Motor control device

Abstract

Provided is a motor control device that can suppress the generation of an inter-system torque difference even when a DC voltage difference occurs between systems when DC power supplies are provided in the respective systems. When the first controller (9a) determines that the first DC voltage (Vdc1) is higher than the second DC voltage (Vdc2), it controls such that the first q-axis current detection value (Iq1_det) approaches the second q-axis current detection value (Iq2_det) or the second q-axis current command value (Iq2_ref) obtained from the second controller (9b). When the second controller (9b) determines that the second DC voltage (Vdc2) is higher than the first DC voltage (Vdc1), it controls such that the second q-axis current detection value (Iq2_det) approaches the first q-axis current detection value (Iq1_det) or the first q-axis current command value (Iq1_ref) obtained from the first controller (9a).

Description

Technical Field

[0001] The present invention relates to a motor control device. Background Art

[0002] In an electric power steering system, a redundant system including motor windings, inverters, and controllers of multiple systems is becoming popular. With this system, even if any one of the systems fails, the operation can continue through other systems.

[0003] In Patent Document 1, the controllers of each system are divided into a main controller and slave controllers other than the main controller. A method is disclosed in which the main controller sends a command value to the slave side, and the slave controller receives the command value from the main side and performs current control based on the command value. According to this method, all the controllers perform current control based on the command of the main controller. Therefore, ideally, the current values flowing through all the motor windings are the same.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2018-129995 Summary of the Invention

[0007] Technical Problem to be Solved by the Invention

[0008] In the control method of Patent Document 1, the q-axis current command value is sent from the first controller 130 on the main side to the second controller 230 on the slave side, and the first control unit 130 and the second controller 230 use the same q-axis current command value. At this time, by using current feedback control of current sum and current difference, the currents flowing through the first three-phase winding and the second three-phase winding can be made almost the same.

[0009] When the induced voltage caused by the three-phase winding reaches the DC voltage of the DC power supply and voltage saturation occurs, and the q-axis current cannot follow the q-axis current command value, the magnitude of the q-axis current changes in direct proportion to the magnitude of the DC voltage. However, for the first inverter and the second inverter, DC power supplies are sometimes separately provided for each system. In this case, due to the secular deterioration of the DC power supply, the reduction of the charge amount, etc., when the DC voltage of one DC power supply drops from the rated voltage, a DC voltage difference occurs between the systems. In this state, when operating in a voltage saturation state, even if the same q-axis current command value is set between the systems, due to the DC voltage difference between the systems, a difference in the q-axis current occurs between the systems. Since the q-axis current of each system is proportional to the torque generated by the three-phase winding of each system, due to the difference in the q-axis current between the systems, a torque difference occurs between the systems, and there is a possibility that high-frequency vibration and noise may occur in the AC rotating machine.

[0010] Therefore, it is desirable to have a motor control device that can suppress the generation of a torque difference between systems even when a DC voltage difference occurs between systems when DC power supplies are separately provided in each system.

[0011] Technical means for solving the technical problem

[0012] The motor control device according to the present application

[0013] is a motor control device that controls an AC rotating electrical machine having a first three-phase winding and a second three-phase winding, and includes:

[0014] A first inverter that applies a first DC voltage of a first DC power supply to the first three-phase winding;

[0015] A first current detector that detects a current flowing through the first three-phase winding;

[0016] A first controller that calculates a first d-axis current detection value and a first q-axis current detection value representing the current detection value of the first three-phase winding detected by the first current detector in a d-axis and q-axis coordinate system that rotates synchronously with the rotational position of the AC rotating electrical machine, calculates a first d-axis current command value and a first q-axis current command value, calculates a first d-axis voltage command value and a first q-axis voltage command value, and controls the first inverter based on the first d-axis voltage command value and the first q-axis voltage command value;

[0017] A second inverter that applies a second DC voltage of a second DC power supply to the second three-phase winding;

[0018] A second current detector that detects a current flowing through the second three-phase winding; and

[0019] A second controller that calculates a second d-axis current detection value and a second q-axis current detection value representing the current detection value of the second three-phase winding detected by the second current detector in the d-axis and q-axis coordinate system, calculates a second d-axis current command value and a second q-axis current command value, calculates a second d-axis voltage command value and a second q-axis voltage command value, and controls the second inverter based on the second d-axis voltage command value and the second q-axis voltage command value;

[0020] The first controller

[0021] When it is determined that the first DC voltage is below the second DC voltage, changes the first q-axis voltage command value so that the first q-axis current detection value approaches the first q-axis current command value,

[0022] When it is determined that the first DC voltage is higher than the second DC voltage, change the first q-axis voltage command value so that the first q-axis current detection value approaches the second q-axis current detection value or the second q-axis current command value obtained from the second controller through communication.

[0023] The second controller

[0024] When it is determined that the second DC voltage is below the first DC voltage, change the second q-axis voltage command value so that the second q-axis current detection value approaches the second q-axis current command value.

[0025] When it is determined that the second DC voltage is higher than the first DC voltage, change the second q-axis voltage command value so that the second q-axis current detection value approaches the first q-axis current detection value or the first q-axis current command value obtained from the first controller through communication.

[0026] Advantages of the Invention

[0027] According to the motor control device involved in the present application, when the first DC voltage is higher than the second DC voltage, the second q-axis current detection value or the second q-axis current command value is set as the final first q-axis current command value, and the first q-axis current is feedback-controlled. Therefore, the first q-axis current can be reduced to the second q-axis current so that the first q-axis current will not be higher than the second q-axis current near the operating state where voltage saturation occurs. Conversely, when the second DC voltage is higher than the first DC voltage, the first q-axis current detection value or the first q-axis current command value is set as the final second q-axis current command value, and the second q-axis current is feedback-controlled. Therefore, the second q-axis current can be reduced to the first q-axis current so that the second q-axis current will not be higher than the first q-axis current near the operating state where voltage saturation occurs. Since the q-axis current is proportional to the torque, the difference in torque between systems due to the difference in DC voltage between systems can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a schematic structural diagram of an AC rotating electrical machine and a motor control device according to Embodiment 1.

[0029] Figure 2 is a block diagram of the first controller and the second controller according to Embodiment 1.

[0030] Figure 3 is a hardware structural diagram of the first controller according to Embodiment 1.

[0031] Figure 4 is a hardware structural diagram of the second controller according to Embodiment 1.

[0032] Figure 5 It is a diagram for explaining the setting of the current command related to Embodiment 1.

[0033] Figure 6 It is a diagram for explaining the setting of the current command related to Embodiment 1.

[0034] Figure 7 It is a diagram for explaining the setting of the current command related to Embodiment 1.

[0035] Figure 8 It is a diagram for explaining the setting of the current command related to Embodiment 1.

[0036] Figure 9 It is a timing diagram for explaining the control behavior related to the comparative example.

[0037] Figure 10 It is a timing diagram for explaining the control behavior related to Embodiment 1.

[0038] Figure 11 It is a block diagram of the first controller and the second controller related to Embodiment 2.

[0039] Figure 12 It is a block diagram of the first controller and the second controller related to Embodiment 3.

[0040] Figure 13 It is a block diagram of the first controller and the second controller related to Embodiment 5. Detailed implementation manners

[0041] 1. Embodiment 1

[0042] Referring to the accompanying drawings, a motor control device for controlling an AC rotating motor 1 related to Embodiment 1 will be described. Figure 1 It is a schematic structural diagram of the AC rotating motor and the motor control device related to this embodiment. The AC rotating motor 1 has a first three-phase winding 12a and a second three-phase winding 12b. A first system for applying a voltage to the first three-phase winding 12a and a second system for applying a voltage to the second three-phase winding 12b are provided independently. As the first system, a first inverter 4a, a first current detector 10a, a first controller 9a, a first DC power supply 3a, and a first voltage detector 11a are provided. As the second system, a second inverter 4b, a second current detector 10b, a second controller 9b, a second DC power supply 3b, and a second voltage detector 11b are provided.

[0043] 1-1. AC rotating motor 1

[0044] The AC rotating electric machine 1 has a first three-phase winding 12a and a second three-phase winding 12b. The first three-phase winding 12a is the winding Cu1 of phase U1, the winding Cv1 of phase V1, and the winding Cw1 of phase W1. The second three-phase winding 12b is the winding Cu2 of phase U2, the winding Cv2 of phase V2, and the winding Cw2 of phase W2. The first three-phase winding 12a and the second three-phase winding 12b are connected in Y, but they can also be connected in Δ. The first three-phase winding 12a and the second three-phase winding 12b are wound around one stator. In the present embodiment, the first three-phase winding 12a and the second three-phase winding 12b are wound around the stator with a phase difference (angle difference) from each other.

[0045] The rotor is disposed radially inside the stator. The AC rotating electric machine 1 can be a permanent magnet synchronous rotating electric machine having a permanent magnet on the rotor, a wound-field synchronous rotating electric machine having an electromagnet on the rotor, an induction rotating electric machine or a synchronous reluctance rotating electric machine having no magnet on the rotor. In the example described below, the case where a permanent magnet is provided on the rotor will be described.

