Control device, line-switching system, control method, and control program

Abstract

This control device comprises: a switching command unit that commands a line-switching device to execute zero-cross switching for switching a connection state of a plurality of windings of an AC motor at a zero-cross point of an electric current; a parameter value determination unit that determines a value of a first control parameter and a value of a second control parameter; and a voltage value determination unit that determines, on the basis of the value of the first control parameter and the value of the second control parameter, a voltage to be applied to the plurality of windings, wherein, when the zero-cross switching is executed, the parameter value determination unit switches the first control parameter from a first pre-switch parameter value to a first post-switch parameter value at a first timing, and switches the second control parameter from a second pre-switch parameter value to a second post-switch parameter value at a second timing.

Description

Control device, winding switching system, control method, and control program

[0001] This application claims priority to Japanese Patent Application No. 2023-032864, filed March 3, 2023, and incorporates by reference the entire contents of that application.

[0002] For example, some motors mounted on electric vehicles can switch between a low-speed, high-torque operating state and a high-speed, low-torque operating state by switching the connections of multiple windings. Patent Document 1 discloses a device that identifies a period during which the AC motor current is below a predetermined value and switches the windings during the identified period in order to prevent surge voltages.

[0003] Japanese Patent Application Laid-Open No. 2020-072632

[0004] A control device according to one aspect of the present disclosure is a control device for controlling an AC motor capable of switching a connection state of a plurality of windings from a first connection state to a second connection state, the control device including: a switching command unit that commands a winding switching device that switches the connection state of the plurality of windings to execute zero-cross switching, in which the connection state of the plurality of windings is switched from the first connection state to the second connection state at a zero-cross point of a current flowing through the windings; a parameter value determination unit that determines a value of a first control parameter for controlling the AC motor and a value of a second control parameter for controlling the AC motor; and a control unit that determines a value of the first control parameter determined by the parameter value determination unit. and a voltage value determination unit that determines a voltage to be applied to the plurality of windings based on a value of a parameter and the value of the second control parameter, wherein when the zero-crossing switching is executed, the parameter value determination unit switches the first control parameter from a first pre-switching parameter value that is a value in the first connection state to a first post-switching parameter value that is a value in the second connection state at a first timing, and switches the second control parameter from a second pre-switching parameter value that is a value in the first connection state to a second post-switching parameter value that is a value in the second connection state at a second timing different from the first timing.

[0005] FIG. 1 is a diagram showing an example of the configuration of a winding switching system according to a first embodiment. FIG. 2 is a circuit diagram showing an example of the configuration of a winding switching device according to the first embodiment. FIG. 3 is a circuit diagram showing an example of the configuration of a control circuit. FIG. 4 is a timing chart showing an example of transitions in the states of signals in the winding switching device according to the first embodiment. FIG. 5 is a block diagram showing an example of the hardware configuration of a control device according to the first embodiment. FIG. 6 is a functional block diagram showing an example of the function of the control device according to the first embodiment. FIG. 7 is a control block diagram showing a motor control system of the control device according to the first embodiment. FIG. 8 is a graph showing an example of switching of parameter values ​​of control parameters. FIG. 9A is the first half of a flowchart showing an example of motor control processing by the control device according to the first embodiment. FIG. 9B is the second half of a flowchart showing an example of motor control processing by the control device according to the first embodiment. FIG. 10 is a circuit diagram showing an example of the configuration of a winding switching device according to a second embodiment. FIG. 11 is a graph showing another example of switching of parameter values ​​of control parameters. FIG. 12 is a circuit diagram showing an example of the configuration of a winding switching device according to a third embodiment. FIG. 13 is a functional block diagram showing an example of the function of a control device according to a fourth embodiment. FIG. 14 is the first half of a flowchart showing an example of a motor control process performed by the control device according to the fourth embodiment.

[0006] <Problem to be Solved by the Present Disclosure> Before and after switching the motor windings, it is necessary to change the values ​​of control parameters (hereinafter also referred to as "parameter values"), such as the target current and feedback gain. For this reason, not only the windings but also the parameter values ​​are switched, but there is a risk of a surge voltage occurring when the parameter values ​​are switched. Furthermore, a sudden change in the parameter values ​​may cause oscillation in the motor current control.

[0007] <Effects of the Present Disclosure> According to the present disclosure, it is possible to suppress the occurrence of surge voltage and suppress the transmission of current control of the motor.

[0008] <Outline of Embodiments of the Present Disclosure> Below, an outline of embodiments of the present disclosure will be listed and described.

[0009] (1) A control device according to this embodiment is a control device for controlling an AC motor capable of switching a connection state of a plurality of windings from a first connection state to a second connection state, and includes a switching command unit that commands a winding switching device that switches the connection state of the plurality of windings to execute zero-cross switching, which switches the connection state of the plurality of windings from the first connection state to the second connection state at a zero-cross point of a current flowing through the windings; a parameter value determination unit that determines a value of a first control parameter for controlling the AC motor and a value of a second control parameter for controlling the AC motor; and a control unit that determines a value of the first control parameter determined by the parameter value determination unit. and a voltage value determination unit that determines a voltage to be applied to the plurality of windings based on a value of the first control parameter and a value of the second control parameter, wherein the parameter value determination unit, when the zero-crossing switching is performed, switches the first control parameter from a first pre-switching parameter value that is a value in the first connection state to a first post-switching parameter value that is a value in the second connection state at a first timing, and switches the second control parameter from a second pre-switching parameter value that is a value in the first connection state to a second post-switching parameter value that is a value in the second connection state at a second timing different from the first timing. In this way, when the zero-crossing switching is performed, the parameter values ​​of the first control parameter and the second control parameter are switched in a stepwise manner, thereby suppressing the generation of a surge voltage and suppressing the transmission of current control of the motor.

[0010] (2) In the above (1), the parameter value determiner may repeatedly determine the value of the first control parameter and the value of the second control parameter for each control cycle, the first timing being a timing in a first control cycle, and the second timing being a timing in a second control cycle different from the first control cycle. This allows the voltages applied to the plurality of windings to change stepwise over a plurality of control cycles when zero-crossing switching is performed, thereby suppressing the occurrence of surge voltages and suppressing transmission of current control of the motor.

[0011] (3) In the above (1) or (2), the first timing may be a first zero-cross point that is a zero-cross point of the AC current supplied to the AC motor, and the second timing may be a second zero-cross point that is a zero-cross point of the AC current different from the first zero-cross point. This allows the parameter values ​​of the first control parameter and the second control parameter to be switched at the zero-cross point, thereby further suppressing the occurrence of surge voltage and suppressing the transmission of current control of the motor.

[0012] (4) In any one of (1) to (3) above, the control device may further include an identifying unit that identifies a switching timing at which the winding switching device executes the zero-crossing switching, and the first timing may be the switching timing identified by the identifying unit. This allows the parameter value of the first control parameter to be switched at the timing at which the zero-crossing switching is executed, thereby further suppressing the occurrence of surge voltage and suppressing the transmission of current control of the motor.

[0013] (5) In any one of (1) to (4) above, the parameter value determination unit may gradually change the first control parameter from the first pre-switching parameter value to the first post-switching parameter value. This prevents the parameter value of the first control parameter from changing suddenly. This suppresses the occurrence of surge voltage and the transmission of motor current control.

[0014] (6) In any one of (1) to (5) above, the parameter value determination unit may gradually change the second control parameter from the second pre-switching parameter value to the second post-switching parameter value. This prevents the parameter value of the second control parameter from changing suddenly. This suppresses the occurrence of surge voltage and the transmission of motor current control.

[0015] (7) In any one of (1) to (6) above, the AC motor may be a multi-phase AC motor, and the parameter value determiner may determine the second pre-switching parameter value and the second post-switching parameter value when the zero-crossing switching is performed, and the voltage value determiner may switch from a pre-switching voltage value determined based on the second pre-switching parameter value to a post-switching voltage value determined based on the second post-switching parameter value at different timings for each phase. This prevents the control voltage values ​​from changing uniformly across all phases. This makes it possible to suppress surge voltages and suppress the transmission of current control signals for the motor.

[0016] (8) In any one of (1) to (7) above, one of the first control parameter and the second control parameter may be a feedback gain, and the parameter value determiner may switch the feedback gain from a pre-switching feedback gain, which is a value in the first connection state, to a post-switching feedback gain, which is a value in the second connection state, via a switching feedback gain corresponding to the zero-crossing switching, when the zero-crossing switching is performed. This prevents the feedback gain from suddenly changing from the pre-switching feedback gain for the first connection state to the post-switching feedback gain for the second connection state when the zero-crossing switching is performed. This prevents surge voltage from occurring and suppresses transmission of current control of the motor.

[0017] (9) A winding switching system according to this embodiment includes an AC motor capable of switching a connection state of a plurality of windings from a first connection state to a second connection state, a power converter that converts power output from a power source into AC power and supplies the AC power to the AC motor, a winding switching device that performs zero-cross switching to switch the connection state of the plurality of windings from the first connection state to the second connection state at a zero-cross point of a current flowing through the windings, and a control device, wherein the control device includes a switching command unit that commands the winding switching device to perform the zero-cross switching, and a parameter value decision unit that determines a value of a first control parameter for controlling the AC motor and a value of a second control parameter for controlling the AC motor. and a voltage value determination unit that determines a voltage to be applied to the plurality of windings based on the value of the first control parameter and the value of the second control parameter determined by the parameter value determination unit, wherein when the zero-crossing switching is performed, the parameter value determination unit switches the first control parameter from a first pre-switching parameter value that is a value in the first connection state to a first post-switching parameter value that is a value in the second connection state at a first timing, and switches the second control parameter from a second pre-switching parameter value that is a value in the first connection state to a second post-switching parameter value that is a value in the second connection state at a second timing different from the first timing. In this way, when the zero-crossing switching is performed, the parameter values ​​of the first control parameter and the second control parameter are switched in a stepwise manner, thereby suppressing the generation of a surge voltage and suppressing the transmission of current control of the motor.

