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

Abstract

The control device is provided with: a switching command unit for commanding the winding switching device to execute zero-crossing switching for switching the connection state of a plurality of windings of the AC motor at the zero-crossing point of the current; a parameter value determination unit that determines a value of the first control parameter and a value of the second control parameter; and a voltage value determination unit that determines a voltage to be applied to the plurality of windings on the basis of the value of the first control parameter and the value of the second control parameter, the parameter value determination unit switching the first control parameter from a first pre-switching parameter value to a first post-switching parameter value at a first timing when the zero-crossing switching is performed, and switching the second control parameter from a second pre-switching parameter value to a second post-switching parameter value at a second timing when the zero-crossing switching is performed. And switching the second control parameter from a second pre-switching parameter value to a second post-switching parameter value at a second time.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a control device, a winding switching system, a control method, and a control program. This application claims priority based on Japanese Application No. 2023-032864 filed on March 3, 2023, and the entire contents described in the Japanese application are incorporated by reference. BACKGROUND

[0002] For example, in an electric motor mounted on an electric automobile, there is an electric motor capable of switching between a low-speed and high-torque operation state and a high-speed and low-torque operation state by switching the connection of a plurality of windings. Patent Literature 1 discloses a device that, in order to prevent a surge voltage, determines a period in which an alternating-current motor current is equal to or less than a predetermined value, and switches the windings during the determined period. PRIOR ART DOCUMENTS PATENT LITERATURE

[0003] Patent Literature 1: Japanese Patent Application Publication No. 2020-072632 SUMMARY

[0004] A control device according to an aspect of the present disclosure is a control device for controlling an alternating-current 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 instruction unit that instructs a winding switching device that switches the connection state of the plurality of windings to perform zero-cross switching that switches the connection state of the plurality of windings from the first connection state to the second connection state at a zero-crossing point of a current flowing in the windings, a parameter value determination unit that determines a value of a first control parameter for controlling the alternating-current motor and a value of a second control parameter for controlling the alternating-current motor, and a voltage value determination unit that determines a voltage 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, the parameter value determination unit switching 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 when the zero-cross switching is performed, and switching 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. BRIEF DESCRIPTION OF DRAWINGS

[0005] Figure 1 FIG. 1 is a diagram showing an example of the structure of a winding switching system according to a first embodiment. Figure 2 FIG. 2 is a circuit diagram showing an example of the structure of a winding switching device according to the first embodiment. Figure 3is a circuit diagram showing an example of the structure of the control circuit. Figure 4 is a timing chart showing an example of the state transition of each signal of the winding switching device according to the first embodiment. Figure 5 is a block diagram showing an example of the hardware structure of the control device according to the first embodiment. Figure 6 is a functional block diagram showing an example of the function of the control device according to the first embodiment. Figure 7 is a control block diagram showing the control system of the motor of the control device according to the first embodiment. Figure 8 is a diagram showing an example of the switching of the parameter value of the control parameter. Figure 9A is a first half of a flowchart showing an example of the motor control processing by the control device according to the first embodiment. Figure 9B is a second half of a flowchart showing an example of the motor control processing by the control device according to the first embodiment. Figure 10 is a circuit diagram showing an example of the structure of the winding switching device according to the second embodiment. Figure 11 is a diagram showing another example of the switching of the parameter value of the control parameter. Figure 12 is a circuit diagram showing an example of the structure of the winding switching device according to the third embodiment. Figure 13 is a functional block diagram showing an example of the function of the control device according to the fourth embodiment. Figure 14 is a first half of a flowchart showing an example of the motor control processing by the control device according to the fourth embodiment. DETAILED DESCRIPTION

[0006] PROBLEMS TO BE SOLVED BY THE DISCLOSURE Before and after the winding switching of the motor, the value of the control parameter such as the target current and the feedback gain (hereinafter also referred to as "parameter value") needs to be changed. Therefore, not only the winding but also the parameter value needs to be switched, but a surge voltage can occur when the parameter value is switched. In addition, due to the drastic change of the parameter value, the current control of the motor can also oscillate.

[0007] EFFECTS OF THE DISCLOSURE According to the present disclosure, the occurrence of a surge voltage can be suppressed, and the oscillation of the current control of the motor can be suppressed.

[0008] <Summary of Embodiments of the Present Disclosure> Hereinafter, a summary of the embodiments of the present disclosure is listed and explained.

[0009] (1) The control device according to the present embodiment is a control device for controlling an alternating-current 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 instruction unit that instructs a winding switching device that switches the connection state of the plurality of windings to perform zero-cross switching that 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 in the windings; a parameter value decision unit that decides a value of a first control parameter for controlling the alternating-current motor and a value of a second control parameter for controlling the alternating-current motor; and a voltage value decision unit that decides a voltage applied to the plurality of windings on the basis of the value of the first control parameter and the value of the second control parameter decided by the parameter value decision unit, the parameter value decision unit switching the first control parameter from a first switching-before parameter value that is a value in the first connection state to a first switching-after parameter value that is a value in the second connection state at a first timing when the zero-cross switching is performed, and switching the second control parameter from a second switching-before parameter value that is a value in the first connection state to a second switching-after parameter value that is a value in the second connection state at a second timing different from the first timing. Thereby, when the zero-cross switching is performed, the parameter value of the first control parameter and the parameter value of the second control parameter are switched in stages, and thus generation of a surge voltage can be suppressed, and signaling of current control of the motor can be suppressed.

[0010] (2) In the above (1), the parameter value decision unit can repeatedly decide the value of the first control parameter and the value of the second control parameter for each control cycle, the first timing can be a timing in a first control cycle, and the second timing can be a timing in a second control cycle different from the first control cycle. Thereby, when the zero-cross switching is performed, the voltage applied to the plurality of windings changes in stages over a plurality of control cycles, and thus generation of a surge voltage can be suppressed, and signaling of current control of the motor can be suppressed.

[0011] (3) In the above (1) or (2), the first timing can be a first zero-cross point that is a zero-cross point of an alternating current supplied to the alternating-current motor, and the second timing can be a second zero-cross point that is a zero-cross point of the alternating current different from the first zero-cross point. Thereby, the parameter value of the first control parameter and the parameter value of the second control parameter can be switched at the zero-cross points, and thus generation of a surge voltage can be further suppressed, and signaling of current control of the motor can be further suppressed.

[0012] (4) In any one of (1) to (3) above, the control device can further include a determination section that determines a switching timing at which the winding switching device performs the zero-cross switching, and the first timing can be the switching timing determined by the determination section. Thus, the parameter value of the first control parameter can be switched at the timing at which the zero-cross switching has been performed, and the generation of surge voltage and the signaling of the current control of the motor can be further suppressed.

[0013] (5) In any one of (1) to (4) above, the parameter value decision section can cause the first control parameter to gradually change from the first pre-switching parameter value to the first post-switching parameter value. Thus, the parameter value of the first control parameter can be prevented from changing abruptly, and the generation of surge voltage and the signaling of the current control of the motor can be suppressed.

[0014] (6) In any one of (1) to (5) above, the parameter value decision section can cause the second control parameter to gradually change from the second pre-switching parameter value to the second post-switching parameter value. Thus, the parameter value of the second control parameter can be prevented from changing abruptly, and the generation of surge voltage and the signaling of the current control of the motor can be suppressed.

[0015] (7) In any one of (1) to (6) above, the alternating-current motor can be a multiphase alternating-current motor, and the parameter value decision section can decide the second pre-switching parameter value and the second post-switching parameter value, respectively, when the zero-cross switching is performed, and the voltage value decision section can switch the pre-switching voltage value decided based on the second pre-switching parameter value to the post-switching voltage value decided based on the second post-switching parameter value at a timing that differs depending on each phase. Thus, a situation in which the control voltage value changes uniformly in all phases can be avoided. Thus, the generation of surge voltage and the signaling of the current control of the motor can be suppressed.

[0016] (8) In any one of (1) to (7) above, one of the first control parameter and the second control parameter can be a feedback gain, and the parameter value decision section can switch the feedback gain from a pre-switching feedback gain that is a value in the first connection state, through a switching feedback gain corresponding to the zero-cross switching, to a post-switching feedback gain that is a value in the second connection state, when the zero-cross switching is performed. Thus, when the zero-cross switching is performed, the feedback gain can be prevented from changing abruptly from the pre-switching feedback gain for the first connection state to the post-switching feedback gain for the second connection state. Thus, the generation of surge voltage and the signaling of the current control of the motor can be suppressed.