[0046] A position detector 2 is provided on the rotor. The position detector 2 is used to detect the rotational position (rotation angle) of the rotor. The output signal of the position detector 2 is input to the first controller 9a and the second controller 9b. Various sensors are used for the position detector 2. For example, the position detector 2 uses a position detector such as a resolver, a Hall element, a TMR element, or a GMR element, and a rotation detector such as an electromagnetic type, a magnetoelectric type, or an optoelectronic type.

[0047] 1-2. Related to the first inverter 4a

[0048] The first inverter 4a is a power converter that applies the first DC voltage Vdc1 of the first DC power supply 3a to the first three-phase winding 12a. The first inverter 4a has a plurality of switching elements.

[0049] The first inverter 4a is provided with three sets of series circuits corresponding to the three-phase windings. Each series circuit is connected in series with a switching element 5a on the positive electrode side connected to the positive terminal of the first DC power supply 3a and a switching element 6a on the negative electrode side connected to the negative terminal of the first DC power supply 3a. Moreover, the connection points of the two switching elements in each series circuit are connected to the windings of the corresponding phase. Each switching element uses an IGBT (Insulated Gate Bipolar Transistor) with diodes 7a and 8a connected in reverse parallel, a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) having the function of a diode connected in reverse parallel, etc. The gate terminals of the respective switching elements 5a and 6a are connected to the first controller 9a via a gate drive circuit or the like. Therefore, each switching element is turned on or off by a switching signal output from the first controller 9a.

[0050] The first current detector 10a detects the current flowing through each phase winding of the first three-phase winding. The first current detector 10a is a Hall element or the like provided on the wire connecting the series circuit of each phase switching element of the first inverter 4a and each phase winding. In addition, the first current detector 10a may be a shunt resistor connected in series with the series circuit of each phase switching element, or a shunt resistor connected in series with the connection wire between the first inverter 4a and the first DC power supply 3a.

[0051] The first DC power supply 3a outputs the first DC voltage Vdc1 to the first inverter 4a. As the first DC power supply 3a, any device that outputs a DC voltage such as a battery, a DC-DC converter, a diode rectifier, a PWM rectifier, etc. is used.

[0052] A first voltage detector 11a for detecting the first DC voltage Vdc1 is provided. The output signal of the first voltage detector 11a is input to the first controller 9a.

[0053] 1-3. Related to the second inverter 4b

[0054] The second inverter 4b is a power converter that applies the second DC voltage Vdc2 of the second DC power supply 3b to the second three-phase winding 12b. The second inverter 4b has a plurality of switching elements.

[0055] The second inverter 4b is provided with three sets of series circuits corresponding to the three-phase windings. Each series circuit is connected in series with a switching element 5b on the positive electrode side connected to the positive terminal of the second DC power supply 3b and a switching element 6b on the negative electrode side connected to the negative terminal of the second DC power supply 3b. Moreover, the connection points of the two switching elements in each series circuit are connected to the windings of the corresponding phases. For each switching element, an IGBT with anti-parallel diodes 7b, 8b, a MOSFET having the function of an anti-parallel diode, etc. are used. The gate terminals of the respective switching elements 5a, 6a are connected to the second controller 9b via a gate drive circuit or the like. Therefore, each switching element is turned on or off by a switching signal output from the second controller 9b.

[0056] The second current detector 10b detects the current flowing through each phase winding of the second three-phase winding. The second current detector 10b is a Hall element or the like provided on the wire connecting the series circuit of each phase switching element of the second inverter 4b and each phase winding. Additionally, the second current detector 10b can be a shunt resistor connected in series with the series circuit of each phase switching element.

[0057] The second DC power supply 3b outputs a second DC voltage Vdc2 to the second inverter 4b. As the second DC power supply 3b, any device that outputs a DC voltage such as a battery, a DC-DC converter, a diode rectifier, a PWM rectifier, etc. is used.

[0058] A second voltage detector 11b for detecting the second DC voltage Vdc2 is provided. The output signal of the second voltage detector 11b is input to the second controller 9b.

[0059] 1-4. Basic Structure of the First Controller 9a

[0060] As Figure 2 shown, the first controller 9a includes a first current detection unit 901a, a first current command calculation unit 902a, a first current command selection unit 903a, a first voltage command calculation unit 904a, a first voltage coordinate conversion unit 905a, a first voltage application unit 906a, a first rotational position detection unit 907a, and a first DC voltage detection unit 908a, etc.

[0061] The functions of the respective functional units 901a to 908a, etc. of the first controller 9a are realized by the processing circuit included in the first controller 9a. Specifically, the first controller 9a is as Figure 3As shown in the figure, the processing circuit includes an arithmetic processing device 90 (computer) such as a CPU (Central Processing Unit), a storage device 91 for exchanging data with the arithmetic processing device 90, an input circuit 92 for inputting an external signal to the arithmetic processing device 90, an output circuit 93 for outputting a signal from the arithmetic processing device 90 to the outside, and a communication device 94 for performing data communication with an external device 50 and a second controller 9b. The first controller 9a transmits specific control information such as the first q-axis current detection value Iq1_det and the first d-axis current command value Id1_ref to the second controller 9b through the communication device 94.

[0062] As the arithmetic processing device 90, it may include an ASIC (Application Specific Integrated Circuit), an IC (Integrated Circuit), a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), various logic circuits, and various signal processing circuits. In addition, as the arithmetic processing device 90, it may also include multiple arithmetic processing devices of the same type or different types to share and execute each process. As the storage device 91, it may include a RAM (Random Access Memory) and a ROM (Read Only Memory).

[0063] Various sensors such as a position detector 2, a first current detector 10a, and a first voltage detector 11a are connected to the input circuit 92. The input circuit 92 includes an A / D converter that inputs the output signal of the sensor to the arithmetic processing device 90. An electric load such as a gate drive circuit that drives the on / off of multiple switching elements of the first inverter 4a is connected to the output circuit 93, and it includes a drive circuit that outputs a control signal from the arithmetic processing device 90 to these electric loads. The communication device 94 communicates with the external device 50 and the second controller 9b.

[0064] The arithmetic processing device 90 executes software (program) stored in the storage device 91 such as a ROM, and cooperates with other hardware of the first controller 9a such as the storage device 91, the input circuit 92, the output circuit 93, and the communication device 94, thereby realizing the functions of each functional unit 901a to 908a and the like of the first controller 9a. In addition, setting data such as determination values used by each functional unit 901a to 908a and the like is stored in the storage device 91 such as a ROM as a part of the software (program).

[0065] <First rotational position detection unit 907a>

[0066] The first rotational position detection unit 907a detects the rotational position θ1 (magnetic pole position θ1, rotational angle θ1) and the rotational angular velocity ω1 at the electrical angle of the rotor based on the output signal of the position detector 2.

[0067] <First DC voltage detection unit 908a>

[0068] The first DC voltage detection unit 908a detects the first DC voltage Vdc1_det of the first DC power supply 3a based on the output signal of the first voltage detector 11a.

[0069] <First current detection unit 901a>

[0070] The first current detection unit 901a detects the U1-phase current Iu1_det, the V1-phase current Iv1_det, and the W1-phase current Iw1_det (referred to as the first three-phase current detection values Iu1_det, Iv1_det, and Iw1_det) flowing through the first three-phase windings Cu1, Cv1, and Cw1, respectively, based on the output signal of the first current detector 10a. Then, the first current detection unit 901a performs three-phase to two-phase conversion and rotating coordinate conversion on the first three-phase current detection values Iu1_det, Iv1_det, and Iw1_det based on the rotational position θ1, and calculates the first d-axis current detection value Id1_det and the first q-axis current detection value Iq1_det represented in the coordinate system of the d-axis and the q-axis.

[0071] The coordinate system of the d-axis and the q-axis (hereinafter referred to as the dq-axis coordinate system) is a two-axis rotating coordinate system that rotates synchronously with the rotational position θ1 (magnetic pole position θ1) of the AC rotating electrical machine (rotor). More specifically, the dq-axis coordinate system is composed of a d-axis determined at the magnetic pole position θ1 (direction of the N pole of the magnet) of the rotor, and a q-axis determined in a direction that is 90 deg ahead of the electrical angle of the d-axis.

[0072] <First current command calculation unit 902a>

[0073] The first current command calculation unit 902a calculates the first d-axis current command value Id1_ref and the first q-axis current command value Iq1_ref. As shown in the following equation, the first current command calculation unit 902a multiplies the sharing ratio K1 of the first three-phase winding by the torque command value Tall output to the AC rotating electrical machine to calculate the first torque command value T1_ref. The sharing ratio K1 of the first system is set to a value less than 1 (for example, 0.5).