[0018] (10) A control method according to this embodiment is a control method for controlling an AC motor capable of switching a connection state of a plurality of windings from a first connection state to a second connection state, the control method including the steps of: instructing a winding switching device that switches the connection states of the plurality of windings to execute zero-cross switching, which switches the connection state of the plurality of windings from the first connection state to the second connection state at a zero-cross point of a current flowing through the windings; determining a value of a first control parameter for controlling the AC motor and a value of a second control parameter for controlling the AC motor; and determining a value of the first control parameter and a value of the second control parameter based on the determined values ​​of the first control parameter and the second control parameter. and determining a voltage to be applied to the plurality of windings based on the determined values ​​of the first control parameter and the second parameter, wherein, when the zero-crossing switching is performed, the first control parameter is switched from a first pre-switching parameter value, which is a value in the first connection state, to a first post-switching parameter value, which is a value in the second connection state, at a first timing, and the second control parameter is switched from a second pre-switching parameter value, which is a value in the first connection state, to a second post-switching parameter value, which is a value in the second connection state, at a second timing different from the first timing. Thus, when the zero-crossing switching is performed, the parameter values ​​of the first control parameter and the second control parameter are switched in a stepwise manner, thereby suppressing the generation of a surge voltage and the transmission of current control of the motor.

[0019] (11) A control program according to this embodiment is a control program for controlling an AC motor capable of switching a connection state of a plurality of windings from a first connection state to a second connection state, the control program including the steps of: instructing a computer to instruct a winding switching device that switches the connection state of the plurality of windings to execute zero-cross switching to switch the connection state of the plurality of windings from the first connection state to the second connection state at a zero-cross point of a current flowing through the windings; determining values ​​of first control parameters for controlling the AC motor and second control parameters for controlling the AC motor; and determining the determined values ​​of the first control parameters and the second control parameters. and determining a voltage to be applied to the plurality of windings based on a value of the first control parameter and the second parameter, wherein, in the step of determining the value of the first control parameter and the value of the second parameter, when the zero-crossing switching is performed, the first control parameter is switched from a first pre-switching parameter value that is a value in the first connection state to a first post-switching parameter value that is a value in the second connection state at a first timing, and the second control parameter is switched from a second pre-switching parameter value that is a value in the first connection state to a second post-switching parameter value that is a value in the second connection state at a second timing different from the first timing. Thus, when the zero-crossing switching is performed, the parameter value of the first control parameter and the parameter value of the second control parameter are switched in a stepwise manner, thereby suppressing the generation of a surge voltage and suppressing the transmission of current control of the motor.

[0020] The present disclosure can be realized not only as a control device having the above-described characteristic configuration, a winding switching system including the control device, a control method having steps representing characteristic processes in the control device, and a control program for causing a computer to execute the characteristic processes, but also as a semiconductor integrated circuit that realizes part or all of the control device.

[0021] <Details of the embodiments of the present disclosure> Hereinafter, the details of the embodiments of the present disclosure will be described with reference to the drawings. Note that at least some of the embodiments described below may be combined in any manner.

[0022] [1. First Embodiment] [1-1. Winding Switching System] FIG. 1 is a diagram showing an example of the configuration of a winding switching system according to a first embodiment.

[0023] The winding switching system 10 is mounted on a vehicle (hereinafter referred to as an "electric vehicle") that is propelled by a motor, such as an electric vehicle, a plug-in hybrid vehicle, etc. The winding switching system 10 includes a motor 20, a power converter 30, a battery 40, a control device 50, and a winding switching device 100.

[0024] The motor 20 is a traction motor that generates propulsion power for the electric vehicle. The motor 20 is driven by three-phase AC power. An example of the motor 20 is a permanent magnet synchronous motor.

[0025] A position sensor 26 is provided on the output shaft of the motor 20. The position sensor 26 detects the rotation angle of the output shaft of the motor 20. The position sensor 26 is, for example, a rotary encoder or a rotary potentiometer. The position sensor 26 is connected to the control device 50 by a signal line. A detection signal from the position sensor 26 is output to the control signal 50.

[0026] The battery 40 is a battery that supplies power to drive the motor 20. The battery 40 is a secondary battery, such as a lithium ion battery.

[0027] The power converter 30 is an inverter that converts DC power supplied from the battery 40 into three-phase AC power. The power converter 30 may have a function of converting three-phase AC power output when the motor 20 functions as a generator into DC power and charging the battery 40.

[0028] The power converter 30 includes U-phase, V-phase, and W-phase legs. The U-phase leg includes switches 31u and 32u, the V-phase leg includes switches 31v and 32v, and the W-phase leg includes switches 31w and 32w. The switches 31u, 32u, 31v, 32v, 31w, and 32w perform switching to convert DC power into three-phase AC power. The switches 31u, 32u, 31v, 32v, 31w, and 32w are, for example, insulated gate bipolar transistors (IGBTs) or power metal oxide semiconductor field-effect transistors (MOSFETs).

[0029] A power line 35u corresponding to the U phase extends from the U-phase leg, a power line 35v corresponding to the V phase extends from the V-phase leg, and a power line 35w corresponding to the W phase extends from the W-phase leg. In the power converter 30, a current sensor 33u is provided on the power line 35u, a current sensor 33v is provided on the power line 35v, and a current sensor 33w is provided on the power line 35w. The current sensor 33u detects the current value of the U-phase current Iu. The current sensor 33v detects the current value of the V-phase current Iv. The current sensor 33w detects the current value of the W-phase current Iw. The current sensors 33u, 33v, and 33w can detect the current values ​​of the currents Iu, Iv, and Iw flowing through the power lines 35u, 35v, and 35w, including DC and AC components. The current sensors 33u, 33v, and 33w are, for example, DCCTs (direct current transformers) or shunt resistors.

[0030] The current sensors 33u, 33v, and 33w are connected to the control device 50 by signal lines. The detected values ​​of the current sensors 33u, 33v, and 33w are output to the control device 50.

[0031] The winding switching device 100 is disposed between the motor 20 and the power converter 30. However, the position of the winding switching device 100 is not limited to between the motor 20 and the power converter 30. The power converter 30 and the winding switching device 100 are connected by power lines 35u, 35v, and 35w, and the winding switching device 100 and the motor 20 are connected by a plurality of power lines 25. The winding switching device 100 switches the connection state of a plurality of windings of the motor 20. The configuration of the winding switching device 100 will be described later. Three-phase AC currents Iu, Iv, and Iw output from the power converter 30 are supplied to the motor 20 via the winding switching device 100.

[0032] The control device 50 controls the power converter 30 and the winding switching device 100. Specifically, signal lines extend from the control device 50 to each of the switches 31u, 32u, 31v, 32v, 31w, and 32w, and the control device 50 controls the on / off timing of the switches 31u, 32u, 31v, 32v, 31w, and 32w. A signal line extends from the control device 50 to the winding switching device 100, and the control device 50 outputs a switching command signal to the winding switching device 100 to command the switching of the connection state of the windings.

[0033] [1-2. Configuration of the Winding Switching Device] Figure 2 is a circuit diagram showing an example of the configuration of the winding switching device according to the first embodiment. The motor 20 includes a plurality of windings 21u, 22u, 21v, 22v, 21w, and 22w. The windings 21u and 22u correspond to the U phase, the windings 21v and 22v correspond to the V phase, and the windings 21w and 22w correspond to the W phase. However, the number of windings for each phase is not limited to two and may be three or more. The windings 22u, 22v, and 22w are connected at a neutral point 23.

[0034] The winding switching device 100 switches the connection state of the windings 21u, 22u, 21v, 22v, 21w, and 22w for each phase between a series connection state and a parallel connection state. The winding switching device 100 includes current sensors 101u, 101v, and 101w, zero-cross detection circuits 102u, 102v, and 102w, control circuits 103u, 103v, and 103w, and switching circuits 104u, 104v, and 104w.

[0035] The zero-crossing detection circuits 102u, 102v, and 102w detect zero-crossing points of the measured values ​​of the current sensors 101u, 101v, and 101w. In a more specific example, the zero-crossing detection circuits 102u, 102v, and 102w compare the output voltages from the current sensors 101u, 101v, and 101w with zero voltage and detect the zero-crossing points as the points at which the output voltages from the current sensors 101u, 101v, and 101w match zero voltage. The zero voltage is an example of a reference voltage. The reference voltage is a voltage corresponding to the output voltages of the current sensors 101u, 101v, and 101w when the currents flowing through the windings 21u, 22u, 21v, 22v, 21w, and 22w become zero current, and is not limited to zero voltage. The zero-crossing detection circuits 102u, 102v, and 102w are an example of a detection unit. It should be noted that the output voltages from the current sensors 101u, 101v, and 101w do not have to be exactly equal to zero voltage, and the same effect can be obtained by detecting the zero-crossing point as the point at which the output voltages from the current sensors 101u, 101v, and 101w become close to zero voltage.

[0036] The switching circuits 104u, 104v, and 104w switch the connection state of the windings 21u, 22u, 21v, 22v, 21w, and 22w between a series connection state and a parallel connection state when the zero-crossing detection circuits 102u, 102v, and 102w detect a zero-crossing point. The switching circuits 104u, 104v, and 104w are an example of a switching unit. The series connection state is an example of a first connection state, and the parallel connection state is an example of a second connection state.

[0037] The following describes the connection relationship between the winding switching device 100, the power line 35u, and the motor 20 for the U phase. The same applies to the V and W phases, so a description thereof will be omitted.