[0017] (9) The winding switching system according to the present embodiment includes an alternating-current 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 electric power output from a power source into alternating-current electric power and supplies the alternating-current electric power to the alternating-current motor; a winding switching device that performs zero-cross switching that switches the connection state of the plurality of windings from the first connection state to the second connection state at a zero-crossing point of a current flowing in the windings; and a control device including a switching instruction section that instructs the winding switching device to perform the zero-cross switching, a parameter value decision section that decides a value of a first control parameter for controlling the alternating-current motor and a value of a second control parameter for controlling the alternating-current motor, and a voltage value decision section that decides a voltage applied to the plurality of windings on the basis of the value of the first control parameter and the value of the second control parameter decided by the parameter value decision section, the parameter value decision section switching the first control parameter from a first switching-before parameter value that is a value in the first connection state to a first switching-after parameter value that is a value in the second connection state at a first timing when the zero-cross switching is performed, and switching the second control parameter from a second switching-before parameter value that is a value in the first connection state to a second switching-after parameter value that is a value in the second connection state at a second timing different from the first timing. Thus, the parameter value of the first control parameter and the parameter value of the second control parameter are switched in stages when the zero-cross switching is performed, so that generation of a surge voltage can be suppressed and signaling of current control of the motor can be suppressed.

[0018] (10) The control method according to the present embodiment is a control method for controlling an alternating-current motor capable of switching a connection state of a plurality of windings from a first connection state to a second connection state, and includes the steps of: instructing a winding switching device that switches the connection state of the plurality of windings to perform zero-cross switching that 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 in the windings; determining a value of a first control parameter for controlling the alternating-current motor and a value of a second control parameter for controlling the alternating-current motor; and determining a voltage to be applied to the plurality of windings based on the determined value of the first control parameter and the value of the second control parameter, wherein, in the step of determining the value of the first control parameter and the value of the second control parameter, 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 when the zero-cross switching is performed, 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, the parameter value of the first control parameter and the parameter value of the second control parameter are switched in stages when the zero-cross switching is performed, and it is thus possible to suppress generation of a surge voltage and suppress signaling of current control of the motor.

[0019] (11) The control program according to the present embodiment is a control program for controlling an alternating-current motor capable of switching a connection state of a plurality of windings from a first connection state to a second connection state, and causes a computer to execute the steps of: instructing a winding switching device that switches the connection state of the plurality of windings to perform zero-cross switching that 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 in the windings; determining a value of a first control parameter for controlling the alternating-current motor and a value of a second control parameter for controlling the alternating-current motor; and determining a voltage to be applied to the plurality of windings based on the determined value of the first control parameter and the value of the second control parameter, wherein, in the step of determining the value of the first control parameter and the value of the second control parameter, 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 when the zero-cross switching is performed, 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, the parameter value of the first control parameter and the parameter value of the second control parameter are switched in stages when the zero-cross switching is performed, and it is thus possible to suppress generation of a surge voltage and suppress signaling of current control of the motor.

[0020] The present disclosure can be implemented not only as the control device having the above-described characteristic structure, the winding switching system having the control device, the control method in which the characteristic processing in the control device is a step, and the control program for causing a computer to execute the characteristic processing, but also as a semiconductor integrated circuit that implements part or all of the control device.

[0021] <Details of Embodiments of the Present Disclosure> Hereinafter, details of the embodiments of the present disclosure will be described with reference to the drawings. Further, at least a part of the embodiments described below can be arbitrarily combined.

[0022] [1. First Embodiment] [1-1. Winding Switching System] Figure 1 is a drawing illustrating an example of the structure of the winding switching system according to the first embodiment.

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

[0024] The electric motor 20 is a traveling electric motor that generates a propulsion force of the electric vehicle. The electric motor 20 is driven by three-phase alternating current power. An example of the electric motor 20 is a permanent magnet synchronous motor.

[0025] A position sensor 26 is provided at an output shaft of the electric motor 20. The position sensor 26 detects a rotation angle of the output shaft of the electric 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 through a signal line. A detection signal of the position sensor 26 is output to the control device 50.

[0026] The battery 40 is a battery for supplying electric power required for driving the electric 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 direct current power supplied from the battery 40 into three-phase alternating current power. The power converter 30 can also have a function of converting three-phase alternating current power output when the electric motor 20 functions as a generator into direct current power and charging the battery 40.

[0028] The power converter 30 includes bridge arms of U-phase, V-phase, and W-phase. The bridge arm of U-phase includes switches 31u, 32u, the bridge arm of V-phase includes switches 31v, 32v, and the bridge arm of W-phase includes switches 31w, 32w. By switching operations of the switches 31u, 32u, 31v, 32v, 31w, 32w, direct-current power is converted into three-phase alternating-current power. The switches 31u, 32u, 31v, 32v, 31w, 32w are, for example, IGBTs (Insulated Gate Bipolar Transistors) or power MOSFETs (Metal Oxide Semiconductor Field Effect Transistors).

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

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

[0031] The winding switching device 100 is arranged 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 through the power lines 35u, 35v, 35w, and the winding switching device 100 and the motor 20 are connected through a plurality of power lines 25. The winding switching device 100 switches connection states of a plurality of windings of the motor 20. The structure of the winding switching device 100 will be described later. The three-phase alternating currents Iu, Iv, 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 the switches 31u, 32u, 31v, 32v, 31w, 32w, respectively, and the control device 50 controls the on / off timing of the switches 31u, 32u, 31v, 32v, 31w, 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 for instructing switching of the winding connection state to the winding switching device 100.

[0033] [1-2. Structure of Winding Switching Device] Figure 2 Fig. 1 is a circuit diagram showing an example of the structure of the winding switching device according to the first embodiment. The motor 20 includes a plurality of windings 21u, 22u, 21v, 22v, 21w, 22w. The windings 21u, 22u correspond to the U phase, the windings 21v, 22v correspond to the V phase, and the windings 21w, 22w correspond to the W phase. However, the number of windings of each phase is not limited to two, and can be three or more. The windings 22u, 22v, 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, 22w between the series connection state and the parallel connection state for each phase. The winding switching device 100 includes current sensors 101u, 101v, 101w, zero-crossing detection circuits 102u, 102v, 102w, control circuits 103u, 103v, 103w, and switching circuits 104u, 104v, 104w.

[0035] The zero-crossing detection circuits 102u, 102v, 102w detect the zero-crossing point of the measured value of the current sensors 101u, 101v, 101w. In a more specific example, the zero-crossing detection circuits 102u, 102v, 102w compare the output voltage from the current sensors 101u, 101v, 101w with zero voltage, and detect the time point at which the output voltage from the current sensors 101u, 101v, 101w coincides with the zero voltage as the zero-crossing point. The zero voltage is an example of a reference voltage. The reference voltage is a voltage corresponding to the output voltage of the current sensors 101u, 101v, 101w when the current flowing in the windings 21u, 22u, 21v, 22v, 21w, 22w is zero current, and is not limited to zero voltage. The zero-crossing detection circuits 102u, 102v, 102w are examples of detection sections. Furthermore, the output voltage from the current sensors 101u, 101v, 101w can not be completely coincident with the zero voltage, and the same effect can be obtained even if the time point at which the output voltage from the current sensors 101u, 101v, 101w is near the zero voltage is detected as the zero-crossing point.

[0036] The switching circuit 104u, 104v, 104w switches the connection state of the winding 21u, 22u, 21v, 22v, 21w, 22w between the series connection state and the parallel connection state at the timing when the zero-crossing detection circuit 102u, 102v, 102w detects the zero-crossing point. The switching circuit 104u, 104v, 104w is an example of a switching section. The series connection state is an example of the first connection state, and the parallel connection state is an example of the second connection state.

[0037] Hereinafter, the connection relationship between the winding switching device 100, the power line 35u, and the motor 20 will be described with respect to the U phase. The same applies to the V phase and the W phase, and thus the description will be omitted.

