An on-board charging and discharging system for electric vehicles

Abstract

This invention provides an on-board charging and discharging system for electric vehicles, including a first control circuit, a second control circuit, an auxiliary circuit, a battery, and a multiplexing control unit. The stator windings of motor M1 are controlled by a mechanical switch, and the multiplexing control unit controls the on-board charging and discharging system to achieve operating mode switching. The operating modes include drive and regenerative braking modes, single-phase charging / grid-connected mode, and three-phase charging / grid-connected mode. This invention integrates a dual-motor electric vehicle drive system and a vehicle charging system together through auxiliary circuits to form a time-division multiplexing integrated system. This achieves time-division multiplexing of power devices, saving the limited space volume of the electric vehicle, reducing vehicle weight, and significantly reducing overall vehicle cost. In charging mode, this integrated system can achieve single-phase or three-phase charging / grid-connected operation; in drive mode, it can independently control the rotation of the two motors.

Description

Technical Field

[0001] This invention belongs to the field of new energy electric control technology, specifically relating to an on-board charging and discharging system for electric vehicles. Background Technology

[0002] With the rapid development of new energy vehicles, electric vehicles and plug-in hybrid vehicles will become the mainstream models to meet future emission regulations, contributing to the goal of carbon peaking and carbon neutrality. However, the "range anxiety" of electric vehicles is still a major pain point that needs to be addressed.

[0003] The fundamental reason is that the scale of charging infrastructure construction is far smaller than that of gas stations, and the cost and performance of electric vehicle charging equipment are also major factors hindering the development of electric vehicles. Therefore, researching and implementing on-board charging and discharging systems for electric vehicles is urgent. Currently, the charging system and electric drive system of electric vehicles are two completely independent systems, each operating under different conditions, resulting in significant space occupation within the electric vehicle. Furthermore, the power electronic devices used in the two systems are highly similar, leading to high component redundancy and low power device utilization due to the different operating conditions. Integrating these two systems into a single system capable of both driving and charging / discharging through a special structural transformation using the concept of power electronic device reuse would significantly save usable space within the vehicle, reduce costs, and represent a promising development direction.

[0004] In existing technologies, various inventions that integrate dual-motor drives into on-board chargers and dischargers generally require both motors to participate simultaneously in the reconfiguration of the charger and discharger during charging and discharging, increasing the losses of power devices and switching transistors in the motors and their control circuits. Therefore, a charging system is needed that can meet both driving and charging / discharging requirements while also enabling reasonable time-sharing multiplexing of power devices. Summary of the Invention

[0005] In view of this, in order to overcome the shortcomings of the prior art, the purpose of this invention is to provide an on-board charging and discharging system for electric vehicles, which can be applied to electric vehicles with dual or more motor drives. The on-board charger and the electric drive system are integrated together through some auxiliary circuits, realizing time-division multiplexing of power devices, which can effectively reduce the weight of the vehicle, save interior space, and reduce costs. Moreover, this structure can also realize bidirectional charging, effectively enabling vehicle-grid interaction. It can perform peak shaving and valley filling and frequency regulation on the grid side, and earn the price difference for users by charging at low prices and discharging at high prices.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] An on-board charging and discharging system for an electric vehicle includes a first control circuit, a second control circuit, an auxiliary circuit, a battery, and a multiplex control unit.

[0008] The multiplexed control unit controls the on-board charging and discharging system to switch between operating modes, including drive and regenerative braking mode, single-phase charging / grid-connected mode, and three-phase charging / grid-connected mode.

[0009] When the on-board charging and discharging system is in drive and regenerative braking mode, the first control circuit and the second control circuit operate independently in drive or regenerative braking mode; when the on-board charging and discharging system is in single-phase charging / grid-connected mode, the first control circuit is reconfigured into an on-board charging and discharging machine through an auxiliary circuit; when the on-board charging and discharging system is in three-phase charging / grid-connected mode, the first control circuit and the second control circuit are reconfigured into an on-board charging and discharging machine through an auxiliary circuit.

[0010] The auxiliary circuit includes an n:1 transformer and switching transistors T13 and T14. The first control circuit includes a motor M1 and switching transistors T1, T2, T3, T4, T5, and T6. The second control circuit includes a motor M2 and switching transistors T7, T8, T9, T10, T11, T12, T13, and T14. The multiplexing control unit includes switches S1, S2, and S3-S15. The motor M1 controls the opening and closing of the stator windings through mechanical switches.