[0074] T1_ref = K1 × Tall ··· (1)

[0075] The first current command calculation unit 902a calculates the first d-axis current command value Id1_ref and the first q-axis current command value Iq1_ref based on the first torque command value T1_ref, the first DC voltage Vdc1, the rotational angular velocity ω1, etc., according to current vector control methods such as maximum torque current control, field weakening control, and Id = 0 control. In this embodiment, the torque command value Tall is transmitted from the external device 50. The torque command value Tall can be the shared first torque command value T1_ref. The torque command value Tall can be calculated within the first current command calculation unit 902a.

[0076] <First voltage command calculation unit 904a>

[0077] The first voltage command calculation unit 904a calculates the first d-axis voltage command value Vd1_ref and the first q-axis voltage command value Vq1_ref. In this embodiment, the first voltage command calculation unit 904a performs current feedback control to change the first d-axis voltage command value Vd1_ref and the first q-axis voltage command value Vq1_ref so that the first d-axis current detection value Id1_det approaches the first d-axis current command value Id1_ref* selected by the first current command selection unit 903a described later, and the first q-axis current detection value Iq1_det approaches the first q-axis current command value Iq1_ref* selected by the first current command selection unit 903a. When calculating the voltage commands for the d-axis and q-axis, calculations can be performed to prevent mutual interference between the d-axis current and the q-axis current of the first three-phase winding, or calculations can be performed considering the mutual interference between the first three-phase winding and the second three-phase winding.

[0078] <First voltage coordinate conversion unit 905a>

[0079] The first voltage coordinate conversion unit 905a performs fixed coordinate conversion and two-phase to three-phase conversion on the first d-axis voltage command value Vd1_ref and the first q-axis voltage command value Vq1_ref based on the rotational position θ1 (magnetic pole position θ1), thereby converting them into the first three-phase voltage commands Vu1_ref, Vv1_ref, Vw1_ref. Various modulations can also be applied to the three-phase voltage command values.

[0080] <First voltage application unit 906a>

[0081] The first voltage application unit 906a turns on and off a plurality of switching elements included in the first inverter 4a by PWM (Pulse Width Modulation) control based on the first three-phase voltage command values Vu1_ref, Vv1_ref, and Vw1_ref. The first voltage application unit 906a generates switching signals for turning on and off the switching elements of each phase by comparing each of the three-phase voltage command values with a carrier wave. The carrier wave is a triangular wave having an amplitude of the first DC voltage detection value Vdc1_det and vibrating at the carrier frequency. The first voltage application unit 906a turns on the switching signal when the voltage command value exceeds the carrier wave, and turns off the switching signal when the voltage command value is less than the carrier wave. The switching signals are directly transmitted to the switching elements 5a on the positive electrode side, and the switching signals obtained by inverting the switching signals are transmitted to the switching elements 6a on the negative electrode side. Each switching signal is input to the gate terminals of the respective switching elements of the first inverter 4a via a gate drive circuit to turn on or off each switching element.

[0082] 1-5. Basic Structure of the Second Controller 9b

[0083] As Figure 2 shown, the second controller 9b includes a second current detection unit 901b, a second current command calculation unit 902b, a second current command selection unit 903b, a second voltage command calculation unit 904b, a second voltage coordinate conversion unit 905b, a second voltage application unit 906b, a second rotational position detection unit 907b, a second DC voltage detection unit 908b, and the like.

[0084] The functions of the respective functional units 901b to 908b and the like of the second controller 9b are realized by a processing circuit included in the second controller 9b. Specifically, as Figure 4 shown, as a processing circuit, the second controller 9b includes an arithmetic processing device 80 (computer) such as a CPU, a storage device 81 that exchanges data with the arithmetic processing device 80, an input circuit 82 that inputs an external signal to the arithmetic processing device 80, an output circuit 83 that outputs a signal from the arithmetic processing device 80 to the outside, and a communication device 84 that performs data communication with an external device 50 and the first controller 9a, and the like.

[0085] As the arithmetic processing device 80, it may include an ASIC, an IC, a DSP, an FPGA, various logic circuits, various signal processing circuits, and the like. In addition, as the arithmetic processing device 80, it may also include a plurality of arithmetic processing devices of the same type or different types to share and execute each process. As the storage device 81, it includes a RAM and a ROM, and the like.

[0086] Various sensors such as the position detector 2, the second current detector 10b, and the second voltage detector 11b are connected to the input circuit 82. The input circuit 82 includes an A / D converter or the like that inputs the output signals of the sensors to the arithmetic processing unit 80. An electric load such as a gate drive circuit that drives the switching elements of the second inverter 4b to conduct and turn off is connected to the output circuit 83, and it includes a drive circuit or the like that outputs a control signal from the arithmetic processing unit 80 to these electric loads. The communication device 84 communicates with the external device 50 and the first controller 9a. The second controller 9b transmits specific control information such as the second q-axis current detection value Iq2_det and the second q-axis current command value Iq2_ref to the first controller 9a through the communication device 84.

[0087] The arithmetic processing unit 80 executes software (program) stored in a storage device 81 such as a ROM, and cooperates with other hardware of the second controller 9b such as the storage device 81, the input circuit 82, the output circuit 83, and the communication device 84, thereby realizing the functions of each functional unit 901b - 908b and the like of the second controller 9b. In addition, setting data such as determination values used by each functional unit 901b - 908b and the like is stored in the storage device 81 such as a ROM as a part of the software (program).

[0088] <Second rotational position detection unit 907b>

[0089] The second rotational position detection unit 907b detects the rotational position θ2 (magnetic pole position θ2, rotational angle θ2) and the rotational angular velocity ω2 at the electrical angle of the rotor based on the output signal of the position detector 2.

[0090] <Second DC voltage detection unit 908b>

[0091] The second DC voltage detection unit 908b detects the second DC voltage Vdc2_det of the second DC power supply 3b based on the output signal of the second voltage detector 11b.

[0092] <Second current detection unit 901b>

[0093] The second current detection unit 901b detects the U2-phase current Iu2_det, V2-phase current Iv2_det, and W2-phase current Iw2_det (referred to as the second three-phase current detection values Iu2_det, Iv2_det, and Iw2_det) flowing through the second three-phase windings Cu2, Cv2, and Cw2, respectively, based on the output signal of the second current detector 10b. Then, the second current detection unit 901b performs three-phase to two-phase conversion and rotational coordinate conversion on the second three-phase current detection values Iu2_det, Iv2_det, and Iw2_det based on the rotational position θ2, and calculates the second d-axis current detection value Id2_det and the second q-axis current detection value Iq2_det represented in the coordinate system of the d-axis and q-axis.

[0094] The coordinate system of the d-axis and q-axis (hereinafter referred to as the dq-axis coordinate system) is a two-axis rotational coordinate system that rotates synchronously with the rotational position θ2 (magnetic pole position θ2) of the AC rotating electrical machine (rotor). More specifically, the dq-axis coordinate system is composed of a d-axis determined at the magnetic pole position θ2 (direction of the N pole of the magnet) of the rotor, and a q-axis determined in a direction that advances 90 degrees in electrical angle from the d-axis.

[0095] <Second current command calculation unit 902b>

[0096] The first current command calculation unit 902b calculates the second d-axis current command value Id2_ref and the second q-axis current command value Iq2_ref. As shown in the following formula, the second current command calculation unit 902b multiplies the sharing ratio K2 of the second three-phase winding by the torque command value Tall output to the AC rotating electrical machine to calculate the second torque command value T2_ref. The sharing ratio K2 of the second system is set to a value less than 1 (for example, 0.5).

[0097] T2_ref = K2 × Tall ··· (2)

[0098] The second current command calculation unit 902b calculates the second d-axis current command value Id2_ref and the second q-axis current command value Iq2_ref based on the second torque command value T2_ref, the second DC voltage Vdc2, the rotational angular velocity ω2, etc., according to current vector control methods such as maximum torque current control, weak magnetic flux control, and Id = 0 control. In this embodiment, the torque command value Tall is transmitted from the external device 50. The torque command value Tall can be the shared second torque command value T2_ref. The torque command value Tall can be calculated within the second current command calculation unit 902b.

[0099] <Second voltage command calculation unit 904b>

[0100] The second voltage command calculation unit 904b calculates the second d-axis voltage command value Vd2_ref and the second q-axis voltage command value Vq2_ref. In the present embodiment, the second voltage command calculation unit 904b performs current feedback control that changes the second d-axis voltage command value Vd2_ref and the second q-axis voltage command value Vq2_ref so that the second d-axis current detection value Id2_det approaches the second d-axis current command value Id2_ref* selected by the second current command selection unit 903b described later, and the second q-axis current detection value Iq2_det approaches the second q-axis current command value Iq2_ref* selected by the second current command selection unit 903b. When calculating the voltage commands for the d-axis and q-axis, it is possible to perform calculations that do not cause mutual interference between the d-axis current and the q-axis current of the second three-phase winding, or it is possible to perform calculations that take into account the mutual interference between the first three-phase winding and the second three-phase winding.

