Electric drive, charging and v2g multifunctional integrated system and control method for electric vehicle

Abstract

The application discloses a kind of electric drive for electric vehicle, charging and V2G multifunctional integrated system and control method, the system includes by three-phase permanent magnet motor, three-phase voltage type inverter, capacitor, battery three-phase permanent magnet motor drive system, still including switching switch, relay;The switching switch is connected to the middle of the one end tap of three-phase permanent magnet motor winding;One end of the relay is connected to the positive pole of battery and capacitor, and the other end includes a normally closed contact a and a normally open contact b, the normally closed contact a is connected to the positive pole of three-phase voltage type inverter DC side, and normally open contact b is connected to the one end tap of one phase winding of three-phase permanent magnet motor;The negative pole of the capacitor and battery is connected to the negative pole of three-phase voltage type inverter DC side, and the application realizes lightweight, compact, low-cost design, and has V2G function.

Description

Technical Field

[0001] This invention relates to a multi-functional integrated system and control method for electric drive, charging and V2G for electric vehicles, belonging to the field of electric drive and charging technology for electric vehicles. Background Technology

[0002] With several countries announcing the cessation of production of gasoline-powered vehicles, electric vehicles, with their advantages of energy saving, environmental protection, and high efficiency, will replace gasoline-powered vehicles as the mainstream mode of transportation in the near future. Currently, in addition to the difficulty in further increasing battery capacity, the technological bottlenecks of electric vehicles are: 1) the existing charging infrastructure is insufficient to meet the needs of electric vehicle users, resulting in slow charging and charging difficulties; 2) the existing power grid is not yet prepared to connect large-scale mobile loads such as electric vehicles and cannot withstand the energy surge caused by large-scale grid connection of electric vehicles.

[0003] In response to the problems of slow and difficult charging of electric vehicles, in recent years, scholars at home and abroad have proposed an integrated charging system that reuses the electric drive unit of electric vehicles. By reconfiguring and reusing the motor windings and inverters, the charging function is realized, which provides a new idea for the lightweight, compact and low-cost design of electric vehicle electrical units. However, existing results are mostly focused on the realization of the charging function (i.e. AC / DC) and rarely consider the matching problem of charging voltage.

[0004] To address the energy surge caused by the large-scale grid connection of electric vehicles, in addition to grid improvements, some scholars have proposed the concept of feeding energy from electric vehicle batteries into the grid (V2G), using the energy stored in large-scale mobile energy storage units to buffer the fluctuations caused by large loads connecting to the grid. V2G requires charging equipment to have bidirectional energy flow capabilities, a requirement that most existing charging piles and on-board chargers cannot meet. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a multi-functional integrated system and control method for electric vehicles that integrates electric drive, charging and V2G, achieving a lightweight, compact and low-cost design, and possessing V2G functionality.

[0006] To achieve the above objectives, the present invention is implemented using the following technical solution:

[0007] In a first aspect, the present invention provides a multi-functional integrated system for electric drive, charging and V2G for electric vehicles, including a three-phase permanent magnet motor drive system consisting of a three-phase permanent magnet motor, a three-phase voltage-source inverter, a capacitor and a battery, and also including a switching switch and a relay.

[0008] The switching switch is connected to the middle of one tap of the three-phase permanent magnet motor winding;

[0009] One end of the relay is connected to the positive terminal of the battery and the capacitor, and the other end includes a normally closed contact a and a normally open contact b. The normally closed contact a is connected to the positive terminal of the DC side of the three-phase voltage source inverter, and the normally open contact b is connected to one tap of one phase winding of the three-phase permanent magnet motor.

[0010] The negative terminals of the capacitor and battery are connected to the negative terminal of the DC side of the three-phase voltage-source inverter.

[0011] Furthermore, it also includes a single-phase power supply, which is connected in series between the first phase winding and the second phase winding of the three-phase permanent magnet motor.

[0012] Furthermore, the normally open contact b is connected to the third phase winding of the three-phase permanent magnet motor.

