Power battery charging method, motor control circuit, and vehicle

Abstract

To provide a power battery charging method, a motor control circuit, and a vehicle.SOLUTION: A motor control circuit includes a first switch module 102, a three-phase inverter 104, and a control module 108, and a power supply module 101, the first switch module, the three-phase inverter, and a three-phase AC motor 103 form a current circuit. The three-phase AC motor inputs or outputs a current through N wires drawn from connection points of the three-phase coils, and the control module controls the three-phase inverter such that the motor control circuit receives the voltage of the power supply module and outputs direct current. The N wires are drawn from the three-phase AC motor to form a different charging circuit together with the three-phase inverter, the three-phase AC motor, and the power battery, and when it is detected that the voltage of the power supply module is equal to or lower than the voltage of the power battery, the original three-phase inverter and the three-phase AC motor are used to boost the voltage of the power supply module and then charge the power battery.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This disclosure is based on and claims priority to Chinese Patent Application No. 201811574168.8, filed on December 21, 2018, the entire contents of which are incorporated herein by reference.

[0002] The present disclosure relates to the technical field of motor control, and in particular to a charging method for a power battery, a motor control circuit, and a vehicle. [Background technology]

[0003] With the development and rapid popularization of electric vehicles, charging technology for electric vehicle power batteries becomes increasingly important. In addition to meeting the needs of various users, charging technology needs to meet the adaptability and compatibility of electric vehicle power batteries and charging stations.

[0004] At present, DC charging of power batteries is generally divided into two types: direct charging and boost charging. Direct charging refers to the positive and negative poles of the charging post being directly connected to the positive and negative busbars of the power battery via a contactor or relay to charge the battery directly, with no boost or step-down circuit between the charging post and the power battery. Boost charging refers to the addition and connection of a bidirectional step-up / step-down DC / DC bridge circuit to the positive and negative busbars between the charging post and the power battery.

[0005] For direct charging, if the maximum output voltage of the charging post is lower than the voltage of the power battery, the charging post will not be able to charge the battery. For boost charging, a separate boost circuit consisting of a DC / DC bridge circuit, an inductor, and a corresponding control detection circuit, etc., must be added, which increases the volume and cost of the entire device. Summary of the Invention

[0006] The present disclosure aims to provide a power battery charging method, a motor control circuit, and a vehicle to solve the problem in the prior art that a boost circuit needs to be added when charging a power battery using a boost charging method, thereby increasing the volume and cost of the entire device.

[0007] The present disclosure is realized as follows: A motor control circuit according to a first aspect of the present disclosure includes a first switch module, a three-phase inverter, and a control module, a power supply module, the first switch module, the three-phase inverter, and a three-phase AC motor form a current circuit, midpoints of three-phase arms of the three-phase inverter are connected to three-phase coils of the three-phase AC motor, respectively, the three-phase AC motor inputs or outputs current via an N line drawn from a connection point of the three-phase coils, the control module is connected to the three-phase inverter, the first switch module, the three-phase AC motor, and the power supply module, respectively, and the control module controls the three-phase inverter so that the motor control circuit receives a voltage of the power supply module and outputs DC.

[0008] According to a second aspect of the present disclosure, there is provided a method for charging a power battery based on the motor control circuit according to the first aspect, comprising the steps of: Obtaining a voltage of the power supply module and a voltage of the power battery, and selecting a charging method including a boost charging method and a direct charging method based on the voltage of the power supply module and the voltage of the power battery; The method includes controlling the first switch module and the second switch module to be turned on so that the power supply module outputs direct current, and controlling the three-phase inverter so that the power supply module charges the power battery in a selected charging manner.

[0009] A vehicle according to a third aspect of the present disclosure includes the motor control circuit according to the first aspect.

[0010] The present disclosure provides a method for charging a power battery, a motor control circuit, and a vehicle, wherein the motor control circuit includes a first switch module, a three-phase inverter, and a control module, wherein a power supply module, the first switch module, the three-phase inverter, and a three-phase AC motor form a current circuit, and the midpoints of the three-phase arms of the three-phase inverter are respectively connected to the three-phase coils of the three-phase AC motor, and the three-phase AC motor inputs or outputs current via N wires drawn from the connection points of the three-phase coils, and the control module is respectively connected to the three-phase inverter, the first switch module, the three-phase AC motor, and the power supply module, and the control module controls the three-phase inverter so that the motor control circuit receives the voltage of the power supply module and outputs DC. The technical means disclosed in the present disclosure draws out N lines from the three-phase AC motor to form a different charging circuit together with the three-phase inverter, the three-phase AC motor, and the power battery; when the control module detects that the maximum output voltage of the power supply module is lower than the voltage of the power battery, it uses the original three-phase inverter and three-phase AC motor to boost the voltage of the power supply module and then charges the power battery; when the control module detects that the maximum output voltage of the power supply module is higher than the voltage of the power battery, it directly charges the power battery, thereby allowing the power battery to be charged regardless of whether the voltage of the power supply module is high or low, thereby providing high compatibility and applicability, eliminating the need to add an external boost circuit, and eliminating the costs associated with adding a circuit. [Brief description of the drawings]

[0011] In order to more clearly describe the technical means of the embodiments of the present disclosure, the drawings necessary for describing the embodiments or prior art will be briefly described below. Obviously, the drawings described below are only some embodiments of the present disclosure, and those skilled in the art can obtain other drawings based on these drawings without any creative work.

