Electric vehicle three-motor drive system with integrated charging function and working method thereof

Abstract

The present invention discloses a three-motor drive system of an electric vehicle with an integrated charging function and a working method thereof. The system includes a main charging interface, a secondary charging input interface 1, a secondary charging input interface 2, a five-phase mode switcher, a three-phase mode switcher 1, a three-phase mode switcher 2, a five-phase HEFS motor drive unit, two three-phase HEFS motor drive units, a power battery pack and a common bus, wherein the main charging interface is connected to the five-phase HEFS motor drive unit through a five-phase mode switcher, and the two secondary charging interfaces are connected to the two three-phase HEFS motor drive units one by one through a three-phase mode switcher, respectively, and the five-phase HEFS motor drive unit and the two three-phase HEFS motor drive units share a common bus in parallel with the power battery pack, and bus capacitors are connected in parallel on both sides of the common bus. While proposing a high-performance drive architecture for electric vehicles that has the advantages of both centralized and distributed drives, the present invention also provides a flexible and flexible high-power on-board charging solution for electric vehicles.

Description

Technical Field

[0001] The present invention belongs to the technical field of three-motor driven electric vehicle system integration, and specifically relates to an electric vehicle three-motor drive system with integrated charging function and a working method thereof. Background Art

[0002] As for the driving technology of new energy vehicles, after three five-year plans of continuous technical research, the three basic key technologies of "battery, motor, and electronic control" have developed rapidly, and indicators such as power battery energy density and drive motor power density are at the international leading level. At present, the number of new energy vehicles in my country has exceeded 13.1 million, but the cumulative number of existing charging infrastructure is only 5.2 million, which cannot fully meet the charging needs. Therefore, the development of a convenient, low-cost, high-power on-board charging system is a breakthrough to continuously promote the development of the new energy vehicle industry.

[0003] In this context, a type of "Integrated Motor-Driving & Onboard Charging" (IMDOC) system that time-shares the motor windings and their inverters, with one set of hardware and two functions, has received great attention from the industry and academia. This type of system only needs to add a small number or no power devices to meet the vehicle's power charging needs. However, the typical IMDOC system currently available cannot simultaneously solve the problems of introducing additional power devices, generating starting torque and pulsating torque during charging, voltage matching and multi-mode implementation, and is not suitable for the dual-motor / triple-motor drive architecture that is gradually becoming mainstream. Summary of the invention

[0004] The object of the present invention is to provide an electric vehicle three-motor drive system with integrated charging function.

[0005] The technical solution to achieve the purpose of the present invention is: an electric vehicle three-motor drive system with integrated charging function, including a main charging interface, an auxiliary charging input interface 1, an auxiliary charging input interface 2, a five-phase mode switcher, a three-phase mode switcher 1, a three-phase mode switcher 2, a five-phase HEFS motor drive unit, two three-phase HEFS motor drive units, a power battery pack and a common bus, wherein the main charging interface is connected to the five-phase HEFS motor drive unit through a five-phase mode switcher, and the two auxiliary charging interfaces are connected to the two three-phase HEFS motor drive units one by one through a three-phase mode switcher, and the five-phase HEFS motor drive unit and the two three-phase HEFS motor drive units share a common bus and are connected in parallel with the power battery pack, and bus capacitors are connected in parallel on both sides of the common bus; the main charging interface includes two charging interfaces, which are respectively connected to a single-phase AC power supply or a three-phase AC power supply and a DC power supply; the auxiliary charging input interface 1 and the auxiliary charging input interface 2 each include a charging interface for connecting a single-phase AC power supply; the five-phase HEFS motor drive unit includes a five-phase HEFS drive motor, a first full-bridge power converter with a six-phase bridge arm, and a bus switch S1, wherein the five-phase bridge arm of the first full-bridge power converter is connected to the armature winding of the five-phase HEFS motor, and the remaining one-phase bridge arm of the first full-bridge power converter is connected to the excitation winding and connected to the bus through the bus switch S1; each three-phase HEFS motor drive unit includes a three-phase HEFS drive motor and a second full-bridge power converter with a four-phase bridge arm, and a bus switch S2 or a bus switch S3 and a battery positive switch S4 or a battery positive switch S5, wherein the three-phase bridge arm of the second full-bridge power converter is connected to the armature winding of the three-phase HEFS motor, the remaining one-phase bridge arm is connected to the excitation winding and connected to the bus through the bus switch S2 or the bus switch S3, and the neutral point of the three-phase motor is connected to the positive pole of the power battery pack through the port of the three-phase mode switcher 1 or the three-phase mode switcher 2 and the positive switch S4 or the positive switch S5.