[0011] Preferably, in single-phase charging / grid-connected mode, the stator winding of motor M1 is opened by a mechanical switch. After the circuit is opened, the stator coil inside motor M1 serves as three filter inductors. Among them, stator coils L1 and L2 are used as buffer inductors between the single-phase grid and the rectifier / inverter, stator winding L3 is used as the inductor of the DC / DC converter between the rectifier / inverter and the battery, the rectifier is composed of switching transistors T1-T4, and the DC / DC converter is composed of switching transistors T5 and T6 and stator winding L3.

[0012] Preferably, in the three-phase charging / grid-connected mode, the stator winding of motor M1 is opened by a mechanical switch. After the circuit is opened, the stator coil inside motor M1 acts as three filter inductors. One end of stator coils L1, L2, and L3 is connected to the three-phase power grid, and the other end is connected to the three-phase rectifier / inverter composed of switching transistors T1-T6. These serve as buffer inductors between the three-phase power grid and the three-phase rectifier / inverter, thereby converting the three-phase AC power into DC power. n:1 is a DC / DC converter reconstructed from transformer and switching transistors T7-T14.

[0013] Preferably, when the electric vehicle is in driving mode, motors M1 and M2 are in drive or regenerative braking mode. At this time, the winding of motor M1 is closed and motor M1 is in normal working mode. The second control circuit connects to motor M2 for drive control when the electric vehicle is in drive mode.

[0014] When the electric vehicle is charging or connected to the grid, the mechanical switch controls the motor M1 to open the stator winding. At this time, the motor M1 does not work. The motor M1 winding is only used as a filter inductor for single-phase or three-phase charging or grid connection. Switches T1, T2, T3, T4, T5, and T6 are used for the charging / grid connection circuit of the electric vehicle.

[0015] In single-phase charging and grid-connected mode, the second control circuit does not work; in three-phase charging / grid-connected mode, the second control circuit adds an auxiliary circuit for the DC / DC conversion module of the three-phase charging / grid-connected system.

[0016] Preferably, the system operating mode switching of the reused control unit is performed according to the following steps:

[0017] A. Drive and regenerative braking modes:

[0018] When the motor M1 winding is closed, switches S5, S6, S7, S8, S14, and S15 are closed, while switches S9, S10, S11, S12, and S13 are open, and switching transistors T13 and T14 are shielded.

[0019] B. Single-phase charging / grid-connected mode:

[0020] When motor M1 winding is disconnected, switches S1, S2, and S4 are closed, and switches S3, S5, S6, S7, S8, S9, S10, S11, S12, S13, S14, and S15 are disconnected. During charging, the AC power from the grid flows through the stator windings L1 and L2 and then through the rectifier composed of switching transistors T1-T4, thereby converting the AC power into DC power. The DC / DC converter composed of T5, T6, and stator winding L3 then transfers the electrical energy to the electric vehicle battery. The energy flow is reversed when connected to the grid compared to when charging.

[0021] C. Three-phase charging / grid connection mode:

[0022] When the motor M1 winding is disconnected, switches S1, S2, S3, S5, S6, S9, S10, S11, S12, S13, and S14 are closed, while switches S4, S7, S8, and S15 are open. During charging, the three-phase AC power from the grid flows through the stator windings L1, L2, and L3 and is rectified by the three-phase rectifier consisting of T1-T6, thus converting the three-phase AC power into DC power. Then, the high-voltage DC power is regulated by the DC / DC converter formed by the n:1 transformer and the switching transistors T7-T14 before being delivered to the battery for charging. The energy flow is reversed when the battery is connected to the grid.

[0023] The beneficial effects of this invention are:

[0024] The present invention proposes an on-board charging system for electric vehicles that integrates a dual-motor electric vehicle electric drive system and a vehicle charging system together through an auxiliary circuit to form a time-division multiplexing integrated system. It realizes bidirectional energy flow, enables interaction between the vehicle and the power grid, and can perform peak shaving and valley filling and frequency regulation on the power grid end, thus meeting the requirements of electric vehicles for system weight, space and cost constraints.