[0012] [Figure 1] 1 is a schematic configuration diagram of a motor control circuit according to a first embodiment of the present disclosure. [Diagram 2] 4 is another schematic configuration diagram of the motor control circuit according to the first embodiment of the present disclosure. FIG. [Diagram 3]1 is a circuit diagram of a motor control circuit according to a first embodiment of the present disclosure. [Figure 4] 4 is another circuit diagram of the motor control circuit according to the first embodiment of the present disclosure. FIG. [Diagram 5] 11 is a flowchart of a charging method for a power battery according to a second embodiment of the present disclosure. [Figure 6] FIG. 11 is a current path diagram of a motor control circuit in a power battery charging method according to a second embodiment of the present disclosure. [Figure 7] FIG. 11 is another current path diagram of the motor control circuit in the power battery charging method according to the second embodiment of the present disclosure. [Figure 8] FIG. 11 is a further current path diagram of the motor control circuit of the power battery charging method according to the second embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] In order to make the objectives, technical solutions and advantages of the present disclosure clearer, the present disclosure will be described in more detail below with reference to the drawings and examples. Note that the specific examples described herein are merely for interpreting the present disclosure, and are not intended to limit the present disclosure.

[0014] In order to explain the technical means of the present disclosure, specific examples are given below.

[0015] As shown in FIG. 1 , the motor control circuit according to the first embodiment of the present disclosure includes a first switch module 102, a three-phase inverter 104, and a control module 108, in which the power supply module 101, the first switch module 102, the three-phase inverter 104, and the three-phase AC motor 103 form a current circuit, the midpoints of the three-phase arms of the three-phase inverter 104 are connected to the three-phase coils of the three-phase AC motor 103, respectively, the three-phase AC motor 103 inputs or outputs a current via an N line drawn from the connection point of the three-phase coils, the control module 108 is connected to the three-phase inverter 104, the first switch module 102, the three-phase AC motor 103, and the power supply module 101, respectively, and the control module 108 controls the three-phase inverter 104 so that the motor control circuit receives the voltage of the power supply module 101 and outputs DC.

[0016] The power source supplied by the power supply module 101 may be in the form of a power source such as a direct current supplied by a DC charging post, a direct current rectified and output by a single-phase or three-phase AC charging post, electric energy generated by a fuel cell, or a direct current rectified by a generator controller when a range extender such as an engine rotates to drive a generator to generate electricity. The first switch module 102 connects the power supply module 101 to a circuit based on a control signal, and causes the power supply module 101, the first switch module 102, the three-phase AC motor 103 and the three-phase inverter to form a current circuit. The first switch module 102 may be a switch provided at the positive and / or negative poles of the power supply module 101 to realize on / off control of the output current of the power supply module 101. The three-phase AC motor 103 includes three-phase coils connected to a midpoint and may be a permanent magnet synchronous motor or an asynchronous motor. The three-phase AC motor 103 is a three-phase four-wire type, i.e., the three-phase coils The three-phase inverter 104 includes six power switch units, the power switches may be device types such as transistors, IGBTs, MOS tubes, etc., two power switch units form one phase arm, forming a total of three phase arms, and the connection points of the two power switch units of each phase arm are connected to one phase coil of the three-phase AC motor 103. The control module 108 can obtain the voltage, current, and temperature of the power battery 106, the phase current of the three-phase AC motor 103, and the voltage of the power supply module 101. The control module 108 includes a vehicle controller, a motor controller control circuit, and a BMS battery manager circuit, and the three are connected by a CAN line. Different modules of the control module 108 control the on / off of the power switches of the three-phase inverter 104 and the on / off of the first switch module 102 based on the obtained information to realize the on / off of different current circuits.

[0017] The control module 108 controls the first switch module 102 to connect the power supply module 101 to the circuit. For example, when a DC charging gun is inserted into the DC charging inlet of the vehicle, the control module 108 compares the voltage of the power supply module 101 with the voltage of the member to be charged, which may be, for example, a rechargeable battery, and selects a different charging method according to the comparison result to charge the power battery. If the voltage of the power supply module 101 is lower than the voltage of the power battery, the power battery is charged by a DC boost charging method. Since the three-phase coils of the three-phase AC motor 103 can store electrical energy, the control module 108 controls the first switch module 102 and the second switch module 105 to be turned on, and the three-phase inverter 104 controls the power supply module 101, the three-phase inverter 104, and the three-phase coils of the three-phase AC motor 103 to generate inductive energy. 1. A power storage circuit is formed, that is, the power supply module 101 charges the three-phase coils of the three-phase AC motor 103, and then the power battery 106 is charged by the power supply module 101 and the three-phase coils of the three-phase AC motor 103. At this time, the three-phase coils of the three-phase AC motor 103 also output a voltage, so that the voltage output by the power supply module 101 is superimposed on the voltage output by the three-phase coils, thereby realizing the boosting of the voltage of the power supply module 101 and realizing the normal charging of the power battery. When the control module 108 detects that the voltage of the power supply module 101 is higher than the voltage of the power battery, the control module 108 controls the first switch module 102 to be turned on, so that the external power source charges the power battery via the three-phase AC motor 103 and the three-phase inverter 104.

[0018] In an embodiment of the present disclosure, N lines are drawn from a three-phase AC motor to form a different charging circuit together with a three-phase inverter, a three-phase AC motor, and a power battery; when the control module detects that the maximum output voltage of the power supply module is lower than the voltage of the power battery, the original three-phase inverter and three-phase AC motor are used to boost the voltage of the power supply module and then charge the power battery; when the control module detects that the maximum output voltage of the power supply module is higher than the voltage of the power battery, the power battery is directly charged, thereby allowing the power battery to be charged regardless of whether the voltage of the power supply module is high or low, resulting in high compatibility and applicability, and eliminating the need for an external boost circuit and the costs associated with adding a circuit.

[0019] As shown in FIG. 2 , in one embodiment of Example 1 of the present disclosure, the motor control circuit further includes a second switch module 105, where the three-phase inverter 104 is connected to the power battery 106 by the second switch module 105, and the second switch module 105 is connected to the control module 108.

[0020] The second switch module 105 connects the power battery 106 into or out of the circuit.

[0021] Regarding the second switch module 105, in a first embodiment, the second switch module 105 is a third switch, and the third switch is connected between the first end of the three-phase inverter 104 and the positive pole of the power battery 106.