[0038] The power line 35u is connected to one end of the winding 21u. A power line 212u extends from the other end of the winding 21u. A power line 221u extends from one end of the winding 22u, and a power line 222u extends from the other end.

[0039] The switching circuit 104u includes semiconductor relays 111u, 112u, and 113u. The semiconductor relays 111u, 112u, and 113u are, for example, IGBTs or power MOSFETs.

[0040] The power line 35u is drawn into the winding switching device 100. Inside the winding switching device 100, the power line 35u branches off at a midpoint and is connected to a first terminal of a semiconductor relay 111u. A second terminal of the semiconductor relay 111u is connected to a first terminal of a semiconductor relay 112u. A power line 221u extending from the winding 22u is connected to the connection point between the second terminal of the semiconductor relay 111u and the first terminal of the semiconductor relay 112u.

[0041] A second terminal of the semiconductor relay 112u is connected to a first terminal of the semiconductor relay 113u. A power line 212u extending from the winding 21u is connected to the connection point between the second terminal of the semiconductor relay 112u and the first terminal of the semiconductor relay 113u. A power line 222u extending from the winding 22u is connected to a second terminal of the semiconductor relay 113u.

[0042] When the semiconductor relays 111u and 113u are in the OFF state and the semiconductor relay 112u is in the ON state, the windings 21u and 22u are connected in series. When the semiconductor relays 111u and 113u are in the ON state and the semiconductor relay 112u is in the OFF state, the windings 21u and 22u are connected in parallel.

[0043] Signal lines extending from the control circuit 103u are connected to the gate terminals of the semiconductor relays 111u, 112u, and 113u, respectively.

[0044] The power lines 212u, 221u, and 222u extend from the motor 20 and are drawn into the winding switching device 100. A current sensor 101u is attached to the power line 221u. However, the current sensor 101u may be attached to the power lines 35u, 212u, or 222u instead of the power line 221u. The current sensor 101u detects a U-phase current flowing through the power line 221u. The current sensor 101u is, for example, an ACCT that detects only the AC component of the current.

[0045] A signal line extending from the current sensor 101u is connected to the zero-cross detection circuit 102u. A signal line transmitting an output signal of the zero-cross detection circuit 102u (hereinafter referred to as the "zero-cross detection signal") extends from the zero-cross detection circuit 102u to the control circuit 103u. Furthermore, a signal line extending from the control device 50 is connected to the control circuit 103u.

[0046] The zero-crossing detection circuit 102u detects zero-crossing points of the winding current flowing through the power line 221u measured by the current sensor 101u. The zero-crossing detection circuit 102u is a comparator. For example, the inverting input of the comparator is set to a zero reference voltage, and the output signal of the current sensor 101u is applied to the non-inverting input. As a result, the output of the comparator changes from low to high when the AC signal output from the current sensor 101u crosses the zero reference voltage (zero-crossing point).

[0047] 3 is a circuit diagram showing an example of the configuration of the control circuit 103u. The control circuit 103u includes AND circuits 131 and 133, a NOT circuit 132, and a latch circuit 120. A signal line extending from the zero-crossing detection circuit 102u is connected to a first input terminal of the AND circuit 131 and a first input terminal of the AND circuit 133. A signal line extending from the control device 50 is connected to a second input terminal of the AND circuit 131. Furthermore, a signal line from the control device 50 is connected to an input terminal of the NOT circuit 132. A signal line extending from the output terminal of the NOT circuit 132 is connected to a second input terminal of the AND circuit 133.

[0048] The latch circuit 120 is an RS flip-flop. The output terminal of the AND circuit 131 is connected to the input S (set) of the RS flip-flop 120. The output terminal of the AND circuit 133 is connected to the input R (reset) of the RS flip-flop 120. The RS flip-flop 120 includes two NOT circuits 121 and 123 and two NAND circuits 122 and 124. However, the RS flip-flop 120 may also be configured using two NOR circuits.

[0049] The output Q of the RS flip-flop 120 is connected to the gates of the semiconductor relays 111u and 113u, and the output Q bar of the RS flip-flop 120 is connected to the gate of the semiconductor relay 112u.

[0050] When the signal output from the output Q of the RS flip-flop 120 is low and the signal output from the output Q bar of the RS flip-flop 120 is high, the semiconductor relays 111u and 113u are in the off state and the semiconductor relay 112u is in the on state. That is, at this time, the windings 21u and 22u are in a series connection state. When the signal output from the output Q of the RS flip-flop 120 is high and the signal output from the output Q bar of the RS flip-flop 120 is low, the semiconductor relays 111u and 113u are in the on state and the semiconductor relay 112u is in the off state. That is, at this time, the windings 21u and 22u are in a parallel connection state. When the signal output from the output Q of the RS flip-flop 120 switches from low to high and the signal output from the output Q bar of the RS flip-flop 120 switches from high to low, the semiconductor relays 111u and 113u switch from off to on, and the semiconductor relay 112u switches from on to off. That is, the windings 21u and 22u switch from a series-connected state to a parallel-connected state. When the signal output from the output Q of the RS flip-flop 120 switches from high to low and the signal output from the output Q bar of the RS flip-flop 120 switches from low to high, the semiconductor relays 111u and 113u switch from on to off, and the semiconductor relay 112u switches from off to on. That is, the windings 21u and 22u are switched from a parallel connection state to a series connection state.

[0051] [1-3. Zero-Cross Switching of the Winding Switching Device] Next, the zero-cross switching of the winding switching device 100 will be described. Zero-cross switching is an operation of switching the connection state of the windings 21u, 22u, 21v, 22v, 21w, and 22w between a series connection state and a parallel connection state at the zero-cross points of the winding currents Iu, Iv, and Iw. Note that the following description will focus on the operation of switching the connection state of the windings 21u and 22u for the U phase. The same applies to the V and W phases, so their description will be omitted.

[0052] FIG. 4 is a timing chart showing an example of transition of the states of the signals of the winding switching device 100 according to the first embodiment.

[0053] The current sensor 101u measures the winding current Iu flowing through the power line 221u. The zero-crossing detection circuit 102u detects zero-crossing points in the measured value of the winding current Iu. That is, the zero-crossing detection signal output from the zero-crossing detection circuit 102u is low when the winding current Iu is not zero and goes high when the winding current Iu becomes zero. In FIG. 4 , the zero-crossing detection signal is low under normal conditions and high at times T1, T2, T3, and T4.

[0054] The control device 50 sets the value of the switching command signal to Low when windings 21u, 22u, 21v, 22v, 21w, and 22w of motor 20 are connected in series, and sets the value of the switching command signal to High when windings 21u, 22u, 21v, 22v, 21w, and 22w are connected in parallel. In Fig. 4, the switching command signal is Low in the initial state and changes to High at a point in time between times T1 and T2. The switching command signal changes again to Low at a point in time between times T3 and T4.

[0055] The zero-crossing detection signal and the switching command signal are input to an AND circuit 131. The AND circuit 131 outputs a low signal when the zero-crossing detection signal and the switching command signal are a combination of (low, low), (low, high), and (high, low). The AND circuit 131 outputs a high signal when the zero-crossing detection signal and the switching command signal are a combination of (high, high). That is, a low signal is normally input to S of the RS flip-flop 120, and a high signal is input when a zero-crossing point of the winding current Iu is detected and a parallel connection command for the windings 21u, 22u, 21v, 22v, 21w, and 22w is given. In FIG. 4 , the input signal to S is high at times T2 and T3.

[0056] The zero-crossing detection signal and an inverted signal of the switching command signal (the output signal of the NOT circuit 132) are input to the AND circuit 133. The AND circuit 133 outputs a low signal when the zero-crossing detection signal and the switching command signal are combined as (low, low), (high, low), or (high, high). The AND circuit 133 outputs a high signal when the zero-crossing detection signal and the switching command signal are combined as (high, low). That is, a low signal is input to R of the RS flip-flop 120 under normal circumstances, and a high signal is input when a zero-crossing point of the winding current Iu is detected and a command to connect the windings 21u, 22u, 21v, 22v, 21w, and 22w in series is given. In FIG. 4 , the input signal to R is high at times T1 and T4.

[0057] The RS flip-flop 120 holds the previous output values ​​of Q and Q bar when the inputs S and R are Low and Low. The RS flip-flop 120 outputs Low and High for Q and Q bar when the inputs S and R are Low and High, and outputs High and Low for Q and Q bar when the inputs S and R are High and Low. The RS flip-flop 120 prohibits the combination of High and High for the inputs S and R.

[0058] 4, Q is low and Q is high until time T2. Therefore, until time T2, the semiconductor relays 111u and 113u are in the off state and the semiconductor relay 112u is in the on state. Therefore, the windings 21u and 22u are connected in series.

[0059] At time T2, Q changes from low to high and Q changes from high to low. Therefore, the semiconductor relays 111u and 113u change from off to on, and the semiconductor relay 112u changes from on to off. As a result, the connection state of the windings 21u and 22u changes from a series connection state to a parallel connection state.

[0060] From time T2 to T4, Q is high and Q is low. Therefore, from time T2 to T4, the semiconductor relays 111u and 113u are maintained in the on state, and the semiconductor relay 112u is maintained in the off state. As a result, the windings 21u and 22u are maintained in a parallel connection state.

[0061] At time T4, Q changes from high to low, and Q changes from low to high. Therefore, the semiconductor relays 111u and 113u change from on to off, and the semiconductor relay 112u changes from off to on. As a result, the connection state of the windings 21u and 22u switches from a parallel connection state to a series connection state.

[0062] After time T4, Q is low and Q is high. Therefore, until time T2, the semiconductor relays 111u and 113u remain off and the semiconductor relay 112u remains on. As a result, the windings 21u and 22u are maintained in a series connection state.