[0006] Preferably, the five-phase HEFS motor drive unit is a centralized drive motor, and the two three-phase HEFS motor drive units are distributed drive motors.

[0007] Preferably, the three-phase HEFS motor is a distributed drive motor.

[0008] Preferably, the power battery pack is a lithium-ion battery or a lead-acid battery.

[0009] The present invention also proposes a working method of an electric vehicle three-motor drive system with integrated charging function, comprising:

[0010] Driving mode: switches S1, S2, and S3 are closed, and switches S4 and S5 are open; the five-phase mode switcher is responsible for configuring the windings of the five-phase HEFS drive motor to the driving mode connection mode, i.e., star connection, and the motor enters the driving state; the three-phase mode switcher 1 and the three-phase mode switcher 2 are responsible for configuring the windings of the three-phase HEFS drive motor to the driving mode connection mode, i.e., star connection, and the motor enters the driving state; at this time, the system topology is configured as a full-bridge drive system with a front five-phase HEFS motor and two rear three-phase HEFS wheel hub motors, in which one five-phase HEFS motor provides driving force for the front wheels of the vehicle, and two three-phase HEFS motors respectively embedded in the two rear wheel hubs independently provide driving force for the rear wheels of the vehicle, completing the vehicle driving function;

[0011] Three-phase AC charging mode - trickle charging: switch S1 is turned on, and switches S4 and S5 are turned on; the external three-phase AC power supply is connected to the AC interface in the main charging interface; the five-phase mode switcher connects the three-phase AC power supply to the five-phase HEFS motor winding through the U, V, and W three-phase AC interfaces, and is configured as a three-phase AC charging mode connection method, specifically, the A-phase winding is connected to the U interface, the B and E-phase windings are connected to the V interface, and the C and D-phase windings are connected to the W interface; the armature winding of the five-phase HEFS motor and its driving bridge arm constitute the front-stage three-phase Boost-PFC boost rectifier circuit, and the excitation winding and its driving bridge arm constitute the rear-stage Buck step-down circuit, that is, the five-phase HEFS motor drive unit independently completes the trickle charging of the battery pack;

[0012] Three-phase AC charging mode - constant current charging: switch S1 is closed, switches S2 and S3 are opened, and one of switches S4 and S5 is closed, and the front five-phase HEFS motor drive unit and the corresponding three-phase HEFS motor drive unit complete the constant current charging of the battery pack; the external three-phase AC power supply is connected to the AC interface in the main charging interface; the five-phase mode switcher connects the three-phase AC power supply to the five-phase HEFS motor winding through the U, V, and W interfaces, and is configured as a three-phase AC charging mode connection mode; the three-phase mode switcher 1 or the three-phase mode switcher 2 connects the neutral point of the armature winding of the corresponding three-phase HEFS drive motor to the positive electrode of the battery through the O1 port or the O2 port; at this time, the armature winding of the five-phase HEFS motor and its driving bridge arm constitute the front-stage three-phase Boost-PFC boost rectifier circuit, and the armature winding of any three-phase HEFS motor and its driving bridge arm constitute the rear-stage Buck step-down circuit, completing the high-current constant current charging of the battery pack;

[0013] Three-phase AC charging mode - pulse charging: The bus switch and battery positive switch mode, external three-phase AC power connection mode, five-phase mode switch and three-phase mode switch O1 port connection mode are the same as the three-phase AC charging mode - constant current charging. The armature winding of the five-phase HEFS motor and its driving bridge arm form the front-stage three-phase Boost-PFC boost rectifier circuit, and the armature winding of the three-phase HEFS motor and its driving bridge arm form the rear-stage Buck step-down circuit. The armature winding of the three-phase HEFS motor is selectively used, that is, only part of the phase armature winding is used to form the rear-stage Buck step-down circuit;