[0022] As a second embodiment of the second switch module 105, the second switch module 106 is a fourth switch, and the fourth switch is connected between the second end of the three-phase inverter 104 and the negative pole of the power battery.

[0023] As a third embodiment of the second switch module 105, the second switch module 106 includes the above third switch and a fourth switch.

[0024] Regarding the first switch module, as a first embodiment, the first switch module 102 is a first switch, and the first switch is connected between the connection point of the positive pole of the power supply module 101 and the three-phase coils of the three-phase AC motor 103.

[0025] As a second embodiment of the first switch module 102 , the first switch module 102 is a second switch, and the second switch is connected between the negative pole of the power supply module 101 and the second end of the three-phase inverter 104 .

[0026] As a third embodiment of the first switch module 102, the first switch module 102 includes the above-mentioned first switch and a second switch.

[0027] The connection relationships in this embodiment may be as follows: a first end and a second end of the first switch module 102 are connected to the positive and negative poles of the power supply module 101, a third end of the first switch module 102 is connected to the connection points of the three-phase coils of the three-phase AC motor 103, a fourth end of the first switch module 102 is connected to the second end of the three-phase inverter 104 and the second end of the second switch module 105, a first end of the three-phase inverter 104 is connected to the first end of the second switch module 105, and a third end and a fourth end of the second switch module 105 are connected to the positive and negative poles of the power battery 106.

[0028] The first switch module 102 includes a first switch and a second switch, the second switch module 105 includes a third switch and a fourth switch, the first end and the second end of the first switch are respectively the first end and the third end of the first switch module 102, the first end and the second end of the second switch are respectively the second end and the fourth end of the first switch module 102, the first end and the second end of the third switch are respectively the first end and the third end of the second switch module 105, and the first end and the second end of the fourth switch are respectively the second end and the fourth end of the second switch module 105.

[0029] Regarding the three-phase inverter 104, specifically, the three-phase inverter 104 includes a first power switch unit, a second power switch unit, a third power switch unit, a fourth power switch unit, a fifth power switch unit and a sixth power switch unit, a control end of each power switch unit is connected to the control module 108, and input ends of the first power switch unit, the third power switch unit and the fifth power switch unit are commonly connected to form a first end of the three-phase inverter 104, and the second power switch unit The output ends of the first, fourth and sixth power switch units are commonly connected to form a second end of the three-phase inverter 104, the first phase coil of the three-phase AC motor 103 is connected to the output end of the first power switch unit and the input end of the fourth power switch unit, the second phase coil of the three-phase AC motor 103 is connected to the output end of the third power switch unit and the input end of the sixth power switch unit, and the third phase coil of the three-phase AC motor 103 is connected to the output end of the fifth power switch unit and the input end of the second power switch unit.

[0030] In the three-phase inverter 104, the first power switch unit and the fourth power switch unit form an A-phase arm, the third power switch unit and the sixth power switch unit form a B-phase arm, and the input end of the fifth power switch unit and the second power switch unit form a C-phase arm. The control method for the three-phase inverter 104 may be any one of the following or a combination of multiple types. For example, by combining any one, two or three phase arms of the three phase arms A, B and C, a total of seven types of heating control methods can be realized, which is flexible and simple.The switching of the arms is advantageous for selecting low power, medium power and high power for heating. For example, for low power heating, the power switch of any one of the arms of the phase is selected and controlled, and the three arms of the phase are switched in sequence. For example, first, the A-phase arm operates alone to control the first power switch unit and the fourth power switch unit to perform heating for a certain period of time, then the B-phase arm operates alone to control the third power switch unit and the sixth power switch unit to perform heating for the same period of time, and then the C-phase arm operates alone to control the fifth power switch unit to perform heating for the same period of time. The first power switch unit and the second power switch unit are controlled to perform heating for the same period of time, and then the A-phase arm is switched to operate. By repeating this process, the three-phase inverter 104 and the three-phase coils are sequentially energized to generate heat, and the three-phase heating is more balanced. For example, for medium power heating, the power switches of any two phase arms are selected and controlled, and the three-phase arms are switched in sequence. For example, the A- and B-phase arms are first operated, and then the first power switch unit, the fourth power switch unit, the third power switch unit and the sixth power switch unit are switched to operate. The three-phase inverter 104 and the three-phase coils 102 are controlled to perform heating for a certain period of time, then the B- and C-phase arms are operated to control the third power switch unit, the sixth power switch unit, the fifth power switch unit, and the second power switch unit to perform heating for the same period of time, and then the C- and A-phase arms are operated to control the fifth power switch unit, the second power switch unit, the first power switch unit, and the fourth power switch unit to perform heating for the same period of time, and then the A- and B-phase arms are operated. This is repeated to configure the three-phase inverter 104 and the three-phase coils 102 and 102. The heat generation is more balanced, for example, for high power heating, the power switches of the three-phase arms are selected and controlled, and the three-phase circuit is theoretically balanced, so that the three-phase current is balanced, and the heat generation balance of the three-phase inverter 104 and the three-phase coil is realized, the three-phase current is basically direct current, and their average values ​​are basically consistent, and the three-phase winding is symmetrical. At this time, the three-phase composite magnetomotive force inside the motor is basically zero, so the stator magnetic field is basically zero, and the motor basically does not generate torque, which is favorable to greatly reducing the stress of the power train.

[0031] The technical means of the present disclosure will be specifically described below using a specific circuit structure.

