Battery charging circuit and method

Abstract

The present invention discloses a battery charging circuit and method, belonging to the field of charging control technology. The midpoint of each phase bridge arm in the three-phase bridge arm circuit of the present invention is connected to the coil of the corresponding motor, the first end of the electric control switch circuit is connected to the positive pole of the external charging device, the second end of the electric control switch circuit is connected to the positive pole of the three-phase bridge arm circuit, the third end of the electric control switch circuit is connected to the midpoint of the corresponding bridge arm in the three-phase bridge arm circuit, and the fourth end of the electric control switch circuit is respectively connected to the negative pole of the vehicle battery and the negative pole of the three-phase bridge arm circuit. The control unit controls the conduction and shutdown of the electric control switch circuit and the three-phase bridge arm circuit in sequence according to the rotor angle of the motor. The present invention controls the corresponding conduction of the appropriate electric control switch circuit and the three-phase bridge arm circuit according to the rotor angle of the motor, reduces the cost of the boosting equipment and the jitter at the beginning and end of charging, uses the motor coil to realize the boosting function, reduces the cost of the boosting equipment, and improves the user's experience when charging.

Description

Technical Field

[0001] The present invention relates to the technical field of charging control, and in particular to a battery charging circuit and method. Background Art

[0002] As the country pays more and more attention to environmental protection and energy issues, the development of new energy electric vehicles is gradually accelerating. Customers have higher and higher requirements for the voltage range and charging speed of battery charging during use. At present, the voltage levels of existing charging piles on the market are basically 500V and 700V. In order to meet the needs of fast charging, the battery voltage needs to be increased to above 800V. Therefore, some charging piles cannot meet the charging voltage level requirements of the whole vehicle, and additional high-voltage direct current conversion (DC / DC) functional equipment is required, which increases the vehicle charging cost and reduces the user experience.

[0003] The above contents are only used to assist in understanding the technical solution of the present invention and do not constitute an admission that the above contents are prior art. Summary of the invention

[0004] The main purpose of the present invention is to provide a battery charging circuit and method, aiming to solve the technical problem that the existing charging scheme requires additional high-voltage DC conversion function equipment, which increases the vehicle charging cost.

[0005] To achieve the above object, the present invention provides a battery charging circuit, which includes: a three-phase bridge arm circuit, an electric control switch circuit, a motor and a control unit, wherein:

[0006] The positive pole of the three-phase bridge arm circuit is connected to the positive pole of the vehicle battery, the negative pole of the three-phase bridge arm circuit is connected to the negative pole of the vehicle battery, and the midpoint of each phase bridge arm in the three-phase bridge arm circuit is connected to the corresponding coil of the motor;

[0007] The first end of the electronically controlled switch circuit is connected to the positive electrode of the external charging device, the second end of the electronically controlled switch circuit is connected to the positive electrode of the three-phase bridge arm circuit, the third end of the electronically controlled switch circuit is connected to the midpoint of the corresponding bridge arm in the three-phase bridge arm circuit, and the fourth end of the electronically controlled switch circuit is respectively connected to the negative electrode of the vehicle battery and the negative electrode of the three-phase bridge arm circuit;

[0008] When receiving a charging instruction, the control unit controls the on and off of the electric control switch circuit according to the rotor angle of the motor;

[0009] The control unit controls the on and off of the three-phase bridge arm circuit according to the on and off of the electronically controlled switch circuit.

[0010] Optionally, the electronically controlled switch circuit includes a plurality of control switches, a first end of the plurality of control switches is connected to the three-phase bridge arm circuit, and a second end of the plurality of control switches is connected to the external charging device.

[0011] Optionally, the three-phase bridge arm circuit includes a first phase bridge arm, a second phase bridge arm and a third phase bridge arm connected in parallel, and the electronically controlled switch circuit includes a first control switch and a second control switch, wherein the first end of the first control switch is connected to the positive pole of the external charging device, and the second end of the first control switch is respectively connected to the positive pole of the first phase bridge arm, the positive pole of the second phase bridge arm and the positive pole of the third phase bridge arm; the first end of the second control switch is connected to the midpoint of the first phase bridge arm, and the second end of the second control switch is connected to the negative pole of the external charging device.

[0012] Optionally, the electronically controlled switch circuit also includes a third control switch and a fourth control switch, wherein the first end of the third control switch is connected to the positive pole of the external charging device, the second end of the third control switch is connected to the midpoint of the first phase bridge arm, the first end of the fourth control switch is respectively connected to the negative pole of the vehicle battery and the negative pole of the three-phase bridge arm circuit, and the second end of the fourth control switch is connected to the negative pole of the external charging device.

[0013] Optionally, the first control switch, the second control switch, the third control switch and the fourth control switch are relays.

[0014] In addition, to achieve the above object, the present invention also proposes a battery charging method, which is applied to the battery charging circuit as described above, and the battery charging circuit includes: a three-phase bridge arm circuit, an electric control switch circuit, a motor and a control unit;

[0015] The battery charging method comprises:

[0016] When receiving a charging instruction, the control unit controls the on and off of the electric control switch circuit according to the current rotor angle of the motor;

[0017] The control unit controls the conduction of one phase bridge arm in the three-phase bridge arm circuit according to the conduction position of the electronically controlled switch circuit;

[0018] The coil of the motor boosts the voltage input by the external charging device;

[0019] The control unit controls the conduction of two-phase or one-phase bridge arms in the three-phase bridge arm circuit, and the coil of the motor transmits the boosted voltage to the vehicle battery through the three-phase bridge arm circuit.

[0020] Optionally, the control unit stores a first phase, a second phase, and a third phase for determining a rotor angle position interval, and when receiving a charging instruction, the control unit controls the on and off of the electronically controlled switch circuit according to the rotor angle of the current motor, including:

[0021] When receiving a charging instruction, the control unit aligns the zero position of the rotor with the first phase, the second phase, or the third phase;

[0022] It is determined whether the rotor angle of the current motor falls within a position interval between the first phase, the second phase and the third phase, and the on and off of the electronically controlled switch circuit is controlled according to the position interval.

[0023] Optionally, the control unit controls the conduction of one phase bridge arm in the three-phase bridge arm circuit according to the conduction position of the electronically controlled switch circuit, comprising:

[0024] The control unit controls the on and off of one phase bridge arm of the three-phase bridge arm circuit according to the on position of the electronically controlled switch circuit during the voltage boost process.