[0014] Single-phase AC charging mode - front charging: switch S1 is turned on, and switches S4 and S5 are turned on; the external single-phase AC power supply is connected to the AC interface in the main charging interface; the five-phase mode switcher connects the single-phase AC power supply to the five-phase HEFS drive motor winding through the U and O interfaces, and is configured as a single-phase AC charging mode connection mode; at this time, the armature winding of the five-phase HEFS motor and its drive bridge arm constitute the front-stage single-phase Boost-PFC boost rectifier circuit, and the excitation winding and its drive bridge arm constitute the rear-stage Buck step-down circuit, that is, the five-phase HEFS motor drive unit independently completes the single-phase AC charging of the battery pack;

[0015] Single-phase AC charging mode - post-charging: Switches S2, S3, S4, and S5 are turned on; any auxiliary charging interface is selected to connect to the single-phase AC power supply; the three-phase mode switcher 1 or the three-phase mode switcher 2 connects the single-phase AC power supply to the armature winding of the three-phase HEFS motor through the L1, N1 interface or the L2, N2 interface, and configures it to the single-phase AC charging mode connection mode; at this time, the armature winding of the three-phase HEFS motor and its driving bridge arm constitute the front-stage single-phase Boost-PFC boost rectifier circuit, and the excitation winding and its driving bridge arm constitute the rear-stage Buck step-down circuit, that is, any three-phase HEFS motor drive unit independently completes the single-phase AC charging of the battery pack;

[0016] DC charging mode - low-power and low-ripple charging: switches S1, S4, and S5 are turned on; an external DC power supply is connected to the DC interface in the main charging interface; the five-phase mode switcher connects the DC power supply to the armature winding of the five-phase HEFS drive motor through the P and N interfaces, and is configured into a DC charging mode connection; at this time, the armature winding of the five-phase HEFS motor and its driving bridge arm constitute the front-stage Boost DC boost circuit, and the excitation winding and its driving bridge arm constitute the rear-stage Buck buck circuit, that is, the five-phase HEFS motor drive unit independently completes the low-power and low-ripple DC charging of the battery pack.

[0017] DC charging mode - high-power charging: switch S1 is closed, switches S2 and S3 are opened, and one of switches S4 and S5 is closed; the external DC power supply is connected to the DC interface in the main charging interface; the five-phase mode switcher connects the DC power supply to the armature winding of the five-phase HEFS drive motor through the P and N interfaces, and is configured into a DC charging mode connection mode; the three-phase mode switcher 1 and the three-phase mode switcher 2 connect the neutral point of the armature winding of the corresponding three-phase HEFS drive motor to the positive electrode of the battery through the O1 port or the O2 port; at this time, the armature winding of the five-phase HEFS motor and its driving bridge arm constitute the front-stage Boost DC boost circuit, and the armature winding of any three-phase HEFS motor and its driving bridge arm constitute the rear-stage Buck buck circuit, completing the high-power DC charging of the battery pack.

[0018] Compared with the prior art, the present invention has the following significant advantages:

[0019] 1) The present invention can complete the integrated construction of the "drive + charging" system without introducing additional power devices, which meets the lightweight requirements of electric vehicles.

[0020] 2) The present invention can achieve the adaptation of the external charging voltage to the voltage of batteries of various levels.

[0021] 3) The present invention can prevent the motor from generating starting torque in charging mode, thereby ensuring charging safety.

[0022] 4) The present invention can realize multi-mode charging such as single-phase AC, three-phase AC, DC charging, and can be configured into different charging topologies according to charging requirements, which is more advantageous than the existing IMDOC system.

[0023] 5) The present invention can realize flexible charging at multiple locations throughout the vehicle without increasing the cable arrangement, making the charging operation more convenient. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Concept illustration of a three-motor drive system for an electric vehicle with integrated charging capabilities

[0025] Figure 2 A block diagram of a three-motor drive system for an electric vehicle with integrated charging capability;

[0026] Figure 3 It is the equivalent circuit block diagram of the system driving mode;

[0027] Figure 4 The equivalent circuit diagram of the system's three-phase AC charging mode - trickle charging;

[0028] Figure 5 The equivalent circuit diagram of the system's three-phase AC charging mode - constant current charging;

[0029] Figure 6 The equivalent circuit diagram of the system's three-phase AC charging mode - pulse charging;

[0030] Figure 7 The equivalent circuit diagram of the system single-phase AC charging mode - front charging;

[0031] Figure 8 The equivalent circuit diagram of the system single-phase AC charging mode - post-charging;

[0032] Fig. 9 Equivalent circuit diagram for system DC charging mode - low ripple low power charging;

[0033] Fig.10 Equivalent circuit diagram of the system DC charging mode - high power charging; DETAILED DESCRIPTION

[0034] The following will describe the implementation modes of the present invention in detail with reference to the accompanying drawings and embodiments, so that the implementation process of how the present invention applies technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly.

