switching timing tB[2] of the second inverter 20B is set to the end timing tA[1] of the zeroth voltage vector V0A of the first inverter 20A.

[0179] Next, the search process in the second specified period (Ts / 2 to Ts) will be described with reference to FIGS.

[0180] As shown in FIG. 41, the maximum switching numbers SAmax, SBmax, and SCmax in the second specified period are each three.

[0181] 40, the prediction control unit 44 selects candidate timings for the end timing tx of the seventh voltage vector V7A of the first inverter 20A from three switching timings tB[1] to tB[3] of the voltage vectors constituting the switching pattern VtB of the second inverter 20B and three switching timings tC[1] to tC[3] of the voltage vectors constituting the switching pattern VtC of the third inverter 20C. The prediction control unit 44 may perform the above-mentioned exclusion process.

[0182] The candidate timings may be selected from either the group of switching timings tB[1] to tB[3] of the second inverter 20B or the group of switching timings tC[1] to tC[3] of the third inverter 20C.

[0183] FIG. 41 shows an example in which the second switching timing tB[2] of the second inverter 20B is set to the end timing tA[1] of the seventh voltage vector V7A of the first inverter 20A.

[0184] <Other embodiments> Each of the above embodiments may be modified as follows.

[0185] The evaluation function Jcr may be a function defined by the absolute value of the deviation between the inverter sum current Isum and the sum current average value Isave, for example, as shown in the following equation (eq9), instead of the function shown in the above equation (eq5).

[0186]

number

[0187] The candidate timing for the end timing of the voltage vector to be searched may be shifted from the switching timing of each voltage vector constituting the switching pattern of the second inverter 20B.

[0188] The control system may be provided with the same number of rotating electric machines as the 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.

[0189] The number of inverters may be four or more. When the number of inverters is N, the start timing of the switching pattern of each inverter may be shifted by, for example, 1 / N of the specified period.

[0190] The number of phases of the inverter is not limited to three, but may be four or more (for example, five).

[0191] The rotating electric machine may be, for example, an in-wheel motor that is integral with a drive wheel of the vehicle, or an on-board motor that is provided on the body of the vehicle. In addition, the rotating electric machine and the inverter may be integrated with the transmission.

[0192] The control system may be applied not only to vehicles but also to aircraft, ships, or railroad cars. The control system may be applied not only to moving objects such as vehicles but also to robots (e.g., industrial robots), generators, or elevators.

[0193] The control unit and the method described in the present disclosure may be realized by a special-purpose computer provided by configuring a processor and a memory programmed to execute one or more functions embodied in a computer program. Alternatively, the control unit and the method described in the present disclosure may be realized by a special-purpose computer provided by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the control unit and the method described in the present disclosure may be realized by one or more special-purpose computers configured by a combination of a processor and a memory programmed to execute one or more functions and a processor configured with one or more hardware logic circuits. In addition, the computer program may be stored in a computer-readable non-transitory tangible recording medium as instructions executed by the computer. [Explanation of symbols]

[0194] 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) provided on an input side of each of the power conversion circuits and common to each of the power conversion circuits; a setting unit that sets a switching pattern of each of the power conversion circuits in a specified period (Ts / 2, Ts) based on a command voltage vector (VtrA to VtrC) to be applied to the rotating electric machine; a function calculation unit that, when a part of the power conversion circuits among the power conversion circuits is set as a calculation target circuit (20A) and a switching pattern of the calculation target circuit is set as a target pattern (VtA), sets a plurality of candidate timings for switching timings of a part of the voltage vectors among the voltage vectors constituting the target pattern set by the setting unit, and calculates an evaluation function for evaluating a ripple current of the capacitor when each of the candidate timings is set; a determination unit that determines the target pattern in the specified period based on each of the calculated evaluation functions; a switch control unit that, when a power conversion circuit other than the calculation target circuit among the power conversion circuits is set as a non-target circuit (20B, 20C) and a switching pattern of the non-target circuit is set as a reference pattern, performs switching control of the non-target circuit so that the switching pattern of the non-target circuit in the specified period becomes the reference pattern set by the setting unit, and performs switching control of the calculation target circuit so that the switching pattern of the calculation target circuit in the specified period becomes the target pattern determined by the determination unit, The control device for a rotating electric machine, wherein the function calculation unit sets a timing corresponding to a switching timing of a voltage vector that constitutes the reference pattern as the candidate timing.

2. The control device for a rotating electric machine according to claim 1 , wherein the function calculation unit sets the candidate timing from among switching timings of each voltage vector that constitutes the reference pattern.

3. a current acquisition unit that acquires a current flowing through the calculation target circuit, 3. The control device for a rotating electric machine according to claim 1, wherein the function calculation unit calculates a deviation between the current acquired by the current acquisition unit and an average value of the current, and calculates a cumulative value of the calculated deviation in the specified period or a correlation value of the cumulative value as the evaluation function.