[0063] As described above, the connection state of the windings 21u, 22u, 21v, 22v, 21w, and 22w can be switched between a series connection state and a parallel connection state at the timing of the zero-crossing points of the winding currents Iu, Iv, and Iw. Therefore, the occurrence of surge voltages is suppressed. Furthermore, complex processing such as identifying the period during which the winding currents Iu, Iv, and Iw are equal to or less than a predetermined value is not required, and the winding switching device 100 can be configured without using a processor such as a CPU, FPGA, or ASIC.

[0064] 5 is a block diagram showing an example of the hardware configuration of the control device according to embodiment 1. The control device 50 includes a processor 501, a non-volatile memory 502, a volatile memory 503, and an interface (I / F) 504.

[0065] The volatile memory 503 is a semiconductor memory such as a static random access memory (SRAM) or a dynamic random access memory (DRAM). The non-volatile memory 502 is a flash memory, a hard disk, a read-only memory (ROM), or the like. The non-volatile memory 502 stores a motor control program 510, which is a computer program, and data used to execute the motor control program 510. The functions of the control device 50 are realized when the motor control program 510 is executed by the processor 501. The motor control program 510 can be stored in a recording medium such as a flash memory, a ROM, or a CD-ROM. The processor 501 controls the power converter 30 and the winding switching device 100 using the motor control program 510.

[0066] The processor 501 is, for example, a CPU (Central Processing Unit). However, the processor 501 is not limited to a CPU. The processor 501 may be a GPU (Graphics Processing Unit). The processor 501 is, for example, a multi-core processor. The processor 501 may be a single-core processor. The processor 501 may be, for example, an ASIC (Application Specific Integrated Circuit) or a programmable logic device such as a gate array or FPGA (Field Programmable Gate Array). In this case, the ASIC or programmable logic device is configured to be able to execute the same processing as the motor control program 510.

[0067] The I / F 504 is connected to the winding switching device 100 and the power converter 30. The I / F 504 is, for example, an input / output interface or a communication interface. For example, the I / F 504 is connected to current sensors 33u, 33v, and 33w provided in the power converter 30 and can acquire the current value of the U-phase current Iu, the current value of the V-phase current Iv, and the current value of the W-phase current Iw. For example, the I / F 504 is connected to each of the switches 31u, 32u, 31v, 32v, 31w, and 32w of the power converter 30 and can control the on / off of the switches 31u, 32u, 31v, 32v, 31w, and 32w. For example, the I / F 504 is connected to the control circuits 103u, 103v, and 103w of the winding switching device 100 and can output switching command signals to the control circuits 103u, 103v, and 103w.

[0068] 1-5. Functions of the Control Device FIG. 6 is a functional block diagram showing an example of functions of the control device according to the first embodiment.

[0069] When the processor 501 executes the motor control program 510 , the control device 50 executes the functions of a switching command unit 521 , a parameter value determination unit 522 , and a voltage value determination unit 523 .

[0070] The switching command unit 521 commands the winding switching device 100 to execute zero-crossing switching. The command to execute zero-crossing switching is issued by outputting a switching command signal to the control circuits 103u, 103v, and 103w. That is, as described above, when the switching command signal is input to the control circuits 103u, 103v, and 103w, a zero-crossing detection signal is output from the zero-crossing detection circuits 102u, 102v, and 102w at the time of detection of the next zero-crossing point, and zero-crossing switching is executed.

[0071] The parameter value determination unit 522 determines the parameter values ​​of control parameters used to determine the voltages (hereinafter also referred to as "control voltage values") to be applied to the windings 21u, 22u, 21v, 22v, 21w, and 22w. Specifically, the parameter value determination unit 522 determines the parameter values ​​of the control parameters in the following control systems:

[0072] 7 is a control block diagram showing a motor control system of the control device according to the first embodiment. Hereinafter, the determination of the parameter values ​​of the control parameters will be described with reference to FIG.

[0073] The control device 50 sets a target torque 531 for the motor 20. The target torque 531 is calculated from, for example, a target speed of the vehicle.

[0074] The target torque 531 is input to a torque-current converter 532. The torque-current converter 532 converts the target torque 531 into a target current. The conversion from the target torque 531 to the target current is performed based on the output characteristics of the motor 20 stored in advance in the control device 50. For example, the output characteristics when the windings 21u, 22u, 21v, 22v, 21w, and 22w are connected in series are different from the output characteristics when the windings 21u, 22u, 21v, 22v, 21w, and 22w are connected in parallel. For example, the nonvolatile memory 502 of the control device 50 stores two types of output characteristics: the output characteristics when the windings 21u, 22u, 21v, 22v, 21w, and 22w are connected in series, and the output characteristics when the windings 21u, 22u, 21v, 22v, 21w, and 22w are connected in parallel. The torque current converter 532 determines the target current in accordance with output characteristics according to the current connection state of the windings 21u, 22u, 21v, 22v, 21w, and 22w. The target current obtained by the torque current converter 532 is a current value in the dq coordinate system (hereinafter also referred to as a "dq current value"; the voltage value in the dq coordinate system is also referred to as a "dq voltage value").

[0075] The detection values ​​of the current sensors 33u, 33v, and 33w and the detection value of the position sensor 26 are input to the current converter 533. The current converter 533 converts the current value of each phase of the three-phase AC current into a dq current value. The current converter 533 outputs the detection values ​​of the current sensors 33u, 33v, and 33w, i.e., the dq current values ​​corresponding to the winding currents Iu, Iv, and Iw.

[0076] The summing point 534 calculates the difference between the target current output from the torque current converter 532 and the winding current output from the current converter 533. The calculated difference is input to the F / B controller 535.

[0077] The F / B control unit 535 calculates a feedback gain based on the difference between the input target current and the winding current. For example, the correspondence between the difference and the feedback gain is predetermined. For example, two types of correspondence are defined: one for when the windings 21u, 22u, 21v, 22v, 21w, and 22w are connected in series, and the other for when the windings 21u, 22u, 21v, 22v, 21w, and 22w are connected in parallel. The F / B control unit 535 determines the feedback gain from the difference in accordance with the correspondence corresponding to the current connection state of the windings 21u, 22u, 21v, 22v, 21w, and 22w. The feedback gain is part of the drive voltage of the motor 20.

[0078] The F / B control unit 535 determines the feedback gain according to a predetermined control method. For example, the F / B control unit 535 can determine the feedback gain according to any one of P control (proportional control), PI control (proportional integral control), PD control (proportional differential control), and PID control (proportional integral differential control). The above-mentioned correspondence relationship is determined according to such a control method.

[0079] The winding current output from the current converter 533 and the detected value of the position sensor 26 are input to the electromotive force calculator 536. Based on the winding current and the rotational speed of the motor 20, the electromotive force calculator 536 calculates a correction component based on the induced voltage generated in the motor 20, such as a correction component for non-interference control of the AC current of the motor 20, mutual inductance between the d-axis and q-axis, etc. The correction component is a voltage value for correcting the control voltage value to eliminate the influence of the induced voltage. The induced voltage differs when the windings 21u, 22u, 21v, 22v, 21w, and 22w are connected in series and in parallel. Therefore, the electromotive force calculator 536 calculates the correction component based on the induced voltage corresponding to the connection state of the windings 21u, 22u, 21v, 22v, 21w, and 22w at that time.

[0080] The non-interference control will be explained below.

[0081] The state equation (differential equation) of the permanent magnet synchronous motor in the dq coordinate system is expressed by equation (1). where ia = [id, iq] Ｔ is the armature current (winding current), va = [vd, vq] Ｔ is the armature voltage, ω is the rotational angular velocity of the motor, Ψa is the magnet magnetic flux, Ra is the winding resistance, Ld and Lq are the winding inductances, and p is the differential symbol.

[0082] In the non-interference control, the influence of the interference term between the d-axis and the q-axis due to the induced electromotive force is eliminated. Specifically, the d-axis and the q-axis voltages are corrected as shown in the following equation (2). Here, vod is the d-axis component of the induced electromotive force, and voq is the q-axis component of the induced electromotive force.

[0083] Substituting equation (2) into equation (1), the following equation (3) is derived, with v'a=[v'd, v'q] as a new input.

[0084] From equation (3), it can be seen that the d-axis and q-axis can be decoupled, and the disturbance de can be cancelled.

[0085] The feedback gain output from the F / B control unit 535 and the correction component output from the electromotive force calculation unit 536 are input to the summing point 537. The summing point 537 adds the feedback gain output from the F / B control unit 535 and the correction component output from the electromotive force calculation unit 536 together to calculate a control voltage value.

[0086] The control voltage value is input to the voltage conversion unit 538. The voltage conversion unit 538 converts the dq voltage value into a three-phase AC voltage.

[0087] The control voltage value of the three-phase AC voltage output from the voltage conversion unit 538 is input to the PWM unit 539. The PWM unit 539 determines a duty ratio according to the input control voltage value, and generates PWM signals for driving each of the switches 31u, 32u, 31v, 32v, 31w, and 32w of the power converter 30 according to the determined duty ratio. The PWM unit 539 outputs the generated PWM signals to each of the switches 31u, 32u, 31v, 32v, 31w, and 32w.

[0088] Returning to FIG. 6 , the control parameters include a target current, a feedback gain, and a correction component based on an induced voltage (hereinafter also simply referred to as a "correction component"). When the target current is the "first control parameter," the feedback gain or the correction component is the "second control parameter." When the feedback gain is the "first control parameter," the target current or the correction component is the "second control parameter." When the correction component is the "first control parameter," the feedback gain or the target current is the "second control parameter." In the following description, the feedback gain is referred to as the "first control parameter," and the target current and the correction component are referred to as the "second control parameter."