[0035] The present invention is aimed at the great demand for on-board charging of multi-motor driven vehicles, and creatively proposes an electric vehicle three-motor drive system with integrated charging function. While proposing a high-performance drive architecture for electric vehicles that combines the advantages of centralized and distributed drives, the present invention also provides a flexible and flexible high-power on-board charging solution for electric vehicles.

[0036] like Figure 2As shown, a three-motor drive system for an electric vehicle with an integrated charging function includes a main charging interface, an auxiliary charging input interface 1, an auxiliary charging input interface 2, a five-phase mode switcher, a three-phase mode switcher 1, a three-phase mode switcher 2, a five-phase HEFS motor drive unit, two three-phase HEFS motor drive units, a power battery pack and a common bus, wherein the main charging interface is connected to the five-phase HEFS motor drive unit through the five-phase mode switcher, and the two auxiliary charging interfaces are respectively connected to the two three-phase HEFS motor drive units through a three-phase mode switcher in a one-to-one correspondence, the five-phase HEFS motor drive unit and the two three-phase HEFS motor drive units share a common bus and are connected in parallel with the power battery pack, and bus capacitors are connected in parallel on both sides of the common bus; the main charging interface includes two charging interfaces, which are respectively connected to a single-phase AC power supply or a three-phase AC power supply and a DC power supply; the auxiliary charging input interface 1 and the auxiliary charging input interface 2 each include a charging interface for connecting to a single-phase AC power supply; The five-phase HEFS motor drive unit includes a five-phase HEFS drive motor, a first full-bridge power converter with six-phase bridge arms, and a bus switch S1, wherein the five-phase bridge arms of the first full-bridge power converter are connected to the armature winding of the five-phase HEFS motor, and the remaining one-phase bridge arm of the first full-bridge power converter is connected to the excitation winding and connected to the bus through the bus switch S1; each three-phase HEFS motor drive unit includes a three-phase HEFS drive motor and a second full-bridge power converter with four-phase bridge arms, and a bus switch S2 or a bus switch S3 and a battery positive switch S4 or a battery positive switch S5, wherein the three-phase bridge arms of the second full-bridge power converter are connected to the armature winding of the three-phase HEFS motor, and the remaining one-phase bridge arm is connected to the excitation winding and connected to the bus through the bus switch S2 or the bus switch S3, and the neutral point of the three-phase motor is connected to the positive pole of the power battery pack through the port of the three-phase mode switcher 1 or the three-phase mode switcher 2 and the positive switch S4 or the positive switch S5.

[0037] The present invention only utilizes existing resources in the vehicle and is compatible with charging modes such as single-phase AC charging, three-phase AC charging and DC charging without adding additional power devices. It can also realize flexible charging at multiple locations throughout the vehicle without increasing cable layout. No starting torque is generated during the charging process, and matching of multiple voltage levels can be achieved, providing a complete on-board drive + charging integrated solution for future high-performance electric vehicles.

[0038] A method for operating a three-motor drive system for an electric vehicle with an integrated charging function, comprising:

[0039] Drive mode: Figure 3As shown, switches S1, S2, and S3 are closed, and switches S4 and S5 are open; the five-phase mode switcher configures the armature winding of the five-phase HEFS drive motor to be connected in star connection; the three-phase mode switcher 1 / 2 configures the armature winding of the two three-phase HEFS drive motors to be connected in star connection. At this time, the system topology is a full-bridge drive system with a front-mounted five-phase HEFS motor and two rear-mounted three-phase HEFS wheel hub motors to complete the drive function.

[0040] Three-phase AC charging mode - trickle charging: Figure 4 As shown, switch S1 is turned on, and switches S4 and S5 are turned on; the external three-phase AC power supply is connected to the AC interface in the main charging interface; the five-phase mode switcher opens the neutral point of the five-phase HEFS motor, and connects the three-phase AC power supply to the motor armature winding through the U, V, and W interfaces. The specific connection method is that the A-phase winding is connected to the U interface, the B and E-phase windings are connected to the V interface, and the C and D-phase windings are connected to the W interface; at this time, the armature winding of the five-phase HEFS motor and its driving bridge arm constitute the front-stage three-phase Boost-PFC boost rectifier circuit, and the excitation winding and its driving bridge arm constitute the rear-stage Buck step-down circuit; at this time, the AC side current is limited to the rated current of the armature winding of the five-phase HEFS motor, and the battery side current is limited to the rated current of the excitation winding of the five-phase HEFS motor; this mode has a small overcurrent capacity, but the excitation winding inductance is large, which can effectively suppress ripple, and is suitable for trickle charging of three-stage charging to pre-charge the battery.