[0025] In single-phase charging, only one motor is needed to reconfigure the charging and discharging machine, while the second motor is used in three-phase charging, realizing reasonable time-sharing multiplexing of power devices. The two systems share the same converter, realizing time-sharing multiplexing of power devices, saving the limited space volume of electric vehicles, reducing vehicle weight, and significantly reducing the overall vehicle cost. In charging mode, this integrated system can realize single-phase or three-phase charging / grid connection, and in driving mode, it can control the rotation of two motors independently. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a system block diagram of the electric vehicle on-board charging system of the present invention;

[0028] Figure 2 This is a schematic diagram of the structure and energy flow of the system of the present invention when it is operating in drive and regenerative braking modes;

[0029] Figure 3 This is a schematic diagram of the structure and energy flow of the system of the present invention when it is operating in single-phase charging / grid-connected mode;

[0030] Figure 4 This is a schematic diagram of the structure and energy flow of the system of the present invention when it is operating in three-phase charging / grid-connected mode. Detailed Implementation

[0031] Specific embodiments are given below to further clarify, completely, and in detail the technical solution of the present invention. These embodiments are the preferred embodiments based on the technical solution of the present invention, but the scope of protection of the present invention is not limited to the following embodiments.

[0032] The present invention provides a reference for an on-board charging system for electric vehicles. Figure 1 As shown, this system is suitable for electric vehicles with dual-motor or multi-motor drives. The system mainly consists of four parts:

[0033] The first part is the first control circuit, which includes motor M1 and its switching transistors T1, T2, T3, T4, T5, and T6, which serve as the control circuit for motor M1.

[0034] The second part is the second control circuit, which includes the motor M2 and the switching transistors T7, T8, T9, T10, T11, and T12 that serve as the control circuit for the motor M2;

[0035] The third part is an auxiliary circuit consisting of an n:1 transformer and two switching transistors, T13 and T14.

[0036] The fourth part is the electric vehicle battery and its reuse control unit.

[0037] By integrating the on-board charger and discharger of the electric vehicle with the electric drive system through the above four parts, time-division multiplexing of power devices is achieved, which can effectively reduce the weight of the vehicle, save interior space, and reduce costs.

[0038] The multiplexed control unit controls the on-board charging and discharging system to switch operating modes, including drive and regenerative braking mode, single-phase charging / grid-connected mode, and three-phase charging / grid-connected mode. When the on-board charging and discharging system is in drive and regenerative braking mode, the first control circuit and the second control circuit operate independently in either drive or regenerative braking mode. When the on-board charging and discharging system is in single-phase charging / grid-connected mode, the first control circuit is reconfigured into an on-board charger / discharger via an auxiliary circuit. When the on-board charging and discharging system is in three-phase charging / grid-connected mode, the first control circuit and the second control circuit are reconfigured into an on-board charger / discharger via an auxiliary circuit.

[0039] Preferably, the multiplexing control unit includes switches S1-S15, which control the switching of the different modes mentioned above. The motor M1 regulates the opening and closing of the stator windings through mechanical switches.

[0040] When the electric vehicle is in motion, the motor is in drive or regenerative braking mode. At this time, the winding of motor M1 is closed and the motor is in normal working condition.

[0041] When the electric vehicle is charging or connected to the grid, the mechanical switch controls the stator winding of the motor M1 to open the circuit. At this time, the motor M1 does not work. The winding of the motor M1 is only used as a filter inductor for single-phase or three-phase charging / grid connection. The control circuit of the motor M1 is used for the charging / grid connection circuit of the electric vehicle.

[0042] In electric vehicle drive mode, the control circuit of motor M2 connects to the motor for drive control. In three-phase charging / grid-connected mode, the control circuit of motor M2 uses an auxiliary circuit for the DC / DC converter module of the three-phase charging / grid-connected system. In single-phase charging / grid-connected mode, motor M2 and its control circuit do not operate. By using time-division multiplexing of the power devices and adding auxiliary circuits, the electric vehicle charging and drive system are integrated, effectively reducing vehicle weight, saving interior space, and lowering costs.