[0101] <Second voltage coordinate conversion unit 905b>

[0102] Based on the rotational position θ2 (magnetic pole position θ2), the second voltage coordinate conversion unit 905b performs fixed coordinate conversion and two-phase to three-phase conversion on the second d-axis voltage command value Vd2_ref and the second q-axis voltage command value Vq2_ref, thereby converting them into the second three-phase voltage command values Vu2_ref, Vv2_ref, and Vw2_ref. It is also possible to apply various modulations to the three-phase voltage command values.

[0103] <Second voltage application unit 906b>

[0104] Based on the second three-phase voltage command values Vu2_ref, Vv2_ref, and Vw2_ref, the second voltage application unit 906b turns on and off a plurality of switching elements included in the second inverter 4b through PWM control. The second voltage application unit 906b generates switching signals for turning on and off the switching elements of each phase by comparing each of the three-phase voltage command values with a carrier wave. The carrier wave is a triangular wave having an amplitude of the second DC voltage detection value Vdc2_det and vibrating at the carrier frequency. The second voltage application unit 906b turns on the switching signal when the voltage command value exceeds the carrier wave, and turns off the switching signal when the voltage command value is less than the carrier wave. The switching signal is directly transmitted to the switching elements 5b on the positive side, and the switching signal obtained by inverting the switching signal is transmitted to the switching elements 6b on the negative side. Each switching signal is input to the gate terminals of the respective switching elements of the second inverter 4b via a gate drive circuit to turn on or off each switching element.

[0105] 1-6. First and second current command selection units

[0106] 1-6-1. Method for setting current commands

[0107] In this embodiment, the first current command calculator 902a and the second current command calculator 902b are configured to set current commands as follows. The parameters on which the first current command calculator 902a and the second current command calculator 902b are based are only different in the first torque command value T1_ref, the first DC voltage Vdc1 and the rotational angular velocity ω1, and the second torque command value T2_ref, the second DC voltage Vdc2 and the rotational angular velocity ω2. The setting methods themselves are the same. Therefore, the first current command calculator 902a will be taken as a representative for explanation.

[0108] In this embodiment, as Figure 5 shown, the first current command calculator 902a switches between Id = 0 control and field-weakening control according to the rotational angular velocity ω1, the first torque command value T1_ref, and the first DC voltage Vdc1. Maximum torque per ampere control can be used instead of Id = 0 control. When the rotational angular velocity ω1 is below the base rotational angular velocity ω1a, the maximum torque that can be output through the first three-phase winding is determined by limiting the winding current to the rated current and becomes a constant value with respect to the change in the rotational angular velocity ω1. When the rotational angular velocity ω1 is greater than the base rotational angular velocity ω1a, the maximum torque is determined by limiting the line-to-line voltage (induced voltage) of the first three-phase winding to the first DC voltage Vdc1 and decreases as the rotational angular velocity ω1 increases.

[0109] In this embodiment, in the field-weakening control, the d-axis current Id is limited by a lower limit of the d-axis current minimum value Id_min to prevent irreversible demagnetization of the permanent magnet due to the increase in field weakening caused by the decrease of the d-axis current Id from zero. Therefore, when the rotational angular velocity ω1 is greater than the d-axis current limit rotational speed ω1b, the maximum torque is determined by limiting the line-to-line voltage of the first three-phase winding to the first DC voltage Vdc1 and limiting the d-axis current Id to the d-axis current minimum value Id_min, and decreases as the rotational angular velocity ω1 increases.

[0110] The base rotational angular velocity ω1a is the rotational angular velocity at which the maximum torque in the Id = 0 control is determined by limiting the winding current to the rated current and the line-to-line voltage (induced voltage) of the winding starts to be limited by the first DC voltage Vdc1. Therefore, as the first DC voltage Vdc1 decreases, the base rotational angular velocity ω1a decreases, and the maximum torque in the field-weakening control determined by limiting the line-to-line voltage (induced voltage) of the winding by the first DC voltage Vdc1 also decreases.

[0111] Using Figure 6The set first d-axis current command value Id1_ref and first q-axis current command value Iq1_ref are described in terms of the dq-axis coordinates shown. The first d-axis and first q-axis current command values Id1_ref and Iq1_ref at the maximum torque during Id = 0 control are set to the intersection point A between the line of d-axis current Id = 0 and the current limit circle obtained based on the rated current.

[0112] Moreover, the first d-axis and first q-axis current command values Id1_ref and Iq1_ref at the maximum torque during weak magnetic flux control are set to the intersection point B between the current limit circle and the voltage limit ellipse (constant induced voltage ellipse). As the rotational angular velocity ω1 increases, the voltage limit ellipse narrows, and the first d-axis and first q-axis current command values Id1_ref and Iq1_ref of the intersection point B decrease as shown by the arrows in Figure 5 the figure.

[0113] Then, due to the increase in the rotational angular velocity ω1, when the first d-axis current command value Id1_ref reaches the minimum d-axis current Id_min for suppressing irreversible demagnetization, the first d-axis and first q-axis current command values Id1_ref and Iq1_ref are set to the intersection point C between the current limit circle and the minimum d-axis current Id_min. After that, as the rotational angular velocity ω1 increases, the voltage limit ellipse narrows. Therefore, the actual first d-axis current Id and first q-axis current Iq become the intersection point between the voltage limit ellipse and the line of the minimum d-axis current Id_min, and as the rotational angular velocity ω1 increases, they decrease from the intersection point C along the line of the minimum d-axis current Id_min to zero.

[0114] The second current command calculation unit 902b sets the second d-axis current command value Id2_ref and the second q-axis current command value Iq2_ref using the same method as the first current command calculation unit 902a based on the rotational angular velocity ω2, the second torque command value T2_ref, and the second DC voltage Vdc2.

[0115] 1-6-2. Problems Caused by DC Voltage Difference between Systems

[0116] The first DC voltage Vdc1 and the second DC voltage Vdc2 may be lower than the rated voltage due to the secular deterioration of the DC power supply and the reduction of the charge amount. For example, when the second DC voltage Vdc2 is lower than the rated voltage and the first DC voltage Vdc1 is maintained at the rated voltage, a voltage difference is generated between the first DC voltage Vdc1 and the second DC voltage Vdc2. As shown in Figure 5As shown, as the DC voltage decreases, the basic rotational angular velocity ω1a decreases, and the maximum torque of the weak magnetic flux control decreases. Therefore, a torque difference is generated between the maximum torque of the first three-phase winding and the maximum torque of the second three-phase winding. When a torque difference is generated, high-frequency vibration and noise are generated in the AC rotating electrical machine 1.

[0117] For example, as Figure 7 shown, when the maximum torque output of the weak magnetic flux control is reduced, if the second DC voltage Vdc2 is reduced from the rated voltage, the voltage limit ellipse becomes narrower, and the second d-axis current command value Id2_ref and the second q-axis current command value Iq2_ref are reduced compared to the first d-axis current command value Id1_ref and the first q-axis current command value Iq1_ref maintained at the rated voltage. In addition, as Figure 8 shown, when the maximum torque output of the d-axis current minimum value limit is considered, if the second DC voltage Vdc2 is reduced from the rated voltage, the voltage limit ellipse becomes narrower, and the second q-axis current detection value Id2_det is reduced compared to the first q-axis current detection value Iq1_det maintained at the rated voltage.

[0118] <Control behavior of a comparative example without a current command selection unit>

[0119] Figure 9 The control behavior of a comparative example is shown when the rotational angular velocity gradually increases from zero in a state where the maximum torque is output to the first three-phase winding and the second three-phase winding. In this example, the first DC voltage Vdc1 is maintained at the rated voltage, and the second DC voltage Vdc2 is reduced from the rated voltage (Vdc1 > Vdc2). Therefore, the basic rotational angular velocity ω2a of the second three-phase winding becomes lower than the basic rotational angular velocity ω1a of the first three-phase winding.

[0120] At time t2, the rotational angular velocity of the first three-phase winding reaches the basic rotational angular velocity ω1a of the first three-phase winding. On the other hand, as the basic rotational angular velocity ω2a decreases, at time t1 earlier than time t2, the rotational angular velocity of the second three-phase winding reaches the basic rotational angular velocity ω2a of the second three-phase winding.

[0121] During the period until time t2 for the first three-phase winding and during the period until time t1 for the second three-phase winding, since the rotational angular velocity is lower than the basic rotational angular velocities ω1a and ω2a of the first three-phase winding or the second three-phase winding, the Id = 0 control is executed, as Figure 5 and Figure 6As shown, the first d-axis current command value Id1_ref and the second d-axis current command value Id2_ref are set to zero, and the first q-axis current command value Iq1_ref and the second q-axis current command value Iq2_ref are set to the maximum current Iq_max corresponding to the rated current. The maximum torque T1_max of the first three-phase winding and the maximum torque T2_max of the second three-phase winding become constant. In this Id = 0 control, due to the difference in DC voltage between systems, there is no difference in dq-axis current and torque between systems.

