Multi - working - mode six - phase permanent - magnet synchronous motor drive system for electric vehicles

Abstract

The present invention relates to a multi-operation-mode six-phase permanent magnet synchronous motor drive system for electric vehicles, which includes a motor driver and a permanent magnet synchronous motor. The permanent magnet synchronous motor includes six-phase lines, a neutral line, a stator winding, a rotor permanent magnet, and a position sensor. Inside the motor driver, there are a positive bus P1, a positive bus P2, and a negative bus N. The motor driver is composed of a DC high-voltage input module, an inverter module, a switching module, and a control module. The DC high-voltage input module includes two external DC power input interfaces VH1 and VH2. The inverter module includes 2 inverters, and each inverter includes three-phase bridge arms and corresponding three-phase outputs. The switching module includes two bridge arms and corresponding two outputs. The control module is respectively connected to twelve switching devices of the 2 inverters and four switching devices in the switching module. Compared with the prior art, the present invention meets the requirements of multi-operation modes and improves the performance of electric vehicles and fuel cell vehicles.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle drive motors, and particularly to a multi-operation-mode six-phase permanent magnet synchronous motor drive system for electric vehicles. Background Art

[0002] To promote the development of sustainable energy and meet the growing energy demand, the development of the electric vehicle industry has received extensive attention. As one of the core components of the electric vehicle power system, the performance of the power battery directly affects the safety and reliability of the whole vehicle.

[0003] Currently, lithium-ion batteries are widely used in electric vehicles due to their high energy density and good charge-discharge cycle performance. However, their performance is significantly affected by low-temperature environments. For example, the internal resistance of the battery increases sharply, the available capacity and power are greatly reduced, resulting in problems such as shortened driving range and difficult charging of the vehicle. Moreover, the service life of the battery is shortened, and there are potential safety hazards. Therefore, the battery needs to be preheated at low temperatures before the vehicle starts. On the one hand, it is required that the battery pack be preheated accurately to eliminate the negative effects caused by low temperatures and ensure the overall performance of the battery within the full temperature range. On the other hand, it is necessary to reduce the energy loss during preheating, save energy fully, and reduce energy consumption.

[0004] The low-temperature preheating methods of power batteries can be divided into two types: external preheating and internal preheating according to the position of the main heat source during the preheating process. The heat required for external preheating is provided by an external heat source, and the heat is transferred through convection and heat conduction to achieve battery preheating. For example, heaters are installed in the battery or the battery coolant is heated. Internal preheating usually heats through battery pulse discharge or battery AC charge-discharge. It mainly uses the heat generated by the internal resistance of the battery itself for direct heating. Its advantage is that the electrolyte inside the battery is heated evenly, and there is no need to heat the electrolyte by increasing the temperature of the external battery case, thus avoiding complex heat transfer processes and heat losses during the process. The heating efficiency and effect are better than external heating, and rapid heating under high-rate charge-discharge conditions can be achieved. However, the power consumption required for the battery pulse discharge heating method is relatively large, and the efficiency is low. The decline in the discharge capacity of lithium-ion batteries in low-temperature environments will affect the heating effect. The battery AC charge-discharge heating method requires an external AC heating source or two independent energy storage devices in the system to meet the energy exchange during battery charge and discharge, and it is difficult to achieve low-temperature preheating of the battery through on-vehicle devices. Summary of the Invention

[0005] The purpose of the present invention is to overcome the above-mentioned defects existing in the prior art and provide a multi-operation-mode six-phase permanent magnet synchronous motor drive system for electric vehicles.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A multi - working - mode six - phase permanent - magnet synchronous motor drive system for electric vehicles. The system includes a motor driver and a permanent - magnet synchronous motor. Inside the motor driver, there are two independent positive busbars P1, P2 and a negative busbar N. The motor driver consists of a DC high - voltage input module, an inverter module, a switching module, and a control module;

[0008] The DC high - voltage input module includes two external DC power input interfaces for connecting to an external power supply. The positive pole of the high - voltage DC power interface VH1 is connected to the positive busbar P1, the negative pole of the high - voltage DC power interface VH1 is connected to the positive busbar P2, the positive pole of the high - voltage DC power interface VH2 is connected to the positive busbar P2, and the negative pole of the high - voltage DC power interface VH2 is connected to the negative busbar N;

[0009] The inverter module includes a first inverter and a second inverter. Each inverter component includes three - phase bridge arms and corresponding three - phase outputs. The three - phase bridge arms include a first - phase bridge arm, a second - phase bridge arm, and a third - phase bridge arm with the same structure. The three - phase outputs include a first - phase output, a second - phase output, and a third - phase output;

[0010] The switching module includes two bridge arms and corresponding two outputs. The bridge arms include a seventh bridge arm and an eighth bridge arm with the same structure. The two outputs include the output 7 corresponding to the seventh bridge arm and the output 8 corresponding to the eighth bridge arm;

[0011] The control module is respectively connected to twelve switching devices of the first inverter and the second inverter in the inverter module and four switching devices of the switching module, and performs combined control by sending signals to achieve different working modes of the motor drive system.

[0012] Furthermore, the three - phase bridge arms of the first inverter and the second inverter in the inverter module, and the seventh bridge arm and the eighth bridge arm of the switching module are each composed of two series - connected switching devices. The switching devices include diodes and switching tubes. The three - phase bridge arms of the first inverter and the seventh bridge arm of the switching module are both connected across the positive busbar P1 and the positive busbar P2. The three - phase bridge arms of the second inverter and the eighth bridge arm of the switching module are both connected across the positive busbar P2 and the negative busbar N. The three - phase outputs of the first inverter and the second inverter, and the outputs 7 and 8 of the switching module are respectively located between the two switching devices of each three - phase bridge arm, the seventh bridge arm, and the eighth bridge arm.

[0013] Furthermore, the permanent magnet synchronous motor includes a stator winding, a neutral line, six-phase lines, a rotor permanent magnet, and a position sensor. The permanent magnet synchronous motor is an 8-pole 48-slot six-phase motor. The stator winding includes three-phase stator windings A, B, and C and three-phase stator windings a, b, and c. The six-phase lines include three-phase lines A, B, and C and three-phase lines a, b, and c. The neutral line includes three-phase neutral lines A, B, and C and three-phase neutral lines a, b, and c. The phase belt angle of the six-phase stator winding is 120°, and the coil type of the motor stator winding is round wire.

[0014] Furthermore, the three-phase stator windings A, B, and C and the three-phase stator windings a, b, and c of the permanent magnet synchronous motor are all connected in a Y shape. One end of the three-phase stator windings A, B, and C is connected to the neutral points of the three phases A, B, and C. The three-phase lines A, B, and C include the lead wires of the three-phase stator windings A, B, and C respectively connected to the three-phase outputs of the first inverter of the inverter module. The neutral points of the three phases A, B, and C are connected to the output 7 of the seventh bridge arm of the switch module through the three-phase neutral lines A, B, and C. The three-phase lines a, b, and c include the lead wires of the three-phase stator windings a, b, and c respectively connected to the three-phase outputs of the second inverter of the inverter module. The neutral points of the three phases a, b, and c are connected to the output 8 of the eighth bridge arm of the switch module through the three-phase neutral lines a, b, and c. The position sensor is connected to the control module of the motor driver and sends a signal θ to it to obtain the relative position between the stator and the rotor of the motor.