[0041] Three-phase AC charging mode - constant current charging: Figure 5 As shown, switch S1 is closed, switches S2 and S3 are opened, and one of switches S4 and S5 is closed (hereinafter, closing S4 is taken as an example); the external three-phase AC power supply is connected to the AC interface in the main charging interface; the five-phase mode switcher connects the three-phase AC power supply to the five-phase HEFS motor winding through the U, V, and W interfaces, and the connection method is the same as the three-phase AC charging mode-trickle charging; the three-phase mode switcher 1 connects the neutral point of the armature winding of the three-phase HEFS drive motor 1 to the positive electrode of the battery through the O1 port; at this time, the five-phase HEFS The armature winding of the S motor and its driving bridge arm constitute the front-stage three-phase Boost-PFC boost rectifier circuit, and the armature winding of the three-phase HEFS motor 1 and its driving bridge arm constitute the rear-stage Buck step-down circuit; at this time, the AC side current is limited to the rated current of the armature winding of the five-phase HEFS motor, and the battery side current is limited to 3 times the rated current of the armature winding of the three-phase HEFS motor. The overcurrent capacity is the strongest, but the total inductance is the smallest, and the ripple suppression ability is weak; this mode is suitable for constant current charging in three-stage charging, and can quickly charge the battery.

[0042] Three-phase AC charging mode - pulse charging: Figure 6As shown, the connection method is the same as the three-phase AC charging mode - constant current charging. The armature winding of the five-phase HEFS motor and its driving bridge arm also form the front-stage three-phase Boost-PFC boost rectifier circuit, and the armature winding of 1 / 2 of the three-phase HEFS motor and its driving bridge arm form the rear-stage Buck step-down circuit. The difference is that in this step, the charging current is reduced, so the armature winding of the three-phase HEFS motor can be selectively used, such as Figure 5 As shown in the figure, only the A and B phases of the three-phase HEFS motor are used, thereby increasing the output side inductance to reduce current pulsation; at this time, the AC side current limit is the rated current of the armature winding of the five-phase HEFS motor, and the battery side current limit is twice the rated current of the armature winding of the three-phase HEFS motor, which has both overcurrent capability and ripple suppression capability; this mode is suitable for pulse charging of three-stage charging, eliminating the battery polarization phenomenon caused by high current charging.

[0043] Single-phase AC charging mode - front charging: Figure 7 As shown, switch S1 is turned on, and switches S4 and S5 are turned on; an external single-phase AC power supply is connected to the AC interface in the main charging interface; the five-phase mode switcher opens the neutral point of the five-phase HEFS motor, and connects the single-phase AC power supply to the five-phase HEFS drive motor winding through the U and O interfaces. The specific connection method is that the A and C phase windings are connected to the U interface, and the B and D phase windings are connected to the O interface; at this time, the armature windings of the five-phase HEFS motor and its driving bridge arm constitute the front-stage single-phase Boost-PFC boost rectifier circuit, and the excitation winding and its driving bridge arm constitute the rear-stage Buck step-down circuit, that is, the five-phase HEFS motor drive unit independently completes the single-phase AC charging of the battery pack, and the single-phase slow charging is performed at the main charging interface at the front of the vehicle.

[0044] Single-phase AC charging mode - post-charging: Figure 8 As shown, switches S2, S3, S4, and S5 are turned on; any auxiliary charging interface 1 / 2 is selected to connect to the single-phase AC power supply; taking the auxiliary charging interface 1 as an example, the three-phase mode switcher 1 opens the neutral point of the three-phase HEFS motor, and connects the single-phase AC power supply to the armature winding of the three-phase HEFS motor 1 through the L1 and N1 interfaces. The specific connection method is that the A-phase winding is connected to the L1 interface, and the C-phase winding is connected to the N1 interface; at this time, the armature winding of the three-phase HEFS motor and its driving bridge arm constitute the front-stage single-phase Boost-PFC boost rectifier circuit, and the excitation winding and its driving bridge arm constitute the rear-stage Buck step-down circuit, that is, the three-phase HEFS motor drive unit 1 independently completes the single-phase AC charging of the battery pack, and the two auxiliary charging interfaces at the rear of the vehicle are used for single-phase slow charging.