[0122] The first three-phase winding performs field weakening control during the period from time t2 to time t4, and the second three-phase winding performs field weakening control during the period from time t1 to time t3, as Figure 5 and Figure 6 shown. As the rotational angular velocity increases, the first d-axis current command value Id1_ref and the second d-axis current command value Id2_ref decrease, the first q-axis current command value and the second q-axis current command values Iq1_ref, Iq2_ref decrease, and the maximum torques T1_max, T2_max of the first three-phase winding and the second three-phase winding decrease.

[0123] At this time, as Figure 5 and Figure 7 shown, since the second DC voltage Vdc2 decreases, the current command values Id2_ref, Iq2_ref of the second three-phase winding and the maximum torque T2_max decrease offset compared to the current command values Id1_ref, Iq1_ref and the maximum torque T1_max of the first three-phase winding. Therefore, in the field weakening control related to this comparative example, due to the difference in DC voltage, there is a difference in dq-axis current and torque between systems, and high-frequency vibration and noise are generated in the AC rotating electrical machine 1.

[0124] In the first three-phase winding, at time t4, the first d-axis current command value Id1_ref reaches the d-axis current minimum value Id_min and is limited by the lower limit. On the other hand, in the second three-phase winding, due to the offset decrease of the d-axis current command value, at time t3 earlier than time t4, the second d-axis current command value Id2_ref reaches the d-axis current minimum value Id_min and is limited by the lower limit.

[0125] The first three-phase winding performs d-axis current minimum value limitation in the field weakening control during the period after time t4, and the second three-phase winding performs d-axis current minimum value limitation in the field weakening control during the period after time t3, as Figure 5 and Figure 6As shown, with respect to the increase in the rotational angular velocity, the first d-axis current command value Id1_ref and the second d-axis current command value Id2_ref are set to the d-axis current minimum value Id_min, and the first q-axis current command value Iq1_ref and the second q-axis current command value Iq2_ref are also set to the q-axis current minimum value Iq_min. On the other hand, since the actual first q-axis current Iq1 and the second q-axis current Iq2 decrease as the rotational angular velocity increases, the maximum torques T1_max and T2_max of the first three-phase winding and the second three-phase winding decrease.

[0126] At this time, as Figure 5 and Figure 8 shown, since the second DC voltage Vdc2 decreases, the actual second q-axis current Iq2 and the maximum torque T2_max decrease offset from the actual first q-axis current Iq1 and the maximum torque T1_max. Therefore, in this d-axis current minimum value limit, due to the difference in DC voltage between systems, a difference in q-axis current and torque between systems is generated, and high-frequency vibrations and noises are generated in the AC rotating electrical machine 1. In addition, an offset difference also occurs between the first d-axis current command value Id1_ref and the second d-axis current command value Id2_ref calculated by the field weakening control before being limited by the lower limit of the d-axis current minimum value Id_min. In addition, an offset difference also occurs between the first q-axis current command value Iq1_ref and the second q-axis current command value Iq2_ref calculated by the field weakening control before being limited by the lower limit of the d-axis current minimum value Id_min.

[0127] Thus, in the field weakening control and the d-axis current minimum value limit in the field weakening control, due to the DC voltage difference between systems, a difference in the maximum torque between systems is generated, and a difference in the detected values of dq-axis currents and a difference in dq-axis current commands are generated.

[0128] In order to reduce the torque difference between systems caused by the DC voltage difference between systems, the dq-axis current with a higher DC voltage can be matched with the dq-axis current with a lower DC voltage. In addition, due to the narrowing of the voltage limit ellipse, the dq-axis current with a lower DC voltage cannot be matched with the dq-axis current with a higher DC voltage. In addition, since the q-axis current is proportional to the torque, in order to reduce the torque difference, the q-axis current is more important than the d-axis current.

[0129] 1-6-3. Structure of the First and Second Current Command Selection Units

[0130] <Selecting the q-axis Current Command According to the DC Voltage Difference between Systems>

[0131] Therefore, as shown in the following formula, when it is determined that the first DC voltage Vdc1 is less than or equal to the second DC voltage Vdc2, the first current command selection unit 903a sets the first q-axis current command value Iq1_ref to the selected first q-axis current command value Iq1_ref*. When it is determined that the first DC voltage Vdc1 is higher than the second DC voltage Vdc2, the first current command selection unit 903a sets the second q-axis current detection value Iq2_det obtained by communication from the second controller 9b to the selected first q-axis current command value Iq1_ref*. As described above, the first voltage command calculation unit 904a changes the first q-axis voltage command value Vq1_ref so that the first q-axis current detection value Iq1_det approaches the selected first q-axis current command value Iq1_ref*.

[0132] 1) When it is determined that Vdc1 ≤ Vdc2,

[0133] Iq1_ref* = Iq1_ref

[0134] 2) When it is determined that Vdc1 > Vdc2,

[0135] Iq1_ref* = Iq2_det ··· (3)

[0136] Therefore, as shown in the following formula, when it is determined that the second DC voltage Vdc2 is less than or equal to the first DC voltage Vdc1, the second current command selection unit 903b sets the second q-axis current command value Iq2_ref to the selected second q-axis current command value Iq2_ref*. When it is determined that the second DC voltage Vdc2 is higher than the first DC voltage Vdc1, the second current command selection unit 903b sets the first q-axis current detection value Iq1_det obtained by communication from the first controller 9a to the selected second q-axis current command value Iq2_ref*. As described above, the second voltage command calculation unit 904b changes the second q-axis voltage command value Vq2_ref so that the second q-axis current detection value Iq2_det approaches the selected second q-axis current command value Iq2_ref*.

[0137] 1) When it is determined that Vdc2 ≤ Vdc1,

[0138] Iq2_ref* = Iq2_ref

[0139] 2) When it is determined that Vdc2 > Vdc1,

[0140] Iq2_ref* = Iq1_det ··· (4)

[0141] According to the above structure, when the first DC voltage Vdc1 becomes higher than the second DC voltage Vdc2, the detected value Iq2_det of the second q-axis current is set to the selected first q-axis current command value Iq1_ref*. Therefore, the first q-axis current can be reduced to the second q-axis current, so that the first q-axis current will not be higher than the second q-axis current near the maximum torque of the weak magnetic flux control. Conversely, when the second DC voltage Vdc2 becomes higher than the first DC voltage Vdc1, the detected value Iq1_det of the first q-axis current is set to the selected second q-axis current command value Iq2_ref*. Therefore, the second q-axis current can be reduced to the first q-axis current, so that the second q-axis current will not be higher than the first q-axis current near the maximum torque of the weak magnetic flux control. Since the q-axis current is proportional to the torque, the difference in torque between systems caused by the difference in DC voltage between systems can be suppressed.

[0142] <Selecting the d-axis current command according to the DC voltage difference between systems>

[0143] In the present embodiment, as shown in the following formula, when it is determined that the first DC voltage Vdc1 is less than or equal to the second DC voltage Vdc2, the first current command selection unit 903a sets the first d-axis current command value Id1_ref to the selected first d-axis current command value Id1_ref*. When it is determined that the first DC voltage Vdc1 is higher than the second DC voltage Vdc2, the first current command selection unit 903a sets the detected value Id2_ref of the second d-axis current obtained from the second controller 9b through communication to the selected first d-axis current command value Id1_ref*. As described above, the first voltage command calculation unit 904a changes the first d-axis voltage command value Vd1_ref so that the detected value Id1_det of the first d-axis current approaches the selected first d-axis current command value Id1_ref*.

[0144] 1) When it is determined that Vdc1 ≤ Vdc2,

[0145] Id1_ref* = Id1_ref

[0146] 2) When it is determined that Vdc1 > Vdc2,

[0147] Id1_ref* = Id2_ref ··· (5)

[0148] Further, as shown in the following equation, when it is determined that the second DC voltage Vdc2 is equal to or lower than the first DC voltage Vdc1, the second current command selection unit 903b sets the second d-axis current command value Id2_ref to the selected second d-axis current command value Id2_ref*. When it is determined that the second DC voltage Vdc2 is higher than the first DC voltage Vdc1, the second current command selection unit 903b sets the first d-axis current detection value Id1_ref obtained from the first controller 9a through communication to the selected second d-axis current command value Id2_ref*. As described above, the second voltage command calculation unit 904b changes the second d-axis voltage command value Vd2_ref so that the second d-axis current detection value Id2_det approaches the selected second q-axis current command value Id2_ref*.

[0149] 1) When it is determined that Vdc2 ≤ Vdc1,

[0150] Id2_ref* = Id2_ref

[0151] 2) When it is determined that Vdc2 > Vdc1,

[0152] Id2_ref* = Id1_ref ··· (6)

[0153] According to the above structure, when the first DC voltage Vdc1 becomes higher than the second DC voltage Vdc2, the second d-axis current command value Id2_ref is set to the selected first d-axis current command value Id1_ref*. Therefore, the first d-axis current can be reduced to the second d-axis current, so that the first d-axis current will not be higher than the second d-axis current near the maximum torque of the weak magnetic field control. Conversely, when the second DC voltage Vdc2 becomes higher than the first DC voltage Vdc1, the first d-axis current command value Id1_ref is set to the selected second d-axis current command value Id2_ref*. Therefore, the second d-axis current can be reduced to the first d-axis current, so that the second d-axis current will not be higher than the first d-axis current near the maximum torque of the weak magnetic field control. Therefore, in addition to the q-axis current, the difference in the d-axis current between systems can also be reduced, so that the difference in torque between systems caused by the difference in DC voltage between systems can be suppressed with higher precision.