[0032] FIG. 3 is a circuit diagram of an example of a motor control circuit of the present disclosure. For convenience of explanation of the motor control circuit, other electric equipment is omitted in the diagram, and only the power battery 106, the three-phase inverter 104, and the three-phase AC motor 103 are considered. The first switch module 102 includes a switch K1 and a switch K2, the second switch module 105 includes a switch K3 and a switch K4, the first power switch unit of the three-phase inverter 104 includes a first upper arm VT1 and a first upper arm diode VD1, the second power switch unit includes a second lower arm VT2 and a second lower arm diode VD2, and the third power switch unit includes a third upper arm VT the third and third upper arm diodes VD3, the fourth power switch unit includes a fourth lower arm VT4 and a fourth lower arm diode VD4, the fifth power switch unit includes a fifth upper arm VT5 and a fifth upper arm diode VD5, the sixth power switch unit includes a sixth lower arm VT6 and a sixth lower arm diode VD6, the three-phase AC motor 103 is a three-phase four-wire type, with an N line drawn from the connection point of the three-phase coils and connected to a switch K1, the three-phase coils are respectively connected between the upper and lower arms of the A-, B- and C-phase of the three-phase inverter 104, and both ends of the power battery 106 are also connected in parallel to the capacitor C2.

[0033] 4 is a circuit diagram of another example of the motor control circuit of the present disclosure, which is different from FIG. 3 in that an inductor L1 is connected in series between the switch K1 and the positive pole of the power supply module 101, and a capacitor C1 is connected in parallel between the power supply module and the switches K1 and K2, and the capacitor C1 may be selected according to local relevant charging regulations, charging protocols, etc., and the capacitance value may be adjusted according to actual needs. Note that the inductor L1 may be provided between the capacitor C1 and the switch K1.

[0034] As shown in FIG. 5, the method for charging a power battery based on the motor control circuit according to the first embodiment of the present disclosure includes the following steps S101 to S102.

[0035] In step S101, the voltage of the power supply module and the voltage of the power battery are obtained, and a charging method including a boost charging method and a direct charging method is selected based on the voltage of the power supply module and the voltage of the power battery.

[0036] In step S102, the first switch module is controlled to be turned on so that the power supply module outputs direct current, and the three-phase inverter is controlled so that the power supply module charges the power battery in the selected charging manner.

[0037] In the above steps, as shown in FIG. 1, the execution body is the control module 108. When the control module 108 detects that the power supply module 101 is connected to the circuit, for example, when a charging gun is inserted into a DC charging inlet of a vehicle, the control module 108 compares the voltage of the power supply module 101 with the voltage of the power battery 106, and selects a different charging method to charge the power battery 106 according to the comparison result. If the maximum output voltage of the power supply module 101 is lower than the voltage of the power battery 106, the control module 108 charges the power battery 106 using a DC boost charging method, and selects a charging method to charge the three-phase AC motor 103. Since the three-phase coils can store electrical energy, the first switch module 102 is controlled to be turned on, and the power supply module 101 charges the three-phase coils of the three-phase AC motor 103, and then the three-phase inverter 103 is controlled so that the power supply module 101 and the three-phase coils of the three-phase AC motor 103 charge the power battery 106. In the discharging process, the three-phase coils of the three-phase AC motor 104 also output voltages, so that the voltages output by the power supply module 101 and the voltages output by the three-phase coils are superimposed to provide a power supply. When the control module 108 detects that the maximum output voltage of the power supply module 101 is higher than the voltage of the power battery 106, the control module 108 controls the first switch module 102 to be turned on, so that the output voltage of the power supply module 101 directly charges the power battery 106. In the embodiment of the present disclosure, N wires are drawn out from the three-phase coils of the three-phase AC motor to form a different charge and discharge circuit together with the power battery and the three-phase inverter. When the control module detects that the maximum output voltage of the power supply module is lower than the voltage of the power battery, the original three-phase inverter 103 and the three-phase AC motor are used to boost the voltage of the power supply module and then charge the power battery. When the control module detects that the maximum output voltage of the power supply module is higher than the voltage of the power battery, the voltage of the power supply module is directly charged by the power battery. This allows the power battery to be charged regardless of the voltage of the power supply module, and has high compatibility and applicability, and there is no need to add an external step-up or step-down circuit, and there is no cost associated with adding a circuit.

[0038] Furthermore, the step of selecting a charging method based on the voltage of the power supply module and the voltage of the power battery includes: The step of selecting a boost charging method when detecting that the voltage of the power supply module is equal to or lower than the voltage of the power battery is included.

[0039] The step of controlling the three-phase inverter so that the power supply module charges the power battery in the selected charging method includes: The method includes a step of controlling a three-phase inverter to boost the charging voltage of the power supply module and then charging the power battery so that a charging process to the three-phase coils of the three-phase AC motor by the power supply module and a discharging process to the power battery by the power supply module and the three-phase coils of the three-phase AC motor are alternately performed.

[0040] As one embodiment, as shown in FIG. 1, a power supply module 101, a first switch module 102, a three-phase AC motor 103, and a three-phase inverter 104 form a charging circuit, and the power supply module 101, the first switch module 102, the three-phase AC motor 103, the three-phase inverter 104, and a power battery 106 form a discharging circuit.

[0041] The step of controlling the three-phase inverter so that a charging process to the three-phase coils of the three-phase AC motor by the power supply module and a discharging process to the power battery by the power supply module and the three-phase coils of the three-phase AC motor are alternately performed, The method includes controlling the three-phase inverter 104 to alternately turn on the charging and discharging circuits.

[0042] In this embodiment, a neutral wire is drawn from the three-phase AC motor 103 and connected to the power supply module 101 by the first switch module 102, thereby controlling the three-phase inverter 104, and realizing that the three-phase AC motor 103, together with the power supply module 101, the three-phase inverter 104, and the power battery 106, form a charging circuit and a discharging circuit. By controlling the charging circuit and the discharging circuit to be turned on alternately, it is possible to charge the power battery 106 even when the voltage of the power supply module 101 is lower than the voltage of the power battery 106, which has high compatibility and applicability, and eliminates the need to add an external boost circuit and the costs associated with adding circuits.