[0038] The power line 35u is connected to one end of the winding 21u. The power line 212u extends from the other end of the winding 21u. The power line 221u extends from one end of the winding 22u, and the 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, 113u are, for example, IGBTs or power MOSFETs.

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

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

[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] A signal line extending from the control circuit 103u is connected to the gate terminal of the semiconductor relay 111u, 112u, 113u.

[0044] The power line 221u is provided with a current sensor 101u. However, the current sensor 101u can be provided on the power line 35u, 212u or 222u, instead of the power line 221u. The current sensor 101u detects the U-phase current flowing in 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-crossing detection circuit 102u. A signal line transmitting the output signal of the zero-crossing detection circuit 102u (hereinafter referred to as "zero-crossing detection signal") extends from the zero-crossing detection circuit 102u to the control circuit 103u. In addition, a signal line extending from the control device 50 is connected to the control circuit 103u.

[0046] The zero-crossing detection circuit 102u detects the zero-crossing point of the measured value of the current sensor 101u of the winding current flowing in the power line 221u. 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. Thus, at the time point (zero-crossing point) at which the AC signal output from the current sensor 101u crosses the zero reference voltage, the output of the comparator changes from low to high.

[0047] Figure 3 is a circuit diagram showing an example of the structure of the control circuit 103u. The control circuit 103u includes AND circuits 131, 133, a NOT circuit 132, and a latch circuit 120. A signal line extending from the zero-crossing detection circuit 102u is connected to the first input terminal of the AND circuit 131 and the first input terminal of the AND circuit 133. A signal line extending from the control device 50 is connected to the second input terminal of the AND circuit 131. In addition, a signal line from the control device 50 is connected to the input terminal of the NOT circuit 132. A signal line extending from the output terminal of the NOT circuit 132 is connected to the 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, 123 and two NAND circuits 122, 124. However, the RS flip-flop 120 can also be constituted by 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. The output Q non (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 at a low level and the signal output from the output Q non of the RS flip-flop 120 is at a high level, the semiconductor relays 111u and 113u are in an off state and the semiconductor relay 112u is in an on state. That is, at this time, the windings 21u, 22u are in a series connection state. When the signal output from the output Q of the RS flip-flop 120 is at a high level and the signal output from the output Q non of the RS flip-flop 120 is at a low level, the semiconductor relays 111u and 113u are in an on state and the semiconductor relay 112u is in an off state. That is, at this time, the windings 21u, 22u are in a parallel connection state. When the signal output from the output Q of the RS flip-flop 120 is switched from a low level to a high level and the signal output from the output Q non of the RS flip-flop 120 is switched from a high level to a low level, the semiconductor relays 111u and 113u are switched from an off state to an on state and the semiconductor relay 112u is switched from an on state to an off state. That is, the windings 21u, 22u are switched from a series connection state to a parallel connection state. When the signal output from the output Q of the RS flip-flop 120 is switched from a high level to a low level and the signal output from the output Q non of the RS flip-flop 120 is switched from a low level to a high level, the semiconductor relays 111u and 113u are switched from an on state to an off state and the semiconductor relay 112u is switched from an off state to an on state. That is, the windings 21u, 22u are switched from a parallel connection state to a series connection state.

[0051] [1-3. Zero-crossing switching of winding switching device] Next, zero-crossing switching of the winding switching device 100 will be described. The zero-crossing switching is an action of switching the connection state of the windings 21u, 22u, 21v, 22v, 21w, 22w between the series connection state and the parallel connection state at the zero-crossing point of the winding currents Iu, Iv, Iw. Further, in the following, the switching action of the connection state of the windings 21u, 22u of the U phase will be described representatively. As for the V phase and the W phase, it is the same, and thus the description will be omitted.

[0052] Figure 4 is a timing chart showing an example of state transition of each signal of the winding switching device 100 according to the first embodiment.

[0053] The current sensor 101u measures the winding current Iu flowing in the power line 221u. The zero-crossing detection circuit 102u detects the zero-crossing point of the measured value of the winding current Iu. That is, the zero-crossing detection signal output from the zero-crossing detection circuit 102u is at a low level when the winding current Iu is not zero, and becomes a high level at the time point when the winding current Iu is zero. In Figure 4 In the example of Fig. 10, the zero-crossing detection signal is at a low level at ordinary times, and is at a high level at the time points T1, T2, T3, T4.

[0054] The control device 50 sets the value of the switching instruction signal to a low level in the case where the windings 21u, 22u, 21v, 22v, 21w, 22w of the motor 20 are connected in series, and sets the value of the switching instruction signal to a high level in the case where the windings 21u, 22u, 21v, 22v, 21w, 22w are connected in parallel. In Figure 4 In the example of Fig. 10, the switching instruction signal is at a low level in the initial state, and becomes a high level at some time point between the time points T1 and T2. The switching instruction signal becomes a low level again at some time point between the time points T3 and T4.

[0055] The zero-crossing detection signal and the switching instruction signal are input to the AND circuit 131. The AND circuit 131 outputs a low level when the zero-crossing detection signal and the switching instruction signal are in the combinations of (low level, low level), (low level, high level), and (high level, low level). The AND circuit 131 outputs a high level when the zero-crossing detection signal and the switching instruction signal are in the combination of (high level, high level). That is, S of the RS flip-flop 120 is input with a low level at ordinary times, and is input with a high level in the case where the zero-crossing point of the winding current Iu is detected and the parallel connection instruction of the windings 21u, 22u, 21v, 22v, 21w, 22w is provided. In Figure 4 In the example of Fig. 10, the input signal of S is a high level at the time points T2 and T3.

[0056] The inverted signal of the zero-crossing detection signal and the switching instruction signal (output signal of the NOT circuit 132) is input to the AND circuit 133. The AND circuit 133 outputs a low level when the combination of the zero-crossing detection signal and the switching instruction signal is (low level, low level), (high level, low level), and (high level, high level). The AND circuit 133 outputs a high level when the combination of the zero-crossing detection signal and the switching instruction signal is (high level, low level). That is, the R of the RS flip-flop 120 is input with a low level at ordinary times, and is input with a high level when the zero-crossing point of the winding current Iu is detected and the series connection instruction of the windings 21u, 22u, 21v, 22v, 21w, 22w is given. In the case of the example shown in FIG. 7, the input signal of the R is a high level at the time points Tl and T4. Figure 4

[0057] When the input S, R is low level, low level, the RS flip-flop 120 holds the Q, Q non to the output value thereof. When the input S, R is low level, high level, the Q, Q non of the RS flip-flop 120 outputs low level, high level. When the input S, R is high level, low level, the Q, Q non of the RS flip-flop 120 outputs high level, low level. In the RS flip-flop 120, the combination of the input S, R being high level, high level is prohibited.

[0058] In the example shown in FIG. 7, the Q is low level and the Q non is high level until the time point T2. Therefore, the semiconductor relays 111u and 113u are in the off state and the semiconductor relay 112u is in the on state until the time point T2. Thus, the windings 21u and 22u are connected in series. Figure 4

[0059] When the time point T2 comes, the Q changes from low level to high level and the Q non changes from high level to low level. Therefore, the semiconductor relays 111u and 113u change from the off state to the on state and the semiconductor relay 112u changes from the on state to the off state. Thus, the connection state of the windings 21u and 22u is switched from the series connection state to the parallel connection state.

[0060] From the time point T2 to T4, the Q is high level and the Q non is low level. Therefore, the semiconductor relays 111u and 113u maintain the on state and the semiconductor relay 112u maintains the off state from the time point T2 to T4. Thus, the connection state of the windings 21u and 22u is maintained as the parallel connection state.

[0061] When the time point T4 comes, the Q changes from high level to low level and the Q non changes from low level to high level. Therefore, the semiconductor relays 111u and 113u change from the on state to the off state and the semiconductor relay 112u changes from the off state to the on state. Thus, the connection state of the windings 21u and 22u is switched from the parallel connection state to the series connection state.​​

[0062] After time T4, Q is low and Qnon is high. Therefore, the semiconductor relays 111u and 113u maintain the off state, and the semiconductor relay 112u maintains the on state until time T2. Thus, the connection state of the windings 21u and 22u is maintained in the series connection state.