[0154] <Determination of the DC voltage difference between systems caused by the d-axis current>

[0155] In the present embodiment, as shown in the following formula, when the absolute value of the first d-axis current command value Id1_ref is greater than or equal to the absolute value of the second d-axis current command value Id2_ref obtained from the second controller 9b through communication, the first current command selection unit 903a determines that the first DC voltage Vdc1 is less than or equal to the second DC voltage Vdc2. When the absolute value of the first d-axis current command value Id1_ref is less than the absolute value of the second d-axis current command value Id2_ref obtained from the second controller 9b through communication, the first current command selection unit 903a determines that the first DC voltage Vdc1 is higher than the second DC voltage Vdc2.

[0156] 1) It is determined that when |Id1_ref| ≥ |Id2_ref|

[0157] Vdc1 ≤ Vdc2

[0158] 2) It is determined that when |Id1_ref| < |Id2_ref|

[0159] Vdc1 > Vdc2 ··· (7)

[0160] In addition, as shown in the following formula, when the absolute value of the second d-axis current command value Id2_ref is greater than or equal to the absolute value of the first d-axis current command value Id1_ref obtained from the first controller 9a through communication, the second current command selection unit 903b determines that the second DC voltage Vdc2 is less than or equal to the absolute value of the first DC voltage Vdc1. When the absolute value of the second d-axis current command value Id2_ref is less than the absolute value of the first d-axis current command value Id1_ref obtained from the first controller 9a through communication, the second current command selection unit 903b determines that the second DC voltage Vdc2 is higher than the first DC voltage Vdc1.

[0161] 1) It is determined that when |Id2_ref| ≥ |Id1_ref|

[0162] Vdc2 ≤ Vdc1

[0163] 2) It is determined that when |Id2_ref| < |Id1_ref|

[0164] Vdc2 > Vdc1 ··· (8)

[0165] In addition, as in the present embodiment, the first d-axis current command value Id1_ref and the second d-axis current command value Id2_ref are limited by the lower limit of the d-axis current minimum value Id_min. When the two become the same value, in Equations (7) and (8), the first d-axis current command value and the second d-axis current command value calculated by the weak magnetic flux control before being limited by the lower limit of the d-axis current minimum value Id_min can be used to replace the first d-axis current command value Id1_ref and the second d-axis current command value Id2_ref.

[0166] According to the above structure, since the first and second d-axis current command values Id1_ref and Id2_ref used in the setting of the selected first d-axis current command value Id1_ref* and the second d-axis current command value Id2_ref* can be used to determine the DC voltage difference between systems, the data communication volume between the first controller 9a and the second controller 9b can be reduced.

[0167] <Control Behavior of the Present Embodiment>

[0168] Figure 10 This represents the control behavior of the embodiment when the rotational angular velocity gradually increases from zero in a state where the maximum torque is output to the first three-phase winding and the second three-phase winding. In this example, similar to the Figure 9 comparative example, the first DC voltage Vdc1 is maintained at the rated voltage, and the second DC voltage Vdc2 is lower than the rated voltage (Vdc1 > Vdc2). Therefore, the basic rotational angular velocity ω2a of the second three-phase winding becomes lower than the basic rotational angular velocity ω1a of the first three-phase winding.

[0169] For the first three-phase winding, at time t22, the rotational angular velocity reaches the basic rotational angular velocity ω1a of the first three-phase winding. On the other hand, due to the decrease in the basic rotational angular velocity ω2a, at a time t21 earlier than time t22, the rotational angular velocity of the second three-phase winding reaches the basic rotational angular velocity ω2a of the second three-phase winding.

[0170] During the period until time t21, both the first three-phase winding and the second three-phase winding perform Id = 0 control. Due to the DC voltage difference between systems, no dq-axis current and torque differences between systems are generated.

[0171] During the period from time t22 to time t24 for the first three-phase winding and during the period from time t21 to time t23 for the second three-phase winding, the dq-axis voltage command values are calculated by weak magnetic flux control. As Figure 5 and Figure 7As shown, since the second DC voltage Vdc2 becomes lower than the first DC voltage Vdc1, the absolute value of the second d-axis current command value Id2_ref becomes greater than the absolute value of the first d-axis current command value Id1_ref. Therefore, the first current command selection unit 903a and the second current command selection unit 903b determine that the second DC voltage Vdc2 is below the first DC voltage Vdc1, and the second q-axis current detection value Iq2_det is set as the selected first q-axis current command value Iq1_ref*, and the second d-axis current detection value Id2_det is set as the selected first d-axis current command value Id1_ref*.

[0172] Therefore, compared with Figure 9 the comparative example, the first q-axis current can be reduced to the second q-axis current, and the first d-axis current can be reduced to the second d-axis current. Therefore, the maximum torque T1_max of the first three-phase winding can be reduced to the maximum torque T2_max of the second three-phase winding, and the torque difference between systems can be reduced.

[0173] During the period after time t24 for the first three-phase winding and during the period after time t23 for the second three-phase winding, for each d-axis current command calculated by field weakening control, it is limited by the lower limit of the d-axis current minimum value Id_min, and the first d-axis current command value Id1_ref and the second d-axis current command value Id2_ref are set to the d-axis current minimum value Id_min. For each q-axis current command calculated by field weakening control, it is limited by the lower limit of the q-axis current minimum value Iq_min, and the first q-axis current command value Iq1_ref and the second q-axis current command value Iq2_ref are set to the q-axis current minimum value Iq_min.

[0174] At this time, before being limited by the lower limits of the d-axis and q-axis current minimum values Id_min and Iq_min, the absolute value of the second d-axis current command value calculated by field weakening control also becomes greater than the absolute value of the first d-axis current command value before being limited by the lower limit. Therefore, the first current command selection unit 903a and the second current command selection unit 903b determine that the second DC voltage Vdc2 is below the first DC voltage Vdc1, and the second q-axis current detection value Iq2_det is set as the selected first q-axis current command value Iq1_ref*, and the second d-axis current detection value Id2_ref is set as the selected first d-axis current command value Id1_ref*.

[0175] Therefore, compared with Figure 9Compared with the comparative example, the first d-axis current and the second d-axis current can be maintained at the minimum d-axis current Id_min without change, and the detected value Iq1_det of the first q-axis current can be reduced to the detected value Iq2_det of the second q-axis current. Therefore, the maximum torque T1_max of the first three-phase winding can be reduced to the maximum torque T2_max of the second three-phase winding, and the torque difference between systems can be reduced.

[0176] As described above, even if a DC voltage difference between systems occurs, the torque difference between systems can be suppressed in the entire region of the rotational angular velocity, regardless of the Id = 0 control and the weak magnetic flux control.

[0177] 2. Embodiment 2

[0178] Next, the AC rotating electrical machine 1 and the motor control device according to Embodiment 2 will be described. The description of the same structural parts as those in the above Embodiment 1 will be omitted. The basic structures of the AC rotating electrical machine 1 and the motor control device according to this embodiment are the same as those in Embodiment 1, but the processing of the first current command selection unit 903a and the second current command selection unit 903b is different from that in Embodiment 1. Figure 11 The block diagram showing the first controller 9a and the second controller 9b according to this embodiment.

[0179] In this embodiment, instead of Equation (3), as shown in the following equation, when it is determined that the first DC voltage Vdc1 is less than or equal to the second DC voltage Vdc2, the first current command selection unit 903a sets the first q-axis current command value Iq1_ref to the selected first q-axis current command value Iq1_ref*. When it is determined that the first DC voltage Vdc1 is higher than the second DC voltage Vdc2, the first current command selection unit 903a sets the detected value Iq2_ref of the second q-axis current obtained from the second controller 9b through communication to the selected first q-axis current command value Iq1_ref*. As described above, the first voltage command calculation unit 904a changes the first q-axis voltage command value Vq1_ref so that the detected value Iq1_det of the first q-axis current approaches the selected first q-axis current command value Iq1_ref*.

[0180] 1) When it is determined that Vdc1 ≤ Vdc2,

[0181] Iq1_ref* = Iq1_ref

[0182] 2) When it is determined that Vdc1 > Vdc2,

[0183] Iq1_ref* = Iq2_ref ··· (9)

[0184] Further, instead of Expression (4), as shown in the following expression, when it is determined that the second DC voltage Vdc2 is equal to or lower than the first DC voltage Vdc1, the second current command selection unit 903b sets the second q-axis current command value Iq2_ref to the selected second q-axis current command value Iq2_ref*. When it is determined that the second DC voltage Vdc2 is higher than the first DC voltage Vdc1, the second current command selection unit 903b sets the first q-axis current command value Iq1_ref obtained from the first controller 9a through communication to the selected second q-axis current command value Iq2_ref*. As described above, the second voltage command calculation unit 904b changes the second q-axis voltage command value Vq2_ref so that the second q-axis current detection value Iq2_det approaches the selected second q-axis current command value Iq2_ref*.