[0089] The parameter value determiner 522 can determine a target current for the series connection state of the windings 21u, 22u, 21v, 22v, 21w, and 22w, a target current for the parallel connection state, a feedback gain for the series connection state, a feedback gain for the parallel connection state, a correction component based on the induced voltage for the series connection state, and a correction component based on the induced voltage for the parallel connection state. That is, when the windings 21u, 22u, 21v, 22v, 21w, and 22w are in the series connection state, the parameter value determiner 522 determines a target current for the series connection state, a feedback gain for the series connection state, and a correction component based on the induced voltage for the series connection state. When the windings 21u, 22u, 21v, 22v, 21w, and 22w are in the parallel connection state, the parameter value determiner 522 determines a target current for the parallel connection state, a feedback gain for the parallel connection state, and a correction component based on the induced voltage for the parallel connection state.

[0090] The voltage value determiner 523 determines a control voltage value. Specifically, the voltage value determiner 523 can calculate the control voltage value by adding the feedback gain determined by the parameter value determiner 522 to a correction component based on the induced voltage. The voltage value determiner 523 determines a control voltage value when the windings 21u, 22u, 21v, 22v, 21w, and 22w are connected in series and a control voltage value when the windings 21u, 22u, 21v, 22v, 21w, and 22w are connected in parallel. That is, the voltage value determiner 523 adds the feedback gain when the windings 21u, 22u, 21v, 22v, 21w, and 22w are connected in series to the correction component based on the induced voltage in the series connection, to calculate the control voltage value in the series connection state. The voltage value determination unit 523 adds the feedback gain in the parallel connection state of the windings 21u, 22u, 21v, 22v, 21w, and 22w to a correction component based on the induced voltage in the parallel connection state, and calculates a control voltage value in the parallel connection state.

[0091] For example, when zero-crossing switching is performed, for example, after a switching command signal is output, the parameter value determiner 522 switches the feedback gain from a parameter value in the connection state of the windings 21u, 22u, 21v, 22v, 21w, and 22w before the switching (hereinafter also referred to as the “gain before the switching”) to a parameter value in the connection state after the switching (hereinafter also referred to as the “gain after the switching”). At a timing (second timing) different from the timing (first timing) at which the parameter value of the feedback gain is switched, the parameter value determiner switches the target current from a parameter value in the connection state of the windings 21u, 22u, 21v, 22v, 21w, and 22w before the switching (hereinafter also referred to as the “target current before the switching”) to a parameter value in the connection state after the switching (hereinafter also referred to as the “target current after the switching”). The parameter value determination unit switches the parameter value in the connection state of the windings 21u, 22u, 21v, 22v, 21w, and 22w before the switching (hereinafter also referred to as the "correction component before the switching") to the parameter value in the connection state after the switching (hereinafter also referred to as the "correction component after the switching") at a timing different from the timing at which the parameter value of the feedback gain is switched.

[0092] In a specific example, the parameter value determination unit 522 repeatedly determines the target current, the feedback gain, and the correction component for each control cycle. Here, a control cycle is a control sequence in the above-described control system, from determining a PWM duty ratio and outputting a PWM signal, to determining a next duty ratio and outputting the next PWM signal.

[0093] 8 is a graph showing an example of switching of the parameter values ​​of the control parameters. In FIG. 8, the vertical axis represents the winding current Iu, and the horizontal axis represents time. Note that although the switching of the parameter values ​​of the control parameters will be described using the winding current Iu of the U phase, the same applies to the V phase and the W phase.

[0094] In the example of Fig. 8, the connection state of the windings 21u, 22u, 21v, 22v, 21w, and 22w is switched from a series connection state to a parallel connection state. In the example of Fig. 8, at time T11, the feedback gain is switched from the pre-switching gain (i.e., the feedback gain when the windings 21u, 22u, 21v, 22v, 21w, and 22w are connected in series) to the post-switching gain (i.e., the feedback gain when the windings 21u, 22u, 21v, 22v, 21w, and 22w are connected in parallel). This switching of parameter values ​​changes the control voltage value, thereby increasing the amplitude of the winding current Iu. In Fig. 8, the waveform of the winding current Iu when the feedback gain is not switched at time T11 is shown by the dashed dotted line.

[0095] At time T12 after time T11, the target current is switched from the pre-switching target current (i.e., the target current in the series-connected state of the windings 21u, 22u, 21v, 22v, 21w, and 22w) to the post-switching target current (i.e., the target current in the parallel-connected state of the windings 21u, 22u, 21v, 22v, 21w, and 22w), and the correction component is switched from the pre-switching correction component (i.e., the correction component in the series-connected state of the windings 21u, 22u, 21v, 22v, 21w, and 22w) to the post-switching correction component (i.e., the correction component in the parallel-connected state of the windings 21u, 22u, 21v, 22v, 21w, and 22w). The switching of these parameter values ​​changes the control voltage value, thereby increasing the amplitude of the winding current Iu. In FIG. 8 , the dashed line indicates the waveform of the winding current Iu when the target current and correction component are not switched at time T12.

[0096] In this way, the feedback gain, the target current, and the correction component are switched in stages, so that the amplitude of the winding current Iu increases in stages, thereby suppressing the occurrence of surge voltages and oscillations in current control.

[0097] 6 , when zero-crossing switching is performed, the parameter value determiner 522 switches the feedback gain from a pre-switching gain to a post-switching gain in a first control cycle. The parameter value determiner 522 switches the target current from a pre-switching target current to a post-switching target current in a second control cycle different from the first control cycle. The parameter value determiner 522 switches the correction component from a pre-switching eye correction component to a post-switching correction component in the second control cycle. Note that the parameter value determiner 522 may also switch the correction component from a pre-switching eye correction component to a post-switching correction component in a third control cycle different from both the first and second control cycles.

[0098] That is, the above-mentioned time T11 is included in the first control cycle, and time T12 is included in the second control cycle. The first control cycle and the second control cycle do not have to be adjacent control cycles. That is, one or more control cycles may exist between the first control cycle and the second control cycle.

[0099] As described above, the feedback gain is determined using one of P control, PI control, PD control, and PID control. Here, the I control (integral control) changes gradually over time. Therefore, by using a control method including I control, when the feedback gain is switched from the pre-switching gain to the post-switching gain, the feedback gain after switching can be changed gradually, thereby suppressing the occurrence of surge voltage and oscillation of current control.

[0100] For example, the parameter value determination unit 522 can switch the feedback gain from the pre-switching gain to the post-switching gain, and switch the target current and the correction component after the change in the feedback gain has converged. This can prevent abrupt changes in the control parameters (feedback gain, target current, and correction component). However, the parameter value determination unit 522 may switch the target current and the correction component after switching the feedback gain from the pre-switching gain to the post-switching gain and before the change in the feedback gain has converged. For example, the parameter value determination unit 522 may switch the target current and the correction component after a predetermined time has elapsed after switching the feedback gain from the pre-switching gain to the post-switching gain.

[0101] 1-6. Operation of the Control Device Next, a description will be given of the operation of the control device 50. The control device 50 executes a motor control process by the processor 501 executing a motor control program 510.

[0102] 9A and 9B are flowcharts showing an example of a motor control process performed by the control device according to the first embodiment.

[0103] For example, the processor 501 determines to perform zero-cross switching when a gear shift command is given to the control device 50. The processor 501 determines whether or not it has been determined to perform zero-cross switching (step S101).

[0104] If it has not been determined to execute zero-crossing switching (NO in step S101), the processor 501 acquires the detection values ​​output from the current sensors 33u, 33v, and 33w and the detection value output from the position sensor 26 (step S102). The processor 501 calculates the rotation speed of the motor 20 based on the detection values ​​from the position sensor 26.

[0105] The processor 501 determines the parameter values ​​of the control parameters according to the current connection states of the windings 21u, 22u, 21v, 22v, 21w, 22w, and 21u, 22u, Iu, Iv, and Iw based on the acquired current values ​​of the winding currents Iu, Iv, and Iw and the rotational speed of the motor 20 (step S103). The control parameters include a target current, a feedback gain, and a control component based on the induced voltage.

[0106] Based on the determined parameter values, the processor 501 determines control voltage values ​​according to the connection states of the windings 21u, 22u, 21v, 22v, 21w, 22w, 21u, 22uIu, Iv, and Iw at that time (step S104).

[0107] The processor 501 determines a duty ratio based on the determined control voltage value and outputs a PWM signal having the determined duty ratio (step S105). The switches 31u, 32u, 31v, 32v, 31w, and 32w are driven in accordance with the PWM signal, and winding currents Iu, Iv, and Iw are supplied to the motor 20. After step S105, the processor 501 returns to step S101.

[0108] If it has been determined that zero-cross switching should be performed (YES in step S101), the processor 501 outputs a switching command signal to the winding switching device 100 (step S106).

[0109] The processor 501 acquires the detection values ​​output from the current sensors 33u, 33v, and 33w and the detection value output from the position sensor 26 (step S107). The processor 501 calculates the rotation speed of the motor 20 based on the detection values ​​from the position sensor 26.

[0110] The processor 501 switches the feedback gain from the pre-switching gain to the post-switching gain (step S108).

[0111] The processor 501 determines the parameter values ​​of the control parameters based on the acquired current values ​​of the winding currents Iu, Iv, and Iw and the rotational speed of the motor 20 (step S109). That is, the processor 501 determines the pre-switching target current and the pre-switching correction component, and determines the post-switching gain.

[0112] The processor 501 determines a control voltage value based on the determined parameter value (step S110). The processor 501 determines a duty ratio based on the control voltage value and outputs a PWM signal having the determined duty ratio (step S111). The switches 31u, 32u, 31v, 32v, 31w, and 32w are driven in accordance with the PWM signal, and winding currents Iu, Iv, and Iw are supplied to the motor 20.

[0113] The processor 501 determines whether the feedback gain has converged (step S112). If the feedback gain has not converged (NO in step S112), the processor 501 returns to step S107. By repeating steps S107 to S112, for example, the integral action of the feedback gain converges.