[0043] Preferably, the following vehicle operating modes are switched using a reused control unit:

[0044] 1. Drive and regenerative braking mode. Motor M1 winding is closed, switches S5, S6, S7, S8, S14, and S15 are closed, and switches S9, S10, S11, S12, and S13 are open. The system's equivalent structure and energy flow diagram are shown below. Figure 2 As shown. At this time, switching transistors T13 and T14 are shielded;

[0045] When the system is in drive mode, energy is supplied by the high-voltage battery to drive the two load motors through their respective three-phase inverter drivers, and the vehicle is in motion. When the system is in regenerative braking mode, the energy generated during braking is used to charge the vehicle's battery through the motors and the three-phase inverter, thus reducing energy loss caused by braking.

[0046] 2. Single-phase charging / grid-connected mode. Motor M1 winding is disconnected, switches S1, S2, and S4 are closed, and switches S3, S5, S6, S7, S8, S9, S10, S11, S12, S13, S14, and S15 are open. The system equivalent structure and energy flow diagram are shown below. Figure 3 As shown. In this system mode, motor M2 and its control circuit do not need to participate in the charging / grid connection process; only motor M1 and its control circuit need to participate in the reconfiguration into a single-phase charging / grid connection circuit. At this time, the stator winding of motor M1 is opened via a mechanical switch. After opening, the internal stator coils of motor M1 can act as three filter inductors. Stator coils L1 and L2 serve as buffer inductors between the single-phase grid and the rectifier / inverter, while stator winding L3 serves as the inductor for the DC / DC converter between the rectifier / inverter and the battery. During charging, the AC power from the grid flows through stator windings L1 and L2 and through the rectifier composed of switching transistors T1-T4, thus converting the AC power into DC power. This DC power is then transferred to the electric vehicle battery by the DC / DC converter composed of T5, T6, and stator winding L3. The energy flow during grid connection is the opposite of that during charging.

[0047] 3. Three-phase charging / grid-connected mode. Motor M1 winding is disconnected; switches S1, S2, S3, S5, S6, S9, S10, S11, S12, S13, and S14 are closed; switches S4, S7, S8, and S15 are open. The system equivalent structure and energy flow diagram are shown below. Figure 4 As shown. In this system mode, motor M1 and its control circuit, along with motor M2 and its control circuit and auxiliary circuit, simultaneously participate in the reconfiguration into a three-phase charging / grid-connected circuit. At this time, the stator windings of motor M1 are opened via a mechanical switch. After opening, the internal stator windings of motor M1 can act as three filter inductors. One end of stator coils L1, L2, and L3 is connected to the three-phase power grid, and the other end is connected to the three-phase rectifier / inverter composed of T1-T6. The n:1 transformer is connected to the circuit via switches S10-S13 and reconfigured with switching transistors T7-T14 into a DC / DC converter. During charging, the three-phase AC power from the power grid flows through the stator windings L1, L2, and L3 through the three-phase rectifier composed of T1-T6, thus converting the three-phase AC power into DC power. This DC power is then regulated by the DC / DC converter formed by the n:1 transformer and switching transistors T7-T14 before being delivered to the battery for charging. The energy flow during grid connection is the opposite of that during charging.

[0048] In summary, the electric vehicle on-board charging and discharging system of the present invention integrates the dual-motor electric vehicle electric drive system and the vehicle charging system together through auxiliary circuits to form a time-division multiplexing integrated system, and realizes bidirectional energy flow, enabling interaction between the vehicle and the power grid; the two systems share the same converter, saving the limited space volume of the electric vehicle, reducing the weight of the vehicle, and significantly reducing the overall vehicle cost.

