Winding switching device and winding switching system

Abstract

A winding switching device for switching a connection state of a plurality of windings of a motor capable of switching the connection state of the plurality of windings between a first connection state and a second connection state, the winding switching device comprising: a detection unit that detects a zero crossing point of a measurement value of a current sensor, and detects a zero crossing point of the measurement value of the current sensor; the current sensor measures the current flowing through the winding; and a switching unit that switches a connection state of the plurality of windings between the first connection state and the second connection state at a timing when the detection unit detects the zero crossing point.

Description

Technical Field

[0001] The present disclosure relates to a winding switching device and a winding switching system. This application claims priority based on Japanese application No. 2022-109213 filed on July 6, 2022, and all the contents described in the above Japanese application are cited here. Background Art

[0002] For example, in the electric motors mounted in electric vehicles, there are electric motors that can switch between a low-speed and high-torque operating state and a high-speed and low-torque operating state by switching the connection of a plurality of windings. Patent document 1 discloses the following device: in order to prevent surge voltage, a period during which the AC motor current is below a specified value is determined, and the windings are switched during the determined period.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2020-072632 Summary of the invention

[0006] One embodiment of the present disclosure involves a winding switching device for switching the connection state of multiple windings of an electric motor, wherein the electric motor is capable of switching the connection state of the multiple windings between a first connection state and a second connection state, wherein the winding switching device comprises: a detection unit for detecting a zero-crossing point of a measurement value of a current sensor, wherein the current sensor measures the current flowing through the winding; and a switching unit for switching the connection state of the multiple windings between the first connection state and the second connection state when the detection unit detects the zero-crossing point. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 This is a diagram showing an example of the configuration of the winding switching system according to the first embodiment.

[0008] Figure 2 1 is a circuit diagram showing an example of the configuration of the winding switching device according to the first embodiment.

[0009] Figure 3 This is a circuit diagram showing an example of the configuration of a control circuit.

[0010] Figure 4 This is a timing chart showing an example of transition of the states of each signal of the winding switching device according to the first embodiment.

[0011] Figure 5 1 is a circuit diagram showing an example of the configuration of a winding switching device according to the second embodiment.

[0012] Figure 6 1 is a circuit diagram showing an example of the configuration of a winding switching device according to the third embodiment.

[0013] Figure 7 : is a circuit diagram showing an example of the configuration of a correction circuit.

[0014] Fig. 8A is a graph showing waveforms of a voltage signal from a current sensor and a voltage signal from a filter.

[0015] Figure 8B is a graph showing the waveform of the voltage signal from the subtraction circuit.

[0016] Fig. 9 This is a circuit diagram showing a modified example of the structure of the winding switching device according to the third embodiment.

[0017] Fig.10 1 is a circuit diagram showing an example of the configuration of a winding switching device according to a fourth embodiment. DETAILED DESCRIPTION

[0018] <Problems to be Solved by the Present Disclosure>

[0019] In the device disclosed in Patent Document 1, a processor such as a microcomputer, FPGA (Field-Programmable Gate Array), or ASIC (Application-Specific Integrated Circuit) is used to determine the period during which the motor current is below a specified value. However, the connection switching of the windings needs to be performed in a short time of several microseconds to sub-microseconds, which may not be possible in the program processing in the microcomputer. On the other hand, although FPGA or ASIC can perform high-speed processing, it is expensive.

[0020] <Effects of the Present Disclosure>

[0021] According to the present disclosure, generation of surge voltage can be suppressed with an inexpensive structure.

[0022] <Overview of Embodiments of the Present Disclosure>

[0023] Hereinafter, the outline of the embodiments of the present disclosure will be described.

[0024] (1) The winding switching device involved in this embodiment is used to switch the connection state of multiple windings of an electric motor, and the electric motor can switch the connection state of the multiple windings between a first connection state and a second connection state, wherein the winding switching device includes: a detection unit that detects the zero crossing point of the measurement value of a current sensor, and the current sensor measures the current flowing through the winding; and a switching unit that switches the connection state of the multiple windings between the first connection state and the second connection state when the detection unit detects the zero crossing point. As a result, there is no need to perform complex processing such as determining the period when the motor current is below a specified value. Therefore, the structure of the detection unit can be simplified, and the generation of surge voltage can be suppressed with an inexpensive structure.

[0025] (2) In the above (1), the motor may be a multi-phase AC motor, the detection unit detects the zero crossing point for each phase, and the switching unit switches the connection state of the plurality of windings between the first connection state and the second connection state for each phase. Thus, the connection state of the windings is switched at the zero crossing point for each phase, thereby suppressing the generation of surge voltages in each phase.