[0025] Optionally, the three-phase bridge arm circuit includes a first phase bridge arm, a second phase bridge arm and a third phase bridge arm connected in parallel, and the electronically controlled switch circuit includes a first control switch and a second control switch, wherein the first end of the first control switch is connected to the positive electrode of the external charging device, and the second end of the first control switch is respectively connected to the positive electrode of the first phase bridge arm, the positive electrode of the second phase bridge arm and the positive electrode of the third phase bridge arm; the first end of the second control switch is connected to the midpoint of the first phase bridge arm, and the second end of the second control switch is connected to the negative electrode of the external charging device;

[0026] When receiving the charging instruction, the control unit controls the on and off of the electric control switch circuit according to the current rotor angle of the motor, including:

[0027] When receiving the charging instruction, the control unit controls the first control switch and the second control switch to be turned on according to the current rotor angle of the motor;

[0028] The control unit controls the conduction of the corresponding bridge arm in the three-phase bridge arm circuit according to the conduction position of the electronically controlled switch circuit, including:

[0029] The control unit controls the upper bridge of the second phase bridge arm to be turned on and the lower bridge of the second phase bridge arm to be turned off according to the conduction position of the electronically controlled switch circuit;

[0030] The control unit changes the conduction position of the three-phase bridge arm circuit, including:

[0031] The control unit controls the upper bridge of the second phase bridge arm to be turned on and the lower bridge of the second phase bridge arm to be turned off, and controls the upper bridge of the first phase bridge arm to be turned off and the lower bridge of the first phase bridge arm to be turned on.

[0032] Optionally, the three-phase bridge arm circuit includes a first phase bridge arm, a second phase bridge arm and a third phase bridge arm connected in parallel, and the electronically controlled switch circuit includes a first control switch and a second control switch, wherein the first end of the first control switch is connected to the positive electrode of the external charging device, and the second end of the first control switch is respectively connected to the positive electrode of the first phase bridge arm, the positive electrode of the second phase bridge arm and the positive electrode of the third phase bridge arm; the first end of the second control switch is connected to the midpoint of the first phase bridge arm, and the second end of the second control switch is connected to the negative electrode of the external charging device;

[0033] When receiving the charging instruction, the control unit controls the on and off of the electric control switch circuit according to the current rotor angle of the motor, including:

[0034] When receiving the charging instruction, the control unit controls the first control switch and the second control switch to be turned on according to the current rotor angle of the motor;

[0035] The control unit controls the conduction of the corresponding bridge arm in the three-phase bridge arm circuit according to the conduction position of the electronically controlled switch circuit, including:

[0036] The control unit controls the upper bridge of the third phase bridge arm to be turned on and the lower bridge of the third phase bridge arm to be turned off according to the conduction position of the electronically controlled switch circuit;

[0037] The control unit changes the conduction position of the three-phase bridge arm circuit, including:

[0038] The control unit controls the upper bridge of the third phase bridge arm to be turned on and the lower bridge of the third phase bridge arm to be turned off, and controls the upper bridge of the first phase bridge arm to be turned off and the lower bridge of the first phase bridge arm to be turned on.

[0039] Optionally, the three-phase bridge arm circuit includes a first-phase bridge arm, a second-phase bridge arm and a third-phase bridge arm connected in parallel with each other, and the electronically controlled switch circuit also includes a third control switch and a fourth control switch, wherein a first end of the third control switch is connected to the positive electrode of the external charging device, a second end of the third control switch is connected to the midpoint of the first-phase bridge arm, a first end of the fourth control switch is respectively connected to the negative electrode of the vehicle battery and the negative electrode of the three-phase bridge arm circuit, and a second end of the fourth control switch is connected to the negative electrode of the external charging device;

[0040] When receiving the charging instruction, the control unit controls the on and off of the electric control switch circuit according to the current rotor angle of the motor, including:

[0041] When receiving the charging instruction, the control unit controls the third control switch and the fourth control switch to be turned on according to the current rotor angle of the motor;

[0042] The control unit controls the conduction of the corresponding bridge arm in the three-phase bridge arm circuit according to the conduction position of the electronically controlled switch circuit, including:

[0043] The control unit controls the lower bridge of the second phase bridge arm to be turned on and the upper bridge of the second phase bridge arm to be turned off according to the conduction position of the electronically controlled switch circuit;

[0044] The control unit changes the conduction position of the three-phase bridge arm circuit, including:

[0045] The control unit controls the lower bridge of the second phase bridge arm to be turned off and the upper bridge of the second phase bridge arm to be turned on.

[0046] The battery charging circuit of the present invention comprises: a three-phase bridge arm circuit, an electric control switch circuit, a motor and a control unit, wherein the positive pole of the three-phase bridge arm circuit is connected to the positive pole of the vehicle battery, the negative pole of the three-phase bridge arm circuit is connected to the negative pole of the vehicle battery, the midpoint of each phase bridge arm in the three-phase bridge arm circuit is connected to the coil of the corresponding motor, the first end of the electric control switch circuit is connected to the positive pole of the external charging device, the second end of the electric control switch circuit is connected to the positive pole of the three-phase bridge arm circuit, the third end of the electric control switch circuit is connected to the midpoint of the corresponding bridge arm in the three-phase bridge arm circuit, and the electric control switch circuit is connected to the positive pole of the three-phase bridge arm circuit. The fourth end is respectively connected to the negative electrode of the vehicle battery and the negative electrode of the three-phase bridge arm circuit. When receiving the charging instruction, the control unit controls the on and off of the electronically controlled switch circuit according to the rotor angle of the motor. The control unit controls the on and off of the three-phase bridge arm circuit according to the on and off of the electronically controlled switch circuit. The present invention reduces the cost of the boosting equipment and the jitter at the beginning and end of charging by controlling the appropriate electronically controlled switch circuit and the corresponding conduction of the three-phase bridge arm circuit according to the rotor angle of the motor, and uses the motor coil to realize the boosting function, thereby reducing the cost of the boosting equipment and improving the user's charging experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 It is a structural schematic diagram of a first embodiment of a battery charging circuit of the present invention;

[0048] Figure 2 A schematic diagram of the motor rotor angle of an embodiment of a battery charging circuit of the present invention;

[0049] Figure 3 A schematic diagram of a flow chart of a first embodiment of a battery charging method of the present invention;