[0063] As described above, the connection state of the windings 21u, 22u, 21v, 22v, 21w, and 22w can be switched between the series connection state and the parallel connection state at the timing of the zero-crossing point of the winding currents lu, lv, and lw. Therefore, the generation of the surge voltage can be suppressed. Further, a complicated process of determining the period in which the winding currents lu, lv, and lw are equal to or lower than predetermined values is not required, and the winding switching device 100 can be configured without using a processor such as a CPU, an FPGA, and an ASIC.

[0064] [1-4. Hardware structure of control device] Figure 5 is a block diagram illustrating an example of a hardware structure of the control device according to the first embodiment. The control device 50 includes a processor 501, a nonvolatile memory 502, a volatile memory 503, and an interface (I / F) 504.

[0065] The volatile memory 503 is a semiconductor memory such as an SRAM (Static Random Access Memory) and a DRAM (Dynamic Random Access Memory). The nonvolatile memory 502 is, for example, a flash memory, a hard disk, and a ROM (Read Only Memory). In the nonvolatile memory 502, a motor control program 510 as a computer program and data used for executing the motor control program 510 are stored. Each function of the control device 50 is realized by the processor 501 executing the motor control program 510. The motor control program 510 can be stored in a recording medium such as a flash memory, a ROM, and a CD-ROM. The processor 501 controls the power converter 30 and the winding switching device 100 by 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 the CPU. The processor 501 can also be a GPU (Graphics Processing Unit). The processor 501 is, for example, a multi-core processor. The processor 501 can also be a single-core processor. The processor 501 can also be, for example, an ASIC (Application Specific Integrated Circuit), and can also be a programmable logic device such as a gate array and an FPGA (Field Programmable Gate Array). In this case, the ASIC or the programmable logic device is configured to be able to perform 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. The I / F 504 is connected to the current sensors 33u, 33v, 33w provided in the power converter 30, for example, and can acquire the current value of the U-phase current lu, the current value of the V-phase current Iv, and the current value of the W-phase current Iw. The I / F 504 is connected to the switches 31u, 32u, 31v, 32v, 31w, 32w of the power converter 30, respectively, for example, and can perform on / off control of the switches 31u, 32u, 31v, 32v, 31w, 32w. The I / F 504 is connected to the control circuits 103u, 103v, 103w of the winding switching device 100, for example, and can output the switching instruction signal to the control circuits 103u, 103v, 103w.

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

[0069] The control device 50 realizes each function of the switching instruction section 521, the parameter value decision section 522, and the voltage value decision section 523 by executing the motor control program 510 by the processor 501.

[0070] The switching instruction section 521 instructs the winding switching device 100 to perform the zero-cross switching. The instruction to perform the zero-cross switching is performed by outputting the switching instruction signal to the control circuits 103u, 103v, 103w. That is, as described above, when the switching instruction signal is input to the control circuits 103u, 103v, 103w, the zero-cross detection signal is output from the zero-cross detection circuits 102u, 102v, 102w at the time point at which the next zero-cross point is detected, and the zero-cross switching is performed.

[0071] The parameter value decision section 522 decides the parameter value of the control parameter used in deciding the voltage to be applied to the windings 21u, 22u, 21v, 22v, 21w, 22w (hereinafter also referred to as "control voltage value"). Specifically, the parameter value decision section 522 decides the parameter value of the control parameter in the following control system.

[0072] Figure 7 is a control block diagram illustrating the control system of the motor of the control device according to the first embodiment. Hereinafter, the control system of the motor of the control device according to the first embodiment will be described using the block diagram. Figure 7 The decision of the parameter value of the control parameter will be described.

[0073] The control device 50 sets the target torque 531 of the motor 20. The target torque 531 is calculated, for example, in accordance with the target speed of the vehicle or the like.

[0074] The target torque 531 is input to a torque-current conversion section 532. The torque-current conversion section 532 converts the target torque 531 into a target current. The conversion from the target torque 531 to the target current is performed on the basis of an output characteristic of the motor 20 that is stored in advance in the control device 50. For example, the output characteristic when the windings 21u, 22u, 21v, 22v, 21w, 22w are in the series connection state is different from the output characteristic when the windings 21u, 22u, 21v, 22v, 21w, 22w are in the parallel connection state. For example, both the output characteristic when the windings 21u, 22u, 21v, 22v, 21w, 22w are in the series connection state and the output characteristic when the windings 21u, 22u, 21v, 22v, 21w, 22w are in the parallel connection state are stored in a nonvolatile memory 502 of the control device 50. The torque-current conversion section 532 determines the target current in accordance with the output characteristic corresponding to the connection state of the windings 21u, 22u, 21v, 22v, 21w, 22w at the time point. The target current obtained by the torque-current conversion section 532 is a current value in the dq coordinate system (hereinafter also referred to as "dq current value". A voltage value in the dq coordinate system is also referred to as "dq voltage value").

[0075] The detection values of the current sensors 33u, 33v, 33w and the detection value of the position sensor 26 are input to a current conversion section 533. The current conversion section 533 converts the current values of the respective phases of the three-phase alternating current into dq current values. The dq current values corresponding to the detection values of the current sensors 33u, 33v, 33w, that is, the winding currents Iu, Iv, Iw are output from the current conversion section 533.

[0076] At a summing point 534, the difference between the target current output from the torque-current conversion section 532 and the winding current output from the current conversion section 533 is calculated. The calculated difference is input to an F / B control section 535.

[0077] The F / B control section 535 calculates a feedback gain on the basis of the difference between the input target current and winding current. For example, the correspondence relationship between the difference and the feedback gain is determined in advance. For example, both the correspondence relationship when the windings 21u, 22u, 21v, 22v, 21w, 22w are in the series connection state and the correspondence relationship when the windings 21u, 22u, 21v, 22v, 21w, 22w are in the parallel connection state are determined. The F / B control section 535 determines the feedback gain from the difference in accordance with the correspondence relationship corresponding to the connection state of the windings 21u, 22u, 21v, 22v, 21w, 22w at the time point. The feedback gain is a part of the drive voltage of the motor 20.

[0078] The F / B control section 535 determines the feedback gain by a predetermined control method. For example, the F / B control section 535 can determine the feedback gain in accordance with 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-described correspondence is determined in accordance with such a control method.

[0079] The winding current output from the current conversion section 533 and the detection value of the position sensor 26 are input to the electromotive force calculation section 536. The electromotive force calculation section 536 calculates a correction component based on an induced voltage generated in the motor 20, such as a non-interference control of the alternating current of the motor 20, mutual inductance between the d- and q-axes, and the like, based on the winding current and the rotational speed of the motor 20. The correction component is a voltage value for correcting the control voltage value in order to eliminate the influence of the induced voltage. The induced voltage differs between when the windings 21u, 22u, 21v, 22v, 21w, 22w are connected in series and when they are connected in parallel. Therefore, the electromotive force calculation section 536 calculates the correction component based on the induced voltage corresponding to the connection state of the windings 21u, 22u, 21v, 22v, 21w, 22w at the time point.

[0080] Hereinafter, the non-interference control will be described.

[0081] The state equation (differential equation) of the permanent magnet synchronous motor in the d-q coordinate system is represented by Equation (1). [Equation 1] Here, ia = [id, iq]T is the armature current (winding current), va = [vd, vq]T is the armature voltage, ω is the rotational angular speed of the motor, Ψa is the magnet flux, Ra is the winding resistance, Ld, Lq are the inductances of the windings, and p is the differential symbol.

[0082] In the non-interference control, the influence of the interference term between the d- and q-axes caused by the induced electromotive force is eliminated. Specifically, the d- and q-axis voltages are corrected as in Equation (2) below. [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] When Equation (2) is substituted into Equation (1), the following Equation (3) is derived as a new input with v'a = [v'd, v'q]. [Equation 3]

[0084] From equation (3), it is possible to make the d-axis and q-axis non-interfering, and it is possible to eliminate the interference de.

[0085] The feedback gain output from the F / B control section 535 and the correction component output from the electromotive force calculation section 536 are input to an adder calculation point 537. The adder calculation point 537 adds the feedback gain output from the F / B control section 535 and the correction component output from the electromotive force calculation section 536, and calculates a control voltage value.