[0026] (3) In the above (1) or (2), the detection unit may compare the output voltage from the current sensor with a reference voltage corresponding to the output voltage of the current sensor when the current flowing through the winding is zero current, and detect the time point when the output voltage from the current sensor matches the reference voltage as a zero crossing point. Thus, the detection unit only needs to perform a simple process of comparing the output voltage from the current sensor with the reference voltage, which can simplify the structure of the detection unit.

[0027] (4) In the above (3), the detection unit may be a comparator. In this way, the detection unit can be formed by an inexpensive comparator.

[0028] (5) In any of the above (1) to (4), the detection unit may convert the DC power output from the battery into AC power, and the current sensor may be shared with the control of a power converter, and the power converter may supply the AC power to the motor. In this way, the number of current sensors in the entire system can be reduced, and a more inexpensive structure can be achieved.

[0029] (6) In the above (5), the current sensor may be disposed in the winding switching device. In this way, the current flowing through the winding can be measured by the winding switching device alone, and the zero-crossing point can be detected.

[0030] (7) In the above (6), the current sensor may be an AC current transformer. If only the zero-crossing point of the winding current is to be detected, an AC current transformer (ACCT) that can only measure the AC component of the current can be used. Therefore, the generation of surge voltage can be suppressed with a low-cost structure.

[0031] (8) In the above (5), a signal line extending from the current sensor may be connected to the detection unit and arranged in the power converter. Thus, the zero-crossing point of the winding current can be detected by the current sensor provided in the power converter.

[0032] (9) In the above (8), the winding switching device may further include a correction unit that removes a DC component from the output signal of the current sensor, and the detection unit may detect a zero-crossing point of the output signal of the current sensor from which the DC component has been removed by the correction unit. In this way, the DC component can be removed from the output signal of the current sensor and the zero-crossing point can be accurately detected.

[0033] (10) The winding switching system according to the present embodiment comprises: an electric motor capable of switching the connection state of a plurality of windings between a first connection state and a second connection state; a power converter for converting DC power output from a battery into AC power and supplying the AC power to the electric motor; and a winding switching device for switching the connection state of the plurality of windings, the winding switching device comprising: a detection unit for detecting a zero-crossing point of a measurement value of a current sensor, the current sensor measuring a current flowing through the winding; and a switching unit for switching the connection state of the plurality of windings between the first connection state and the second connection state at a timing when the detection unit detects the zero-crossing point. Thus, there is no need to perform a complicated process such as determining a period during which the motor current is below a specified value. Therefore, the structure of the detection unit can be simplified, and the generation of surge voltage can be suppressed with an inexpensive structure.

[0034] The present disclosure can be implemented not only as a winding switching device having the characteristic structure as described above and a winding switching system including the winding switching device, but also as a winding switching method that takes the characteristic processing in the winding switching device as a step, or as a computer program for enabling a computer to perform the characteristic processing, or as a semiconductor integrated circuit that implements part or all of the winding switching device.

[0035] <Details of Embodiments of the Present Disclosure>

[0036] Hereinafter, details of the embodiments of the present invention will be described with reference to the drawings. In addition, at least a part of the embodiments described below may be arbitrarily combined.

[0037] [1. First embodiment]

[0038] [1-1. Winding switching system]

[0039] Figure 1 This is a diagram showing an example of the configuration of the winding switching system according to the first embodiment.

[0040] The winding switching system 10 is mounted on a vehicle propelled by an electric motor such as an electric vehicle or a plug-in hybrid vehicle (hereinafter referred to as an “electric vehicle”). The winding switching system 10 includes a motor 20 , a power converter 30 , a battery 40 , a control device 50 , and a winding switching device 100 .

[0041] The electric motor 20 is a motor for driving the electric vehicle and generates a propulsion force. The electric motor 20 is driven by three-phase AC power. An example of the electric motor 20 is a permanent magnet synchronous motor.

[0042] The battery 40 is a battery for supplying electric power for driving the motor 20. The battery 40 is a secondary battery, such as a lithium ion battery.

[0043] Power converter 30 is an inverter that converts DC power supplied from battery 40 into three-phase AC power. Power converter 30 may also have a function of converting three-phase AC power output when motor 20 functions as a generator into DC power and charging battery 40.