[0015] Furthermore, the control module sends pulse width modulation PWM signals and switch control signals to the twelve switching devices of the inverter module and the four switching devices of the switch module. The pulse width modulation PWM signals include signals S1, S2, S3, S4, S5, and S6 for controlling the states of the six switching devices in the first inverter of the inverter module, and signals S7, S8, S9, S10, S11, and S12 for controlling the states of the six switching devices in the second inverter. The switch control signals include signals S13, S14, S15, and S16 for controlling the states of the four switching devices of the switch module, so as to realize different generation methods of the DC bus current and the six-phase current of the motor.

[0016] Furthermore, the operating modes of the six-phase permanent magnet synchronous motor drive system include:

[0017] Mode 1: Detection of the AC impedance of the power battery when the electric vehicle is in the parking state;

[0018] Mode 2: High-power high-frequency charge and discharge of the power battery when the electric vehicle is in the parking state.

[0019] Furthermore, when applying this system to realize the detection of the AC impedance of the battery in the parking state, there is:

[0020] The described high-voltage DC power supply interface is separately connected to an external power supply. The high-voltage DC power supply interface VH1 is connected to the upper package of the power battery pack, and the high-voltage DC power supply interface VH2 is connected to the lower package of the power battery pack. The control module is controlled by a motor current control method based on the target torque. The specific control process is as follows: By means of SVPWM (Space Vector Pulse Width Modulation) method, the switching tubes of the three-phase bridges of the first inverter and the second inverter of the inverter module are respectively driven, and the upper and lower switching tubes of the seventh and eighth bridge arms of the switching module are kept cut off. The control module sends PWM (Pulse Width Modulation) signals to the first inverter and the second inverter to respectively excite the A, B, C phases and the a, b, c phases of the permanent magnet synchronous motor. By using the reciprocating sliding of the motor current on the constant torque curve of the permanent magnet synchronous motor to cause the alternation of the motor armature magnetic energy, the A, B, C phase windings and the a, b, c phase windings respectively generate target torques with the same amplitude and opposite directions in the rotor. At the same time, an AC component is superimposed on the DC currents of the high-voltage DC power supply interfaces VH1 and VH2, so as to realize the high-frequency current injection of the power battery packs connected to the high-voltage DC power supply interfaces VH1 and VH2 under the condition that the permanent magnet synchronous motor has no actual torque output, thereby facilitating the AC impedance detection of the power battery packs.

[0021] Furthermore, when applying this system to achieve high-power high-frequency charge and discharge of the battery in the parking state, there is:

[0022] The control module realizes the charging from the upper package of the power battery pack connected to the external power supply of the high-voltage DC power supply interface VH1 to the lower package of the power battery pack connected to the external power supply of the high-voltage DC power supply interface VH2 and the charging from the lower package of the power battery pack connected to the external power supply of the high-voltage DC power supply interface VH2 to the upper package of the power battery pack connected to the external power supply of the high-voltage DC power supply interface VH1 respectively through the BUCK PWM (Pulse Width Modulation) mode and the BOOST PWM (Pulse Width Modulation) mode, that is, through the switching between the two to realize the bidirectional flow of current and electric energy between the upper package of the power battery pack connected to the external power supply of the high-voltage DC power supply interface VH1 and the lower package of the power battery pack connected to the external power supply of the high-voltage DC power supply interface VH2.

[0023] Furthermore, when the upper package of the power battery pack connected to the external power supply of the high-voltage DC power supply interface VH1 charges the lower package of the power battery pack connected to the external power supply of the high-voltage DC power supply interface VH2:

[0024] The described control module controls based on the first inverter BUCK PWM pulse width modulation mode and the second inverter BOOST PWM pulse width modulation mode of the inverter module. The target current in this control mode is the a, b, and c phase currents of the permanent magnet synchronous motor. The value of the target current is determined by the discharge demand of the external power battery pack of the upper pack of the high-voltage DC power supply interface VH1. The inverter equivalently represents the three groups of inductors of the permanent magnet synchronous motor, the switching tubes of the three-phase upper bridge arm of the first inverter in the inverter module, the diodes and switching tubes of the three-phase lower bridge arm, and the switching tube of the lower bridge arm of the seventh bridge arm of the switching module as three parallel BUCK circuits, and represents the three groups of inductors of the permanent magnet synchronous motor, the diodes of the three-phase upper bridge arm of the second inverter in the inverter module, the switching tubes of the three-phase lower bridge arm, and the diodes of the lower bridge arm of the eighth bridge arm of the switching module as three parallel BOOST circuits. The switching tubes of the first inverter of the inverter module are driven by three BUCK PWM signals to adjust the A, B, and C phase currents. Based on the electromagnetic induction law, a, b, and c phase currents opposite to the directions of the A, B, and C phase currents are generated. The switching tubes of the second inverter of the inverter module are driven by three BOOST PWM signals to adjust the a, b, and c phase currents, realizing the transfer of electrical energy from the external power battery pack of the upper pack of the high-voltage DC power supply interface VH1 to the external power battery pack of the lower pack of the high-voltage DC power supply interface VH2;

[0025] When the external power battery pack of the lower pack of the high-voltage DC power supply interface VH2 charges the external power battery pack of the upper pack of the high-voltage DC power supply interface VH1:

[0026] The described control module controls based on the BOOST PWM pulse width modulation mode of the first inverter and the BUCK PWM pulse width modulation mode of the second inverter in the inverter module. The target current in this control mode is the three-phase current of the permanent magnet synchronous motor, and the value of the target current is determined by the discharge demand of the external power battery pack of the lower pack of the high-voltage DC power supply interface VH2. The inverter equivalently represents the three sets of inductors of the permanent magnet synchronous motor, the switching tubes of the three-phase upper bridge arm of the second inverter in the inverter module, the diodes of the three-phase lower bridge arm, and the switching tube of the lower bridge arm of the eighth bridge arm of the switching module as three parallel BUCK circuits, and represents the three sets of inductors of the permanent magnet synchronous motor, the diodes of the three-phase upper bridge arm of the first inverter in the inverter module, the switching tubes of the three-phase lower bridge arm, and the diodes of the lower bridge arm of the seventh bridge arm of the switching module as three parallel BOOST circuits. The three-phase current of a, b, and c is regulated by driving the switching tubes of the second inverter in the inverter module with three BUCK PWM signals. Based on the electromagnetic induction law, three-phase currents of A, B, and C in the opposite direction of the three-phase currents of a, b, and c are generated. The three-phase currents of A, B, and C are regulated by driving the switching tubes of the first inverter in the inverter module with three BOOST PWM signals, realizing the transfer of electrical energy from the lower pack of the external power battery pack of the high-voltage DC power supply interface VH2 to the upper pack of the external power battery pack of the high-voltage DC power supply interface VH1.