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

[0087] The control voltage value of the three-phase alternating voltage output from the voltage conversion section 538 is input to a PWM section 539. The PWM section 539 decides a duty ratio corresponding to the input control voltage value, and generates a PWM signal for driving each of the switches 31u, 32u, 31v, 32v, 31w, 32w of the power converter 30 in accordance with the decided duty ratio. The PWM section 539 outputs the generated PWM signal to each of the switches 31u, 32u, 31v, 32v, 31w, 32w.

[0088] Returning to Figure 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 "correction component"). When the target current is "first control parameter", the feedback gain or the correction component is "second control parameter". When the feedback gain is "first control parameter", the target current or the correction component is "second control parameter". When the correction component is "first control parameter", the feedback gain or the target current is "second control parameter". In the following description, the feedback gain is taken as "first control parameter", and the target current and the correction component are taken as "second control parameter".

[0089] The parameter value decision unit 522 can decide the target current in the series connection state, the target current in the parallel connection state, the feedback gain in the series connection state, the feedback gain in the parallel connection state, the correction component based on the induced voltage in the series connection state, and the correction component based on the induced voltage in the parallel connection state, respectively, for the windings 21u, 22u, 21v, 22v, 21w, 22w. That is, the parameter value decision unit 522 decides the target current in the series connection state, the feedback gain in the series connection state, and the correction component based on the induced voltage in the series connection state, respectively, when the windings 21u, 22u, 21v, 22v, 21w, 22w are in the series connection state. The parameter value decision unit 522 decides the target current in the parallel connection state, the feedback gain in the parallel connection state, and the correction component based on the induced voltage in the parallel connection state, respectively, when the windings 21u, 22u, 21v, 22v, 21w, 22w are in the parallel connection state.

[0090] The voltage value decision unit 523 decides the control voltage value. Specifically, the voltage value decision unit 523 can add the feedback gain decided by the parameter value decision unit 522 to the correction component based on the induced voltage to calculate the control voltage value. The voltage value decision unit 523 decides the control voltage value in the series connection state of the windings 21u, 22u, 21v, 22v, 21w, 22w and the control voltage value in the parallel connection state of the windings 21u, 22u, 21v, 22v, 21w, 22w. That is, the voltage value decision unit 523 adds the feedback gain in the series connection state of the windings 21u, 22u, 21v, 22v, 21w, 22w to the correction component based on the induced voltage in the series connection state to calculate the control voltage value in the series connection state. The voltage value decision unit 523 adds the feedback gain in the parallel connection state of the windings 21u, 22u, 21v, 22v, 21w, 22w to the correction component based on the induced voltage in the parallel connection state to calculate the control voltage value in the parallel connection state.

[0091] For example, the parameter value determining section 522 switches the feedback gain from the parameter value in the connection state of the windings 21u, 22u, 21v, 22v, 21w, 22w before the switching (hereinafter also referred to as "pre-switching gain") to the parameter value in the connection state after the switching (hereinafter also referred to as "post-switching gain") when the zero-crossing switching is performed, for example, after the switching instruction signal has been output. The parameter value determining section switches the target current from the parameter value in the connection state of the windings 21u, 22u, 21v, 22v, 21w, 22w before the switching (hereinafter also referred to as "pre-switching target current") to the parameter value in the connection state after the switching (hereinafter also referred to as "post-switching target current") at a timing (second timing) different from the timing (first timing) after the parameter value of the feedback gain is switched. The parameter value determining section switches the correction component from the parameter value in the connection state of the windings 21u, 22u, 21v, 22v, 21w, 22w before the switching (hereinafter also referred to as "pre-switching correction component") to the parameter value in the connection state after the switching (hereinafter also referred to as "post-switching correction component") at a timing different from the timing after the parameter value of the feedback gain is switched.

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

[0093] Figure 8 is a graph showing an example of switching of the parameter value of the control parameter. In Figure 8 , the vertical axis represents the winding current lu, and the horizontal axis represents time. Furthermore, the switching of the parameter value of the control parameter is explained using the winding current lu of the U-phase here, but the same applies to the V-phase and the W-phase.

[0094] In the example of Figure 8 , the connection state of the windings 21u, 22u, 21v, 22v, 21w, 22w is switched from the series connection state to the parallel connection state. In the example of Figure 8 , at time T11, the feedback gain has been switched from the pre-switching gain (i.e., the feedback gain in the series connection state of the windings 21u, 22u, 21v, 22v, 21w, 22w) to the post-switching gain (i.e., the feedback gain in the parallel connection state of the windings 21u, 22u, 21v, 22v, 21w, 22w). With this switching of the parameter value, the control voltage value changes, and as a result, the amplitude of the winding current lu increases. In Figure 8 , the waveform of the winding current lu in the case where the feedback gain is not switched at time T11 is represented by a single-dot chain 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 state where the windings 21u, 22u, 21v, 22v, 21w, 22w are connected in series) to the post-switching target current (i.e., the target current in the state where the windings 21u, 22u, 21v, 22v, 21w, 22w are connected in parallel), and the correction component is switched from the pre-switching correction component (i.e., the correction component in the state where the windings 21u, 22u, 21v, 22v, 21w, 22w are connected in series) to the post-switching correction component (i.e., the correction component in the state where the windings 21u, 22u, 21v, 22v, 21w, 22w are connected in parallel). With these switching of the parameter values, the control voltage value changes, whereby the amplitude of the winding current Iu increases. In Figure 8 In the above, the waveform of the winding current Iu in the case where the target current and the correction component are not switched at time T12 is indicated by a broken line.

[0096] In this way, since the feedback gain and the target current and the correction component are switched in stages, the amplitude of the winding current Iu increases in stages. Therefore, the generation of surge voltage can be suppressed, and the oscillation of current control can be suppressed.

[0097] Returning to Figure 6 , the parameter value decision section 522 switches the feedback gain from the pre-switching gain to the post-switching gain in the first control cycle when the zero-crossing switching is performed. The parameter value decision section 522 switches the target current from the pre-switching target current to the post-switching target current in the second control cycle different from the first control cycle. The parameter value decision section 522 switches the correction component from the pre-switching correction component to the post-switching correction component in the second control cycle. Further, the parameter value decision section 522 can switch the correction component from the pre-switching correction component to the post-switching correction component in the third control cycle different from each of the first control cycle and the second control cycle.

[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 can not be adjacent control cycles. That is, one or more control cycles can be present between the first control cycle and the second control cycle.

[0099] As described above, the feedback gain is decided using any one of P control, PI control, PD control, and PID control. Here, the I action (integral action) changes slowly with time. Therefore, by adopting a control method including the I action, when the feedback gain is switched from the pre-switching gain to the post-switching gain, the post-switching feedback gain can be made to change slowly, whereby the generation of surge voltage can be suppressed, and the oscillation of current control can be suppressed.

[0100] For example, the parameter value decision unit 522 can switch the target current and the correction component after the feedback gain is switched from the pre-switching gain to the post-switching gain and the variation of the feedback gain converges. Thus, it is possible to suppress a drastic change in the control parameters (the feedback gain, the target current, and the correction component). However, the parameter value decision unit 522 can also switch the target current and the correction component before the variation of the feedback gain converges after the feedback gain is switched from the pre-switching gain to the post-switching gain. For example, the parameter value decision unit 522 can also switch the target current and the correction component after a predetermined time elapses after the feedback gain is switched from the pre-switching gain to the post-switching gain.

[0101] [1-6. Operation of the control device] Next, the operation of the control device 50 will be described. The control device 50 performs motor control processing by the processor 501 executing the motor control program 510.

[0102] Figure 9A and Figure 9B is a flowchart showing an example of the motor control processing performed by the control device according to the first embodiment.

[0103] For example, when a shift instruction is provided to the control device 50, the processor 501 decides to perform zero-crossing switching. The processor 501 determines whether or not it has decided to perform zero-crossing switching (step S101).

[0104] In the case where it has not decided to perform zero-crossing switching (NO in step S101), the processor 501 acquires the detection values output from the current sensors 33u, 33v, 33w and the detection value output from the position sensor 26 (step S102). The processor 501 calculates the rotational speed of the motor 20 on the basis of the detection value from the position sensor 26.