[0044] The power converter 30 includes branches for the U phase, the V phase, and the W phase. The branch for the U phase includes switches 31u and 32u, the branch for the V phase includes switches 31v and 32v, and the branch for the W phase includes switches 31w and 32w. By switching the switches 31u, 32u, 31v, 32v, 31w, and 32w, the DC power is converted into three-phase AC power. The switches 31u, 32u, 31v, 32v, 31w, and 32w are, for example, IGBTs (Insulated Gate Bipolar Transistors) or power MOSFETs (Metal Oxide Semiconductor Field-Effect Transistors).

[0045] The power line 35u corresponding to U extends from the branch of the U phase, the power line 35v corresponding to V extends from the branch of the V phase, and the power line 35w corresponding to W extends from the branch of the W phase. In the power converter 30, a current sensor 33u is provided on the power line 35u, a current sensor 33v is provided on the power line 35v, and a current sensor 33w is provided on the power line 35w. The current sensor 33u detects the current value of the current Iu of the U phase. The current sensor 33v detects the current value of the current Iv of the V phase. The current sensor 33w detects the current value of the current Iw of the W phase. The current sensors 33u, 33v, and 33w include a DC component and an AC component, and can detect the current values ​​of the currents Iu, Iv, and Iw flowing in the power lines 35u, 35v, and 35w. The current sensors 33u, 33v, and 33w are, for example, DCCTs (direct current transformers) or shunt resistors.

[0046] 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 power lines 35u, 35v, and 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 the connection state of the plurality of windings of the motor 20. The structure of the winding switching device 100 will be described later. The three-phase AC currents Iu, Iv, and Iw output from the power converter 30 are supplied to the motor 20 via the winding switching device 100.

[0047] 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, and 32w, respectively, and the control device 50 controls the on / off timing of the switches 31u, 32u, 31v, 32v, 31w, and 32w. The signal line extends from the control device 50 to the winding switching device 100, and the control device 50 outputs a switching instruction signal for instructing the switching of the connection state of the winding to the winding switching device 100.

[0048] The control device 50 includes a processor, a memory, an input / output interface, and a communication interface (not shown). The processor is, for example, a CPU (Central Processing Unit). However, the processor is not limited to a CPU. The processor may be a GPU (Graphics Processing Unit). The processor may be, for example, an ASIC (Application Specific Integrated Circuit), or a programmable logic device such as a gate array or an FPGA (Field Programmable Gate Array).

[0049] [1-2. Structure of winding switching device]

[0050] Figure 2 2 is a circuit diagram showing an example of the structure of the winding switching device involved in the first embodiment. The motor 20 includes a plurality of windings 21u, 22u, 21v, 22v, 21w, and 22w. The windings 21u and 22u correspond to U, the windings 21v and 22v correspond to V, and the windings 21w and 22w correspond to W. However, the number of windings of each phase is not limited to two, and may be three or more. The windings 22u, 22v, and 22w are connected at a neutral point 23.

[0051] The winding switching device 100 switches the connection state of the windings 21u, 22u, 21v, 22v, 21w, 22w between a series connection state and a 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.

[0052] 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 the zero voltage, and detect the time point when 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 through the windings 21u, 22u, 21v, 22v, 21w, 22w is zero current, and is not limited to the zero voltage. The zero-crossing detection circuits 102u, 102v, 102w are an example of a detection unit.

[0053] The switching circuits 104u, 104v, and 104w switch the connection state of the windings 21u, 22u, 21v, 22v, 21w, and 22w between the series connection state and the parallel connection state when the zero-crossing detection circuits 102u, 102v, and 102w detect the zero-crossing point. The switching circuits 104u, 104v, and 104w are an example of a switching unit. The series connection state is an example of a first connection state, and the parallel connection state is an example of a second connection state.

[0054] Hereinafter, the U phase will be described representatively using the connection relationship among the winding switching device 100, the power line 35u, and the motor 20. The V phase is the same as the W phase, and thus the description thereof will be omitted.

[0055] 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.

[0056] The switching circuit 104u includes semiconductor relays 111u, 112u, and 113u. The semiconductor relays 111u, 112u, and 113u are, for example, IGBTs or power MOSFETs.

[0057] The power line 35u is introduced into the interior of the winding switching device 100. In the winding switching device 100, the power line 35u is branched at the middle point and connected to the first terminal of the semiconductor relay 111u. The second terminal of the semiconductor relay 111u is connected to the first terminal of the semiconductor relay 112u. The power line 221u extending from the winding 22u is connected to the connection point between the second terminal of the semiconductor relay 111u and the first terminal of the semiconductor relay 112u.