[0045] DC charging mode - low power and low ripple charging: Fig. 9As shown, switches S1, S4, and S5 are turned on; an external DC power supply is connected to the DC interface in the main charging interface; the five-phase mode switcher connects the DC power supply to the armature winding of the five-phase HEFS drive motor through the P and N interfaces. The specific connection method is that the neutral point of the motor is connected to the P interface, and the negative pole of the common bus DC- is connected to the N interface; at this time, the armature winding of the five-phase HEFS motor and its driving bridge arm constitute a front-stage Boost DC boost circuit, and the excitation winding and its driving bridge arm constitute a rear-stage Buck buck circuit, that is, the five-phase HEFS motor drive unit independently completes the low-power and low-ripple DC charging of the battery pack; at this time, the front-stage current limit is 5 times the rated current of the armature winding of the five-phase HEFS motor, and the rear-stage current limit is the rated current of the excitation winding of the five-phase HEFS motor. Thanks to the large inductance of the excitation winding, the charging current ripple will be effectively suppressed, which is suitable for completing the low-power and low-ripple DC charging of the battery pack.

[0046] DC charging mode - high power charging: Fig.10 As shown, switch S1 is closed, switches S2 and S3 are opened, and one of switches S4 and S5 is closed (hereinafter, closing S4 is taken as an example); the external DC power supply is connected to the DC interface in the main charging interface; the five-phase mode switcher connects the DC power supply to the armature winding of the five-phase HEFS drive motor through the P and N interfaces; the three-phase mode switcher 1 connects the neutral point of the armature winding of the three-phase HEFS drive motor 1 to the positive electrode of the battery through the O1 port; at this time, the armature winding of the five-phase HEFS motor and its driving bridge arm constitute the front-stage Boost DC boost circuit, and the armature winding of the three-phase HEFS motor 1 and its driving bridge arm constitute the rear-stage Buck step-down circuit; at this time, the front-stage current limit is 5 times the rated current of the armature winding of the five-phase HEFS motor, and the rear-stage current limit is 3 times the rated current of the armature winding of the three-phase HEFS motor. The overcurrent capacity is the strongest, which is suitable for completing high-power DC charging of the battery pack.

[0047] The present invention can be used alone or in combination in a charging cycle according to actual conditions. The user can select a charging mode according to actual conditions, needs, and charging convenience.

[0048] The present invention is based on an electric vehicle platform driven by three motors. On the basis of not affecting its original driving performance, it makes full use of the independent excitation winding of the HEFS motor, combines the windings provided by the three drive motors and their drive bridge arm resources, and more conveniently performs function reuse and topology reconstruction to realize single / three-phase AC and DC charging functions; by reconstructing the windings and bridge arm connections to construct a two-stage buck-boost charging topology structure, the charging matching of the grid voltage and the battery voltage can be achieved without introducing additional power devices; multi-phase motors are adopted and the connection method of the windings and the grid is reasonably selected to effectively eliminate the starting torque during the charging process; thanks to the position distribution of the three motors in the chassis, the present invention can realize flexible charging at multiple positions of the entire vehicle without increasing the cable arrangement, and the charging operation is more convenient

[0049] In summary, the electric vehicle three-motor drive system with integrated charging function proposed in the present invention aims to meet the industry's major demand for low-cost, convenient and high-power charging of new energy vehicles on board, breaks through multiple existing key technical bottlenecks of the IMDOC system, and provides a good solution for convenient, efficient and low-cost on-board charging.

[0050] The above is a detailed description of the embodiments of the present invention in conjunction with the accompanying drawings, but the present invention is not limited to the described embodiments. For those skilled in the art, within the scope of the principles and technical ideas of the present invention, various changes, modifications, substitutions and deformations of these embodiments still fall within the protection scope of the present invention.