[0013] Furthermore, the three-phase voltage source inverter includes three phase arms, namely the first phase arm, the second phase arm, and the third phase arm.

[0014] Secondly, the present invention provides a multi-functional integrated method for electric drive, charging, and VG in electric vehicles, applicable to the multi-functional integrated system for electric drive, charging, and VG in electric vehicles described in any of the preceding claims, the method comprising:

[0015] In electric drive mode, the switching switch is closed, the relay switches to normally closed contact a, one end of the first phase winding, the second phase winding, and the third phase winding are short-circuited to form a neutral point, and the other end of the first phase winding, the second phase winding, and the third phase winding are respectively connected to the midpoint of the first phase bridge arm, the second phase bridge arm, and the third phase bridge arm, and the permanent magnet motor is driven by the battery.

[0016] Furthermore, the method also includes:

[0017] In charging / VG mode, the switching switch is turned on, the relay switches to normally open contact b, one end of the first phase winding and the second phase winding are connected to the single-phase power supply, and the other end is connected to the midpoint of the first phase bridge arm and the second phase bridge arm respectively, forming an H-bridge converter. One end of the third phase winding is connected to the positive terminal of the DC bus through the relay, and the other end is connected to the midpoint of the third phase bridge arm, forming a DC / DC converter.

[0018] Furthermore, the method also includes:

[0019] In charging mode, the H-bridge converter is used as a rectifier to convert AC power from the grid into DC power, and the DC / DC converter is used as a Buck converter to adjust the rectified DC power to a suitable charging voltage level.

[0020] Furthermore, the method also includes:

[0021] In V2G mode, the DC / DC converter is used as a Boost converter to regulate the battery voltage to a suitable grid-connected voltage level, and the H-bridge converter is used as an inverter to convert DC power into AC power for feeding into the grid.

[0022] Furthermore, when the system operates in electric drive mode, a field-oriented control strategy is used to drive the motor.

[0023] Furthermore, when the system operates in charging mode, it employs a dual closed-loop control strategy of outer loop of bus voltage and inner loop of grid current to control the rectifier, and a dual closed-loop control strategy of outer loop of charging current and inner loop of charging voltage to control the Buck converter.

[0024] Furthermore, when the system operates in V2G mode, a dual closed-loop control strategy of outer loop of bus voltage and inner loop of discharge current is used to control the Boost converter, and a single closed-loop control strategy of grid current is used to control the inverter.

[0025] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0026] This invention provides a multi-functional integrated system and control method for electric vehicles, encompassing electric drive, charging, and V2G. Based on the concept of an integrated charging system, it designs an on-board device that integrates electric drive, charging, and V2G functions, which is beneficial for the lightweight and compact design of the electric vehicle's electrical components. Compared to a standard drive system, only a pair of switching switches and a relay are needed to achieve multi-mode operation, resulting in lower costs. In charging / V2G mode, it combines rectification / inversion and DC / DC functions, enabling matching of battery charging voltage. The introduction of V2G functionality facilitates energy interaction between the vehicle and the power grid, aligning with current trends in electric vehicle technology development. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of a multi-functional integrated system for electric drive, charging and V2G for electric vehicles provided in an embodiment of the present invention;

[0028] Figure 2 This is an equivalent circuit diagram in the charging / V2G mode provided in the embodiment of the present invention.