[0043] Regarding the three-phase inverter 104, in one embodiment, the three-phase inverter 104 includes three-phase arms, each of which includes two power switch units connected in series, and the three-phase coils of the three-phase AC motor 103 are respectively connected to the connection points of the two power switch units of the arms of each phase.

[0044] The step of controlling the three-phase inverter so that a charging process to the three-phase coils of the three-phase AC motor by the power supply module and a discharging process to the power battery by the power supply module and the three-phase coils of the three-phase AC motor are alternately performed, The method includes a step of controlling two power switch units of at least one phase arm in the three-phase inverter 104 to be alternately turned on so that a charging process to the three-phase coils of the three-phase AC motor 103 by the power supply module 101 and a discharging process to the power battery 106 by the power supply module 101 and the three-phase coils of the three-phase AC motor 103 are alternately performed.

[0045] Regarding the control of the three-phase inverter 104, it is possible to switch to different arms as needed and control them to be turned on to realize the DC charging function. For example, the arm controlled to be turned on may be any one, two or three phase arm of the three phase arms, and charging is performed with a total of seven types of switching methods.

[0046] Furthermore, the step of controlling two power switch units of at least one phase arm in the three-phase inverter to be alternately turned on includes: The method includes a step of obtaining the number of ON arms of the three-phase inverter 104 based on the power to be charged of the power battery 106, and controlling the corresponding number of arms to operate based on the number of ON arms.

[0047] The number of arms to be turned on is selected based on the power to be charged of the power battery 106, and the power to be charged of the power battery 106 can be obtained according to the charging power command issued by the battery manager. Controlling the corresponding number of arms to operate means that current is passed through the arm of the phase, that is, the two power switch units of the arm of the phase are turned on alternately to participate in different current circuits. For example, for low power boost charging, boost charging can be performed by operating any one of the arms of the phase, for medium power boost charging, boost charging can be performed by operating any two of the arms of the phase, and for high power boost charging, boost charging can be performed by operating the arms of three phases simultaneously.

[0048] In this embodiment, based on the power to be charged of the power battery, a corresponding number of arms are operated to perform boost charging, and based on the power to be charged of the power battery, a corresponding control method is implemented to improve the charging efficiency of the power battery.

[0049] As a first embodiment, the step of obtaining the number of ON arms of the three-phase inverter based on the power to be charged of the power battery, and controlling the corresponding number of arms to operate based on the number of ON arms, When it is detected that the power to be charged in the power battery 106 is smaller than a first predetermined power, the method includes a step of determining that the number of arms of the three-phase inverter 104 that are turned on is one, and controlling so that one of the three phase arms operates or the three phase arms are switched in sequence to operate.

[0050] When the control module 108 detects that the power to be charged of the power battery 106 is small, it controls one of the three-phase arms to be turned on, which satisfies the charging requirement. Assuming that the three-phase arms include an A-phase arm, a B-phase arm, and a C-phase arm, it may control one of the three-phase arms to always operate, or may control the three-phase arms to operate in sequence. Switching the three-phase arms in sequence means that the three-phase arms operate in sequence. For example, first, the A-phase arm is controlled to operate, and the B-phase arm and the C-phase arm are controlled not to operate, then the B-phase arm is controlled to operate, and the A-phase arm and the C-phase arm are controlled not to operate, then the C-phase arm is controlled to operate, and the A-phase arm and the B-phase arm are controlled not to operate, and then the C-phase arm is controlled to operate, and then the A-phase arm and the B-phase arm are controlled not to operate, and then the three-phase arms are controlled to switch in sequence, thereby achieving a balance in the heat generation of the three-phase inverter 104 and the three-phase coils.

[0051] As a second embodiment, the step of obtaining the number of ON arms of the three-phase inverter based on the power to be charged of the power battery, and controlling the corresponding number of arms to operate based on the number of ON arms, When it is detected that the power to be charged of the power battery 106 is equal to or greater than a first predetermined power and less than a second predetermined power, the method includes a step of determining that the number of arms of the three-phase inverter 104 that are turned on is two, and controlling so that any two of the three-phase arms operate or three sets of two-phase arms of the three-phase arms operate in sequence, where the three-phase inverter includes an A-phase arm, a B-phase arm and a C-phase arm, the first set of two-phase arms includes an A-phase arm and a B-phase arm, the second set of two-phase arms includes an A-phase arm and a C-phase arm, and the first set of three-phase arms includes a B-phase arm and a C-phase arm.

[0052] When the control module 108 detects that the power to be charged of the power battery 106 is equal to or greater than the first predetermined power and smaller than the second predetermined power, it controls two of the three-phase arms to be turned on to satisfy the charging requirement. It may control any two of the three-phase arms to be always operating, or it may control three sets of two-phase arms of the three-phase arms to be switched to operate in sequence. For example, the A-phase arm and the B-phase arm are the first set of two-phase arms, and the A-phase arm and the C-phase arm are the second set of two-phase arms. By configuring two sets of two-phase arms, and configuring the B-phase arm and the C-phase arm as a third set of two-phase arms, that is, first, controlling the first set of two-phase arms to operate and the C-phase arm not to operate, then controlling the second set of two-phase arms to operate and the B-phase arm not to operate, then controlling the third set of two-phase arms to operate and the A-phase arm not to operate, and thereafter controlling the three sets of two-phase arms to operate in sequence, it is possible to achieve a balance in the heat generation of the three-phase inverter 104 and the three-phase coils.

[0053] In the second embodiment, when the control module detects that the power to be charged in the power battery is equal to or greater than the first predetermined power and smaller than the second predetermined power, after the step of determining that the number of arms of the three-phase inverter that are turned on is two, the control module further The control module 108 includes a step of transmitting PWM control signals having a phase difference of 180 degrees to each of the two phase arms.