[0027] Further, a 120° phase shift angle is inserted between the three BUCK PWM signals and between the BOOST PWM signals respectively to generate a smooth current waveform.

[0028] Compared with the prior art, the present invention has the following advantages:

[0029] (1) On the basis of satisfying the normal motor drive function, the present invention, through the combined control of the inverter in the inverter module by the control module, superimposes an AC component in the power battery pack and its external circuit, and at the same time enables the motor A, B, C phases and the a, b, c phase windings to generate target torques with the same amplitude and opposite directions in the rotor respectively, so as to facilitate the detection of the AC impedance of the power battery pack when the motor has no actual torque output.

[0030] (2) Through the combined control of the inverter module and the switching module by the control module, based on the electromagnetic induction principle, the present invention enables an induced current to be generated between the motor A, B, C phase windings and the a, b, c phase windings, and charges and discharges the battery pack through the external circuit of the power battery pack, thereby realizing high-power high-frequency charging and discharging of the power battery in the vehicle parking state.

[0031] (3) In the drive system of the present invention, there is no need to add an additional energy storage device or an external AC heating source. The energy exchange between the upper and lower battery packs of the power battery pack can be achieved through the mutual AC charging and discharging between the upper and lower battery packs, improving the performance of electric vehicles and fuel cell vehicles. Description of the Drawings

[0032] Figure 1 It is the circuit and energy flow diagram for AC impedance detection of the battery in the parking state in the embodiment of the present invention;

[0033] Figure 2 It is the circuit and energy flow diagram for high-power high-frequency charging and discharging of the battery in the parking state in the embodiment of the present invention (in the BUCK PWM pulse width modulation mode of the first inverter, the three-phase upper bridge arm switching tubes are turned on, in the BOOST PWM pulse width modulation mode of the second inverter, the three-phase lower bridge arm switching tubes are turned off, the lower bridge arm switching tube of the seventh bridge arm of the switching module is turned on, and the lower bridge arm switching tube of the eighth bridge arm is turned off);

[0034] Figure 3 It is the circuit and energy flow diagram for high-power high-frequency charging and discharging of the battery in the parking state in the embodiment of the present invention. Among them, in the BUCK PWM pulse width modulation mode of the first inverter, the three-phase upper bridge arm switching tubes are turned on, in the BOOST PWM pulse width modulation mode of the second inverter, the three-phase lower bridge arm switching tubes are turned on, the lower bridge arm switching tube of the seventh bridge arm of the switching module is turned on, and the lower bridge arm switching tube of the eighth bridge arm is turned off;

[0035] Figure 4 It is the circuit and energy flow diagram for high-power high-frequency charging and discharging of the battery in the parking state in the embodiment of the present invention. Among them, in the BUCK PWM pulse width modulation mode of the first inverter, the three-phase upper bridge arm switching tubes are turned off, in the BOOST PWM pulse width modulation mode of the second inverter, the three-phase lower bridge arm switching tubes are turned on, the lower bridge arm switching tube of the seventh bridge arm of the switching module is turned on, and the lower bridge arm switching tube of the eighth bridge arm is turned off;

[0036] Figure 5 It is the circuit and energy flow diagram for high-power high-frequency charging and discharging of the battery in the parking state in the embodiment of the present invention. Among them, in the BUCK PWM pulse width modulation mode of the first inverter, the three-phase upper bridge arm switching tubes are turned off, in the BOOST PWM pulse width modulation mode of the second inverter, the three-phase lower bridge arm switching tubes are turned off, the lower bridge arm switching tube of the seventh bridge arm of the switching module is turned on, and the lower bridge arm switching tube of the eighth bridge arm is turned off;

[0037] Figure 6This is the circuit and energy flow diagram for high-power high-frequency charging and discharging of the battery in the parking state in the embodiments of the present invention. Among them, in the BOOST PWM pulse width modulation mode of the first inverter, the three-phase lower arm switching tubes are turned off; in the BUCK PWM pulse width modulation mode of the second inverter, the three-phase upper arm switching tubes are turned on; the lower arm switching tube of the seventh arm of the switching module is turned off, and the lower arm switching tube of the eighth arm is turned on;

[0038] Figure 7 This is the circuit and energy flow diagram for high-power high-frequency charging and discharging of the battery in the parking state in the embodiments of the present invention. Among them, in the BOOST PWM pulse width modulation mode of the first inverter, the three-phase lower arm switching tubes are turned on; in the BUCK PWM pulse width modulation mode of the second inverter, the three-phase upper arm switching tubes are turned on; the lower arm switching tube of the seventh arm of the switching module is turned off, and the lower arm switching tube of the eighth arm is turned on;

[0039] Figure 8 This is the circuit and energy flow diagram for high-power high-frequency charging and discharging of the battery in the parking state in the embodiments of the present invention. Among them, in the BOOST PWM pulse width modulation mode of the first inverter, the three-phase lower arm switching tubes are turned on; in the BUCK PWM pulse width modulation mode of the second inverter, the three-phase upper arm switching tubes are turned off; the lower arm switching tube of the seventh arm of the switching module is turned off, and the lower arm switching tube of the eighth arm is turned on;

[0040] Figure 9 This is the circuit and energy flow diagram for high-power high-frequency charging and discharging of the battery in the parking state in the embodiments of the present invention. Among them, in the BOOST PWM pulse width modulation mode of the first inverter, the three-phase lower arm switching tubes are turned off; in the BUCK PWM pulse width modulation mode of the second inverter, the three-phase upper arm switching tubes are turned off; the lower arm switching tube of the seventh arm of the switching module is turned off, and the lower arm switching tube of the eighth arm is turned on;

[0041] Figure 10 This is the developed winding diagram of the permanent magnet synchronous motor in the embodiments of the present invention.

[0042] Figure 11 This is the schematic diagram of the structure topology of the present invention. Detailed implementation manners

[0043] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0044] Such as Figure 11As shown in the figure, the present invention provides a multi-mode six-phase permanent magnet synchronous motor drive system for electric vehicles. The system includes a motor driver 1 and a permanent magnet synchronous motor 2.

[0045] The motor driver 1 is composed of a DC high-voltage input module 11, an inverter module 12, a switching module 13 and a control module 14. Inside the motor driver 1, there are two independent positive buses P1, P2 and a negative bus N. The DC high-voltage input module 11 contains two external DC power input interfaces and supplies power to the inverter module 12 and the permanent magnet synchronous motor 2 through the positive and negative buses.