[0114] If the feedback gain has converged (YES in step S112), the processor 501 acquires the detection values ​​output from the current sensors 33u, 33v, and 33w and the detection value output from the position sensor 26 (step S113). The processor 501 calculates the rotation speed of the motor 20 based on the detection values ​​from the position sensor 26.

[0115] The processor 501 switches the target current from the pre-switching target current to the post-switching target current, and switches the correction component from the pre-switching correction component to the post-switching correction component (step S114).

[0116] The processor 501 determines the parameter values ​​of the control parameters based on the acquired current values ​​of the winding currents Iu, Iv, and Iw and the rotational speed of the motor 20 (step S115). That is, the processor 501 determines the post-switching gain, the post-switching target current, and the post-switching correction component.

[0117] The processor 501 determines a control voltage value based on the determined parameter value (step S116). The processor 501 determines a duty ratio based on the control voltage value and outputs a PWM signal having the determined duty ratio (step S117). The switches 31u, 32u, 31v, 32v, 31w, and 32w are driven in accordance with the PWM signal, and winding currents Iu, Iv, and Iw are supplied to the motor 20. After step S117, the processor 501 returns to step S101.

[0118] [2. Second Embodiment] A winding switching device according to a second embodiment switches the connection state of a plurality of windings of a motor between a full connection state in which all of the plurality of windings are connected, and a partial connection state in which some of the plurality of windings are connected.

[0119] 10 is a circuit diagram showing an example of the configuration of a winding switching device according to the second embodiment. A motor 20A includes a plurality of windings 24u, 25u, 24v, 25v, 24w, and 25w. The windings 24u and 25u correspond to the U phase, the windings 24v and 25v correspond to the V phase, and the windings 24w and 25w correspond to the W phase. However, the number of windings for each phase is not limited to two and may be three or more.

[0120] The winding switching device 100A switches the connection states of the windings 24u, 25u, 24v, 25v, 24w, and 25w for each phase between a fully connected state and a partially connected state. The winding switching device 100A includes current sensors 131u, 131v, and 131w, zero-crossing detection circuits 102u, 102v, and 102w, control circuits 103u, 103v, and 103w, and switching circuits 140u, 140v, and 140w.

[0121] The zero-cross detection circuits 102u, 102v, and 102w detect zero-cross points of the measured values ​​of the current sensors 131u, 131v, and 131w. The configurations of the zero-cross detection circuits 102u, 102v, and 102w are the same as those in the first embodiment, and therefore description thereof will be omitted.

[0122] The switching circuits 140u, 140v, and 140w switch the connection states of the windings 24u, 25u, 24v, 25v, 24w, and 25w between a fully connected state and a partially connected state when the zero-crossing detection circuits 102u, 102v, and 102w detect a zero-crossing point. The switching circuits 140u, 140v, and 140w are an example of a switching unit. The fully connected state is an example of a first connected state, and the partially connected state is an example of a second connected state.

[0123] The power line 35u is connected to one end of the winding 24u. The other end of the winding 24u and one end of the winding 25u are connected to each other, and a power line 241u extends from the midpoint between the windings 24u and 25u. The power line 241u branches into power lines 242u and 243w. A power line 251u extends from the other end of the winding 25u. The power line 251u branches into power lines 252u and 253w.

[0124] Power line 35v is connected to one end of winding 24v. The other end of winding 24v and one end of winding 25v are connected to each other, and power line 241v extends from the midpoint between windings 24v and 25v. Power line 241v branches into power lines 242v and 243u. Power line 251v extends from the other end of winding 25v. Power line 251v branches into power lines 252v and 253u.

[0125] Power line 35w is connected to one end of winding 24w. The other end of winding 24w and one end of winding 25w are connected to each other, and power line 241w extends from the midpoint between windings 24w and 25w. Power line 241w branches into power lines 242w and 243v. Power line 251w extends from the other end of winding 25w. Power line 251w branches into power lines 252w and 253v.

[0126] The switching circuit 140u includes semiconductor relays 141u and 142u. The switching circuit 140v includes semiconductor relays 141v and 142v. The switching circuit 140w includes semiconductor relays 141w and 142w. The semiconductor relays 141u, 142u, 141v, 142v, 141w, and 142w are, for example, IGBTs or power MOSFETs.

[0127] In the switching circuit 140u, a first terminal of a semiconductor relay 141u is connected to a power line 242u, and a second terminal of the semiconductor relay 142u is connected to a power line 252u, and a second terminal of the semiconductor relay 142u is connected to a power line 253u. The connection relationship between the switching circuits 140v and 140w is the same as that of the switching circuit 140u, and therefore will not be described here.

[0128] When the semiconductor relays 141u, 141v, and 141w are in the OFF state and the semiconductor relays 142u, 142v, and 142w are in the ON state, all of the windings 24u, 25u, 24v, 25v, 24w, and 25w are connected, resulting in a fully connected state. When the semiconductor relays 141u, 141v, and 141w are in the ON state and the semiconductor relays 142u, 142v, and 142w are in the OFF state, only the windings 24u, 24v, and 24w are connected, resulting in a partially connected state.

[0129] The power line 35u is drawn into the winding switching device 100. A current sensor 131u is attached to the power line 35u. The current sensor 131u detects the U-phase current flowing through the power line 35u. The current sensor 131u is, for example, an ACCT that detects only the AC component of the current. A signal line extending from the current sensor 131u is connected to the zero-crossing detection circuit 102u. The same applies to the V-phase and W-phase.

[0130] The output Q of the RS flip-flop 120 of the control circuit 103u is connected to the gate of the semiconductor relay 141u. The output Q bar of the RS flip-flop 120 is connected to the gate of the semiconductor relay 142u. The same applies to the V-phase and W-phase.

[0131] The other configurations of the winding switching device 100A according to the second embodiment are similar to those of the winding switching device 100 according to the first embodiment, so the same components are given the same reference numerals and their description will be omitted.

[0132] In the second embodiment, the control device 50 sets the value of the switching command signal to Low when the windings 24u, 25u, 24v, 25v, 24w, and 25w of the motor 20 are to be fully connected, and sets the value of the switching command signal to High when the windings 24u, 25u, 24v, 25v, 24w, and 25w are to be partially connected.

[0133] When the windings are in the fully connected state, output Q goes low and output Q goes high at the timing when both the zero-crossing detection signal and the switching command signal go high. Therefore, semiconductor relay 141u changes from the on state to the off state, and semiconductor relay 142u changes from the off state to the on state. The same applies to the V-phase and W-phase. Therefore, the connection states of windings 24u, 25u, 24v, 25v, 24w, and 25w change from the fully connected state to the partially connected state.

[0134] When the windings are in the partially connected state, the zero-crossing detection signal goes high and the switching command signal goes low, causing output Q to go high and output Q bar to go low. Therefore, semiconductor relay 141u changes from the off state to the on state, and semiconductor relay 142u changes from the on state to the off state. The same applies to the V-phase and W-phase. Therefore, the connection states of windings 24u, 25u, 24v, 25v, 24w, and 25w are switched from the partially connected state to the fully connected state.

[0135] As described above, the connection states of the windings 21u, 22u, 21v, 22v, 21w, and 22w can be switched between a fully connected state and a partially connected state at the timing of the zero crossing points of the winding currents Iu, Iv, and Iw.

[0136] The configurations and operations of the power converter 30 and the control device 50 according to the second embodiment are similar to those of the power converter 30 and the control device 50 according to the first embodiment, and therefore will not be described here.

[0137] 6 . A parameter value determiner 522 of a control device 50 according to a third embodiment switches the feedback gain from a switching gain to a post-switching gain at a first zero-crossing point of the winding currents Iu, Iv, and Iw. The parameter value determiner 522 switches the target current from a pre-switching target current to a post-switching target current at a second zero-crossing point of the winding currents Iu, Iv, and Iw that is different from the first zero-crossing point. The parameter value determiner 522 switches the correction component from a pre-switching correction component to a post-switching correction component at the second zero-crossing point.

[0138] In a specific example, the parameter value determiner 522 acquires detection values ​​from the current sensors 33u, 33v, and 33w and detects zero-crossing points of the winding currents Iu, Iv, and Iw based on the acquired detection values. The parameter value determiner 522 determines one zero-crossing point as a first zero-crossing point and switches the feedback gain from the switching gain to the post-switching gain at the first zero-crossing point. The parameter value determiner 522 determines one zero-crossing point after the first zero-crossing point as a second zero-crossing point and switches the target current from the pre-switching target current to the post-switching target current and the correction component from the pre-switching correction component to the post-switching correction component at the second zero-crossing point.

[0139] The first zero cross point and the second zero cross point may be zero cross points in the same phase, or may be zero cross points in different phases.

[0140] 11 is a graph showing another example of switching of parameter values ​​of control parameters. In FIG. 11, the vertical axis represents winding current Iu and the horizontal axis represents time. Note that the zero crossing points of U-phase winding current Iu are designated as the first zero crossing point and the second zero crossing point.

[0141] In the example of Fig. 11 , the connection state of the windings 21u, 22u, 21v, 22v, 21w, and 22w is switched from a series connection state to a parallel connection state. In the example of Fig. 11 , at zero-crossing point T21, the feedback gain is switched from the pre-switching gain (i.e., the feedback gain when the windings 21u, 22u, 21v, 22v, 21w, and 22w are connected in series) to the post-switching gain (i.e., the feedback gain when the windings 21u, 22u, 21v, 22v, 21w, and 22w are connected in parallel). This switching of parameter values ​​changes the control voltage value, thereby increasing the amplitude of the winding current Iu. The zero-crossing point T21 is the first zero-crossing point. In Fig. 11 , the dashed line indicates the waveform of the winding current Iu when the feedback gain is not switched at the zero-crossing point T21.