[0185] 1) When it is determined that Vdc2 ≤ Vdc1,

[0186] Iq2_ref* = Iq2_ref

[0187] 2) When it is determined that Vdc2 > Vdc1,

[0188] Iq2_ref* = Iq1_ref ··· (10)

[0189] Further, as in the present embodiment, the first q-axis current command value Iq1_ref and the second q-axis current command value Iq2_ref are limited by the lower limit of the q-axis current minimum value Iq_min corresponding to the d-axis current minimum value Id_min. When the two become the same value, in 2) of Expression (9) and Expression (10), the first q-axis current command value and the second q-axis current command value calculated by the weak magnetic flux control before being limited by the lower limit of the q-axis current minimum value Iq_min can be used instead of the first q-axis current command value Iq1_ref and the second q-axis current command value Iq2_ref.

[0190] According to the above structure, when the first DC voltage Vdc1 becomes higher than the second DC voltage Vdc2, the second q-axis current command value Iq2_ref is set to the selected first q-axis current command value Iq1_ref*. Therefore, the first q-axis current can be reduced to the second q-axis current, so that the first q-axis current is not higher than the second q-axis current near the maximum torque of the weak magnetic flux control. Conversely, when the second DC voltage Vdc2 becomes higher than the first DC voltage Vdc1, the first q-axis current command value Iq1_ref is set to the selected second q-axis current command value Iq2_ref*. Therefore, the second q-axis current can be reduced to the first q-axis current, so that the second q-axis current is not higher than the first q-axis current near the maximum torque of the weak magnetic flux control. Since the q-axis current is proportional to the torque, the difference in torque between systems caused by the difference in DC voltage between systems can be suppressed.

[0191] 3. Embodiment 3

[0192] Next, the AC rotating electrical machine 1 and the motor control device according to Embodiment 3 will be described. The description of the same structural parts as those in the above Embodiment 1 will be omitted. The basic structures of the AC rotating electrical machine 1 and the motor control device according to the present embodiment are the same as those in Embodiment 1, but the processing of the first current command selection unit 903a and the second current command selection unit 903b is different from that in Embodiment 1. Figure 12 The block diagram showing the first controller 9a and the second controller 9b according to the present embodiment.

[0193] In the present embodiment, instead of Equation (5), as shown in the following equation, when it is determined that the first DC voltage Vdc1 is less than or equal to the second DC voltage Vdc2, the first current command selection unit 903a sets the first d-axis current command value Id1_ref to the selected first d-axis current command value Id1_ref*. When it is determined that the first DC voltage Vdc1 is higher than the second DC voltage Vdc2, the second d-axis current detection value Id2_det obtained from the second controller 9b through communication is set to the selected first d-axis current command value Id1_ref*. As described above, the first voltage command calculation unit 904a changes the first d-axis voltage command value Vd1_ref so that the first d-axis current detection value Id1_det approaches the selected first d-axis current command value Id1_ref*.

[0194] 1) When it is determined that Vdc1 ≤ Vdc2,

[0195] Id1_ref*=Id1_ref

[0196] 2) When it is determined that Vdc1 > Vdc2,

[0197] Id1_ref* = Id2_det ··· (11)

[0198] In addition, substituting formula (6), as shown below, when it is determined that the second DC voltage Vdc2 is less than or equal to the first DC voltage Vdc1, the second current command selection unit 903b sets the second d-axis current command value Id2_ref to the selected second d-axis current command value Id2_ref*. When it is determined that the second DC voltage Vdc2 is higher than the first DC voltage Vdc1, the second current command selection unit 903b sets the first d-axis current detection value Id1_det obtained from the first controller 9a through communication to the selected second d-axis current command value Id2_ref*. As described above, the second voltage command calculation unit 904b changes the second d-axis voltage command value Vd2_ref so that the second d-axis current detection value Id2_det approaches the selected second d-axis current command value Id2_ref*.

[0199] 1) When it is determined that Vdc2 ≤ Vdc1

[0200] Id2_ref* = Id2_ref

[0201] 2) When it is determined that Vdc2 > Vdc1

[0202] Id2_ref* = Id1_det ··· (12)

[0203] According to the above structure, when the first DC voltage Vdc1 becomes higher than the second DC voltage Vdc2, the second d-axis current command value Id2_ref is set to the selected first d-axis current command value Id1_ref*. Therefore, the first d-axis current can be reduced to the second d-axis current, so that the first d-axis current will not be higher than the second d-axis current near the maximum torque of the weak magnetic flux control. Conversely, when the second DC voltage Vdc2 becomes higher than the first DC voltage Vdc1, the first d-axis current detection value Id1_det is set to the selected second d-axis current command value Id2_ref*. Therefore, the second d-axis current can be reduced to the first d-axis current, so that the second d-axis current will not be higher than the first d-axis current near the maximum torque of the weak magnetic flux control. Therefore, in addition to the q-axis current, the difference between the d-axis currents between systems can also be reduced, so that the difference in torque between systems caused by the difference in DC voltage between systems can be suppressed with higher precision.

[0204] 4. Embodiment 4

[0205] Next, the AC rotating electrical machine 1 and the motor control device according to Embodiment 4 will be described. The description of the structural parts identical to those of the above-described Embodiment 2 will be omitted. The basic structures of the AC rotating electrical machine 1 and the motor control device according to the present embodiment are the same as those of Embodiment 2, but the processing of the first current command selection unit 903a and the second current command selection unit 903b is different from that of Embodiment 1. The block diagrams of the first controller 9a and the second controller 9b according to the present embodiment are the same as those of Embodiment 2's Figure 11 same.

[0206] In the present embodiment, instead of Equation (7), as shown in the following equation, when the absolute value of the first q-axis current command value Iq1_ref is greater than or equal to the absolute value of the second q-axis current command value Iq2_ref acquired from the second controller 9b through communication, the first current command selection unit 903a determines that the first DC voltage Vdc1 is higher than the second DC voltage Vdc2. When the absolute value of the first q-axis current command value Iq1_ref is less than the absolute value of the second q-axis current command value Iq2_ref acquired from the second controller 9b through communication, the first current command selection unit 903a determines that the first DC voltage Vdc1 is lower than the second DC voltage Vdc2.

[0207] 1) When |Iq1_ref| ≥ |Iq2_ref|, it is determined that

[0208] Vdc1 > Vdc2

[0209] 2) When |Id1_ref| < |Id2_ref|, it is determined that

[0210] Vdc1 ≤ Vdc2 ··· (13)

[0211] In addition, instead of Equation (8), as shown in the following equation, when the absolute value of the second q-axis current command value Iq2_ref is greater than or equal to the absolute value of the first q-axis current command value Iq1_ref acquired from the first controller 9a through communication, the second current command selection unit 903b determines that the second DC voltage Vdc2 is higher than the first DC voltage Vdc1. When the absolute value of the second q-axis current command value Iq2_ref is less than the absolute value of the first q-axis current command value Iq1_ref acquired from the first controller 9a through communication, the second current command selection unit 903b determines that the second DC voltage Vdc2 is lower than the first DC voltage Vdc1.

[0212] 1) When |Iq2_ref| ≥ |Iq1_ref|, it is determined that

[0213] Vdc2 > Vdc1

[0214] 2) Determine that when |Iq2_ref| < |Iq1_ref|

[0215] Vdc2 ≤ Vdc1 ···(14)

[0216] In addition, as in this embodiment, the first q-axis current command value Iq1_ref and the second q-axis current command value Iq2_ref are limited by the lower limit of the q-axis current minimum value Iq_min corresponding to the d-axis current minimum value Id_min. When the two become the same value, in Equations (9) and (10), the first q-axis current command value and the second q-axis current command value calculated by the weak magnetic flux control before being limited by the lower limit of the q-axis current minimum value Iq_min can be used to replace the first q-axis current command value Iq1_ref and the second q-axis current command value Iq2_ref.

[0217] 5. Embodiment 5

[0218] Next, the AC rotating electrical machine 1 and the motor control device according to Embodiment 2 will be described. The description of the same structural parts as those in the above Embodiment 1 will be omitted. The basic structures of the AC rotating electrical machine 1 and the motor control device according to this embodiment are the same as those in Embodiment 1, but the determination method of the magnitude relationship between the first DC voltage Vdc1 and the second DC voltage Vdc2 in the first current command selection unit 903a and the second current command selection unit 903b is different from that in Embodiment 1. Figure 13 The block diagram showing the first controller 9a and the second controller 9b according to this embodiment.