[0046] Specifically, the inverter module 12 includes a first inverter 121 and a second inverter 122. Each inverter component includes three-phase bridge arms and corresponding three-phase outputs. The three-phase bridge arms include a first-phase bridge arm, a second-phase bridge arm and a third-phase bridge arm with the same structure. The three-phase outputs include a first-phase output, a second-phase output and a third-phase output. Each phase of the three-phase bridge arms is composed of two series-connected switching devices. The switching devices include diodes and switching tubes. Each phase bridge arm of the first inverter 121 is connected across the positive bus P1 and the positive bus P2. The three switching devices close to the positive bus P1 form the three-phase upper bridge arm, and the three switching devices close to the positive bus P2 form the three-phase lower bridge arm. The first-phase output, the second-phase output and the third-phase output are respectively located between the two switching devices of the first-phase bridge arm, the second-phase bridge arm and the third-phase bridge arm. Each phase bridge arm of the second inverter 122 is connected across the positive bus P2 and the negative bus N. The three switching devices close to the positive bus P2 form the three-phase upper bridge arm, and the three switching devices close to the negative bus N form the three-phase lower bridge arm. The first-phase output, the second-phase output and the third-phase output are respectively located between the two switching devices of the first-phase bridge arm, the second-phase bridge arm and the third-phase bridge arm.

[0047] Specifically, the switch module 13 includes two bridge arms and corresponding two outputs. The bridge arms include a seventh bridge arm 131 and an eighth bridge arm 132 with the same structure. The two outputs include an output 7 corresponding to the seventh bridge arm 131 and an output 8 corresponding to the eighth bridge arm 132. Both the seventh bridge arm 131 and the eighth bridge arm 132 of the switch module 13 are respectively composed of two series-connected switching devices. The switching devices include diodes and switching tubes. The seventh bridge arm 131 is connected across the positive bus P1 and the positive bus P2. One switching device near the positive bus P1 forms the upper bridge arm, and one switching device near the positive bus P2 forms the lower bridge arm. The output 7 is located between the seventh bridge arm 131 and the two switching devices of the seventh bridge arm 131. The eighth bridge arm 132 is connected across the positive bus P2 and the negative bus N. One switching device near the positive bus P2 forms the upper bridge arm, and one switching device near the negative bus N forms the lower bridge arm. The output 8 is located between the eighth bridge arm 132 and the two switching devices of the eighth bridge arm 132.

[0048] Specifically, the control module 14 performs combined control on the switching states of the twelve switching devices of the inverter module 12 and the four switching devices of the switch module 13 by sending pulse width modulation signals (PWM) and switching signals, so as to realize different DC bus current and motor six-phase current generation modes.

[0049] Specifically, the permanent magnet synchronous motor 2 includes a stator winding 21, a neutral line 22, six-phase lines 23, a rotor permanent magnet 24, and a position sensor 25.

[0050] Specifically, the permanent magnet synchronous motor 2 is an 8-pole 48-slot six-phase motor. The stator winding 21 includes three-phase stator windings A, B, and C and three-phase stator windings a, b, and c. The phase belt angle of the six-phase stator winding is 120°, and it can be regarded as two sets of double three-phase motors with a phase shift of 0°. The coil type of the motor stator winding 21 is round wire.

[0051] Specifically, the neutral line 22 includes three-phase neutral lines 222 of A, B, and C and three-phase neutral lines 221 of a, b, and c.

[0052] Specifically, the six-phase lines 23 include an A-phase line 231, a B-phase line 232, a C-phase line 233, an a-phase line 234, a b-phase line 235, and a c-phase line 236.

[0053] As Figure 10 shown in the developed view of the permanent magnet synchronous motor winding, in the developed view of the winding, the U, V, and W phases respectively correspond to the A, B, and C phases, and the X, Y, and Z phases respectively correspond to the a, b, and c phases.

[0054] Specifically, the three-phase leads A, B, and C of the stator winding of the permanent magnet synchronous motor 2 are respectively connected to the three-phase outputs of the first inverter 121 of the inverter module 12 in the motor driver 1. The neutral lines 222 of the three phases A, B, and C are introduced into the motor driver 1 and connected to the output 7 of the seventh bridge arm 131 of the switch module 13 inside the motor driver 1. The three-phase leads a, b, and c of the stator winding of the permanent magnet synchronous motor 2 are respectively connected to the three-phase outputs of the second inverter 122 of the inverter module 12 in the machine driver. The neutral lines 221 of the three phases a, b, and c are introduced into the motor driver 1 and connected to the output 8 of the eighth bridge arm 132 of the switch module 13 inside the motor driver 1. The signal θ of the position sensor 25 of the permanent magnet synchronous motor 2 is directly connected to the control module 14 of the motor driver 1 and sends the signal θ to it to obtain the relative position between the stator and the rotor of the motor. The rotor permanent magnet 24 of the permanent magnet synchronous motor 2 is made of ferrite or samarium cobalt-based high-resistivity materials.

[0055] As Figure 1 shown in the embodiment of the circuit and energy flow diagram for detecting the AC impedance of the battery in the parking state, the high-voltage DC power supply interface is externally connected to the power battery pack for independent power supply. The high-voltage DC power supply interface VH1 is connected to the upper pack of the power battery pack, and the high-voltage DC power supply interface VH2 is connected to the lower pack of the power battery pack. The control module 14 is controlled by a motor current control method based on the target torque.

[0056] Specifically, the switching tubes of the three-phase bridge arms of the first inverter 121 and the second inverter 122 of the inverter module 12 are respectively driven by the SVPWM (Space Vector Pulse Width Modulation) method, and the upper and lower switching tubes of the seventh bridge arm 131 and the eighth bridge arm 132 of the switching module 13 are kept cut off. Taking the SVPWM (1 0 0) switching state as an example, the control module 14 sends Pulse Width Modulation (PWM) signals to the first inverter 121 and the second inverter 122 to respectively excite the A, B, and C phases and the a, b, and c phases of the permanent magnet synchronous motor. For the upper pack of the power battery pack, electrical energy flows from the high-voltage DC power interface VH1 through the positive bus P1 to the upper switching tube of the first-phase bridge arm of the first inverter 121, then through the first-phase output to the A-phase winding of the motor - the neutral point of the A, B, and C phases - the B and C phase windings - the lower switching tubes of the second and third-phase bridge arms of the first inverter 121, and finally flows back to the high-voltage DC power interface VH1 through the positive bus P2; for the lower pack of the power battery pack, electrical energy flows from the high-voltage DC power interface VH2 through the positive bus P2 to the upper switching tube of the first-phase bridge arm of the second inverter 122, then through the first-phase output to the a-phase winding of the motor - the neutral point of the a, b, and c phases - the b and c phase windings - the lower switching tubes of the second and third-phase bridge arms of the second inverter 122, and finally flows back to the high-voltage DC power interface VH2 through the negative bus N. Voltage vectors of (1 0 0) are respectively generated in the A, B, and C phases and the a, b, and c phases. The first inverter 121 and the second inverter 122 can also be controlled according to the switching states of (0 1 0), (0 0 1), (1 1 0), (1 0 1), (0 1 1), (1 1 1), and (0 0 0) to generate voltage vectors corresponding to each switching state, so as to guide the magnetic fluxes of the A, B, and C phases and the a, b, and c phases of the motor stator to form a quasi-circular trajectory. Furthermore, the A, B, and C phases and the a, b, and c phases of the six-phase permanent magnet synchronous motor are respectively excited in the way of controlling the three-phase permanent magnet synchronous motor. By using the reciprocating sliding of the motor current on the constant torque curve of the permanent magnet synchronous motor 2 to cause the alternation of the armature magnetic energy of the motor, target torques with the same amplitude but opposite directions are respectively generated in the A, B, and C phases and the a, b, and c phases. At the same time, an AC component is superimposed on the DC currents of the high-voltage DC power interfaces VH1 and VH2 to realize the high-frequency current injection of the power battery packs connected to the high-voltage DC power interfaces VH1 and VH2 under the condition that the permanent magnet synchronous motor 2 has no actual torque output, so as to facilitate the AC impedance detection of the power battery packs.