[0142] At zero-crossing point T22 after zero-crossing point T21, the target current is switched from the pre-switching target current (i.e., the target current in the series-connected state of windings 21u, 22u, 21v, 22v, 21w, and 22w) to the post-switching target current (i.e., the target current in the parallel-connected state of windings 21u, 22u, 21v, 22v, 21w, and 22w), and the correction component is switched from the pre-switching correction component (i.e., the correction component in the series-connected state of windings 21u, 22u, 21v, 22v, 21w, and 22w) to the post-switching correction component (i.e., the correction component in the parallel-connected state of windings 21u, 22u, 21v, 22v, 21w, and 22w). The switching of these parameter values ​​changes the control voltage value, thereby increasing the amplitude of winding current Iu. Zero-crossing point T22 is the second zero-crossing point. In FIG. 11, the waveform of the winding current Iu when the target current and the correction component are not switched at the zero cross point T22 is shown by a broken line.

[0143] 12 is a circuit diagram showing an example of the configuration of a winding switching device according to Embodiment 3. In the third embodiment, a signal indicating the timing for switching the connection states of the windings 21u, 22u, 21v, 22v, 21w, and 22w (hereinafter also referred to as a “switching timing signal”) is input to a control device 50.

[0144] The signal output from output Q of RS flip-flop 120 is a signal (switching timing signal) indicating the timing for switching the connection state of windings 21u and 22u. As shown in FIG. 11 , a signal line extending from control circuit 103u to the gate terminal of semiconductor relay 111u branches at its midpoint, with the branching end connected to control device 50. A U-phase switching timing signal is input to control device 50 via this signal line. Similarly, a signal line extending from control circuit 103v to the gate terminal of semiconductor relay 111v branches at its midpoint, with the branching end connected to control device 50. A V-phase switching timing signal is input to control device 50 via this signal line. A signal line extending from control circuit 103w to the gate terminal of semiconductor relay 111w branches at its midpoint, with the branching end connected to control device 50. A W-phase switching timing signal is input to control device 50 via this signal line. Specifically, the switching timing signal is input to I / F 504 of control device 50.

[0145] FIG. 13 is a functional block diagram illustrating an example of functions of the control device according to the fourth embodiment.

[0146] When the processor 501 executes the motor control program 510, the control device 50 executes the functions of a switching command unit 521, a parameter value determination unit 522, a voltage value determination unit 523, an input unit 524, and an identification unit 525.

[0147] The input unit 524 receives a switching timing signal output at the timing when the winding switching device 100 executes zero-crossing switching. That is, the input unit 524 receives a switching timing signal output from each of the control circuits 103u, 103v, and 103w of the winding switching device 100 to the gate terminals of the semiconductor relays 111u, 111v, and 111w.

[0148] The specifying unit 525 specifies the switching timing at which zero-crossing switching is performed to switch the connection states of the windings 21u, 22u, 21v, 22v, 21w, and 22w from a series connection state to a parallel connection state or from a parallel connection state to a series connection state at a zero-crossing point of the winding currents Iu, Iv, and Iw. In a specific example, the specifying unit 525 specifies the switching timing based on the input of a switching timing signal to the input unit 524. For example, the specifying unit 525 can specify the switching timing for each of the U phase, the V phase, and the W phase.

[0149] The parameter value determining unit 522 switches the feedback gain from the switching gain to the post-switching gain, using the switching timing identified by the identifying unit 525 as the first timing.

[0150] For example, the parameter value determiner 522 can switch the target current from a pre-switching target current to a post-switching target current at a second timing that is different from the first timing and that is identified by the identifyr 525. The parameter value determiner 522 can switch the correction component from a pre-switching correction component to a post-switching correction component at the second timing. Specifically, when the first timing is the switching timing of the U phase identified by the identifyr 525, the parameter value determiner 522 can switch the correction component from a pre-switching correction component to a post-switching correction component.

[0151] 14 is a flowchart showing the first half of an example of a motor control process performed by a control device according to the fourth embodiment. The second half of the flowchart is the same as that shown in FIG. 9B.

[0152] Steps S101 to S106 are the same as steps S101 to S106 in the first embodiment.

[0153] In the fourth embodiment, a switching timing signal is output from the winding switching device 100 to the control device 50. The processor 501 determines the switching timing based on the switching timing signal.

[0154] The processor 501 determines whether or not the switching timing has arrived (step S201). If the switching timing has not arrived (NO in step S201), the processor 501 executes step S201 again.

[0155] If the switching timing has arrived (YES in step S201), the processor 501 executes steps S107 to S111. Steps S107 to S111 are the same as steps S107 to S111 in the first embodiment.

[0156] The processor 501 determines whether the switching timing has arrived (step S202). The switching timing in step S202 is a switching timing in a different phase from the switching timing in step S201. If the switching timing has not arrived (NO in step S202), the processor 501 executes step S202 again.

[0157] If the switching timing has arrived (YES in step S202), the processor 501 executes steps S113 to S117, which are the same as steps S113 to S117 in the first embodiment (see FIG. 9B).

[0158] 5. Fifth Embodiment An identification unit 525 of a control device 50 according to a fifth embodiment detects zero-crossing points of winding currents Iu, Iv, and Iw, and estimates the switching timing based on the detected zero-crossing points. For example, the identification unit 525 can identify the waveforms of winding currents Iu, Iv, and Iw from the time-series detection values ​​of current sensors 33u, 33v, and 33w, and detect the zero-crossing points in each of the U-phase, V-phase, and W-phase.

[0159] In a specific example, the specifying unit 525 can estimate that the switching timing is the next zero cross point that arrives after the switching command signal is input to the winding switching device 100. For example, the specifying unit 525 can estimate the switching timing for each of the U phase, V phase, and W phase.

[0160] In the fifth embodiment, the input unit 524 receives the detection values ​​of the current sensors 33u, 33v, and 33w instead of the switching timing signal from the winding switching device 100. The identification unit 525 detects the zero-crossing points of the winding currents Iu, Iv, and Iw based on the detection values ​​of the current sensors 33u, 33v, and 33w input to the input unit 524.

[0161] Other functions of the control device 50 according to the fifth embodiment are similar to those of the control device 50 according to the fourth embodiment, and therefore descriptions thereof will be omitted. Other configurations of the winding switching system according to the fifth embodiment are similar to those of the winding switching system 10 according to the first embodiment, and therefore descriptions thereof will be omitted.

[0162] 6. Sixth Embodiment Referring to Fig. 6, a parameter value determination unit 522 of a control device 50 according to the sixth embodiment switches the feedback gain in stages from a pre-switching gain to a post-switching gain. In a specific example, when a switching command unit 521 outputs a switching command signal, the parameter value determination unit 522 determines a feedback gain for switching (hereinafter also referred to as a "switching gain").

[0163] The switching gain is, for example, a feedback gain having a value between the pre-switching gain and the post-switching gain. In a specific example, in the case of PID control, the constant (P gain) of the P term (proportional term) for determining the switching gain is a value between the constant of the P term for determining the pre-switching gain and the constant of the P term for determining the post-switching gain. The constant (I gain) of the I term (integral term) for determining the switching gain is a value between the constant of the I term for determining the pre-switching gain and the constant of the I term for determining the post-switching gain. The constant (D gain) of the D term (differential term) for determining the switching gain is a value between the constant of the D term for determining the pre-switching gain and the constant of the D term for determining the post-switching gain.

[0164] For example, the parameter value determination unit 522 can determine the switching gain as the feedback gain for a predetermined period of time after the switching command unit 521 outputs the switching command signal. The predetermined period of time is, for example, a period of time corresponding to a specified number of control cycles.

[0165] This allows the feedback gain to transition gradually from the pre-switching gain to the post-switching gain, thereby suppressing the occurrence of surge voltages and oscillations in current control.

[0166] 6 . When the switching command unit 521 outputs a switching command signal, the parameter value determination unit 522 of the control device 50 according to the seventh embodiment gradually changes the feedback gain from the pre-switching gain to the post-switching gain. In a specific example, the parameter value determination unit 522 changes the feedback gain from the pre-switching gain to the post-switching gain in a ramp-like manner over time.

[0167] The gradual change in the parameter value of the feedback gain is not limited to a ramp-like change, but may be a curved change.

[0168] Here, "gradually changing a parameter value" includes changing the parameter value in stages. That is, "gradually changing a parameter value" is not limited to smoothly changing the parameter value over time. For example, the parameter value may be changed in multiple stages or discretely.

[0169] In a specific example, when the switching command unit 521 outputs a switching command signal, the parameter value determination unit 522 calculates both the pre-switching gain and the post-switching gain. For example, the parameter value determination unit 522 gradually increases or decreases the parameter value of the feedback gain over time from the pre-switching gain to the post-switching gain.

[0170] This allows the feedback gain to transition gradually from the pre-switching gain to the post-switching gain, thereby suppressing the occurrence of surge voltages and oscillations in current control.

[0171] 8. Eighth Embodiment See FIG. 6 . The parameter value determiner 522 of the control device 50 according to the eighth embodiment gradually changes the target current from a pre-switching target current to a post-switching target current, and gradually changes the correction component from a pre-switching correction component to a post-switching correction component. In a specific example, the parameter value determiner 522 changes the target current in a ramp-like manner from the pre-switching target current to the post-switching target current over time. The parameter value determiner 522 changes the correction component in a ramp-like manner from the pre-switching correction component to the post-switching correction component over time.

[0172] The parameter value determination unit 522 may gradually change the parameter value of either the target current or the correction component from the parameter value before switching to the parameter value after switching.

[0173] The gradual change in the parameter value is not limited to a ramp-like change, but may be a curved change, for example.