Claims

1. An electric vehicle three-motor drive system with integrated charging function, characterized in that: It includes a main charging interface, an auxiliary charging input interface 1, an auxiliary charging input interface 2, a five-phase mode switcher, a three-phase mode switcher 1, a three-phase mode switcher 2, a five-phase HEFS motor drive unit, two three-phase HEFS motor drive units, a power battery pack and a common bus, wherein the main charging interface is connected to the five-phase HEFS motor drive unit through a five-phase mode switcher, and the two auxiliary charging interfaces are respectively connected to the two three-phase HEFS motor drive units through a three-phase mode switcher in a one-to-one correspondence, the five-phase HEFS motor drive unit and the two three-phase HEFS motor drive units share a common bus and are connected in parallel with the power battery pack, and bus capacitors are connected in parallel on both sides of the common bus; the main charging interface includes two charging interfaces, which are respectively connected to a single-phase AC power supply or a three-phase AC power supply and a DC power supply; the auxiliary charging input interface 1 and the auxiliary charging input interface 2 each include a charging interface for connecting to a single-phase AC power supply; the five-phase HEFS motor drive unit The element includes a five-phase HEFS drive motor, a first full-bridge power converter with six-phase bridge arms, and a bus switch S1, wherein the five-phase bridge arms of the first full-bridge power converter are connected to the armature winding of the five-phase HEFS motor, and the remaining one-phase bridge arm of the first full-bridge power converter is connected to the excitation winding and connected to the bus through the bus switch S1; each three-phase HEFS motor drive unit includes a three-phase HEFS drive motor and a second full-bridge power converter with four-phase bridge arms, and a bus switch S2 or a bus switch S3 and a battery positive switch S4 or a battery positive switch S5, wherein the three-phase bridge arms of the second full-bridge power converter are connected to the armature winding of the three-phase HEFS motor, and the remaining one-phase bridge arm is connected to the excitation winding and connected to the bus through the bus switch S2 or the bus switch S3, and the neutral point of the three-phase motor is connected to the positive pole of the power battery pack through the port of the three-phase mode switcher 1 or the three-phase mode switcher 2 and the positive switch S4 or the positive switch S5.

2. The operating method of the electric vehicle three-motor drive system with integrated charging function as claimed in claim 1, characterized in that: The five-phase HEFS motor drive unit is a centralized drive motor, and the two three-phase HEFS motor drive units are distributed drive motors.

3. The operating method of the electric vehicle three-motor drive system with integrated charging function as claimed in claim 1, characterized in that: The three-phase HEFS motor is a distributed drive motor.

4. The electric vehicle three-motor drive system with integrated charging function as claimed in claim 1, characterized in that: The power battery pack is a lithium-ion battery or a lead-acid battery.