[0058] The second terminal of semiconductor relay 112u is connected to the first terminal of semiconductor relay 113u. A power line 212u extending from winding 21u is connected to the connection point between the second terminal of semiconductor relay 112u and the first terminal of semiconductor relay 113u. The second terminal of semiconductor relay 113u is connected to power line 222u extending from winding 22u.

[0059] 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.

[0060] The gate terminals of the semiconductor relays 111u, 112u, and 113u are respectively connected to signal lines extending from the control circuit 103u.

[0061] The power lines 212u, 221u, and 222u extend from the motor 20 and are introduced into the interior of the winding switching device 100. A current sensor 101u is installed on the power line 221u. However, the current sensor 101u may be installed on the power line 35u, 212u, or 222u instead of the power line 221u. The current sensor 101u detects the current of the U phase flowing through the power line 221u. The current sensor 101u is, for example, an ACCT that detects only the AC component of the current.

[0062] The signal line extending from the current sensor 101u is connected to the zero-crossing detection circuit 102u. The signal line that transmits the output signal of the zero-crossing detection circuit 102u (hereinafter referred to as the "zero-crossing detection signal") extends from the zero-crossing detection circuit 102u to the control circuit 103u. In addition, the signal line extending from the control device 50 is connected to the control circuit 103u.

[0063] The zero-crossing detection circuit 102u detects the zero-crossing point of the winding current flowing through the power line 221u based on the measured value of the current sensor 101u. The zero-crossing detection circuit 102u is a comparator. For example, the inverting input of the comparator is set to a zero reference voltage, and the output signal of the current sensor 101u is applied to the non-inverting input. Thus, at the time point (zero-crossing point) when the AC signal output from the current sensor 101u crosses the zero reference voltage, the output of the comparator changes from a low level (Low) to a high level (High).

[0064] Figure 3 1 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.

[0065] The latch circuit 120 is an RS flip-flop. The output terminal of the AND circuit 131 is connected to the input S (set) of the RS flip-flop 120. The output terminal of the AND circuit 133 is connected to the input R (reset) of the RS flip-flop 120. The RS flip-flop 120 includes two NOT circuits 121 and 123 and two NAND circuits (NAND circuits) 122 and 124. However, the RS flip-flop 120 may also be composed of two NOR circuits.

[0066] The output Q of the RS flip-flop 120 is connected to the gates of the semiconductor relays 111u and 113u. Connected to the gate of semiconductor relay 112u.

[0067] In addition, the latch circuit 120 may be formed of a D flip-flop instead of an RS flip-flop.

[0068] [1-3. Operation of the winding switching device]

[0069] Next, the operation of the winding switching device 100 will be described. In addition, the following description will be given of the switching operation of the connection state of the windings 21u and 22u of the U phase as a representative. The V phase and the W phase are the same, so the description is omitted.

[0070] Figure 4 This is a timing chart showing an example of transition of the state of each signal of the winding switching device 100 according to the first embodiment.

[0071] The current sensor 101u measures the winding current Iu flowing through 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 low level when the winding current Iu is not zero, and becomes high level when the winding current Iu becomes zero. Figure 4 In the embodiment, the zero-crossing detection signal is at a low level at normal times and at a high level at times T1, T2, T3, and T4.

[0072] The control device 50 sets the value of the switching command signal to a low level when the windings 21u, 22u, 21v, 22v, 21w, and 22w of the motor 20 are connected in series, and sets the value of the switching command signal to a high level when the windings 21u, 22u, 21v, 22v, 21w, and 22w are connected in parallel. Figure 4 In the example, the switching command signal is at a low level in the initial state, and changes to a high level at a certain time point between time T1 and time T2. The switching command signal changes to a low level again at a certain time point between time T3 and time T4.

[0073] The zero-crossing detection signal and the switching command 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 command signal are a combination 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 command signal are a combination of (high level, high level). That is, in S of the RS trigger 120, a low level is normally input, and a high level is input when the zero-crossing point of the winding current Iu is detected and a parallel connection instruction for the windings 21u, 22u, 21v, 22v, 21w, and 22w is provided. Figure 4 In the example, at time T2 and T3, the input signal of S is at a high level.

[0074] The inversion signal of the zero-crossing detection signal and the switching command signal (the output signal of the NOT circuit 132) is input to the AND circuit 133. The AND circuit 133 outputs a low level when the zero-crossing detection signal and the switching command signal are a combination of (low level, low level), (high level, low level) and (high level, high level). The AND circuit 133 outputs a high level when the zero-crossing detection signal and the switching command signal are a combination of (high level, low level). That is, in R of the RS trigger 120, a low level is normally input, and a high level is input when the zero-crossing point of the winding current Iu is detected and a series connection instruction for the windings 21u, 22u, 21v, 22v, 21w, and 22w is provided. Figure 4 In the example, at times T1 and T4, the input signal of R is at a high level.