[0050] Figure 4 A schematic diagram of the three-phase voltage vector relationship of the battery charging method of the present invention;

[0051] Figure 5 A schematic diagram of the vector relationship of the first angle interval of the battery charging method of the present invention;

[0052] Figure 6 A schematic diagram of a current path in a voltage boosting process in a first angle sub-interval of a battery charging method according to the present invention;

[0053] Figure 7 A schematic diagram of a current path of a charging process in a first angle sub-interval of a battery charging method according to the present invention;

[0054] Figure 8 A schematic diagram of the vector relationship of the second angle interval of the battery charging method of the present invention;

[0055] Fig. 9 A schematic diagram of a current path of a voltage boost process in a second angle sub-interval of a battery charging method according to the present invention;

[0056] Fig.10 A schematic diagram of a current path of a charging process in a second angle sub-interval of a battery charging method according to the present invention;

[0057] Fig.11 A schematic diagram of the vector relationship of the third angle interval of the battery charging method of the present invention;

[0058] Fig.12 A schematic diagram of a current path in a voltage boosting process in a third angle sub-interval of a battery charging method according to the present invention;

[0059] Fig.13 A schematic diagram of a current path of a charging process in a third angle sub-interval of a battery charging method according to the present invention;

[0060] Fig.14 A schematic diagram of the vector relationship of the fourth angle interval of the battery charging method of the present invention;

[0061] Fig.15 A schematic diagram of a current path of a voltage boost process in a fourth angle sub-interval of a battery charging method according to the present invention;

[0062] Fig.16 Schematic diagram of the current path of the charging process in the fourth angle sub-interval of the battery charging method of the present invention.

[0063] Description of Figure Numbers:

[0064] Label name Label name 10 Three-phase bridge arm circuit U First phase bridge arm 20 Electronically controlled switch circuit V Second phase bridge arm 30 Motor W The third phase bridge arm 40 Car battery VT1~VT6 The first to sixth switching tubes 50 External charging device VD1~VD6 The first to sixth diodes + positive electrode R1~R5 First to fifth control switches - negative electrode

[0065] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0066] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0067] Reference Figure 1 , Figure 1 It is a structural schematic diagram of a first embodiment of a battery charging circuit of the present invention.

[0068] The battery charging circuit comprises: a three-phase bridge arm circuit, an electric control switch circuit, a motor and a control unit, wherein:

[0069] The positive pole of the three-phase bridge arm circuit is connected to the positive pole of the vehicle battery, the negative pole of the three-phase bridge arm circuit is connected to the negative pole of the vehicle battery, and the midpoint of each phase bridge arm in the three-phase bridge arm circuit is connected to the corresponding coil of the motor;

[0070] The first end of the electronically controlled switch circuit is connected to the positive electrode of the external charging device, the second end of the electronically controlled switch circuit is connected to the positive electrode of the three-phase bridge arm circuit, the third end of the electronically controlled switch circuit is connected to the midpoint of the corresponding bridge arm in the three-phase bridge arm circuit, and the fourth end of the electronically controlled switch circuit is respectively connected to the negative electrode of the vehicle battery and the negative electrode of the three-phase bridge arm circuit;

[0071] When receiving a charging instruction, the control unit controls the on and off of the electronically controlled switch circuit according to the rotor angle of the motor.

[0072] It is understandable that the electronically controlled switch circuit receives the charging instruction, indicating that charging can be started. The electronically controlled switch circuit can obtain the rotor angle of the motor, such as Figure 2 , where S represents the south pole of the magnet, N represents the north pole of the magnet, and the coordinate axis is established with the zero point direction of the motor as the horizontal coordinate. The angle α between the horizontal coordinate direction and the direction of the south pole of the magnet represents the rotor angle of the motor. The rotor angle of the motor can be detected by using a resolver sensor.

[0073] It is easy to understand that by determining the position interval of the rotor angle, the on and off of the two control switches in the electronically controlled switch circuit can be determined according to the position interval, thereby further satisfying the charging start condition.

[0074] The control unit controls the on and off of the three-phase bridge arm circuit according to the on and off of the electronically controlled switch circuit.

[0075] It is easy to understand that the control unit controls the on and off of the two control switches in the electronically controlled switch circuit corresponding to the rotor angle according to the rotor angle, and further controls the on and off of the switches (switch tubes) of two-phase bridge arm circuits or one-phase bridge arm circuit in the three-phase bridge arm circuit according to the on and off of the two control switches in the electronically controlled switch circuit. The switches (switch tubes) of each phase bridge arm circuit can be fully turned on or partially turned on, or fully turned off or partially turned off.

[0076] It can be understood that when the control switch of the electronically controlled switching circuit and the switch (switch tube) corresponding to the two-phase bridge arm circuit or one-phase bridge arm circuit of the rotor angle are closed, the motor can convert the low-voltage charging voltage input by the external charging device into a high-voltage charging voltage through the motor coil (inductor). Among them, the use of motor inductance and switching elements to achieve the boost function can reduce the cost of additional boost equipment, so that it can be suitable for charging at different voltages, and can reduce the temperature rise and torque of the motor during charging. At the same time, selecting a suitable two-phase inductor for charging according to the actual position of the motor's rotor can greatly reduce the jitter at the beginning and end of charging, and improve the user's charging experience.

[0077] It should be noted that during the charging process of the whole vehicle, if only one phase of the motor inductance is used for charging, the charging efficiency is low and the motor heats up seriously, which increases the heat dissipation burden of the whole machine. Long-term use under high temperature conditions will reduce the life and reliability of the device. If only the two-phase inductance of the motor is used for charging without corresponding switch elements, if the position where the motor stops differs too much from the position of the magnetic flux formed by the two-phase inductance, there will be a large jitter at the beginning or end of charging, which will reduce the user experience.

[0078] It is easy to understand that the motor outputs the high-voltage charging voltage to the three-phase bridge arm circuit, and after the switches (switch tubes) of two-phase bridge arm circuits or one-phase bridge arm circuit of the three-phase bridge arm circuit are turned on, the high-voltage charging voltage is output to the vehicle battery.