[0054] In order to reduce the total ripple of the charging circuit, an inverter switch phase shift control method can be used, and when only two-phase arms need to operate, the phases of the two-phase control signals respectively sent to the two-phase arms are shifted by about 180°, in this way the positive ripple and negative ripple of the two-phase coils are mutually superimposed and mutually offset, so that the total ripple can be greatly reduced.

[0055] As a third embodiment, the step of the control module obtaining the number of arms of the three-phase inverter to be turned on based on the power to be charged of the power battery, and controlling the corresponding number of arms to be operated based on the number of arms to be turned on, When the control module 108 detects that the power to be charged of the power battery 106 is equal to or greater than a second predetermined power, it determines that the number of arms of the three-phase inverter 104 that are turned on is three, and controls the three-phase arms to operate simultaneously.

[0056] When the control module 108 detects that the power to be charged of the power battery 106 is large, it controls three of the three-phase arms to be turned on to meet the charging requirement, and controls three of the three-phase arms to operate simultaneously. Since the three-phase circuit is theoretically balanced, the current output by the three-phase arms is balanced, and the heat generation balance of the three-phase inverter 104 and the three-phase coils is realized.

[0057] In the above third embodiment, when the control module detects that the power to be charged of the power battery is equal to or greater than a second predetermined power, after the step of determining that the number of arms of the three-phase inverter that are turned on is three, sending phase-matched PWM control signals to three phase arms; Alternatively, it may include a step of transmitting PWM control signals of different phases to three-phase arms, with the phase of the PWM control signal of one phase arm being shifted by 120 degrees and -120 degrees from the phases of the PWM control signals of the other two phase arms, respectively.

[0058] In order to reduce the total ripple of the charging circuit, the inverter switch phase shift control method can be used, and when the three-phase arms are controlled to operate, the three-phase control signals output to the three-phase arms are phase shifted by about 120°, so that the positive and negative ripples of the three-phase coils are mutually superimposed and mutually offset, thereby greatly reducing the total ripple.Furthermore, a synchronous control method can be used, that is, the power switches of the three-phase arms are controlled simultaneously, turned on synchronously, and turned off synchronously, so that the currents of the three phases increase simultaneously when they are turned on, and decrease simultaneously when they are turned off, which is favorable for the currents of the three phases to be more equal at any moment, so that the three-phase composite magnetomotive force tends to be zero, the stator magnetic field tends to be zero, and the motor basically does not generate torque.

[0059] In the above third embodiment, the control module 108 further acquires the current values ​​of the arms of each phase when the arms of the three phases operate simultaneously, and adjusts the control signals of the arms of each phase so that the average current values ​​of the arms of the three phases are within the same predetermined current range.

[0060] In an actual circuit, the three-phase circuits of the three-phase AC motor 103 and the motor controller may not always be completely identical, so during open-loop control, the three-phase currents are not always equal, and the current difference may become increasingly larger over a long period of time, so it is necessary to perform independent closed-loop control of the three-phase currents to control the average values ​​of the three-phase currents within the same predetermined balance value accuracy range.

[0061] In the above third embodiment, further, the control module 108 acquires the current values ​​of the arms of each phase when the arms of the three phases operate simultaneously, and adjusts the control signals of the arms of each phase so that the current values ​​of the arms of the three phases are not completely the same, and the current difference value between the arms of each two phases is smaller than a predetermined current threshold value.

[0062] When performing independent closed-loop control of the three-phase current, the current of one of them can be controlled to be slightly larger than the current of the other two phases, and the current of the other two phases can be controlled to be two-phase currents with equal or slightly unequal average values, in which case the magnetic field generated by the three-phase currents is not zero but very small, and the torque of the motor is also not zero but very small, so that the motor shaft in the vehicle outputs a small torque to engage the gear gap, which is favorable to reducing the jitter and noise caused by torque fluctuation, and the magnitude of the current and the magnitude of the output torque can be determined by controlling the magnitude of the three-phase currents according to actual needs.

[0063] In one embodiment, the charging circuit and the discharging circuit can be controlled to be turned on alternately in the following manner: the control module 108 outputs a PWM control signal to the three-phase inverter 104 to turn on the charging circuit and the discharging circuit alternately, obtains the power to be charged of the power battery 106, obtains a corresponding current based on the power to be charged, compares the actual charging current to the power battery 106 with the corresponding current obtained based on the power to be charged, and adjusts the duty ratio of the PWM control signal according to the comparison result to adjust the current output to the power battery 106.

[0064] The control module 108 receives the power to be charged sent by the battery manager, obtains the current corresponding to the power to be charged, compares the charging current for charging the power battery 106 with the current corresponding to the power to be charged, and adjusts the PWM on duty ratio to increase if the charging current is smaller than the current value corresponding to the required charging power, and adjusts the PWM on duty ratio to decrease if the charging current is larger than the current value corresponding to the required charging power to meet the charging power.

[0065] The technical means of the present disclosure will be specifically described below using a specific circuit structure shown in FIG.

[0066] Specifically, the control steps of the control module 108 include the following steps 1 to 5.

[0067] In step 1, the control module 108 controls the switches K1, K2, and K3 to be closed.

[0068] As shown in FIG. 6, in step 2, the control module 108 sends a PWM control signal to the three-phase inverter 104, and during the on period in each PWM control signal cycle, the control module 108 controls the A-phase fourth lower arm VT4 of the three-phase inverter 104 to be on, the first upper arm VT1 to be off, and the other two phases B and C upper and lower arm power switches to be off. At this time, the A-phase coil is turned on, the current increases, the inductor starts to store energy, the voltage of the A-phase inductor is positive at the right end and negative at the left end, and the voltages of the B and C-phase inductors are opposite to that of the A-phase.