[0075] RS flip-flop 120 holds Q, R when inputs S and R are low. The output value so far. When the input S and R of RS flip-flop 120 are low level and high level, Q, Output low level, high level, when input S, R is high level, low level, Q, Output high level, low level. In the RS flip-flop 120, the combination of input S and R being high level and high level is prohibited.

[0076] exist Figure 4 In the example, Q is low until time T2. is high level. Therefore, until time T2, semiconductor relays 111u and 113u are in the off state, and semiconductor relay 112u is in the on state. Therefore, windings 21u and 22u are connected in series.

[0077] When time T2 arrives, Q changes from low level to high level. The high level changes to the 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. Therefore, the connection state of the windings 21u and 22u is switched from the series connection state to the parallel connection state.

[0078] From time T2 to T4, Q is high level. is low level. Therefore, from time T2 to T4, the semiconductor relays 111u and 113u are maintained in the on state, and the semiconductor relay 112u is maintained in the off state. Therefore, the connection state of the windings 21u and 22u is maintained in the parallel connection state.

[0079] When time T4 arrives, Q changes from high level to low level. 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. Therefore, the connection state of the windings 21u and 22u is switched from the parallel connection state to the series connection state.

[0080] After time T4, Q is low level. is high level. Therefore, before time T2, the semiconductor relays 111u and 113u are maintained in the off state, and the semiconductor relay 112u is maintained in the on state. Therefore, the connection state of the windings 21u and 22u is maintained in the series connection state.

[0081] As described above, at the timing of the zero crossing of the winding currents Iu, Iv, and Iw, 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. Therefore, the generation of surge voltage is suppressed. Furthermore, there is no need for complicated processing such as determining the period during which the winding currents Iu, Iv, and Iw are below a specified value, and the winding switching device 100 can be constructed without using a processor such as a CPU, FPGA, or ASIC.

[0082] [2. Second Embodiment]

[0083] A winding switching device according to a second embodiment switches the connection state of a plurality of windings of a motor between a full connection state in which all of the plurality of windings are connected and a partial connection state in which a part of the plurality of windings are connected.

[0084] Figure 52 is a circuit diagram showing an example of the structure of the winding switching device involved in the second embodiment. The motor 20A includes a plurality of windings 24u, 25u, 24v, 25v, 24w, and 25w. The windings 24u and 25u correspond to U, the windings 24v and 25v correspond to V, and the windings 24w and 25w correspond to W. However, the number of windings of each phase is not limited to two, and may be three or more.

[0085] The winding switching device 100A switches the connection state of the windings 24u, 25u, 24v, 25v, 24w, 25w between a full connection state and a 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.

[0086] The zero-crossing detection circuits 102u, 102v, and 102w detect the zero-crossing points of the measured values ​​of the current sensors 131u, 131v, and 131w. The configurations of the zero-crossing detection circuits 102u, 102v, and 102w are the same as those of the first embodiment, and thus description thereof will be omitted.

[0087] The switching circuits 140u, 140v, and 140w switch the connection states of the windings 24u, 25u, 24v, 25v, 24w, and 25w between the full connection state and the partial connection state when the zero-crossing detection circuits 102u, 102v, and 102w detect the zero-crossing point. The switching circuits 140u, 140v, and 140w are examples of switching units. 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.

[0088] Power line 35u is connected to one end of winding 24u. The other end of winding 24u is connected to one end of winding 25u, and power line 241u extends from the middle point between winding 24u and winding 25u. Power line 241u branches into power lines 242u and 243w. Power line 251u extends from the other end of winding 25u. Power line 251u branches into power lines 252u and 253w.

[0089] The power line 35v is connected to one end of the winding 24v. The other end of the winding 24v is connected to one end of the winding 25v, and the power line 241v extends from the middle point between the winding 24v and the winding 25v. The power line 241v branches into power lines 242v and 243u. The power line 251v extends from the other end of the winding 25v. The power line 251v branches into power lines 252v and 253u.

[0090] Power line 35w is connected to one end of winding 24w. The other end of winding 24w is connected to one end of winding 25w, and power line 241w extends from the middle point between winding 24w and winding 25w. Power line 241w branches into power lines 242w and 243v. Power line 251w extends from the other end of winding 25w. Power line 251w branches into power lines 252w and 253v.