[0079] The battery charging circuit of this embodiment includes: a three-phase bridge arm circuit, an electronically controlled switch circuit, a motor and a control unit, wherein the positive electrode of the three-phase bridge arm circuit is connected to the positive electrode of the vehicle battery, the negative electrode of the three-phase bridge arm circuit is connected to the negative electrode of the vehicle battery, the midpoint of each phase bridge arm in the three-phase bridge arm circuit is connected to the coil of the corresponding motor, the first end of the electronically controlled switch circuit is connected to the positive electrode of the external charging device, the second end of the electronically controlled switch circuit is connected to the positive electrode of the three-phase bridge arm circuit, the third end of the electronically controlled switch circuit is connected to the midpoint of the corresponding bridge arm in the three-phase bridge arm circuit, and the first end of the electronically controlled switch circuit is connected to the positive electrode of the external charging device. The four ends are respectively connected to the negative electrode of the vehicle battery and the negative electrode of the three-phase bridge arm circuit. When receiving the charging instruction, the control unit controls the on and off of the electronically controlled switch circuit according to the rotor angle of the motor. The control unit controls the on and off of the three-phase bridge arm circuit according to the on and off of the electronically controlled switch circuit. This embodiment reduces the cost of the boosting equipment and the jitter at the beginning and end of charging by controlling the appropriate electronically controlled switch circuit and the corresponding conduction of the three-phase bridge arm circuit according to the rotor angle position of the motor, and uses the motor coil to realize the boosting function, thereby reducing the cost of the boosting equipment and improving the user's charging experience.

[0080] Furthermore, the electronically controlled switch circuit includes a plurality of control switches, a first end of the plurality of control switches is connected to the three-phase bridge arm circuit, a second end of the plurality of control switches is connected to the external charging device, and the control unit selects the conduction and shutdown of the corresponding control switches according to the rotor angle of the motor.

[0081] It is easy to understand that the control unit can determine the corresponding control switch in the electronic control switch circuit according to the position range by judging the position range of the rotor angle, and control the conduction and disconnection of the corresponding control switch. Multiple control switches are respectively connected to the external charging device and the three-phase bridge arm circuit, and can control the conduction state of the charging line from the external charging device to the three-phase bridge arm circuit.

[0082] The three-phase bridge arm circuit includes a first phase bridge arm, a second phase bridge arm and a third phase bridge arm connected in parallel to each other, and the electronically controlled switch circuit includes a first control switch and a second control switch, wherein the first end of the first control switch is connected to the positive pole of the external charging device, and the second end of the first control switch is respectively connected to the positive pole of the first phase bridge arm, the positive pole of the second phase bridge arm and the positive pole of the third phase bridge arm; the first end of the second control switch is connected to the midpoint of the first phase bridge arm, and the second end of the second control switch is connected to the negative pole of the external charging device.

[0083] The electronically controlled switch circuit also includes a third control switch and a fourth control switch, wherein a first end of the third control switch is connected to the positive electrode of the external charging device, a second end of the third control switch is connected to the midpoint of the first phase bridge arm, a first end of the fourth control switch is respectively connected to the negative electrode of the vehicle battery and the negative electrode of the three-phase bridge arm circuit, and a second end of the fourth control switch is connected to the negative electrode of the external charging device.

[0084] In a specific implementation, the first phase bridge arm includes: a first switch tube, a second switch tube, a first diode and a second diode; the emitter of the first switch tube is respectively connected to the anode of the first diode and the first end of the motor, and the collector of the first switch tube is connected to the cathode of the first diode; the collector of the second switch tube is respectively connected to the cathode of the second diode and the first end of the motor, and the emitter of the second switch tube is connected to the anode of the second diode.

[0085] The second phase bridge arm includes: a third switch tube, a fourth switch tube, a third diode and a fourth diode; the emitter of the third switch tube is respectively connected to the anode of the third diode and the second end of the motor, and the collector of the third switch tube is connected to the cathode of the third diode; the collector of the fourth switch tube is respectively connected to the cathode of the fourth diode and the second end of the motor, and the emitter of the fourth switch tube is connected to the anode of the fourth diode.

[0086] The third phase bridge arm includes: a fifth switch tube, a sixth switch tube, a fifth diode and a sixth diode; the emitter of the fifth switch tube is respectively connected to the anode of the fifth diode and the third end of the motor, and the collector of the fifth switch tube is connected to the cathode of the fifth diode; the collector of the sixth switch tube is respectively connected to the cathode of the sixth diode and the third end of the motor, and the emitter of the sixth switch tube is connected to the anode of the sixth diode.

[0087] It is easy to understand that the first switch tube, the second switch tube, the third switch tube, the fourth switch tube, the fifth switch tube and the sixth switch tube can be specifically insulated gate bipolar transistors (IGBT tubes), and the first diode, the second diode, the third diode, the fourth diode, the fifth diode and the sixth diode can be specifically freewheeling diodes. Each phase switch subcircuit can include two switch tubes and two diodes, and the switch function is realized by controlling the conduction or disconnection of the switch tube. The control unit conducts by selecting a suitable charging line to improve the charging efficiency.

[0088] The first control switch, the second control switch, the third control switch and the fourth control switch are relays.

[0089] It is easy to understand that the electronically controlled switch circuit includes a first control switch, a second control switch and a third control switch. The first control switch, the second control switch and the third control switch can be devices with switching functions such as relays. The control unit selects the conduction and disconnection of one of the first control switch, the second control switch and the third control switch according to the rotor angle of the motor.

[0090] The electronically controlled switch circuit of this embodiment includes a first control switch, a second control switch, a third control switch and a fourth control switch. The three-phase bridge arm circuit includes a first phase bridge arm, a second phase bridge arm and a third phase bridge arm connected in parallel. Each phase bridge arm includes two switch tubes and two diodes to realize the switching function. The first control switch, the second control switch, the third control switch and the fourth control switch are all relays. Through the coordinated action of each switch element, a suitable line is selected to be turned on to realize the switching function and reduce the cost of the boosting equipment.

[0091] The embodiment of the present invention provides a battery charging method, referring to Figure 3 , Figure 3 This is a flow chart of a first embodiment of a battery charging method of the present invention. The battery charging method is applied to the battery charging circuit as described above.

[0092] In this embodiment, the battery charging method includes the following steps:

[0093] Step S10: When receiving the charging instruction, the control unit controls the on and off of the electronically controlled switch circuit according to the current rotor angle of the motor.