[0057] Specifically, the energy conversion of the whole process is as follows: the electrical energy of the upper pack of the power battery pack connected to the high-voltage DC power interface VH1 and the lower pack of the power battery pack connected to the high-voltage DC power interface VH2 is converted into the mechanical energy of the permanent magnet synchronous motor 2, and there are changes in the armature magnetic energy of the A, B, and C phase windings and the a, b, and c phase windings of the motor.

[0058] Such as Figure 2 , Figure 3 ,Figure 4 , Figure 5 , Figure 6 , Figure 7 , Figure 8 , Figure 9 In the embodiment shown, the circuit and energy flow diagram for high-power high-frequency charging and discharging of the battery in the parking state. The high-voltage DC power supply interface is externally connected to the power battery pack for independent power supply. The high-voltage DC power supply interface VH1 is connected to the upper package of the power battery pack, and the high-voltage DC power supply interface VH2 is connected to the lower package of the power battery pack. The control module 14 realizes the charging of the external power battery pack of the high-voltage DC power supply interface VH2 from the external power battery pack of the high-voltage DC power supply interface VH1 and the charging of the external power battery pack of the high-voltage DC power supply interface VH1 from the external power battery pack of the high-voltage DC power supply interface VH2 through the BUCK PWM pulse width modulation mode and the BOOST PWM pulse width modulation mode respectively. A 120° phase shift angle is inserted between the three-way BUCK PWM / BOOST PWM signals of the first inverter 121 and the second inverter 122 to reduce the high-frequency current ripple.

[0059] Specifically, as Figure 2 , Figure 3 , Figure 4 , Figure 5 shown, the specific process of the control module 14 controlling based on the BUCK PWM pulse width modulation mode of the first inverter 121 and the BOOST PWM pulse width modulation mode of the second inverter 122 in the inverter module 12 is as follows:

[0060] The control module 14 controls based on the three-phase current control mode of motors A, B, and C. Under this control mode, the target current is the three-phase current of the permanent magnet synchronous motor 2, and the value of the target current is determined by the discharge demand of the external power battery pack of the upper pack of the high-voltage DC power supply interface VH1. The inverter equivalently represents the three groups of inductors of the permanent magnet synchronous motor 2, the switching tubes of the three-phase upper bridge arm of the first inverter 121 in the inverter module 12, the diodes and switching tubes of the three-phase lower bridge arm of the seventh bridge arm 131 of the switching module 13 as three parallel BUCK circuits, and represents the three groups of inductors of the permanent magnet synchronous motor 2, the diodes of the three-phase upper bridge arm of the second inverter 122 in the inverter module 12, the switching tubes of the three-phase lower bridge arm, and the diodes of the lower bridge arm of the eighth bridge arm 132 of the switching module 13 as three parallel BOOST circuits. The switching tubes of the first inverter 121 of the inverter module 12 are driven by three-way BUCK PWM signals to adjust the three-phase current of A, B, and C. Based on the electromagnetic induction law, three-phase currents of a, b, and c in the opposite direction of the three-phase currents of A, B, and C are generated. The switching tubes of the second inverter 122 of the inverter module 12 are driven by three-way BOOST PWM signals to adjust the three-phase current of a, b, and c, realizing the transfer of electrical energy from the external power battery pack of the upper pack of the high-voltage DC power supply interface VH1 to the external power battery pack of the lower pack of the high-voltage DC power supply interface VH2.

[0061] Specifically, as Figure 6 , Figure 7 , Figure 8 , Figure 9 shown, the specific process of the control module 14 controlling based on the BOOST PWM pulse width modulation mode of the first inverter 121 of the inverter module 12 and the BUCK PWM pulse width modulation mode of the second inverter 122 is as follows:

[0062] The control module 14 controls based on the control method of the three-phase currents of motors a, b, and c. The target currents in this control method are the three-phase currents of the permanent magnet synchronous motor 2, namely A, B, and C phases. The values of the target currents are determined by the discharge demand of the external power battery pack of the lower pack of the high-voltage DC power supply interface VH2. The inverter equivalently represents the three groups of inductors of the permanent magnet synchronous motor 2, the switching tubes of the three-phase upper bridge arms of the second inverter 122 in the inverter module 12, the diodes of the three-phase lower bridge arms, and the switching tubes of the lower bridge arm of the eighth bridge arm 132 of the switching module 13 as three parallel BUCK circuits, and represents the three groups of inductors of the permanent magnet synchronous motor 2, the diodes of the three-phase upper bridge arms of the first inverter 121 in the inverter module 12, the switching tubes of the three-phase lower bridge arms, and the diodes of the lower bridge arm of the seventh bridge arm 131 of the switching module 13 as three parallel BOOST circuits. The switching tubes of the second inverter 122 in the inverter module 12 are driven by three BUCK PWM signals to adjust the three-phase currents of a, b, and c. Based on the electromagnetic induction law, three-phase currents of A, B, and C opposite to the directions of the three-phase currents of a, b, and c are generated. The switching tubes of the first inverter 121 in the inverter module 12 are driven by three BOOST PWM signals to adjust the three-phase currents of A, B, and C, realizing the transfer of electrical energy from the external power battery pack of the lower pack of the high-voltage DC power supply interface VH2 to the external power battery pack of the upper pack of the high-voltage DC power supply interface VH1;