[0069] As shown in FIG. 7, in step 3, during the off period in each PWM control signal cycle, the control module 108 controls the A-phase fourth lower arm VT4 of the three-phase inverter 104 to be turned off, the first upper arm VT1 to be turned on, and all the other two phases, B and C, of ​​the upper and lower arm power switches to be turned off. The A-phase current flows through the upper arm diode and is commutated, the inductor starts to discharge, and the current decreases. At this time, the voltage of the A-phase inductor is positive at the left end and negative at the right end, and the voltages of the B and C-phase inductors are opposite to that of the A-phase. By superimposing the voltage of the A-phase inductor and the voltage of the power supply module 101, it is possible to boost the voltage and charge the battery.

[0070] In step 4, the control module 108 obtains the battery charging current, and adjusts the PWM on duty ratio to increase if the current is smaller than the current value corresponding to the required charging power, and adjusts the PWM on duty ratio to decrease if the current is larger than the current value corresponding to the required charging power, to meet the charging power, and also detects the three-phase current of the motor to help control overcurrent and overtemperature.

[0071] In step 5, steps 2 to 4 are repeated before the battery is fully charged, and when the battery is fully charged, the control detection circuit turns off switches K1, K2, K3, and K4.

[0072] For ease of understanding, arrows showing the direction of current flow in the energy storage stage and the discharge stage are shown in both Figures 6 and 7. The above two figures only show a switching method for realizing charging using an A-phase arm and an A-phase coil, and as necessary, it is possible to switch to a method for realizing charging using either one of the B-phase and C-phase arms and either one of the B-phase and C-phase coils, a method for realizing charging using either two arms and either two coils, or a charge control method in which the three coils of a three-phase arm operate simultaneously.

[0073] Assuming that the maximum output voltage of the DC charging post is higher than the voltage of the power battery 106, in a specific implementation, Figure 8 is a circuit schematic diagram of one embodiment of the motor control circuit of the present disclosure, the connection method of which is completely consistent with Figure 3, during direct charging, the three-phase coils are naturally turned on through the upper arm diodes of the three-phase inverter 104 to form a three-phase charging current, so this charging method cannot realize the switching of three different arms and coils like boost charging. In a specific implementation, in order to realize the direct charging method, as shown in Figure 8, the control steps specifically include the following steps 1 to 4:

[0074] In step 1, the control module 108 controls all six power switches of the three-phase inverter 104 to be turned off.

[0075] In step 2, the control module 108 controls the switches K1, K2, K3, and K4 to be closed, the power supply module 101 starts supplying power, and charging to the power battery 106 starts through the three-phase coils of the three-phase AC motor 103 and the upper arm diode of the three-phase inverter 104, and the magnitude of the charging current is controlled by the control module 108 sending charging power or charging current to the DC charging post.

[0076] In step 3, the control module 108 obtains the battery charging current and the three-phase current of the motor to perform over-current and over-temperature control in the charging process.

[0077] In step 4, before the power battery is fully charged, steps 2 to 3 are repeated, and when the power battery is fully charged, the control module 108 turns off the switches K1, K2, K3, and K4.

[0078] For ease of understanding, arrows showing the direction of current flow are shown in Fig. 8. The three-phase currents are direct currents and their average values ​​are basically the same, so the three-phase heat generation of the motor and the inverter is basically the same, and the three-phase windings are symmetrical, and at this time the three-phase composite magnetomotive force inside the motor is basically zero, so the stator magnetic field is basically zero and the motor basically does not generate torque, which is favorable for greatly reducing the stress of the powertrain.

[0079] The DC charging method for a power battery and the corresponding system and device disclosed herein can be applied to the above-mentioned embodiments, but are not limited thereto, and can be applied to vehicle types such as electric vehicles and plug-in hybrid cars.

[0080] A vehicle according to a third embodiment of the present disclosure includes the motor control circuit according to the above embodiments.

[0081] The above embodiments are merely for explaining the technical means of the present disclosure, and are not limiting. The present disclosure has been described in detail with reference to the above embodiments. However, those skilled in the art should understand that the technical means described in each of the above embodiments may still be modified or some of the technical features may be replaced with equivalents. With these modifications or replacements, the essence of the corresponding technical means will not deviate from the spirit and scope of the technical means in each of the embodiments of the present disclosure, and all of them should be included in the protection scope of the present disclosure.

Claims

1. A motor control circuit including a first switch module, a three-phase inverter, and a control module; a power supply module, the first switch module, the three-phase inverter, and a three-phase AC motor form a current circuit, and midpoints of three-phase arms of the three-phase inverter are connected to three-phase coils of the three-phase AC motor, respectively; The three-phase AC motor inputs or outputs a current through N wires drawn from the connection points of the three-phase coils, the control module is connected to the three-phase inverter, the first switch module, the three-phase AC motor, and the power supply module, The control module controls the three-phase inverter so that the motor control circuit receives a voltage from a power supply module and outputs direct current.

2. The motor control circuit of claim 1 further comprising a second switch module, the three-phase inverter being connected to a power battery by the second switch module, the second switch module being connected to the control module.

3. 3. The motor control circuit according to claim 2, wherein a first end and a second end of the first switch module are connected to a positive electrode and a negative electrode of a power supply module, a third end of the first switch module is connected to a connection point of three-phase coils of the three-phase AC motor, a fourth end of the first switch module is connected to a second end of the three-phase inverter and a second end of the second switch module, a first end of the three-phase inverter is connected to a first end of the second switch module, and a third end and a fourth end of the second switch module are connected to a positive electrode and a negative electrode of a power battery.

4. 4. The motor control circuit of claim 2, wherein the first switch module includes a first switch and a second switch, the second switch module includes a third switch and a fourth switch, a first end and a second end of the first switch are the first end and a third end of the first switch module, a first end and a second end of the second switch are the second end and a fourth end of the first switch module, a first end and a second end of the third switch are the first end and a third end of the second switch module, and a first end and a second end of the fourth switch are the second end and a fourth end of the second switch module,

5. the first switch module is a first switch, and the first switch is connected between a positive electrode of a power supply module and a connection point of three-phase coils of the three-phase AC motor; Alternatively, the first switch module is a second switch, and the second switch is connected between the negative pole of the power supply module and the second end of the three-phase inverter. The motor control circuit according to any one of claims 1 to 4.