[0094] It is understandable that the electronically controlled switch circuit receives the charging instruction, indicating that it has detected that charging can start. The electronically controlled switch circuit can obtain the rotor angle of the motor, and by determining the position interval where the rotor angle is located, the on and off of the two control switches in the electronically controlled switch circuit can be determined according to the position interval, thereby further satisfying the charging start condition.

[0095] Step S20: the control unit controls the conduction of one phase bridge arm in the three-phase bridge arm circuit according to the conduction position of the electronically controlled switch circuit.

[0096] It is easy to understand that the control unit controls the on and off of the two control switches in the electronically controlled switch circuit corresponding to the rotor angle according to the rotor angle, and further controls the on and off of the switches of two-phase bridge arm circuits or one-phase bridge arm circuit in the three-phase bridge arm circuit according to the on and off of the two control switches in the electronically controlled switch circuit. The switches of each phase bridge arm circuit can be fully turned on or partially turned on, or fully turned off or partially turned off.

[0097] Step S30: The coil of the motor boosts the voltage input by the external charging device.

[0098] It can be understood that when the switches of the electronically controlled switching circuit and the rotor angles corresponding to the switches (switching tubes) of the two-phase bridge arm circuit or the one-phase bridge arm circuit are closed, the motor can convert the low-voltage charging voltage input by the external charging device into a high-voltage charging voltage through the motor coil (inductor). Among them, the use of motor inductance and switching elements to achieve the boost function can reduce the cost of additional boost equipment, so that it can be suitable for charging at different voltages, and can reduce the temperature rise and torque of the motor during charging. At the same time, selecting a suitable two-phase inductor for charging according to the actual position of the motor can greatly reduce the jitter at the beginning and end of charging, and improve the user's charging experience.

[0099] It should be noted that during the charging process of the whole vehicle, if only one phase of the motor inductance is used for charging, the charging efficiency is low and the motor heats up seriously, which increases the heat dissipation burden of the whole machine. Long-term use under high temperature conditions will reduce the life and reliability of the device. If only the two-phase inductance of the motor is used for charging without corresponding switch elements, if the position where the motor stops differs too much from the position of the magnetic flux formed by the two-phase inductance, there will be a large jitter at the beginning or end of charging, which will reduce the user experience.

[0100] Step S40: the control unit controls the conduction of two-phase or one-phase bridge arm in the three-phase bridge arm circuit, and the coil of the motor transmits the boosted voltage to the vehicle battery through the three-phase bridge arm circuit.

[0101] It is easy to understand that when the control unit controls the conduction of two-phase bridge arms in the three-phase bridge arm circuit, the control unit does not change the on-off state of the switch (switch tube) of the one-phase bridge arm circuit that has been controlled in the three-phase bridge arm circuit, and increases the on-off state of the switch (switch tube) of the one-phase bridge arm circuit that has not been controlled in the three-phase bridge arm circuit. When the control unit controls the conduction of one-phase bridge arm in the three-phase bridge arm circuit, the control unit changes the on-off state of the switch (switch tube) of the one-phase bridge arm circuit that has been controlled in the three-phase bridge arm circuit. The motor outputs the high-voltage charging voltage to the three-phase bridge arm circuit, and after the switch (switch tube) of the three-phase bridge arm circuit is turned on, the high-voltage charging voltage is output to the vehicle battery.

[0102] The battery charging circuit of this embodiment includes: a three-phase bridge arm circuit, an electric control switch circuit, a motor and a control unit, wherein the positive electrode of the three-phase bridge arm circuit is connected to the positive electrode of the vehicle battery, the negative electrode of the three-phase bridge arm circuit is connected to the negative electrode of the vehicle battery, the midpoint of each phase bridge arm in the three-phase bridge arm circuit is connected to the coil of the corresponding motor, the first end of the electric control switch circuit is connected to the positive electrode of the external charging device, the second end of the electric control switch circuit is connected to the positive electrode of the three-phase bridge arm circuit, the third end of the electric control switch circuit is connected to the midpoint of the corresponding bridge arm in the three-phase bridge arm circuit, and the electric control switch circuit The fourth end is respectively connected to the negative electrode of the vehicle battery and the negative electrode of the three-phase bridge arm circuit. When receiving the charging instruction, the control unit controls the conduction and shutdown of the electronic control switch circuit according to the rotor angle of the motor. The control unit controls the conduction and shutdown of the three-phase bridge arm circuit according to the conduction and shutdown of the electronic control switch circuit. This embodiment reduces the cost of the boosting equipment and the jitter at the beginning and end of charging by controlling the appropriate electronic control switch circuit and the corresponding conduction of the three-phase bridge arm circuit according to the rotor angle of the motor, and uses the motor coil to realize the boosting function, thereby reducing the cost of the boosting equipment and improving the user's charging experience.

[0103] Based on the above embodiment, in the vehicle battery charging method of this embodiment, the control unit stores the first phase, the second phase and the third phase for determining the rotor angle position interval, and the step S10 includes:

[0104] When receiving a charging instruction, the control unit aligns the zero position of the rotor with the first phase, the second phase, or the third phase;

[0105] It is determined whether the rotor angle of the current motor falls within a position interval between the first phase, the second phase and the third phase, and the on and off of the electronically controlled switch circuit is controlled according to the position interval.

[0106] It is easy to understand that Figure 4 , the spatial angles between the first phase, the second phase and the third phase are all 120°, and the spatial angles between the first phase, the second phase and the third phase are divided into four equal parts, that is, four position intervals are set, and the position intervals include the first angle interval (0°≤α﹤90°), the second angle interval (90°≤α﹤180°), the third angle interval (180°≤α﹤270°) and the fourth angle interval (270°≤α﹤360°). The control unit can control the conduction and disconnection of the two switches in the corresponding electric control switch circuit in the interval according to the angle interval of the current rotor angle.

[0107] The step S20 comprises:

[0108] The control unit controls the on and off of one phase bridge arm of the three-phase bridge arm circuit according to the on position of the electronically controlled switch circuit during the voltage boost process.

[0109] During the charging process, the control unit controls the on and off of two phases or one phase of the three-phase bridge arm circuit according to the on position of the electronically controlled switch circuit.