[0091] 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.

[0092] 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 and 140w is the same as that of the switching circuit 140u, so the description is omitted.

[0093] When the semiconductor relays 141u, 141v, 141w are in the off state and the semiconductor relays 142u, 142v, 142w are in the on state, the windings 24u, 25u, 24v, 25v, 24w, 25w are all connected in a fully connected state. When the semiconductor relays 141u, 141v, 141w are in the on state and the semiconductor relays 142u, 142v, 142w are in the off state, only the windings 24u, 24v, 24w among the windings 24u, 25u, 24v, 25v, 24w, 25w are connected in a partially connected state.

[0094] The power line 35u is introduced into the interior of the winding switching device 100. A current sensor 131u is installed on the power line 35u. The current sensor 131u detects the current of the U phase flowing through the power line 35u. The current sensor 131u is, for example, an ACCT that detects only the AC component of the current. The 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.

[0095] The output Q of the RS flip-flop 120 of the control circuit 103u is connected to the gate of the semiconductor relay 141u. It is connected to the gate of semiconductor relay 142u. The same applies to the V phase and the W phase.

[0096] The other structures of the winding switching device 100A according to the second embodiment are the same as those of the winding switching device 100 according to the first embodiment, and therefore the same components are denoted by the same reference numerals and their description is omitted.

[0097] In the second embodiment, the control device 50 sets the value of the switching command signal to a low level when the windings 24u, 25u, 24v, 25v, 24w, and 25w of the motor 20 are set to a fully connected state, and sets the value of the switching command signal to a high level when the windings 24u, 25u, 24v, 25v, 24w, and 25w are partially connected.

[0098] When the winding is in full connection state, when the zero-crossing detection signal and the switching command signal both become high level, the output Q becomes low level, and the output =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. Therefore, the connection state of the windings 24u, 25u, 24v, 25v, 24w, and 25w is switched from the fully connected state to the partially connected state.

[0099] When the winding is partially connected, when the zero-crossing detection signal becomes high and the switching command signal becomes low, the output Q becomes high and the output becomes a low level. 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 is true for the V phase and the W phase. Therefore, the connection state of the windings 24u, 25u, 24v, 25v, 24w, and 25w is switched from the partially connected state to the fully connected state.

[0100] As described above, at the timing of the zero-crossing points of the winding currents Iu, Iv, Iw, 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.

[0101] [3. Third embodiment]

[0102] Figure 6 1 is a circuit diagram showing an example of the structure of the winding switching device involved in the third embodiment. In the winding switching device 100B involved in the third embodiment, the signal lines 331u, 331v, 331w extending from the current sensors 33u, 33v, 33w arranged in the power converter 30 are connected to the zero crossing detection circuits 102u, 102v, 102w.

[0103] In a more specific example, the winding switching device 100B includes correction circuits 150u, 150v, 150w for removing DC components from output signals of the current sensors 33u, 33v, 33w. The correction circuits 150u, 150v, 150w are examples of correction units.

[0104] Hereinafter, regarding the U phase, the configuration of the correction circuit 150u will be described as a representative example. Since the V phase and the W phase are the same, the description thereof will be omitted.

[0105] The signal line 331u extending from the power converter 30 is introduced into the interior of the winding switching device 100B. That is, the signal line 331u extending from the current sensor 33u is directly introduced into the winding switching device 100B without passing through a signal processing circuit or the like. In the winding switching device 100B, the signal line 331u branches, and one signal line is connected to the first input terminal of the subtraction circuit 152u. The other signal line is connected to the input terminal of the filter 151u. The signal line extends from the output terminal of the filter 151u, and the signal line is connected to the second input terminal of the subtraction circuit 152u. The signal line extends from the output terminal of the subtraction circuit 152u, and the signal line is connected to the zero-crossing detection circuit 102u.

[0106] Figure 7 1 is a circuit diagram showing an example of the structure of the correction circuit. The filter 151u is a low-pass filter including a resistor and a capacitor. The filter 151u removes the frequency component above the threshold value which is lower than the frequency of the winding current Iu, Iv, Iw at the time when the connection state of the winding of the motor 20 is switched from the voltage signal Vin output by the current sensor 33u. The filter 151u outputs a voltage Vfilt obtained by removing the above-mentioned frequency component from the input voltage Vin.

[0107] The subtraction circuit 152u receives inputs of a voltage signal Vin from the current sensor 33u and a voltage signal Vfilt from the filter 151u, and outputs a differential voltage Vout between Vin and Vfilt.