4. The control device for a rotating electric machine according to any one of claims 1 to 3, wherein, when there is a candidate timing among the plurality of candidate timings at which the voltage vector applied to the rotating electric machine cannot be made the command voltage vector, the function calculation unit does not execute calculation of the evaluation function corresponding to the candidate timing at which the command voltage vector cannot be made.

5. The control device for a rotating electric machine according to any one of claims 1 to 4, wherein the determination unit selects the candidate timing corresponding to an evaluation function that can minimize the ripple current from among the evaluation functions corresponding to each of the candidate timings, and determines the target pattern.

6. The function calculation unit is Sequentially selecting candidate timings to be used in the calculation of the evaluation function from among the candidate timings, and calculating the evaluation function; 6. The control device for a rotating electric machine according to claim 5, wherein, before calculation of the evaluation functions corresponding to all of the candidate timings is completed, if it is determined that the value of the evaluation function calculated this time is greater than the minimum value of the evaluation function calculated so far, calculation of the evaluation function is discontinued.

7. The control device for a rotating electric machine according to any one of claims 1 to 6, wherein the setting unit sets a switching pattern consisting of a combination of two effective voltage vectors sandwiching the command voltage vector and one or more reactive voltage vectors during the specified period.

8. the setting unit sets, in the specified period, a switching pattern including a combination of two active voltage vectors and two reactive voltage vectors that are spaced apart by the command voltage vector and have a phase difference of 60 degrees, The control device for a rotating electric machine according to claim 7 , wherein the function calculation unit sets the candidate timing by searching for an output end timing of a voltage vector that appears first in the specified period.

9. the setting unit sets, in the specified period, a switching pattern including a combination of two active voltage vectors and two reactive voltage vectors that are spaced apart by the command voltage vector and have a phase difference of 120 degrees, The control device for a rotating electric machine according to claim 7 , wherein the function calculation unit sets the candidate timing by searching for an output end timing of a reactive voltage vector that appears first in the specified period.

10. the setting unit sets, in the specified period, a switching pattern including a combination of two active voltage vectors sandwiching the command voltage vector and having a phase difference of 120 degrees, and one reactive voltage vector; The control device for a rotating electric machine according to claim 7 , wherein the function calculation unit sets the candidate timing by searching for an output end timing of a reactive voltage vector that appears first in the specified period.

11. the setting unit sets a switching pattern including a combination of three or more effective voltage vectors sandwiching the command voltage vector in the specified period; 7. The control device for a rotating electric machine according to claim 1, wherein the function calculation unit sets the candidate timing by searching for an output end timing of an effective voltage vector that appears first in the specified period.

12. the setting unit sets, in the specified period, a switching pattern consisting of a combination of two effective voltage vectors sandwiching the command voltage vector and having a phase difference of 60 degrees, and one effective voltage vector among two effective voltage vectors sandwiching the command voltage vector and having a phase difference of 120 degrees, which is different from the two effective voltage vectors having a phase difference of 60 degrees; The control device for a rotating electric machine according to claim 11 , wherein the function calculation unit sets an output end timing of an effective voltage vector that appears first in the specified period as the candidate timing.

13. A rotating electric machine (10), A plurality of power conversion circuits (20A to 20C) electrically connected to the rotating electric machine; a capacitor (22) provided on the input side of each of the power conversion circuits and common to each of the power conversion circuits; A program applied to a system including a computer (40a), The computer, a setting unit that sets a switching pattern of each of the power conversion circuits in a specified period (Ts / 2, Ts) based on a command voltage vector (VtrA to VtrC) to be applied to the rotating electric machine; a function calculation unit that, when a part of the power conversion circuits among the power conversion circuits is set as a calculation target circuit (20A) and a switching pattern of the calculation target circuit is set as a target pattern (VtA), sets a plurality of candidate timings for switching timings of a part of the voltage vectors among the voltage vectors constituting the target pattern set by the setting unit, and calculates an evaluation function for evaluating a ripple current of the capacitor when each of the candidate timings is set; a determination unit that determines the target pattern in the specified period based on each of the calculated evaluation functions; When the power conversion circuits other than the calculation target circuit among the power conversion circuits are set as non-target circuits (20B, 20C) and a switching pattern of the non-target circuit is set as a reference pattern, the switching control unit controls the switching of the non-target circuit so that the switching pattern of the non-target circuit in the specified period becomes the reference pattern set by the setting unit, and controls the switching of the calculation target circuit so that the switching pattern of the calculation target circuit in the specified period becomes the target pattern determined by the determination unit, The function calculation unit sets, as the candidate timing, a timing corresponding to a switching timing of a voltage vector that constitutes the reference pattern.

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