[0110] It is easy to understand that during the boost process, the control unit controls the on and off of the switch (switch tube) of one phase of the three-phase bridge arm circuit according to the on and off of the two control switches in the electronically controlled switch circuit, such as controlling the upper bridge of one phase of the three-phase bridge arm circuit to be on and the lower bridge to be off, or the upper bridge to be off and the lower bridge to be on. The boost process is that the coil of the motor boosts the voltage input by the external charging device. During the charging process, the control unit controls the on and off of the switches (switch tubes) of two phases of the three-phase bridge arm circuit or one phase of the three-phase bridge arm circuit according to the on and off of the two control switches in the electronically controlled switch circuit, such as controlling the upper bridge of another phase of the bridge arm circuit to be off and the lower bridge to be on based on the on and off of the upper bridge of the one-phase bridge arm circuit that has been controlled. Or the control unit changes the on and off state of the controlled one-phase bridge arm circuit according to the on and off of the two switches in the electronically controlled switch circuit, so that it changes from the upper bridge to be off and the lower bridge to the upper bridge to be on and the lower bridge to be off. The charging process is that the motor coil outputs the boosted voltage to the three-phase bridge arm circuit, the upper bridge is turned on, and the lower bridge is turned off.

[0111] In a specific implementation, the three-phase bridge arm circuit includes a first phase bridge arm, a second phase bridge arm and a third phase bridge arm connected in parallel, and the electronically controlled switch circuit includes a first control switch and a second control switch, wherein the first end of the first control switch is connected to the positive pole of the external charging device, and the second end of the first control switch is respectively connected to the positive pole of the first phase bridge arm, the positive pole of the second phase bridge arm and the positive pole of the third phase bridge arm; the first end of the second control switch is connected to the midpoint of the first phase bridge arm, and the second end of the second control switch is connected to the negative pole of the external charging device.

[0112] When receiving a charging instruction, the control unit controls the first control switch and the second control switch to be turned on according to the current rotor angle of the motor; the control unit controls the upper bridge of the third phase bridge arm to be turned on and the lower bridge of the third phase bridge arm to be turned off according to the conduction position of the electronically controlled switch circuit; the control unit controls the upper bridge of the third phase bridge arm to be turned on and the lower bridge of the third phase bridge arm to be turned off, and controls the upper bridge of the first phase bridge arm to be turned off and the lower bridge of the first phase bridge arm to be turned on.

[0113] It is easy to understand that Figure 5 , if the rotor angle is 30°, it satisfies 0°≤α﹤90° (the first angle interval). Figure 6During the boost process, the control unit controls the first control switch and the second control switch to close (the third control switch, the fourth control switch and the fifth control switch to open), and controls the switch (VT5) of the upper bridge arm of the third phase bridge arm circuit to close. At this time, the boost current path flows through the first control switch, VT5, the motor coil, the second electric control switch, and finally returns to the external charging device. Figure 7 During the charging process, the control unit controls the first control switch, the second control switch and the fifth control switch to close (the third control switch and the fourth control switch are disconnected), and controls the switch (VT2) of the lower bridge arm of the first phase bridge arm circuit and the switch (VT5) of the upper bridge arm of the third phase bridge arm circuit to close, so that the current enters from the coil (W phase) connected to the third phase bridge arm circuit and exits from the lower bridge arm (U phase) of the first phase bridge arm circuit. At this time, the charging current path flows through the first control switch, the fifth control switch, the vehicle battery, VT2, the motor coil, VT5, the fifth control switch, the vehicle battery, VT2, the second electric control switch, and finally returns to the external charging device.

[0114] In a specific implementation, the three-phase bridge arm circuit includes a first-phase bridge arm, a second-phase bridge arm and a third-phase bridge arm connected in parallel, and the electronically controlled switch circuit also includes a third control switch and a fourth control switch, wherein the first end of the third control switch is connected to the positive pole of the external charging device, the second end of the third control switch is connected to the midpoint of the first-phase bridge arm, the first end of the fourth control switch is respectively connected to the negative pole of the vehicle battery and the negative pole of the three-phase bridge arm circuit, and the second end of the fourth control switch is connected to the negative pole of the external charging device.

[0115] When receiving a charging instruction, the control unit controls the third control switch and the fourth control switch to be turned on according to the current rotor angle of the motor; the control unit controls the lower bridge of the second phase bridge arm to be turned on and the upper bridge of the second phase bridge arm to be turned off according to the conduction position of the electronically controlled switch circuit; the control unit controls the lower bridge of the second phase bridge arm to be turned off and the upper bridge of the second phase bridge arm to be turned on.

[0116] It is easy to understand that Figure 8 , if the rotor angle is 150°, it satisfies 90°≤α﹤180° (the second angle interval). Fig. 9 During the boost process, the control unit controls the third control switch and the fourth control switch to close (the first control switch and the second control switch are open), and controls the switch (VT4) of the lower bridge arm of the second phase bridge arm circuit to close. At this time, the boost current path flows through the third control switch, the motor coil, VT4, the fourth control switch, and finally returns to the external charging device. Fig.10During the charging process, the control unit controls the third control switch, the fourth control switch and the fifth control switch to close (the first control switch and the second control switch are disconnected), and controls the switch (VT3) of the upper bridge arm of the second phase bridge arm circuit to close, so that the current enters from the coil (U phase) connected to the first phase bridge arm circuit and exits from the upper bridge arm (V phase) of the second phase bridge arm circuit. At this time, the charging current path flows through the third control switch, the coil of the motor, VT3, the fifth control switch, the vehicle battery, the fourth electric control switch, and finally returns to the external charging device.

[0117] When receiving a charging instruction, the control unit controls the third control switch and the fourth control switch to be turned on according to the current rotor angle of the motor; the control unit controls the lower bridge of the third phase bridge arm to be turned on and the upper bridge of the third phase bridge arm to be turned off according to the conduction position of the electronically controlled switch circuit; the control unit controls the lower bridge of the third phase bridge arm to be turned off and the upper bridge of the third phase bridge arm to be turned on.

[0118] It is easy to understand that Fig.11 , if the rotor angle is 210°, it satisfies 180°≤α﹤270° (the third angle interval). Fig.12 During the voltage boost process, the control unit controls the third control switch and the fourth control switch to close (the first control switch and the second control switch are open), and controls the switch (VT6) of the lower bridge arm of the third phase bridge arm circuit to close. At this time, the boost current path flows through the third control switch, the motor coil, VT6, the fourth control switch, and finally returns to the external charging device. Fig.13 During the charging process, the control unit controls the third control switch, the fourth control switch and the fifth control switch to close (the first control switch and the second control switch are disconnected), and controls the switch (VT5) of the upper bridge arm of the third-phase bridge arm circuit to close, so that the current enters from the coil (U phase) connected to the first-phase bridge arm circuit and exits from the upper bridge arm (W phase) of the third-phase bridge arm circuit. At this time, the charging current path flows through the third control switch, the coil of the motor, VT5, the fifth control switch, the vehicle battery, the fourth electric control switch, and finally returns to the external charging device.