[0219] In this embodiment, instead of Equation (7), as shown in the following equation, when the first DC voltage detection value Vdc1_det is less than or equal to the second DC voltage detection value Vdc2_det obtained from the second controller 9b through communication, the first current command selection unit 903a determines that the first DC voltage Vdc1 is less than or equal to the second DC voltage Vdc2. When the first DC voltage detection value Vdc1_det is higher than the second DC voltage detection value Vdc2_det obtained from the second controller 9b through communication, the first current command selection unit 903a determines that the first DC voltage Vdc1 is higher than the second DC voltage Vdc2.

[0220] 1) Determine that when Vdc1_det ≤ Vdc2_det

[0221] Vdc1 ≤ Vdc2

[0222] 2) Determine that when Vdc1_det > Vdc2_det

[0223] Vdc1 > Vdc2 ···(15)

[0224] The substitution formula (8) is as shown below. When the second DC voltage detection value Vdc2_det is less than or equal to the first DC voltage detection value Vdc1_det obtained from the first controller 9a through communication, the second current command selection unit 903b determines that the second DC voltage Vdc2 is less than or equal to the first DC voltage Vdc1. When the second DC voltage detection value Vdc2_det is higher than the first DC voltage detection value Vdc1_det obtained from the first controller 9a through communication, the second current command selection unit 903b determines that the second DC voltage Vdc2 is higher than the first DC voltage Vdc1.

[0225] 1) It is determined that when Vdc2_det ≤ Vdc1_det

[0226] Vdc2 ≤ Vdc1

[0227] 2) It is determined that when Vdc2_det > Vdc1_det

[0228] Vdc2 > Vdc1 ··· (16)

[0229] According to the above structure, by using the DC voltage detection values obtained through communication between the controllers, the DC voltage difference between the systems can be directly determined, thus ensuring the determination accuracy.

[0230] [Other Embodiments]

[0231] Finally, other embodiments of the present application will be described. In addition, the structures of the embodiments described below are not limited to being applied separately. As long as there is no contradiction, they can also be combined with the structures of other embodiments for application.

[0232] (1) In the above embodiments, the case where the d-axis current command is limited by the lower limit of the d-axis current minimum value Id_min in the weak magnetic flux control is taken as an example for description. However, it may not be limited by the lower limit of the d-axis current minimum value Id_min.

[0233] (2) In the above embodiments, the case where the Id = 0 control is performed is taken as an example for description. However, other vector controls such as the maximum torque current control can be executed to replace the Id = 0 control.

[0234] (3) Embodiments 1 to 5 can also be implemented in any combination.

[0235] Although this application describes various exemplary embodiments and examples, the various features, methods, and functions described in one or more embodiments are not limited to the application of a specific embodiment and can be applied individually or in various combinations to the embodiments. Therefore, it can be considered that countless variations not illustrated are also included within the technical scope disclosed in the specification of this application. For example, it is assumed to include cases where at least one component is deformed, added, or omitted, and cases where at least one component is extracted and combined with the components of other embodiments.

[0236] Reference Numeral Explanation

[0237] 1 AC rotating electric machine

[0238] 3a First DC power supply

[0239] 3b Second DC power supply

[0240] 4a First inverter

[0241] 4b Second inverter

[0242] 9a First controller

[0243] 9b Second controller

[0244] 10a First current detector

[0245] 10b Second current detector

[0246] Id1_det First d-axis current detection value

[0247] Id1_ref First d-axis current command value

[0248] Id2_det Second d-axis current detection value

[0249] Id2_ref Second d-axis current command value

[0250] Iq1_det First q-axis current detection value

[0251] Iq1_ref First q-axis current command value

[0252] Iq2_det Second q-axis current detection value

[0253] Iq2_ref Second q-axis current command value

[0254] Vdc1 First DC voltage

[0255] Vdc1_det First DC voltage detection value

[0256] Vdc2 Second DC voltage

[0257] Vdc2_det Second DC voltage detection value

[0258] Vd1_ref First d-axis voltage command value

[0259] Vd2_ref Second d-axis voltage command value

[0260] Vq1_ref First q-axis voltage command value

[0261] Vq2_ref Second q-axis voltage command value.

Claims

1. A motor control device is a motor control device that controls an AC rotating electrical machine having a first three-phase winding and a second three-phase winding, characterized in that, Comprising: A first inverter that applies a first DC voltage of a first DC power supply to the first three-phase winding; A first current detector that detects a current flowing through the first three-phase winding; A first controller that calculates a first d-axis current detection value and a first q-axis current detection value representing the current detection value of the first three-phase winding detected by the first current detector in a d-axis and q-axis coordinate system that rotates synchronously with the rotational position of the AC rotating machine, calculates a first d-axis current command value and a first q-axis current command value, calculates a first d-axis voltage command value and a first q-axis voltage command value, and controls the first inverter based on the first d-axis voltage command value and the first q-axis voltage command value; A second inverter that applies a second DC voltage of a second DC power supply to the second three-phase winding; A second current detector that detects a current flowing through the second three-phase winding; And A second controller that calculates a second d-axis current detection value and a second q-axis current detection value representing the current detection value of the second three-phase winding detected by the second current detector in the d-axis and q-axis coordinate system, calculates a second d-axis current command value and a second q-axis current command value, calculates a second d-axis voltage command value and a second q-axis voltage command value, and controls the second inverter based on the second d-axis voltage command value and the second q-axis voltage command value; When the first controller determines that the first DC voltage is below the second DC voltage, it changes the first q-axis voltage command value so that the first q-axis current detection value approaches the first q-axis current command value. When it determines that the first DC voltage is higher than the second DC voltage, it changes the first q-axis voltage command value so that the first q-axis current detection value approaches the second q-axis current detection value or the second q-axis current command value obtained from the second controller through communication; When the second controller determines that the second DC voltage is below the first DC voltage, it changes the second q-axis voltage command value so that the second q-axis current detection value approaches the second q-axis current command value. When it determines that the second DC voltage is higher than the first DC voltage, it changes the second q-axis voltage command value so that the second q-axis current detection value approaches the first q-axis current detection value or the first q-axis current command value obtained from the first controller through communication.

2. The motor control device according to claim 1, wherein When the first controller determines that the first DC voltage is below the second DC voltage, it changes the first d-axis voltage command value so that the first d-axis current detection value approaches the first d-axis current command value. When it determines that the first DC voltage is higher than the second DC voltage, it changes the first d-axis voltage command value so that the first d-axis current detection value approaches the second d-axis current detection value or the second d-axis current command value obtained from the second controller through communication. When the second controller determines that the second DC voltage is below the first DC voltage, it changes the second d-axis voltage command value so that the second d-axis current detection value approaches the second d-axis current command value. When it determines that the second DC voltage is higher than the first DC voltage, it changes the second q-axis voltage command value so that the second d-axis current detection value approaches the first d-axis current detection value or the first d-axis current command value obtained from the first controller through communication.

3. The motor control device according to claim 1 or 2, characterized in that: The first controller determines that the first DC voltage is below the second DC voltage when the absolute value of the first d-axis current command value is greater than or equal to the absolute value of the second d-axis current command value obtained from the second controller through communication, and determines that the first DC voltage is higher than the second DC voltage when the absolute value of the first d-axis current command value is less than the absolute value of the second d-axis current command value obtained from the second controller through communication. The second controller determines that the second DC voltage is below the first DC voltage when the absolute value of the second d-axis current command value is greater than or equal to the absolute value of the first d-axis current command value obtained from the first controller through communication, and determines that the second DC voltage is higher than the first DC voltage when the absolute value of the second d-axis current command value is less than the absolute value of the first d-axis current command value obtained from the first controller through communication.

4. The motor control device according to claim 1 or 2, characterized in that: The first controller determines that the first DC voltage is higher than the second DC voltage when the absolute value of the first q-axis current command value is greater than or equal to the absolute value of the second q-axis current command value obtained from the second controller through communication, and determines that the first DC voltage is below the second DC voltage when the absolute value of the first q-axis current command value is less than the absolute value of the second q-axis current command value obtained from the second controller through communication. When the absolute value of the second q-axis current command value is greater than or equal to the absolute value of the first q-axis current command value obtained from the first controller through communication, the second controller determines that the second DC voltage is higher than the first DC voltage. When the absolute value of the second q-axis current command value is less than the absolute value of the first q-axis current command value obtained from the first controller through communication, the second controller determines that the second DC voltage is lower than the first DC voltage.

5. The motor control device according to claim 1 or 2, wherein When the first DC voltage is less than or equal to the second DC voltage obtained from the second controller through communication, the first controller determines that the first DC voltage is lower than the second DC voltage. When the first DC voltage is less than the second DC voltage obtained from the second controller through communication, the first controller determines that the first DC voltage is higher than the second DC voltage. When the second DC voltage is less than or equal to the first DC voltage obtained from the first controller through communication, the second controller determines that the second DC voltage is lower than the first DC voltage. When the second DC voltage is higher than the first DC voltage obtained from the first controller through communication, the second controller determines that the second DC voltage is higher than the first DC voltage.

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