[0105] The processor 501 decides the parameter values of the control parameters corresponding to the connection state of the windings 21u, 22u, 21v, 22v, 21w, 22w 21u, 22u, Iv, Iv, Iw at the time point on the basis of the acquired current values of the winding currents Iu, Iv, Iw and the rotational speed of the motor 20 (step S103). The control parameters include the target current, the feedback gain, and the control component based on the induced voltage.

[0106] The processor 501 decides the control voltage values corresponding to the connection state of the windings 21u, 22u, 21v, 22v, 21w, 22w 21u, 22u, Iv, Iv, Iw at the time point on the basis of the decided parameter values (step S104).

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

[0108] In a case where it is decided to perform the zero-crossing switching (Yes in the step S101), the processor 501 outputs a switching instruction signal to the winding switching device 100 (step S106).

[0109] The processor 501 acquires the detection values output from the current sensors 33u, 33v, 33w and the detection value output from the position sensor 26 (step S107). The processor 501 calculates the rotational speed of the motor 20 based on the detection value 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 decides the parameter values of the respective control parameters based on the acquired current values of the winding currents lu, Iv, Iw and the rotational speed of the motor 20 (step S109). That is, the processor 501 decides the pre-switching target current and the pre-switching correction component, and decides the post-switching gain.

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

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

[0114] In a case where the feedback gain has converged (Yes in the step S112), the processor 501 acquires the detection values output from the current sensors 33u, 33v, 33w and the detection value output from the position sensor 26 (step S113). The processor 501 calculates the rotational speed of the motor 20 based on the detection value 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 respective control parameters based on the acquired current values of the winding currents Iu, Iv, 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 the control voltage value based on the determined parameter values (step S116). The processor 501 determines the duty ratio based on the control voltage value and outputs a PWM signal of the determined duty ratio (step S117). The switches 31u, 32u, 31v, 32v, 31w, 32w are driven in accordance with the PWM signal, and the winding currents Iu, Iv, Iw are supplied to the motor 20. After step S117, the processor 501 returns to step S101.

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

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

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

[0121] The zero-crossing detection circuits 102u, 102v, 102w detect the zero-crossing points of the measured values of the current sensors 131u, 131v, 131w. The structure of the zero-crossing detection circuits 102u, 102v, 102w is the same as that of the first embodiment, and thus the description is omitted.

[0122] The switching circuit 140u, 140v, 140w switches the connection state of the winding 24u, 25u, 24v, 25v, 24w, 25w between the full connection state and the partial connection state at the timing when the zero-crossing detection circuit 102u, 102v, 102w detects the zero-crossing point. The switching circuit 140u, 140v, 140w is an example of a switching section. The full connection state is an example of the first connection state, and the partial connection state is an example of the second connection 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 the power line 241u extends from the middle point of the winding 24u and the winding 25u. The power line 241u branches into the power lines 242u and 243w. The power line 251u extends from the other end of the winding 25u. The power line 251u branches into the power lines 252u and 253w.

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

[0125] The power line 35w is connected to one end of the winding 24w. The other end of the winding 24w and one end of the winding 25w are connected to each other, and the power line 241w extends from the middle point of the winding 24w and the winding 25w. The power line 241w branches into the power lines 242w and 243v. The power line 251w extends from the other end of the winding 25w. The power line 251w branches into the 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, 142w are, for example, IGBTs or power MOSFETs.

[0127] In the switching circuit 140u, the first terminal of the semiconductor relay 141u is connected to the power line 242u, and the second terminal is connected to the power line 243u. The first terminal of the semiconductor relay 142u is connected to the power line 252u, and the second terminal is connected to the power line 253u. The connection relationship of the switching circuits 140v, 140w is the same as that of the switching circuit 140u, and thus the description is omitted.

[0128] When the semiconductor relays 141u, 141v, 141w are in the off state and the semiconductor relays 142u, 142v, 142w are in the on state, a full connection state in which all of the windings 24u, 25u, 24v, 25v, 24w, 25w are connected is established. When the semiconductor relays 141u, 141v, 141w are in the on state and the semiconductor relays 142u, 142v, 142w are in the off state, a partial connection state in which only the windings 24u, 24v, 24w are connected among the windings 24u, 25u, 24v, 25v, 24w, 25w is established.

[0129] The power line 35u is introduced into the inside of 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 in the power line 35u. The current sensor 131u is, for example, an ACCT that detects only the alternating current component of the current. A signal line extending from the current sensor 131u is connected to the zero-crossing detection circuit 102u. The same is true for the V-phase and the 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 non of the RS flip-flop 120 is connected to the gate of the semiconductor relay 142u. The same is true for the V-phase and the W-phase.

[0131] The other structures of the winding switching device 100A related to the second embodiment are the same as those of the winding switching device 100 related to the first embodiment, and therefore the same components are denoted by the same symbols, and the description thereof is omitted.

[0132] In the second embodiment, the control device 50 sets the value of the switching command signal to the low level in the case where the windings 24u, 25u, 24v, 25v, 24w, 25w of the motor 20 are set to the full connection state, and sets the value of the switching command signal to the high level in the case where the windings 24u, 25u, 24v, 25v, 24w, 25w are partially connected.

[0133] When the windings are in the full connection state, at the timing at which both the zero-crossing detection signal and the switching command signal become the high level, the output Q becomes the low level and the output Q non becomes the high level. Therefore, the semiconductor relay 141u changes from the on state to the off state, and the semiconductor relay 142u changes from the off state to the on state. The same is true for the V-phase and the W-phase. Thus, the connection state of the windings 24u, 25u, 24v, 25v, 24w, 25w is switched from the full connection state to the partial connection state.

[0134] When the winding is in the partial connection state, at the timing when the zero-crossing detection signal becomes high and the switching instruction signal becomes low, output Q becomes high and output Qnon becomes low. Therefore, the semiconductor relay 141u changes from the off state to the on state, and the semiconductor relay 142u changes from the on state to the off state. The same applies to the V phase and the W phase. Thus, the connection state of the windings 24u, 25u, 24v, 25v, 24w, 25w is switched from the partial connection state to the full connection state.

[0135] As described above, the connection state of the windings 21u, 22u, 21v, 22v, 21w, 22w can be switched between the full connection state and the partial connection state at the timing of the zero-crossing point of the winding currents lu, lv, lw.

[0136] The structure and operation of the power converter 30 and the control device 50 according to the second embodiment are the same as those of the power converter 30 and the control device 50 according to the first embodiment, and thus the description is omitted.

[0137] [3. Third Embodiment] Referring to Figure 6 The parameter value decision section 522 of the control device 50 according to the third embodiment switches the feedback gain from the switching gain to the post-switching gain at the first zero-crossing point of the winding currents lu, lv, lw. The parameter value decision section 522 switches the target current from the pre-switching target current to the post-switching target current at the second zero-crossing point of the winding currents lu, lv, lw, which is different from the first zero-crossing point. The parameter value decision section 522 switches the correction component from the pre-switching correction component to the post-switching correction component at the second zero-crossing point.

[0138] In a specific example, the parameter value decision section 522 acquires the detection values of the current sensors 33u, 33v, 33w, and detects the zero-crossing points of the winding currents lu, lv, lw based on the acquired detection values. The parameter value decision section 522 takes one of the zero-crossing points as the 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 decision section 522 takes one of the zero-crossing points after the first zero-crossing point as the 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] Further, the first zero-crossing point and the second zero-crossing point can be zero-crossing points in the same phase, or can be zero-crossing points in different phases from each other.

[0140] Figure 11 FIG. 6 is a diagram showing another example of switching of the parameter values of the control parameters. In Figure 11In this case, the vertical axis represents the winding current Iu, and the horizontal axis represents time. Further, the zero-crossing point of the winding current Iu of the U-phase is taken as the first zero-crossing point and the second zero-crossing point.

[0141] In Figure 11 In the example of FIG. 10, the connection state of the windings 21u, 22u, 21v, 22v, 21w, 22w is switched from the series connection state to the parallel connection state. In Figure 11 In the example of FIG. 10, at the zero-crossing point T21, the feedback gain is switched from the pre-switching gain (i.e., the feedback gain in the series connection state of the windings 21u, 22u, 21v, 22v, 21w, 22w) to the post-switching gain (i.e., the feedback gain in the parallel connection state of the windings 21u, 22u, 21v, 22v, 21w, 22w). With this switching of the parameter value, the control voltage value changes, and thus the amplitude of the winding current Iu increases. The zero-crossing point T21 is the first zero-crossing point. In Figure 11 In the example of FIG. 10, the feedback gain is not switched at the zero-crossing point T21. In this case, the waveform of the winding current Iu is represented by a single-dot chain line.