[0108] Fig. 8A is a graph showing the waveforms of the voltage signal Vin from the current sensor 33u and the voltage signal Vfilt from the filter 151u. Fig. 8A In the figure, the vertical axis represents voltage and the horizontal axis represents time. The voltage signal Vin output from the current sensor 33u includes an AC component and a DC component corresponding to U. Therefore, the voltage signal Vin represents a waveform obtained by offsetting the AC current of the same frequency as the AC current corresponding to the U phase by the DC component. Fig. 8A In the example shown in Figure 1, the AC waveform is offset by a 0.2V DC component.

[0109] The filter 151u removes the AC component from the voltage signal Vin. Therefore, the voltage signal output from the filter 151u is the DC component mentioned above. Fig. 8A In the example, Vfilt is a DC voltage of 0.2V.

[0110] Figure 8B 3 is a graph showing the waveform of the voltage signal from the subtraction circuit 152u. The subtraction circuit 152u subtracts Vfilt from the voltage signal Vin output by the current sensor 33u. Therefore, the voltage signal Vout output from the subtraction circuit 152u is a signal obtained by correcting the offset from Vin to 0, that is, an AC voltage signal that does not contain a DC component.

[0111] With the above configuration, the zero-crossing detection circuit 102u can detect the zero-crossing point in the U-phase winding current Iu without being affected by the DC component included in the output voltage of the current sensor 33u.

[0112] In addition, the structure of the correction circuit 150u is not limited to the above structure. Fig. 9 : is a circuit diagram showing a modified example of the structure of the winding switching device involved in the third embodiment. Fig. 9 In the modified example shown, the correction circuit is a filter 153u, 153v, 153w. The filter 153u, 153v, 153w is a high-pass filter having a characteristic of passing only frequency components above a threshold value lower than the frequency of the winding current Iu, Iv, Iw at the time when the connection state of the winding of the motor 20 is switched. With such a structure, the DC component can also be removed from the output signal of the current sensor 33u, 33v, 33w.

[0113] [4. Fourth embodiment]

[0114] Fig.10 1 is a circuit diagram showing an example of the configuration of a winding switching device according to the fourth embodiment. A winding switching device 100C according to the fourth embodiment includes current sensors 101U, 101V, and 101W.

[0115] The current sensor 101U is installed, for example, on the power line 35u introduced into the winding switching device 100C. However, the current sensor 101U may be installed on the power line 211u, 212u or 222u instead of the power line 35u. The current sensor 101U detects the current of the U phase flowing through the power line 35u. The current sensors 101V and 101W are also installed on the power lines 35v and 35w in the same manner. The current sensors 101U, 101V, and 101W include a DC component and an AC component, and can detect the current value of the current flowing in the power lines 35u, 35v, and 35w. The current sensor 101U is, for example, a DCCT (direct current transformer) or a shunt resistor.

[0116] Signal lines 331U, 331V, 331W extending from the current sensors 101U, 101V, 101W are connected to the zero-crossing detection circuits 102u, 102v, 102w.

[0117] In a more specific example, the winding switching device 100C includes correction circuits 150u, 150v, 150w for removing DC components from output signals of the current sensors 101U, 101V, 101W. The correction circuits 150u, 150v, 150w are the same as the correction circuits 150u, 150v, 150w described in the second embodiment.

[0118] Signal lines 331U, 331V, and 331W are respectively branched in the middle, and the branch destinations are connected to control device 50. Output signals of current sensors 101U, 101V, and 101W are input to control device 50. In the present embodiment, current sensors 33u, 33v, and 33w provided in power converter 30 are omitted.

[0119] The control device 50 performs feedback control of the motor 20 based on the current values ​​detected by the current sensors 101U, 101V, and 101W. That is, the control device 50 determines the voltage values ​​applied to the windings 21u, 22u, 21v, 22v, 21w, and 22w based on the current values ​​of the currents of the U phase, the V phase, and the W phase input to the motor 20, and turns the switches 31u, 32u, 31v, 32v, 31w, and 32w on and off through PWM control according to the determined voltage values. That is, in the present embodiment, the current sensors 101U, 101V, and 101W are commonly used for controlling the power converter 30. As a result, the number of current sensors in the entire winding switching system can be reduced.

[0120] [4. Notes]

[0121] The embodiments disclosed this time are illustrative in all aspects and are not restrictive. The scope of rights of the present invention is indicated by the claims rather than the above-described embodiments, and includes all modifications within the meaning and scope equivalent to the claims.