[0174] In a specific example, when switching the target current, the parameter value determiner 522 calculates both the pre-switching target current and the post-switching target current. For example, the parameter value determiner gradually increases the parameter value of the target current over time from the pre-switching target current to the post-switching target current. The same applies to the correction component.

[0175] This allows the target current to transition gradually from the pre-switching target current to the post-switching target current, and the correction component to transition gradually from the pre-switching correction component to the post-switching correction component, thereby suppressing the occurrence of surge voltage and oscillation of current control.

[0176] 6 , the voltage value determiner 523 of the control device 50 according to the ninth embodiment switches the correction component used to determine the control voltage value from a pre-switching correction component to a post-switching correction component for each phase when zero-crossing switching is performed. That is, the voltage value determiner 523 switches the correction component used to determine the control voltage value from a pre-switching correction component to a post-switching correction component at different timings for each of the U, V, and W phases.

[0177] In a specific example, when the switching command unit 521 outputs a switching command signal, the parameter value determiner 522 calculates a pre-switching correction component and a post-switching correction component in the dq coordinate system. The voltage value determiner 523 switches the correction component used to determine the control voltage value of the U-phase from the pre-switching correction component to the post-switching correction component, for example, at a zero-crossing point of the U-phase. That is, before the zero-crossing point of the U-phase, the voltage value determiner 523 calculates the control voltage value of the U-phase based on the pre-switching correction component. After the zero-crossing point of the U-phase, the voltage value determiner 523 calculates the control voltage value of the U-phase based on the post-switching correction component. Similarly, at a zero-crossing point of the V-phase, the voltage value determiner 523 switches the correction component used to determine the control voltage value of the V-phase from the pre-switching correction component to the post-switching correction component, and at a zero-crossing point of the W-phase, the voltage value determiner 523 switches the correction component used to determine the control voltage value of the W-phase from the pre-switching correction component to the post-switching correction component.

[0178] In addition, instead of or in addition to the correction component, the target current used to determine the control voltage value may be switched from a pre-switching target current to a post-switching target current for each phase. As yet another example, instead of or in addition to at least one of the correction component and the target current, the feedback gain used to determine the control voltage value may be switched from a pre-switching gain to a post-switching gain for each phase.

[0179] This allows the parameter values ​​used to determine the control voltage value to be switched for each phase.

[0180] [10. Supplementary Note] The embodiments disclosed herein are illustrative in all respects and are not restrictive. The scope of the present invention is defined by the claims, not the above-described embodiments, and includes meanings equivalent to the claims and all modifications within the scope thereof.

[0181] 10 Winding switching system 20 Motor 21u, 22u, 21v, 22v, 21w, 22w Winding 23 Neutral point 25 Power line 26 Position sensor 30 Power converter 31u, 32u, 31v, 32v, 31w, 32w Switch 33u, 33v, 33w Current sensor 35u, 35v, 35w Power line 40 Battery 50 Control device 501 Processor 502 Non-volatile memory 503 Volatile memory 504 Interface (I / F) 510 Motor control program 521 Switching command unit 522 Parameter value determination unit 523 Voltage value determination unit 524 Input unit 525 Identification unit 531 Target torque 532 Torque current conversion unit 533 Current conversion unit 534 Addition point 535 F / B control unit 536 Electromotive force calculation unit 537 Addition point 538 Voltage conversion unit 539 PWM unit 100 Winding switching device 101u, 101v, 101w Current sensor 102u, 102v, 102w Zero cross detection circuit 103u, 103v, 103w Control circuit 104u, 104v, 104w Switching circuit 111u, 112u, 113u, 111v, 112v, 113v, 111w, 112w, 113w Semiconductor relay 212u, 221u, 222u, 212v, 221v, 222v, 212w, 221w, 222w Power line 131, 133 AND circuit 132 NOT circuit 120 Latch circuit (RS flip-flop) 121, 123 NOT circuit 122, 124 NAND circuit 20A motor 24u, 25u, 24v, 25v, 24w, 25w Winding 100A Winding switching device 131u, 131v, 131w Current sensor 140u, 140v, 140w Switching circuit 141u, 142u, 141v, 142v, 141w, 142w Semiconductor relay 241u, 242u, 243u, 251u, 252u, 253u, 241v, 242v, 243v, 251v, 252v, 253v, 241w, 242w, 243w, 251w, 252w, 253w Power line

Claims

1. A control device for controlling an AC motor capable of switching a connection state of a plurality of windings from a first connection state to a second connection state, a switching command unit that commands a winding switching device that switches the connection states of the plurality of windings to execute zero-cross switching to switch the connection states of the plurality of windings from the first connection state to the second connection state at a zero-cross point of a current flowing through the windings; a parameter value determination unit that determines a value of a first control parameter for controlling the AC motor and a value of a second control parameter for controlling the AC motor; a voltage value determination unit that determines voltages to be applied to the plurality of windings based on the values ​​of the first control parameter and the second control parameter determined by the parameter value determination unit; Equipped with the parameter value determination unit, when the zero-crossing switching is executed, switches the first control parameter from a first pre-switching parameter value that is a value in the first connection state to a first post-switching parameter value that is a value in the second connection state at a first timing, and switches the second control parameter from a second pre-switching parameter value that is a value in the first connection state to a second post-switching parameter value that is a value in the second connection state at a second timing different from the first timing; Control device.

2. the parameter value determination unit repeatedly determines the value of the first control parameter and the value of the second control parameter for each control cycle; the first timing is a timing in a first control cycle, the second timing is a timing in a second control cycle different from the first control cycle; The control device according to claim 1 .

3. the first timing is a first zero cross point that is a zero cross point of AC current supplied to the AC motor, the second timing is a second zero cross point that is different from the first zero cross point; The control device according to claim 1 .

4. the control device further includes an identification unit that identifies a switching timing at which the winding switching device executes the zero-crossing switching, the first timing is the switching timing identified by the identification unit; The control device according to claim 1 .

5. the parameter value determination unit gradually changes the first control parameter from the first pre-switching parameter value to the first post-switching parameter value; The control device according to claim 1 .

6. the parameter value determination unit gradually changes the second control parameter from the second pre-switching parameter value to the second post-switching parameter value; The control device according to claim 1 .

7. the AC motor is a polyphase AC motor, the parameter value determiner determines the second pre-switching parameter value and the second post-switching parameter value when the zero-crossing switching is performed; the voltage value determiner switches, at different timings for each phase, from a pre-switching voltage value determined based on the second pre-switching parameter value to a post-switching voltage value determined based on the second post-switching parameter value; The control device according to claim 1 .

8. one of the first control parameter and the second control parameter is a feedback gain; when the zero-crossing switching is performed, the parameter value determiner switches the feedback gain from a pre-switching feedback gain that is a value in the first connection state, via a switching feedback gain corresponding to the zero-crossing switching, to a post-switching feedback gain that is a value in the second connection state. The control device according to any one of claims 1 to 7.

9. an AC motor capable of switching a connection state of a plurality of windings from a first connection state to a second connection state; a power converter that converts power output from a power supply into AC power and supplies the AC power to the AC motor; a winding switching device that performs zero-cross switching to switch the connection states of the plurality of windings from the first connection state to the second connection state at zero-cross points of current flowing through the windings; a control device; Equipped with The control device a switching command unit that commands the winding switching device to perform the zero-cross switching; a parameter value determination unit that determines a value of a first control parameter for controlling the AC motor and a value of a second control parameter for controlling the AC motor; a voltage value determination unit that determines voltages to be applied to the plurality of windings based on the values ​​of the first control parameter and the second control parameter determined by the parameter value determination unit; Including, the parameter value determination unit, when the zero-crossing switching is executed, switches the first control parameter from a first pre-switching parameter value that is a value in the first connection state to a first post-switching parameter value that is a value in the second connection state at a first timing, and switches the second control parameter from a second pre-switching parameter value that is a value in the first connection state to a second post-switching parameter value that is a value in the second connection state at a second timing different from the first timing; Winding switching system.

10. A control method for controlling an AC motor capable of switching a connection state of a plurality of windings from a first connection state to a second connection state, comprising: instructing a winding switching device that switches the connection states of the plurality of windings to execute zero-crossing switching to switch the connection states of the plurality of windings from the first connection state to the second connection state at a zero-crossing point of current flowing through the windings; determining a value of a first control parameter for controlling the AC motor and a value of a second control parameter for controlling the AC motor; determining a voltage to be applied to the plurality of windings based on the determined values ​​of the first control parameter and the second control parameter; Including, In the step of determining the value of the first control parameter and the value of the second parameter, when the zero-crossing switching is performed, the first control parameter is switched from a first pre-switching parameter value that is a value in the first connection state to a first post-switching parameter value that is a value in the second connection state at a first timing, and the second control parameter is switched from a second pre-switching parameter value that is a value in the first connection state to a second post-switching parameter value that is a value in the second connection state at a second timing different from the first timing. Control method.

11. A control program for controlling an AC motor capable of switching a connection state of a plurality of windings from a first connection state to a second connection state, On the computer, instructing a winding switching device that switches the connection states of the plurality of windings to execute zero-crossing switching to switch the connection states of the plurality of windings from the first connection state to the second connection state at a zero-crossing point of current flowing through the windings; determining a value of a first control parameter for controlling the AC motor and a value of a second control parameter for controlling the AC motor; determining a voltage to be applied to the plurality of windings based on the determined values ​​of the first control parameter and the second control parameter; Execute In the step of determining the value of the first control parameter and the value of the second parameter, when the zero-crossing switching is performed, the first control parameter is switched from a first pre-switching parameter value that is a value in the first connection state to a first post-switching parameter value that is a value in the second connection state at a first timing, and the second control parameter is switched from a second pre-switching parameter value that is a value in the first connection state to a second post-switching parameter value that is a value in the second connection state at a second timing different from the first timing. Control program.