[0119] In a specific implementation, the three-phase bridge arm circuit includes a first phase bridge arm, a second phase bridge arm and a third phase bridge arm connected in parallel, and the electronically controlled switch circuit includes a first control switch and a second control switch, wherein the first end of the first control switch is connected to the positive pole of the external charging device, and the second end of the first control switch is respectively connected to the positive pole of the first phase bridge arm, the positive pole of the second phase bridge arm and the positive pole of the third phase bridge arm; the first end of the second control switch is connected to the midpoint of the first phase bridge arm, and the second end of the second control switch is connected to the negative pole of the external charging device.

[0120] When receiving a charging instruction, the control unit controls the first control switch and the second control switch to be turned on according to the current rotor angle of the motor; the control unit controls the upper bridge of the second phase bridge arm to be turned on and the lower bridge of the second phase bridge arm to be turned off according to the conduction position of the electronically controlled switch circuit; the control unit controls the upper bridge of the second phase bridge arm to be turned on and the lower bridge of the second phase bridge arm to be turned off, and controls the upper bridge of the first phase bridge arm to be turned off and the lower bridge of the first phase bridge arm to be turned on.

[0121] It is easy to understand that Fig.14 , if the rotor angle is 330°, it satisfies 270°≤α﹤360° (the fourth angle interval). Fig.15 During the boost process, the control unit controls the first control switch and the second control switch to close (the third control switch, the fourth control switch and the fifth control switch to open), and controls the switch (VT3) of the upper bridge arm of the second phase bridge arm circuit to close. At this time, the boost current path flows through the first control switch, VT3, the motor coil, the second electric control switch, and finally returns to the external charging device. Fig.16 During the charging process, the control unit controls the first control switch, the second control switch and the fifth control switch to close (the third control switch and the fourth control switch are disconnected), and controls the switch (VT2) of the lower bridge arm of the first phase bridge arm circuit and the switch (VT3) of the upper bridge arm of the second phase bridge arm circuit to close, so that the current enters from the coil (V phase) connected to the second phase bridge arm circuit and exits from the upper bridge arm (U phase) of the first phase bridge arm circuit. At this time, the charging current path flows through the first control switch, the fifth control switch, the vehicle battery, VT2, the motor coil, VT3, the fifth control switch, the vehicle battery, VT2, the second electric control switch, and finally returns to the external charging device.

[0122] This embodiment synthesizes a vector position based on the position of the rotor and the phase of the current entering and flowing out. When the position of the rotor is closest to the synthesized vector position, the corresponding control switch and bridge arm circuit are controlled to be turned on and off, so that the current enters and flows out at the desired phase, so that the rotation position of the rotor is minimized during the charging process of the vehicle, thereby reducing the jitter of the entire vehicle during charging.

[0123] It should be understood that the above is only an example and does not constitute any limitation on the technical solution of the present invention. In specific applications, technicians in this field can make settings as needed, and the present invention does not limit this.

[0124] It should be noted that the workflow described above is merely illustrative and does not limit the scope of protection of the present invention. In practical applications, technicians in this field can select part or all of them according to actual needs to achieve the purpose of the present embodiment, and no limitation is made here.

[0125] In addition, for technical details not fully described in this embodiment, reference may be made to the battery charging circuit and method provided in any embodiment of the present invention, which will not be described in detail here.

[0126] In addition, it should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or system including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or system. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or system including the element.

[0127] The serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0128] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A battery charging circuit, characterized in that: The battery charging circuit comprises: a three-phase bridge arm circuit, an electric control switch circuit, a motor and a control unit, wherein: The positive pole of the three-phase bridge arm circuit is connected to the positive pole of the vehicle battery, the negative pole of the three-phase bridge arm circuit is connected to the negative pole of the vehicle battery, and the midpoint of each phase bridge arm in the three-phase bridge arm circuit is connected to the corresponding coil of the motor; The first end of the electronically controlled switch circuit is connected to the positive electrode of the external charging device, the second end of the electronically controlled switch circuit is connected to the positive electrode of the three-phase bridge arm circuit, the third end of the electronically controlled switch circuit is connected to the midpoint of the corresponding bridge arm in the three-phase bridge arm circuit, and the fourth end of the electronically controlled switch circuit is respectively connected to the negative electrode of the vehicle battery and the negative electrode of the three-phase bridge arm circuit; When receiving a charging instruction, the control unit controls the on and off of the electric control switch circuit according to the position interval of the rotor angle of the motor; The control unit controls the on and off of the three-phase bridge arm circuit according to the on and off of the electronically controlled switch circuit, so as to control the conduction state of the charging circuit formed from the external charging device to the three-phase bridge arm circuit.

2. The battery charging circuit according to claim 1, characterized in that: The electronically controlled switch circuit includes a plurality of control switches, wherein first ends of the plurality of control switches are connected to the three-phase bridge arm circuit, and second ends of the plurality of control switches are connected to the external charging device.

3. The battery charging circuit as claimed in claim 2, characterized in that: The three-phase bridge arm circuit includes a first phase bridge arm, a second phase bridge arm and a third phase bridge arm connected in parallel to each other, and the electronically controlled switch circuit includes a first control switch and a second control switch, wherein the first end of the first control switch is connected to the positive pole of the external charging device, and the second end of the first control switch is respectively connected to the positive pole of the first phase bridge arm, the positive pole of the second phase bridge arm and the positive pole of the third phase bridge arm; the first end of the second control switch is connected to the midpoint of the first phase bridge arm, and the second end of the second control switch is connected to the negative pole of the external charging device.

4. The battery charging circuit as claimed in claim 3, characterized in that: The electronically controlled switch circuit also includes a third control switch and a fourth control switch, wherein a first end of the third control switch is connected to the positive electrode of the external charging device, a second end of the third control switch is connected to the midpoint of the first phase bridge arm, a first end of the fourth control switch is respectively connected to the negative electrode of the vehicle battery and the negative electrode of the three-phase bridge arm circuit, and a second end of the fourth control switch is connected to the negative electrode of the external charging device.