[0063] Specifically, as Figure 2 shown, when the switching tubes of the three-phase upper bridge arms of the first inverter 121 in the inverter module 12 and the switching tubes of the lower bridge arm of the seventh bridge arm 131 of the switching module 13 are turned on, and at the same time the switching tubes of the three-phase lower bridge arms of the second inverter 122 and the switching tubes of the lower bridge arm of the eighth bridge arm 132 of the switching module 13 are turned off, electrical energy flows from the high-voltage DC power supply interface VH1 through the switching tubes of the three-phase upper bridge arms of the first inverter 121 to the A, B, and C phase inductors of the permanent magnet synchronous motor 2. At this time, the A, B, and C phase inductors convert the electrical energy into magnetic field energy storage, causing the current flowing through the inductors to increase. Based on the electromagnetic induction law, the a, b, and c phase inductors of the motor induce reverse electromotive forces. At this time, the a, b, and c phase inductors convert the magnetic field energy storage into electrical energy and generate induced currents opposite to the directions in the A, B, and C phases, causing the current flowing through the a, b, and c phase inductors to increase. At this time, the induced current flows from the a, b, and c phase inductors of the motor through the diodes of the three-phase upper bridge arms of the second inverter 122 in the inverter module 12 to the high-voltage DC power supply interface VH2, and the high-voltage DC power supply interface VH1 charges the high-voltage DC power supply interface VH2;

[0064] Specifically, as Figure 3As shown, when the switching tubes of the three-phase upper bridge arm of the first inverter 121 in the inverter module 12 and the switching tubes of the lower bridge arm of the seventh bridge arm 131 of the switching module 13 are turned on, the switching tubes of the lower bridge arm of the eighth bridge arm 132 of the switching module 13 are turned off, and at the same time the switching tubes of the three-phase lower bridge arm of the second inverter 122 in the inverter module 12 are turned on, at this time, the magnetic field energy storage is converted into electrical energy through the a, b, and c phase inductors, and the induced current generated flows from the a, b, and c phase inductors of the motor through the three-phase lower bridge arm of the second inverter 122 in the inverter module 12 to the diode of the lower bridge arm of the eighth bridge arm 132 of the switching module 13, and then flows through the a, b, and c three-phase neutral line 221 to the a, b, and c phase inductors of the motor;

[0065] Specifically, as Figure 4 shown, when the switching tubes of the lower bridge arm of the seventh bridge arm 131 of the switching module 13 are turned on, the switching tubes of the lower bridge arm of the eighth bridge arm 132 of the switching module 13 are turned off, the switching tubes of the three-phase lower bridge arm of the second inverter 122 in the inverter module 12 are turned on, and at the same time the switching tubes of the three-phase upper bridge arm of the first inverter 121 are turned off, the diodes of the three-phase lower bridge arm of the first inverter 121 conduct freewheeling, the A, B, and C phase inductors continuously release energy and maintain the current flow direction unchanged, convert electrical energy into magnetic field energy storage, and then convert the magnetic field energy storage into electrical energy through the a, b, and c phase inductors, generating an induced current that flows from the a, b, and c phase inductors of the motor through the three-phase lower bridge arm of the second inverter 122 in the inverter module 12 to the diode of the lower bridge arm of the eighth bridge arm 132 of the switching module 13, and then flows back to the a, b, and c phase inductors of the motor through the a, b, and c three-phase neutral line 221, and the energy is stored in the a, b, and c phase inductors;

[0066] Specifically, as Figure 5 shown, when the switching tubes of the lower bridge arm of the seventh bridge arm 131 of the switching module 13 are turned on, the switching tubes of the lower bridge arm of the eighth bridge arm 132 of the switching module 13 are turned off, the switching tubes of the three-phase upper bridge arm of the first inverter 121 are turned off, and at the same time the switching tubes of the three-phase lower bridge arm of the second inverter 122 in the inverter module 12 are turned off, the a, b, and c phase inductors release energy, maintain the current flow direction unchanged, and the induced current flows from the a, b, and c phase inductors of the motor through the three-phase upper bridge arm diodes of the second inverter 122 in the inverter module 12 to the high-voltage DC power interface VH2. Since the current decreases, electromotive forces are induced in the motor A, B, and C phase inductors and the a, b, and c phase inductors, and the A, B, and C phase inductors are connected in parallel with the a, b, and c phase inductors to jointly charge the high-voltage DC power interface VH2.

[0067] Specifically, as Figure 6As shown, when the switching tubes of the three-phase lower arm of the first inverter 121 in the inverter module 12 are turned off, and at the same time the switching tubes of the three-phase upper arm of the second inverter 122 are switched from off to on, and the switching tubes of the lower arm of the seventh bridge arm 131 of the switching module 13 are turned off, and the switching tubes of the lower arm of the eighth bridge arm 132 of the switching module 13 are turned on, electrical energy flows from the high-voltage DC power supply interface VH2 through the switching tubes of the three-phase upper arm of the second inverter 122 to the a, b, and c phase inductors of the permanent magnet synchronous motor 2. At this time, the a, b, and c phase inductors convert the electrical energy into magnetic field energy storage, causing the current flowing through the inductors to increase. Based on the electromagnetic induction law, the motor's A, B, and C phase inductors induce a reverse electromotive force. At this time, the A, B, and C phase inductors convert the magnetic field energy storage into electrical energy and generate an induced current in the opposite direction to that in the a, b, and c phases, causing the current flowing through the A, B, and C phase inductors to increase. At this time, the induced current flows from the A, B, and C phase inductors of the motor through the diodes of the three-phase upper arm of the first inverter 121 in the inverter module 12 to the high-voltage DC power supply interface VH1, and the high-voltage DC power supply interface VH2 charges the high-voltage DC power supply interface VH1;

[0068] Specifically, as Figure 7 shown, when the switching tubes of the three-phase upper arm of the second inverter 122 in the inverter module 12 and the switching tubes of the lower arm of the eighth bridge arm 132 of the switching module 13 are turned on, the switching tubes of the lower arm of the seventh bridge arm 131 of the switching module 13 are turned off, and at the same time the switching tubes of the three-phase lower arm of the first inverter 121 are turned on, at this time the magnetic field energy storage is converted into electrical energy through the A, B, and C phase inductors and the generated induced current flows from the A, B, and C phase inductors of the motor through the three-phase lower arm of the first inverter 121 in the inverter module 12 to the diodes of the lower arm of the seventh bridge arm 131 of the switching module 13, and then flows through the A, B, and C three-phase neutral lines 222 to the A, B, and C phase inductors of the motor;

[0069] Specifically, as Figure 8 shown, when the switching tubes of the lower arm of the eighth bridge arm 132 of the switching module 13 are turned on, the switching tubes of the lower arm of the seventh bridge arm 131 of the switching module 13 are turned off, the switching tubes of the three-phase lower arm of the first inverter 121 in the inverter module 12 are turned on, and at the same time the switching tubes of the three-phase upper arm of the second inverter 122 are turned off, the diodes of the three-phase lower arm of the second inverter 122 conduct freewheeling, the a, b, and c phase inductors continuously release energy and maintain the current flow direction therein unchanged, convert the electrical energy into magnetic field energy storage, and then convert the magnetic field energy storage into electrical energy through the A, B, and C phase inductors, generating an induced current that flows from the A, B, and C phase inductors of the motor through the three-phase lower arm of the first inverter 121 in the inverter module 12 to the diodes of the lower arm of the seventh bridge arm 131 of the switching module 13, and then flows back to the A, B, and C phase inductors of the motor through the A, B, and C three-phase neutral lines 222, and the energy is stored in the A, B, and C phase inductors;