[0142] At the zero-crossing point T22 subsequent to the zero-crossing point T21, the target current is switched from the pre-switching target current (i.e., the target current in the series connection state of the windings 21u, 22u, 21v, 22v, 21w, 22w) to the post-switching target current (i.e., the target current in the parallel connection state of the windings 21u, 22u, 21v, 22v, 21w, 22w), and the correction component is switched from the pre-switching correction component (i.e., the correction component in the series connection state of the windings 21u, 22u, 21v, 22v, 21w, 22w) to the post-switching correction component (i.e., the correction component in the parallel connection state of the windings 21u, 22u, 21v, 22v, 21w, 22w). With this switching of the parameter values, the control voltage value changes, and thus the amplitude of the winding current Iu increases. The zero-crossing point T22 is the second zero-crossing point. In Figure 11 In the example of FIG. 10, the target current and the correction component are not switched at the zero-crossing point T22. In this case, the waveform of the winding current Iu is represented by a dashed line.

[0143] [4. Fourth Embodiment] Figure 12 FIG. 11 is a circuit diagram showing an example of the structure of the winding switching device according to the third embodiment. In the third embodiment, a signal indicating the switching timing of the connection state of the windings 21u, 22u, 21v, 22v, 21w, 22w (hereinafter also referred to as "switching timing signal") is input to the control device 50.

[0144] The signal output from the output Q of the RS flip-flop 120 is a signal indicating the switching timing of the connection state of the windings 21u, 22u (switching timing signal). As Figure 11The signal line extending from the control circuit 103u to the gate terminal of the semiconductor relay 111u is branched at an intermediate point, and the branched end is connected to the control device 50. Through this signal line, the switching timing signal of the U phase is input to the control device 50. Similarly, the signal line extending from the control circuit 103v to the gate terminal of the semiconductor relay 111v is branched at an intermediate point, and the branched end is connected to the control device 50. Through this signal line, the switching timing signal of the V phase is input to the control device 50. The signal line extending from the control circuit 103w to the gate terminal of the semiconductor relay 111w is branched at an intermediate point, and the branched end is connected to the control device 50. Through this signal line, the switching timing signal of the W phase is input to the control device 50. Specifically, the switching timing signal is input to the I / F 504 of the control device 50.

[0145] Figure 13 Fig. 9 is a functional block diagram showing an example of the functions of the control device according to the fourth embodiment.

[0146] The control device 50 executes each function of the input section 524 and the determination section 525 in addition to the functions of the switching instruction section 521, the parameter value decision section 522, and the voltage value decision section 523 by executing the motor control program 510 by the processor 501.

[0147] The input section 524 receives the switching timing signal output at the timing at which the winding switching device 100 performs zero-cross switching. That is, the input section 524 receives the switching timing signal output from each of the control circuits 103u, 103v, 103w to the gate terminal of each of the semiconductor relays 111u, 111v, 111w.

[0148] The determination section 525 determines the switching timing of the zero-cross switching that switches the connection state of the windings 21u, 22u, 21v, 22v, 21w, 22w from the series connection state to the parallel connection state, or from the parallel connection state to the series connection state at the zero-cross point of the winding currents lu, lv, lw. In a specific example, the determination section 525 determines the switching timing based on the input of the switching timing signal in the input section 524. For example, the determination section 525 can determine the switching timing in the U phase, the switching timing in the V phase, and the switching timing in the W phase, respectively.

[0149] The parameter value decision section 522 switches the feedback gain from the switching gain to the post-switching gain at the switching timing determined by the determination section 525.

[0150] For example, the parameter value deciding section 522 switches the target current from the pre-switching target current to the post-switching target current at a switching timing determined by the determining section 525 as the second timing. The parameter value deciding section 522 can switch the correction component from the pre-switching correction component to the post-switching correction component at the second timing. Specifically, the parameter value deciding section 522 determines the switching timing of the V-phase or the W-phase determined by the determining section 525 as the second timing in a case where the switching timing of the U-phase determined by the determining section 525 is determined as the first timing.

[0151] Figure 14 is the first half of a flowchart showing an example of the motor control processing performed by the control device according to the fourth embodiment. The latter half of the flowchart is the same as Figure 9B .

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

[0153] In the fourth embodiment, the 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 the switching timing has come (step S201). In a case where the switching timing has not come (NO in step S201), the processor 501 executes step S201 again.

[0155] In a case where the switching timing has come (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 come (step S202). The switching timing in step S202 is a switching timing in a phase different from the switching timing in step S201. In a case where the switching timing has not come (NO in step S202), the processor 501 executes step S202 again.

[0157] In a case where the switching timing has come (YES in step S202), the processor 501 executes steps S113 to S117. Steps S113 to S117 are the same as steps S113 to S117 in the first embodiment (see Figure 9B ).

[0158] [5. Fifth Embodiment] The determination section 525 of the control device 50 according to the fifth embodiment detects zero-crossing points of the winding currents lu, lv, lw, and estimates the switching timing on the basis of the detected zero-crossing points. For example, the determination section 525 can determine the waveforms of the winding currents lu, lv, lw from the time-series detection values of the current sensors 33u, 33v, 33w, and detect the zero-crossing points in each of the U-phase, V-phase, and W-phase.

[0159] In a specific example, the determination section 525 can estimate the next-coming zero-crossing point after the switching instruction signal is input to the winding switching device 100 as the switching timing. For example, the determination section 525 can estimate the switching timing in each of the U-phase, V-phase, and W-phase.

[0160] In the fifth embodiment, the input section 524 receives the detection values of the current sensors 33u, 33v, 33w from the winding switching device 100 instead of the switching timing signal. The determination section 525 detects the zero-crossing points of the winding currents lu, lv, lw on the basis of the detection values of the current sensors 33u, 33v, 33w input to the input section 524.

[0161] The other functions of the control device 50 according to the fifth embodiment are the same as those of the control device 50 according to the fourth embodiment, and thus the description is omitted. The other structure of the winding switching system according to the fifth embodiment is the same as that of the winding switching system 10 according to the first embodiment, and thus the description is omitted.

[0162] [6. Sixth Embodiment] Referring to Figure 6 The parameter value decision section 522 of the control device 50 according to the sixth embodiment switches the feedback gain from the pre-switching gain stage to the post-switching gain. In a specific example, the parameter value decision section 522 decides the feedback gain for switching (hereinafter also referred to as "switching gain") when the switching instruction section 521 outputs the switching instruction signal.

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

[0164] For example, the parameter value decision section 522 can decide the gain for switching to be the feedback gain for a predetermined period from when the switching instruction signal is output from the switching instruction section 521. The predetermined period is, for example, a period corresponding to a prescribed number of control cycles.

[0165] Thus, the feedback gain is gradually transitioned from the pre-switching gain to the post-switching gain. Therefore, generation of a surge voltage can be suppressed, and oscillation of current control can be suppressed.

[0166] [7. Seventh Embodiment] Referring to Figure 6 The parameter value decision section 522 of the control device 50 according to the seventh embodiment causes the feedback gain to gradually change from the pre-switching gain to the post-switching gain when the switching instruction signal is output from the switching instruction section 521. In a specific example, the parameter value decision section 522 causes the feedback gain to change from the pre-switching gain to the post-switching gain in a ramp-like manner as time passes.

[0167] The gradual change in the parameter value of the feedback gain is not limited to a ramp-like manner. For example, the parameter value can be changed in a curved manner.

[0168] Here, causing the parameter value to gradually change includes causing the parameter value to change in stages. That is, causing the parameter value to gradually change is not limited to causing the parameter value to change smoothly as time passes. For example, the parameter value can be changed in multiple stages or discretely.

[0169] In a specific example, the parameter value decision section 522 calculates both the pre-switching gain and the post-switching gain when the switching instruction signal is output from the switching instruction section 521. For example, the parameter value decision section 522 causes the parameter value of the feedback gain to gradually increase or decrease from the pre-switching gain to the post-switching gain as time passes.