[0049] The foregoing has shown and described the main features, basic principles, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention based on actual circumstances without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. An electric vehicle on-board charging and discharging system comprising a first control circuit, a second control circuit, an auxiliary circuit, a battery and a multiplexing control unit, characterized in that: the multiplexing control unit controls the on-board charging and discharging system to realize working mode conversion, and the working modes include driving and braking recovery mode, single-phase charging / grid-connected mode and three-phase charging / grid-connected mode; when the on-board charging and discharging system is in driving and braking recovery mode, the first control circuit and the second control circuit independently work in driving or braking recovery mode; when the on-board charging and discharging system is in single-phase charging / grid-connected mode, the first control circuit is reconfigured into an on-board charging and discharging machine through the auxiliary circuit; when the on-board charging and discharging system is in three-phase charging / grid-connected mode, the first control circuit and the second control circuit are reconfigured into an on-board charging and discharging machine through the auxiliary circuit; the auxiliary circuit comprises an n:1 transformer and switching tubes T13 and T14, the first control circuit comprises a motor M1 and switching tubes T1, T2, T3, T4, T5 and T6, the second control circuit comprises a motor M2 and switching tubes T7, T8, T9, T10, T11, T12, T13 and T14, and the multiplexing control unit comprises switches S1, S2 and S3-S15; the motor M1 is controlled by a mechanical switch to open and close the stator winding; in single-phase charging / grid-connected mode, the mechanical switch is used to open the stator winding of the motor M1, and after the stator winding is opened, the internal stator coil of the motor M1 serves as three filter inductors, wherein the stator coils L1 and L2 are used as buffer inductors between the single-phase power grid and the rectifier / inverter, the stator winding L3 is used as the inductor of the DC / DC converter between the rectifier / inverter and the battery, the rectifier composed of the switching tubes T1-T4, and the DC / DC converter composed of the switching tubes T5 and T6 and the stator winding L3; in three-phase charging / grid-connected mode, the mechanical switch is used to open the stator winding of the motor M1, and after the stator winding is opened, the internal stator coil of the motor M1 serves as three filter inductors, wherein one end of the stator coils L1, L2 and L3 is connected to the three-phase power grid, and the other end is connected to the three-phase rectifier / inverter composed of the switching tubes T1-T6, which is used as buffer inductors between the three-phase power grid and the three-phase rectifier / inverter, so as to convert three-phase alternating current into direct current; the n:1 transformer and the switching tubes T7-T14 are reconfigured into a DC / DC converter.

2. The electric vehicle on-board charging and discharging system according to claim 1, characterized in that: when the electric vehicle is in driving state, the motors M1 and M2 are in driving or braking recovery mode, at this time, the winding of the motor M1 is closed, the motor M1 is in normal working state, and the second control circuit is connected to the motor M2 to drive and control the motor M2 in the driving mode of the electric vehicle; when the electric vehicle is in charging or grid-connected state, the mechanical switch controls the motor M1 to open the stator winding, at this time, the motor M1 does not work, the winding of the motor M1 only serves as filter inductors for single-phase or three-phase charging or grid connection, and the switching tubes T1, T2, T3, T4, T5 and T6 are used for the charging / grid connection circuit of the electric vehicle. In single-phase charging grid-connected mode, the second control circuit does not work; in three-phase charging / grid-connected mode, the second control circuit adds an auxiliary circuit for the DC / DC conversion module of the three-phase charging / grid-connected system.

3. The electric vehicle on-board charging and discharging system according to any one of claims 1-2, characterized in that: The multiplexing control unit switches the system operating mode according to the following steps: A. Drive and brake recovery mode: The motor M1 winding is closed, and the switches S5, S6, S7, S8, S14, S15 are closed, and S9, S10, S11, S12, S13 are disconnected, and the switch tubes T13, T14 are shielded; B. Single-phase charging / grid-connected mode: The motor M1 winding is disconnected, and the switches S1, S2, S4 are closed, and S3, S5, S6, S7, S8, S9, S10, S11, S12, S13, S14, S15 are disconnected; during charging, the grid AC power flows through the rectifier composed of switch tubes T1-T4 through the stator windings L1, L2, thereby converting AC power into DC power, and then the DC / DC converter composed of T5, T6 and the stator winding L3 transmits the electric energy to the electric vehicle battery; during grid connection, the energy flow is opposite to that during charging; C. Three-phase charging / grid-connected mode: The motor M1 winding is disconnected, and the switches S1, S2, S3, S5, S6, S9, S10, S11, S12, S13, S14 are closed, and S4, S7, S8, S15 are disconnected; during charging, three-phase grid AC power flows through the three-phase rectifier composed of T1-T6 through the stator windings L1, L2, L3, thereby converting three-phase AC power into DC power, and then the DC / DC converter composed of n:1 transformer and switch tubes T7-T14 is reconstructed to adjust the high-voltage DC power and deliver it to the battery for charging; during grid connection, the energy flow is opposite to that during charging.

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