[0070] Specifically, as Figure 9As shown, when the switch tube of the lower arm of the eighth bridge arm 132 of the switch module 13 is turned on, the switch tube of the lower arm of the seventh bridge arm 131 of the switch module 13 is turned off, the switch tubes of the three-phase upper arms of the second inverter 122 are turned off, and at the same time, when the switch tubes of the three-phase lower arms of the first inverter 121 of the inverter module 12 are turned off, the inductors of phases A, B, and C release energy to maintain the current flow direction unchanged. The induced current flows from the inductors of phases A, B, and C of the motor through the three-phase upper-arm diodes of the first inverter 121 of the inverter module 12 to the high-voltage DC power supply interface VH1. Since the current decreases, electromotive forces are induced in the inductors of phases A, B, and C and a, b, and c of the motor. The inductors of phases A, B, and C are connected in parallel with the inductors of phases a, b, and c to charge the high-voltage DC power supply interface VH1 together;

[0071] As described above, the above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any staff familiar with the technical field of the present invention can easily think of various equivalent modifications or substitutions within the technical scope disclosed by the present invention, and these modifications or substitutions should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A multi-operation-mode six-phase permanent magnet synchronous motor drive system for an electric vehicle, the system comprising a motor driver (1) and a permanent magnet synchronous motor (2), characterized in that, The interior of the described motor driver (1) includes two independent positive busbars P1, P2 and one negative busbar N. The described motor driver (1) consists of a DC high-voltage input module (11), an inverter module (12), a switch module (13), and a control module (14). The described DC high-voltage input module (11) includes two external DC power input interfaces, namely a high-voltage DC power interface VH1 and a high-voltage DC power interface VH2, for connecting to an external power source. The positive pole of the high-voltage DC power interface VH1 is connected to the positive busbar P1, the negative pole of the high-voltage DC power interface VH1 is connected to the positive busbar P2, the positive pole of the high-voltage DC power interface VH2 is connected to the positive busbar P2, and the negative pole of the high-voltage DC power interface VH2 is connected to the negative busbar N. The described inverter module (12) includes a first inverter (121) and a second inverter (122). Each inverter component includes three-phase bridge arms and corresponding three-phase outputs. The three-phase bridge arms include a first-phase bridge arm, a second-phase bridge arm, and a third-phase bridge arm with the same structure. The three-phase outputs include a first-phase output, a second-phase output, and a third-phase output. The described switch module (13) includes two bridge arms and corresponding two outputs. The bridge arms include a seventh bridge arm (131) and an eighth bridge arm (132) with the same structure. The two outputs include an output 7 corresponding to the seventh bridge arm (131) and an output 8 corresponding to the eighth bridge arm (132). The described control module (14) is respectively connected to twelve switching devices of the first inverter (121) and the second inverter (122) in the inverter module (12) and four switching devices of the switch module (13), and performs combined control by sending signals to achieve different working modes of the motor drive system. The working modes of the described six-phase permanent magnet synchronous motor drive system include: Mode 1: Detection of the AC impedance of the power battery when the electric vehicle is in the parked state. Mode 2: High-power high-frequency charging and discharging of the power battery when the electric vehicle is in the parked state.

2. The multi-mode six-phase permanent magnet synchronous motor drive system for electric vehicles according to claim 1, wherein The three-phase bridge arms of the first inverter (121) and the second inverter (122) in the described inverter module (12), and the seventh bridge arm (131) and the eighth bridge arm (132) of the switch module (13) are each composed of two series-connected switching devices. The switching devices include diodes and switching tubes. The three-phase bridge arms of the first inverter (121) and the seventh bridge arm (131) of the switch module (13) are both connected across the positive busbar P1 and the positive busbar P2. The three-phase bridge arms of the second inverter (122) and the eighth bridge arm (132) of the switch module (13) are both connected across the positive busbar P2 and the negative busbar N. The three-phase outputs of the first inverter (121) and the second inverter (122), and the output 7 and output 8 of the switch module (13) are respectively located between the two switching devices of each three-phase bridge arm and the seventh bridge arm (131) and the eighth bridge arm (132).

3. The multi-mode six-phase permanent magnet synchronous motor drive system for an electric vehicle according to claim 1, wherein The described permanent magnet synchronous motor (2) includes a stator winding (21), a neutral line (22), a six-phase line (23), a rotor permanent magnet (24), and a position sensor (25). The permanent magnet synchronous motor (2) is an 8-pole 48-slot six-phase motor. The stator winding (21) includes three-phase stator windings A, B, and C and three-phase stator windings a, b, and c. The phase belt angle of the six-phase stator winding is 120°. The coil type of the stator winding (21) is round wire. The neutral line (22) includes three-phase neutral lines (222) of A, B, and C and three-phase neutral lines (221) of a, b, and c. The six-phase line (23) includes phase A line (231), phase B line (232), phase C line (233), phase a line (234), phase b line (235), and phase c line (236).

4. The multi-mode six-phase permanent magnet synchronous motor drive system for an electric vehicle according to claim 3, wherein The three-phase stator windings of A, B, and C and the three-phase stator windings of a, b, and c of the permanent magnet synchronous motor are all connected in a Y shape. One end of the three-phase stator windings of A, B, and C is connected to the neutral points of A, B, and C. The three-phase lines of A, B, and C include the lead-out wires of the three-phase stator windings of phase A, phase B, and phase C that are respectively connected to the three-phase outputs of the first inverter (121) of the inverter module (12). The neutral points of A, B, and C are connected to the output 7 of the seventh bridge arm (131) of the switch module (13) through the three-phase neutral lines (222) of A, B, and C. The three-phase lines of a, b, and c include the lead-out wires of the three-phase stator windings of phase a, phase b, and phase c that are respectively connected to the three-phase outputs of the second inverter (122) of the inverter module (12). The neutral points of a, b, and c are connected to the output 8 of the eighth bridge arm (132) of the switch module (13) through the three-phase neutral lines (221) of a, b, and c. The position sensor (25) is connected to the control module (14) of the motor driver (1) and sends a signal θ to it to obtain the relative position between the motor stator and the rotor.

5. The multi-mode six-phase permanent magnet synchronous motor drive system for an electric vehicle according to claim 1, characterized in that, The control module (14) sends pulse width modulation PWM signals and switch control signals to the twelve switching devices of the inverter module (12) and the four switching devices of the switch module (13). The pulse width modulation PWM signals include signals S1, S2, S3, S4, S5, and S6 that control the states of the six switching devices in the first inverter (121) of the inverter module (12), and signals S7, S8, S9, S10, S11, and S12 that control the states of the six switching devices in the second inverter (122). The switch control signals include signals S13, S14, S15, and S16 that control the states of the four switching devices of the switch module (13) to achieve different generation methods of the DC bus current and the motor six-phase current.