[0170] Thus, the feedback gain is gradually transitioned from the pre-switching gain to the post-switching gain. Therefore, generation of a surge voltage can be suppressed, and oscillation of current control can be suppressed.

[0171] [8. Eighth Embodiment] Referring to Figure 6 The parameter value decision section 522 of the control device 50 according to the eighth embodiment causes the target current to gradually change from the pre-switching target current to the post-switching target current, and causes the correction component to gradually change from the pre-switching correction component to the post-switching correction component. In a specific example, the parameter value decision section 522 causes the target current to change from the pre-switching target current to the post-switching target current in a ramp-like manner as time passes. The parameter value decision section 522 causes the correction component to change from the pre-switching correction component to the post-switching correction component in a ramp-like manner as time passes.

[0172] Further, the parameter value determining section 522 can also cause the parameter value of either the target current or the correction component to gradually change from the parameter value before the switching to the parameter value after the switching.

[0173] The gradual change in the parameter value is not limited to a ramp shape. For example, the parameter value can also be caused to change in a curved shape.

[0174] In a specific example, the parameter value determining section 522 calculates both the target current before the switching and the target current after the switching when the target current is switched. For example, the parameter value determining section causes the parameter value of the target current to gradually increase from the target current before the switching to the target current after the switching over time. The same applies to the correction component.

[0175] Thereby, the target current is smoothly transitioned from the target current before the switching to the target current after the switching, and the correction component is smoothly transitioned from the correction component before the switching to the correction component after the switching. Therefore, the generation of a surge voltage can be suppressed, and oscillation of the current control can be suppressed.

[0176] [9. NINTH EMBODIMENT] Referring to Figure 6 The voltage value determining section 523 of the control device 50 according to the ninth embodiment switches the correction component used to determine the control voltage value from the correction component before the switching to the correction component after the switching for each phase in the case where the zero-crossing switching is performed. That is, the voltage value determining section 523 switches the correction component used to determine the control voltage value from the correction component before the switching to the correction component after the switching at a timing that differs according to each of the U phase, the V phase, and the W phase.

[0177] In a specific example, the parameter value determining section 522 calculates the correction component before the switching and the correction component after the switching in the dq coordinate system, respectively, when the switching instruction section 521 outputs the switching instruction signal. For example, the voltage value determining section 523 switches the correction component used to determine the control voltage value of the U phase from the correction component before the switching to the correction component after the switching at the zero-crossing point of the U phase. That is, the voltage value determining section 523 calculates the control voltage value of the U phase based on the correction component before the switching before the zero-crossing point of the U phase. The voltage value determining section 523 calculates the control voltage value of the U phase based on the correction component after the switching after the zero-crossing point of the U phase. Similarly, the voltage value determining section 523 switches the correction component used to determine the control voltage value of the V phase from the correction component before the switching to the correction component after the switching at the zero-crossing point of the V phase, and switches the correction component used to determine the control voltage value of the W phase from the correction component before the switching to the correction component after the switching at the zero-crossing point of the W phase.

[0178] Moreover, the correction component can be replaced, or on the basis of the correction component, the target current for determining the control voltage value can be switched from the pre-switching target current to the post-switching target current for each phase. Furthermore, as other examples, at least one of the correction component and the target current can be replaced, or on the basis of the correction component and the target current, the feedback gain for determining the control voltage value can be switched from the pre-switching gain to the post-switching gain for each phase.

[0179] Thus, the parameter value for determining the control voltage value can be switched for each phase.

[0180] [10. SUPPLEMENT] The embodiments disclosed herein are illustrative in all aspects and are not restrictive. The scope of the present invention is not shown by the above-described embodiments, but is shown by the claims, and includes all modifications within the meaning and range equivalent to the claims. Explanation of Symbols

[0181] 10 Winding switching system

[0182] 20 Motor

[0183] 21u, 22u, 21v, 22v, 21w, 22w Winding

[0184] 23 Neutral point

[0185] 25 Power line

[0186] 26 Position sensor

[0187] 30 Power converter

[0188] 31u, 32u, 31v, 32v, 31w, 32w Switch

[0189] 33u, 33v, 33w Current sensor

[0190] 35u, 35v, 35w Power line

[0191] 40 Battery

[0192] 50 Control device

[0193] 501 Processor

[0194] 502 Nonvolatile memory

[0195] 503 Volatile memory

[0196] 504 Interface (I / F)

[0197] 510 Motor control program

[0198] 521 switching instruction section

[0199] 522 parameter value determining section

[0200] 523 voltage value determining section

[0201] 524 input section

[0202] 525 determining section

[0203] 531 target torque

[0204] 532 torque current converting section

[0205] 533 current converting section

[0206] 534 addition operation point

[0207] 535 F / B control section

[0208] 536 electromotive force calculating section

[0209] 537 addition operation point

[0210] 538 voltage converting section

[0211] 539 PWM section

[0212] 100 winding switching device

[0213] 101u, 101v, 101w current sensor

[0214] 102u, 102v, 102w zero-crossing detection circuit

[0215] 103u, 103v, 103w control circuit

[0216] 104u, 104v, 104w switching circuit

[0217] 111u, 112u, 113u, 111v, 112v, 113v, 111w, 112w, 113w semiconductor relay

[0218] 212u, 221u, 222u, 212v, 221v, 222v, 212w, 221w, 222w power line

[0219] 131, 133 AND circuit

[0220] 132 NOT circuit

[0221] 120 latch circuit (RS flip-flop)

[0222] 121, 123 NOT circuit

[0223] 122, 124 NAND circuit

[0224] 20A electric motor

[0225] 24u, 25u, 24v, 25v, 24w, 25w winding

[0226] 100A winding switching device

[0227] 131u, 131v, 131w current sensor

[0228] 140u, 140v, 140w switching circuit

[0229] 141u, 142u, 141v, 142v, 141w, 142w semiconductor relay

[0230] 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, The control device comprises: a switching instruction unit for instructing a winding switching device for switching the connection states of the plurality of windings to perform zero-cross switching, wherein the zero-cross switching is 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 in the winding; 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 voltage value determination unit that determines voltages 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; The parameter value determination unit switches the first control parameter 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 when the zero-cross switching is performed, and switches the second control parameter 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.

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

3. The control device according to claim 1 or 2, wherein: The first timing is a first zero-crossing point, and the first zero-crossing point is a zero-crossing point of the AC current supplied to the AC motor. The second timing is a second zero-cross point, and the second zero-cross point is a zero-cross point of the alternating current different from the first zero-cross point.

4. The control device according to any one of claims 1 to 3, wherein: The control device further includes a determination unit that determines a switching timing after the winding switching device performs the zero-cross switching. The first timing is the switching timing determined by the determination unit.

5. The control device according to any one of claims 1 to 4, wherein: 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.

6. The control device according to any one of claims 1 to 5, wherein: 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.

7. The control device according to any one of claims 1 to 6, wherein: The AC motor is a multi-phase AC motor. The parameter value determination unit determines the second pre-switching parameter value and the second post-switching parameter value when the zero-cross switching is performed. The voltage value determination unit switches 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 a timing that differs for each phase.

8. The control device according to any one of claims 1 to 7, wherein: One of the first control parameter and the second control parameter is a feedback gain, When the zero-cross switching is performed, the parameter value determination unit switches 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-cross switching.

9. A winding switching system comprising: 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 for performing zero-cross switching, wherein the zero-cross switching is 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 in the winding; as well as control device, The control device comprises: a switching instruction unit for instructing 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; and a voltage value determination unit that determines voltages 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; The parameter value determination unit switches the first control parameter 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 when the zero-cross switching is performed, and switches the second control parameter 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.

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, The control method comprises the following steps: instructing a winding switching device that switches the connection states of the plurality of windings to perform zero-cross switching, wherein the zero-cross switching is 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 in the winding; 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; as well as determining voltages to be applied to the plurality of windings based on the determined values ​​of the first control parameter and the second control parameter; 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, 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.

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, The control program causes the computer to execute the following steps: instructing a winding switching device that switches the connection states of the plurality of windings to perform zero-cross switching, wherein the zero-cross switching is 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 in the winding; 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 voltages to be applied to the plurality of windings based on the determined values ​​of the first control parameter and the second control parameter; 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, 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.

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