5. A method for operating a three-motor drive system for an electric vehicle with an integrated charging function as claimed in any one of claims 1 to 4, characterized in that: include: Driving mode: switches S1, S2, and S3 are closed, and switches S4 and S5 are open; the five-phase mode switcher is responsible for configuring the windings of the five-phase HEFS drive motor to the driving mode connection mode, i.e., star connection, and the motor enters the driving state; the three-phase mode switcher 1 and the three-phase mode switcher 2 are responsible for configuring the windings of the three-phase HEFS drive motor to the driving mode connection mode, i.e., star connection, and the motor enters the driving state; at this time, the system topology is configured as a full-bridge drive system with a front five-phase HEFS motor and two rear three-phase HEFS wheel hub motors, in which one five-phase HEFS motor provides driving force for the front wheels of the vehicle, and two three-phase HEFS motors respectively embedded in the two rear wheel hubs independently provide driving force for the rear wheels of the vehicle, completing the vehicle driving function; Three-phase AC charging mode - trickle charging: switch S1 is turned on, and switches S4 and S5 are turned on; the external three-phase AC power supply is connected to the AC interface in the main charging interface; the five-phase mode switcher connects the three-phase AC power supply to the five-phase HEFS motor winding through the U, V, and W three-phase AC interfaces, and is configured as a three-phase AC charging mode connection method, specifically, the A-phase winding is connected to the U interface, the B and E-phase windings are connected to the V interface, and the C and D-phase windings are connected to the W interface; the armature winding of the five-phase HEFS motor and its driving bridge arm constitute the front-stage three-phase Boost-PFC boost rectifier circuit, and the excitation winding and its driving bridge arm constitute the rear-stage Buck step-down circuit, that is, the five-phase HEFS motor drive unit independently completes the trickle charging of the battery pack; Three-phase AC charging mode - constant current charging: switch S1 is closed, switches S2 and S3 are opened, and one of switches S4 and S5 is closed, and the front five-phase HEFS motor drive unit and the corresponding three-phase HEFS motor drive unit complete the constant current charging of the battery pack; the external three-phase AC power supply is connected to the AC interface in the main charging interface; the five-phase mode switcher connects the three-phase AC power supply to the five-phase HEFS motor winding through the U, V, and W interfaces, and is configured as a three-phase AC charging mode connection mode; the three-phase mode switcher 1 or the three-phase mode switcher 2 connects the neutral point of the armature winding of the corresponding three-phase HEFS drive motor to the positive electrode of the battery through the O1 port or the O2 port; at this time, the armature winding of the five-phase HEFS motor and its driving bridge arm constitute the front-stage three-phase Boost-PFC boost rectifier circuit, and the armature winding of any three-phase HEFS motor and its driving bridge arm constitute the rear-stage Buck step-down circuit, completing the high-current constant current charging of the battery pack; Three-phase AC charging mode - pulse charging: The bus switch and battery positive switch mode, external three-phase AC power connection mode, five-phase mode switch and three-phase mode switch O1 port connection mode are the same as the three-phase AC charging mode - constant current charging. The armature winding of the five-phase HEFS motor and its driving bridge arm form the front-stage three-phase Boost-PFC boost rectifier circuit, and the armature winding of the three-phase HEFS motor and its driving bridge arm form the rear-stage Buck step-down circuit. The armature winding of the three-phase HEFS motor is selectively used, that is, only part of the phase armature winding is used to form the rear-stage Buck step-down circuit; Single-phase AC charging mode - front charging: switch S1 is turned on, and switches S4 and S5 are turned on; the external single-phase AC power supply is connected to the AC interface in the main charging interface; the five-phase mode switcher connects the single-phase AC power supply to the five-phase HEFS drive motor winding through the U and O interfaces, and is configured as a single-phase AC charging mode connection mode; at this time, the armature winding of the five-phase HEFS motor and its drive bridge arm constitute the front-stage single-phase Boost-PFC boost rectifier circuit, and the excitation winding and its drive bridge arm constitute the rear-stage Buck step-down circuit, that is, the five-phase HEFS motor drive unit independently completes the single-phase AC charging of the battery pack; Single-phase AC charging mode - post-charging: Switches S2, S3, S4, and S5 are turned on; any auxiliary charging interface is selected to connect to the single-phase AC power supply; the three-phase mode switcher 1 or the three-phase mode switcher 2 connects the single-phase AC power supply to the armature winding of the three-phase HEFS motor through the L1, N1 interface or the L2, N2 interface, and configures it to the single-phase AC charging mode connection mode; at this time, the armature winding of the three-phase HEFS motor and its driving bridge arm constitute the front-stage single-phase Boost-PFC boost rectifier circuit, and the excitation winding and its driving bridge arm constitute the rear-stage Buck step-down circuit, that is, any three-phase HEFS motor drive unit independently completes the single-phase AC charging of the battery pack; DC charging mode - low-power low-ripple charging: switches S1, S4, and S5 are turned on; the external DC power supply is connected to the DC interface in the main charging interface; the five-phase mode switcher connects the DC power supply to the armature winding of the five-phase HEFS drive motor through the P and N interfaces, and is configured to be in DC charging mode connection mode; at this time, the armature winding of the five-phase HEFS motor and its drive bridge arm constitute the front-stage Boost DC boost circuit, and the excitation winding and its drive bridge arm constitute the rear-stage Buck buck circuit, that is, the five-phase HEFS motor drive unit independently completes the low-power low-ripple DC charging of the battery pack; DC charging mode - high-power charging: switch S1 is closed, switches S2 and S3 are opened, and one of switches S4 and S5 is closed; the external DC power supply is connected to the DC interface in the main charging interface; the five-phase mode switcher connects the DC power supply to the armature winding of the five-phase HEFS drive motor through the P and N interfaces, and is configured into a DC charging mode connection mode; the three-phase mode switcher 1 or the three-phase mode switcher 2 connects the neutral point of the armature winding of the corresponding three-phase HEFS drive motor to the positive electrode of the battery through the O1 port or the O2 port; at this time, the armature winding of the five-phase HEFS motor and its driving bridge arm constitute the front-stage Boost DC boost circuit, and the armature winding of any three-phase HEFS motor and its driving bridge arm constitute the rear-stage Buck buck circuit, completing the high-power DC charging of the battery pack.

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