6. The multi-mode six-phase permanent magnet synchronous motor drive system for an electric vehicle according to claim 1, wherein, When applying this system to detect the AC impedance of the battery in the parking state, there is:[ The described high-voltage DC power supply interface is separately connected to an external power supply. The high-voltage DC power supply interface VH1 is connected to the upper package of the power battery pack, and the high-voltage DC power supply interface VH2 is connected to the lower package of the power battery pack. The control module (14) is controlled by a motor current control method based on the target torque. The specific control process is as follows: The switching tubes of the three-phase bridge arms of the first inverter (121) and the second inverter (122) of the inverter module (12) are respectively driven through the SVPWM (Space Vector Pulse Width Modulation) method, and the upper and lower switching tubes of the seventh bridge arm (131) and the eighth bridge arm (132) of the switching module (13) are kept cut off. The control module (14) sends PWM (Pulse Width Modulation) signals to the first inverter (121) and the second inverter (122) to respectively excite the stator windings of the A, B, C phases and the a, b, c phases of the permanent magnet synchronous motor. By using the reciprocating sliding of the motor current on the constant torque curve of the permanent magnet synchronous motor (2) to cause the alternation of the motor armature magnetic energy, the target torques with the same amplitude and opposite directions are respectively generated in the rotor by the stator windings of the A, B, C phases and the a, b, c phases. At the same time, an AC component is superimposed on the DC currents of the high-voltage DC power supply interfaces VH1 and VH2, so as to realize the high-frequency current injection of the power battery pack connected to the high-voltage DC power supply interfaces VH1 and VH2 under the condition that the permanent magnet synchronous motor (2) has no actual torque output, thereby facilitating the AC impedance detection of the power battery pack.

7. A multi-mode six-phase permanent magnet synchronous motor drive system for an electric vehicle according to claim 1, characterized in that, When applying this system to achieve high-power high-frequency charge and discharge of the battery in the parking state, there is: The control module (14) respectively realizes the charging of the lower package of the power battery pack of the external power supply of the high-voltage DC power supply interface VH2 from the upper package of the power battery pack of the external power supply of the high-voltage DC power supply interface VH1 and the charging of the upper package of the power battery pack of the external power supply of the high-voltage DC power supply interface VH1 from the lower package of the power battery pack of the external power supply of the high-voltage DC power supply interface VH2 through the BUCK PWM (Pulse Width Modulation) mode and the BOOST PWM (Pulse Width Modulation) mode, that is, the bidirectional flow of current and electric energy between the upper package of the power battery pack of the external power supply of the high-voltage DC power supply interface VH1 and the lower package of the power battery pack of the external power supply of the high-voltage DC power supply interface VH2 is realized through the switching between the two.

8. A multi-mode six-phase permanent magnet synchronous motor drive system for an electric vehicle according to claim 7, characterized in that, When the upper package of the power battery pack of the external power supply of the high-voltage DC power supply interface VH1 charges the lower package of the power battery pack of the external power supply of the high-voltage DC power supply interface VH2: The described control module (14) is controlled based on the BUCK PWM pulse width modulation mode of the first inverter (121) and the BOOST PWM pulse width modulation mode of the second inverter (122) of the inverter module (12). The target current in this control mode is the a, b, and c phase currents of the permanent magnet synchronous motor. The value of the target current is determined by the discharge demand of the external power battery pack of the upper pack of the high-voltage DC power supply interface VH1. The inverter equates the A, B, and C groups of inductors of the permanent magnet synchronous motor (2), the switching tubes of the three-phase upper bridge arm and the diodes and switching tubes of the three-phase lower bridge arm of the first inverter (121) in the inverter module (12), and the switching tube of the lower bridge arm of the seventh bridge arm (131) of the switching module (13) to three parallel BUCK circuits, and equates the a, b, and c groups of inductors of the permanent magnet synchronous motor (2), the diodes of the three-phase upper bridge arm and the switching tubes of the three-phase lower bridge arm of the second inverter (122) in the inverter module (12), and the diodes of the lower bridge arm of the eighth bridge arm (132) of the switching module (13) to three parallel BOOST circuits. The switching tubes of the first inverter (121) of the inverter module (12) are driven by three BUCK PWM signals to adjust the A, B, and C phase currents. Based on the electromagnetic induction law, a, b, and c phase currents opposite to the directions of the A, B, and C phase currents are generated. The switching tubes of the second inverter (122) of the inverter module (12) are driven by three BOOST PWM signals to adjust the a, b, and c phase currents, realizing the transfer of electrical energy from the external power battery pack of the upper pack of the high-voltage DC power supply interface VH1 to the external power battery pack of the lower pack of the high-voltage DC power supply interface VH2; When the external power battery pack of the lower pack of the high-voltage DC power supply interface VH2 charges the external power battery pack of the upper pack of the high-voltage DC power supply interface VH1: The described control module (14) is controlled based on the BOOST PWM pulse width modulation mode of the first inverter (121) and the BUCK PWM pulse width modulation mode of the second inverter (122) of the inverter module (12). The target current in this control mode is the three-phase current of the A, B, and C phases of the permanent magnet synchronous motor. The value of the target current is determined by the discharge demand of the external power battery pack of the lower pack of the high-voltage DC power supply interface VH2. The inverter equivalently represents the three groups of inductors of the a, b, and c phases of the permanent magnet synchronous motor (2), the switching tubes of the three-phase upper bridge arm and the diodes and switching tubes of the three-phase lower bridge arm of the second inverter (122) in the inverter module (12), and the switching tubes of the lower bridge arm of the eighth bridge arm (132) of the switching module (13) as three parallel BUCK circuits, and represents the three groups of inductors of the A, B, and C phases of the permanent magnet synchronous motor (2), the diodes of the three-phase upper bridge arm and the switching tubes of the three-phase lower bridge arm of the first inverter (121) in the inverter module (12), and the diodes of the lower bridge arm of the seventh bridge arm (131) of the switching module (13) as three parallel BOOST circuits. The switching tubes of the second inverter (122) of the inverter module (12) are driven by three BUCK PWM signals to adjust the a, b, and c three-phase currents. Based on the electromagnetic induction law, three-phase currents of the A, B, and C phases that are opposite to the directions of the a, b, and c three-phase currents are generated. The switching tubes of the first inverter (121) of the inverter module (12) are driven by three BOOST PWM signals to adjust the A, B, and C three-phase currents, realizing the transfer of electrical energy from the external power battery pack of the lower pack of the high-voltage DC power supply interface VH2 to the external power battery pack of the upper pack of the high-voltage DC power supply interface VH1.

9. The multi-mode six-phase permanent magnet synchronous motor drive system for an electric vehicle according to claim 8, wherein, A 120° phase shift angle is inserted between the three BUCK PWM signals and between the BOOST PWM signals respectively to generate a smooth current waveform.

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