[0122] Description of symbols

[0123] 10 Winding switching system

[0124] 20 Electric Motor

[0125] 21u, 22u, 21v, 22v, 21w, 22w winding

[0126] 23 Neutral point

[0127] 25 Power Lines

[0128] 30 Power Converter

[0129] 31u, 32u, 31v, 32v, 31w, 32w switch

[0130] 33u, 33v, 33w current sensor

[0131] 35u, 35v, 35w power line

[0132] 40 Batteries

[0133] 50 Control device

[0134] 100 Winding switching device

[0135] 101u, 101v, 101w current sensors

[0136] 102u, 102v, 102w zero-crossing detection circuit (detection unit)

[0137] 103u, 103v, 103w control circuit

[0138] 104u, 104v, 104w switching circuit (switching part)

[0139] 111u, 112u, 113u, 111v, 112v, 113v, 111w, 112w, 113w semiconductor relays

[0140] 212u, 221u, 222u, 212v, 221v, 222v, 212w, 221w, 222w power lines

[0141] 131, 133 “AND” circuit

[0142] 132 NOT Circuit

[0143] 120 Latch Circuit (RS Flip-Flop)

[0144] 121, 123 “NOT” circuit

[0145] 122, 124 "NAND" circuit

[0146] 20A Motor

[0147] 24u, 25u, 24v, 25v, 24w, 25w winding

[0148] 100A Winding Switching Device

[0149] 131u, 131v, 131w current sensors

[0150] 140u, 140v, 140w switching circuit

[0151] 141u, 142u, 141v, 142v, 141w, 142w semiconductor relays

[0152] 241u, 242u, 243u, 251u, 252u, 253u, 241v, 242v, 243v, 251v, 252v, 253v, 241w, 242w, 243w, 251w, 252w, 253w power line

[0153] 100B Winding Switching Device

[0154] 150u, 150v, 150w correction circuit

[0155] 151u, 151v, 151w filters

[0156] 152u, 152v, 152w subtraction circuit

[0157] 153u, 153v, 153w filters

[0158] 331u, 331v, 331w signal cable

[0159] 100C Winding Switching Device

[0160] 101U, 101V, 101W Current Sensors

[0161] 331U, 331V, 331W signal cables

[0162] T1, T2, T3, T4 times

Claims

1. A winding switching device for switching the connection state of a plurality of windings of a motor, wherein the motor is capable of switching the connection state of the plurality of windings between a first connection state and a second connection state, wherein: The winding switching device comprises: a detection unit that detects a zero-crossing point of a measurement value of a current sensor that measures a current flowing through the winding; and The switching unit switches the connection state of the plurality of windings between the first connection state and the second connection state at a timing when the detection unit detects the zero-crossing point.

2. The winding switching device according to claim 1, wherein: The electric motor is a multi-phase AC motor, The detection unit detects the zero-crossing point for each phase, The switching unit switches the connection state of the plurality of windings between the first connection state and the second connection state for each phase.

3. The winding switching device according to claim 1 or 2, wherein: The detection unit compares the output voltage from the current sensor with a reference voltage corresponding to the output voltage of the current sensor when the current flowing through the winding is zero current, and detects a time point when the output voltage from the current sensor matches the reference voltage as a zero-crossing point.

4. The winding switching device according to claim 3, wherein: The detection unit is a comparator.

5. The winding switching device according to any one of claims 1 to 4, wherein: The detection unit converts DC power output from a battery into AC power, and shares the current sensor with control of a power converter that supplies the AC power to the motor.

6. The winding switching device according to claim 5, wherein: The current sensor is configured in the winding switching device.

7. The winding switching device according to claim 6, wherein: The current sensor is an AC current transformer.

8. The winding switching device according to claim 5, wherein: The current sensor is disposed in the power converter. A signal line extending from the current sensor is connected to the detection unit.

9. The winding switching device according to claim 8, wherein: The winding switching device further includes a correction unit that removes a DC component from an output signal of the current sensor. The detection unit detects a zero-crossing point of an output signal of the current sensor from which the DC component has been removed by the correction unit.

10. A winding switching system comprising: An electric motor capable of switching a connection state of a plurality of windings between a first connection state and a second connection state; a power converter that converts direct current power output from the battery into alternating current power and supplies the alternating current power to the electric motor; as well as A winding switching device, used for switching the connection state of the plurality of windings, The winding switching device comprises: a detection unit that detects a zero-crossing point of a measurement value of a current sensor that measures a current flowing through the winding; as well as The switching unit switches the connection state of the plurality of windings between the first connection state and the second connection state at a timing when the detection unit detects the zero-crossing point.

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