6. The second switch module is a third switch, and the third switch is connected between a first end of the three-phase inverter and a positive electrode of a power battery; Alternatively, the second switch module is a fourth switch, and the fourth switch is connected between the second end of the three-phase inverter and the negative electrode of a power battery. The motor control circuit according to any one of claims 2 to 4.

7. A method for charging a power battery based on the motor control circuit according to claim 1, comprising the steps of: Obtaining a voltage of the power supply module and a voltage of the power battery, and selecting a charging method including a boost charging method and a direct charging method according to the voltage of the power supply module and the voltage of the power battery; controlling the first switch module to be turned on so that the power supply module outputs direct current, and controlling the three-phase inverter so that the power supply module charges the power battery in a selected charging manner.

8. The step of selecting a charging method based on the voltage of the power supply module and the voltage of the power battery includes: selecting a boost charging method when detecting that the maximum output voltage of the power supply module is equal to or lower than the voltage of the power battery; The step of controlling the three-phase inverter so that the power supply module charges the power battery in the selected charging manner includes:

8. The method for charging a power battery according to claim 7, further comprising the step of controlling the three-phase inverter to boost a charging voltage of the power supply module and then charging the power battery so that a charging process of the three-phase coils of the three-phase AC motor by the power supply module and a discharging process to the power battery by the power supply module and the three-phase coils of the three-phase AC motor are alternately performed.

9. a power supply module, the first switch module, the three-phase AC motor, and the three-phase inverter constitute a charging circuit, and a power supply module, the first switch module, the three-phase AC motor, the three-phase inverter, and a power battery constitute a discharging circuit; the step of controlling the three-phase inverter so that a charging process to the three-phase coils of the three-phase AC motor by a power supply module and a discharging process to a power battery by the power supply module and the three-phase coils of the three-phase AC motor are alternately performed, 9. The method of charging a power battery as claimed in claim 8, further comprising the step of controlling said three-phase inverter to alternately turn on said charging circuit and said discharging circuit.

10. the three-phase inverter includes three-phase arms, each of the phase arms including two power switch units connected in series, and three-phase coils of the three-phase AC motor are connected to connection points of the two power switch units of each of the phase arms, respectively; the step of controlling the three-phase inverter so that a charging process to the three-phase coils of the three-phase AC motor by a power supply module and a discharging process to a power battery by the power supply module and the three-phase coils of the three-phase AC motor are alternately performed, 10. The method for charging a power battery according to claim 8, further comprising a step of controlling two power switch units of at least one phase arm in the three-phase inverter to be alternately turned on so that a charging process to three-phase coils of the three-phase AC motor by a power supply module and a discharging process to the power battery by the power supply module and the three-phase coils of the three-phase AC motor are alternately performed.

11. The step of controlling two power switch units of at least one phase arm in the three-phase inverter to be alternately turned on includes:

11. The method for charging a power battery according to claim 10, comprising the steps of obtaining the number of arms of the three-phase inverter that are turned on based on the power to be charged of the power battery, and controlling the number of arms to operate based on the number of arms that are turned on.

12. The step of obtaining the number of ON arms of the three-phase inverter based on the power to be charged of the power battery, and controlling the corresponding number of arms to operate based on the number of ON arms, 12. The method for charging a power battery according to claim 11, comprising the step of determining that the number of arms of the three-phase inverter that are turned on is one when the control module detects that the power to be charged of the power battery is smaller than a first predetermined power, and controlling so that one of the arms of the three phases operates or the arms of the three phases operate in sequence.

13. The step of obtaining the number of ON arms of the three-phase inverter based on the power to be charged of the power battery, and controlling the corresponding number of arms to operate based on the number of ON arms, 13. The power battery charging method according to claim 11 or 12, further comprising the steps of: determining that the number of ON arms of the three-phase inverter is two when the control module detects that the power to be charged of the power battery is equal to or greater than a first predetermined power and less than a second predetermined power; and controlling so that any two of the three-phase arms operate or three sets of two-phase arms of the three-phase arms operate in sequence; the three-phase inverter includes an A-phase arm, a B-phase arm and a C-phase arm; the first set of two-phase arms includes an A-phase arm and a B-phase arm; the second set of two-phase arms includes an A-phase arm and a C-phase arm; and the first set of three-phase arms includes a B-phase arm and a C-phase arm.

14. When the control module detects that the power to be charged in the power battery is equal to or greater than a first predetermined power and smaller than a second predetermined power, after the step of determining that the number of ON arms of the three-phase inverter is two, further 14. The method for charging a power battery as claimed in claim 13, further comprising the step of: the control module sending PWM control signals having a phase difference of 180 degrees to the two phase arms, respectively.

15. The step of the control module obtaining the number of arms of the three-phase inverter that are turned on based on the power to be charged of the power battery, and controlling the number of arms to operate based on the number of arms that are turned on, A method for charging a power battery according to any one of claims 11 to 14, comprising a step of determining that the number of arms of the three-phase inverter that are turned on is three when the control module detects that the power to be charged of the power battery is equal to or greater than a second predetermined power, and controlling the three-phase arms to operate simultaneously.

16. When the control module detects that the power to be charged of the power battery is equal to or greater than a second predetermined power, after the step of determining that the number of ON arms of the three-phase inverter is three, further transmitting PWM control signals having the same phase to three phase arms; Alternatively, the method for charging a power battery according to claim 15 includes a step of transmitting PWM control signals of different phases to three phase arms, and the phase of the PWM control signal of one phase arm is shifted by 120 degrees and -120 degrees from the phases of the PWM control signals of the other two phase arms, respectively.

17. A vehicle comprising the motor control circuit according to any one of claims 1 to 6.

Images