5. The battery charging circuit as claimed in claim 4, characterized in that: The first control switch, the second control switch, the third control switch and the fourth control switch are relays.

6. A battery charging method, characterized in that: The battery charging method is applied to the battery charging circuit as claimed in any one of claims 1 to 5, wherein the battery charging circuit comprises: a three-phase bridge arm circuit, an electric control switch circuit, a motor and a control unit; The battery charging method comprises: When receiving a charging instruction, the control unit controls the on and off of the electronically controlled switch circuit according to the current rotor angle of the motor; the control unit controls the on-state of one-phase bridge arm in the three-phase bridge arm circuit according to the on-state position of the electronically controlled switch circuit; the coil of the motor boosts the voltage input by the external charging device; the control unit controls the on-state of two-phase or one-phase bridge arm in the three-phase bridge arm circuit, and the coil of the motor transmits the boosted voltage to the vehicle battery through the three-phase bridge arm circuit.

7. The battery charging method according to claim 6, characterized in that: The control unit stores a first phase, a second phase, and a third phase for determining a rotor angle position interval. When receiving a charging instruction, the control unit controls the on and off of the electronically controlled switch circuit according to the rotor angle of the current motor, including: when receiving a charging instruction, the control unit aligns the zero point position of the rotor with the first phase, the second phase, or the third phase; determines whether the rotor angle of the current motor falls within a position interval between the first phase, the second phase, and the third phase, and controls the on and off of the electronically controlled switch circuit according to the position interval.

8. The battery charging method according to claim 7, characterized in that: The control unit controls the conduction of one phase bridge arm in the three-phase bridge arm circuit according to the conduction position of the electronically controlled switch circuit, including: the control unit controls the conduction and disconnection of one phase bridge arm of the three-phase bridge arm circuit according to the conduction position of the electronically controlled switch circuit during the boost process.

9. The battery charging method according to claim 8, characterized in that: The three-phase bridge arm circuit includes a first phase bridge arm, a second phase bridge arm and a third phase bridge arm connected in parallel to each other, and the electronically controlled switch circuit includes a first control switch and a second control switch, wherein the first end of the first control switch is connected to the positive electrode of the external charging device, and the second end of the first control switch is respectively connected to the positive electrode of the first phase bridge arm, the positive electrode of the second phase bridge arm and the positive electrode of the third phase bridge arm; the first end of the second control switch is connected to the midpoint of the first phase bridge arm, and the second end of the second control switch is connected to the negative electrode of the external charging device; When receiving the charging instruction, the control unit controls the on and off of the electric control switch circuit according to the current rotor angle of the motor, including: When receiving the charging instruction, the control unit controls the first control switch and the second control switch to be turned on according to the current rotor angle of the motor; The control unit controls the conduction of the corresponding bridge arm in the three-phase bridge arm circuit according to the conduction position of the electronically controlled switch circuit, including: The control unit controls the upper bridge of the second phase bridge arm to be turned on and the lower bridge of the second phase bridge arm to be turned off according to the conduction position of the electronically controlled switch circuit; The control unit changes the conduction position of the three-phase bridge arm circuit, including: The control unit controls the upper bridge of the second phase bridge arm to be turned on and the lower bridge of the second phase bridge arm to be turned off, and controls the upper bridge of the first phase bridge arm to be turned off and the lower bridge of the first phase bridge arm to be turned on.

10. The battery charging method according to claim 8, characterized in that: The three-phase bridge arm circuit includes a first phase bridge arm, a second phase bridge arm and a third phase bridge arm connected in parallel, and the electronically controlled switch circuit includes a first control switch and a second control switch, wherein the first end of the first control switch is connected to the positive electrode of the external charging device, and the second end of the first control switch is respectively connected to the positive electrode of the first phase bridge arm, the positive electrode of the second phase bridge arm and the positive electrode of the third phase bridge arm; the first end of the second control switch is connected to the midpoint of the first phase bridge arm, and the second end of the second control switch is connected to the negative electrode of the external charging device; When receiving the charging instruction, the control unit controls the on and off of the electric control switch circuit according to the current rotor angle of the motor, including: When receiving the charging instruction, the control unit controls the first control switch and the second control switch to be turned on according to the current rotor angle of the motor; The control unit controls the conduction of the corresponding bridge arm in the three-phase bridge arm circuit according to the conduction position of the electronically controlled switch circuit, including: The control unit controls the upper bridge of the third phase bridge arm to be turned on and the lower bridge of the third phase bridge arm to be turned off according to the conduction position of the electronically controlled switch circuit; The control unit changes the conduction position of the three-phase bridge arm circuit, including: The control unit controls the upper bridge of the third phase bridge arm to be turned on and the lower bridge of the third phase bridge arm to be turned off, and controls the upper bridge of the first phase bridge arm to be turned off and the lower bridge of the first phase bridge arm to be turned on.

11. The battery charging method according to claim 8, characterized in that: The three-phase bridge arm circuit includes a first-phase bridge arm, a second-phase bridge arm and a third-phase bridge arm connected in parallel with each other, and the electronically controlled switch circuit also includes a third control switch and a fourth control switch, wherein a first end of the third control switch is connected to the positive electrode of the external charging device, a second end of the third control switch is connected to the midpoint of the first-phase bridge arm, a first end of the fourth control switch is respectively connected to the negative electrode of the vehicle battery and the negative electrode of the three-phase bridge arm circuit, and a second end of the fourth control switch is connected to the negative electrode of the external charging device; When receiving the charging instruction, the control unit controls the on and off of the electric control switch circuit according to the current rotor angle of the motor, including: When receiving the charging instruction, the control unit controls the third control switch and the fourth control switch to be turned on according to the current rotor angle of the motor; The control unit controls the conduction of the corresponding bridge arm in the three-phase bridge arm circuit according to the conduction position of the electronically controlled switch circuit, including: The control unit controls the lower bridge of the second phase bridge arm to be turned on and the upper bridge of the second phase bridge arm to be turned off according to the conduction position of the electronically controlled switch circuit; The control unit changes the conduction position of the three-phase bridge arm circuit, including: The control unit controls the lower bridge of the second phase bridge arm to be turned off and the upper bridge of the second phase bridge arm to be turned on.

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