[0029] In the diagram: 1. Three-phase permanent magnet motor; 2. Three-phase voltage-source inverter; 3. Switch; 4. Relay; 5. Single-phase power supply; 6. Capacitor; 7. Battery; 1-1. First phase winding; 1-2. Second phase winding; 1-3. Third phase winding; 2-1. First phase bridge arm; 2-2. Second phase bridge arm; 2-3. Third phase bridge arm. Detailed Implementation

[0030] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0031] In the description of this invention, it should be understood that the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0032] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0033] Example 1

[0034] Combination Figure 1 As shown in the figure, this embodiment introduces a multi-functional integrated system for electric drive, charging, and V2G in electric vehicles. It includes a three-phase permanent magnet motor drive system consisting of a three-phase permanent magnet motor 1, a three-phase voltage-source inverter 2, a capacitor 6, and a battery 7. It also includes a switching switch 3, a relay 4, and a single-phase power supply 5. The switching switch 3 is connected to the middle of one tap of the winding of the three-phase permanent magnet motor 1. One end of the relay 4 is connected to the positive terminal of the battery and the capacitor, and the other end includes a normally closed contact a and a normally open contact b. The normally closed contact a is connected to the direct current of the three-phase voltage-source inverter 2. The positive terminal of the DC side; the negative terminals of the capacitor 6 and the battery 7 are connected to the negative terminal of the DC side of the three-phase voltage source inverter 2; the windings of the three-phase permanent magnet motor 1 include a first phase winding 1-1, a second phase winding 1-2, and a third phase winding 1-3, and the single-phase power supply 5 is connected in series between the first phase winding 1-1 and the second phase winding 1-2; the normally open contact b is connected to one tap of the third phase winding 1-3 in the three-phase permanent magnet motor 1; the three-phase voltage source inverter 2 includes three phase bridge arms, namely the first phase bridge arm 2-1, the second phase bridge arm 2-2, and the third phase bridge arm 2-3.

[0035] The specific operation modes of the electric drive and charging / V2G modes of the system described in this invention are as follows: In electric drive mode, the switching switch 3 is closed, and the relay 4 is switched to normally closed contact a. One end of the three-phase winding of the three-phase permanent magnet motor 1 is short-circuited to form a neutral point, and the other end is connected to the midpoint of the three-phase bridge arm of the three-phase voltage source inverter 2. The permanent magnet motor is driven by power supplied by the battery 7. In charging / V2G mode, the switching switch 3 is opened, and the relay 4 is switched to normally open contact b. One end of the first phase winding 1-1 and the second phase winding 1-2 of the three-phase permanent magnet motor 1 are connected to the single-phase power supply 5, and the other end is connected to the midpoint of the first phase bridge arm 2-1 and the second phase bridge arm 2-2 of the three-phase voltage source inverter 2, forming an H-bridge converter. One end of the third phase winding 1-3 of the three-phase permanent magnet motor 1 is connected to the positive terminal of the DC bus through the relay 4, and the other end is connected to the midpoint of the third phase bridge arm 2-3 of the three-phase voltage source inverter 2, forming a DC / DC converter. The equivalent circuit is as follows. Figure 2 As shown.

[0036] In charging mode, the H-bridge converter acts as a rectifier to convert AC power from the grid into DC power, and the DC / DC converter acts as a Buck converter to adjust the rectified DC power to a suitable charging voltage level. In V2G mode, the DC / DC converter acts as a Boost converter to adjust the battery voltage to a suitable grid-connected voltage level, and the H-bridge converter acts as an inverter to invert DC power into AC power to feed into the grid.

[0037] This invention provides a multi-functional integrated system for electric vehicles, combining electric drive, charging, and V2G. Based on the concept of an integrated charging system, it designs an on-board device that integrates electric drive, charging, and V2G functions, which is beneficial for the lightweight and compact design of the electric vehicle's electrical components. Compared to a standard drive system, only a pair of switching switches and a relay are needed to achieve multi-mode operation, resulting in lower costs. In charging / V2G mode, it combines rectification / inversion and DC / DC functions, enabling matching of battery charging voltage. The introduction of V2G function realizes energy interaction between the vehicle and the power grid, which is in line with the current trend of electric vehicle technology development.

[0038] Example 2

[0039] This embodiment provides a method for integrating electric drive, charging, and VG functions for electric vehicles, applicable to the electric vehicle electric drive, charging, and VG multi-functional integrated system described in any one of Embodiments 1. The method includes:

[0040] In electric drive mode, the switching switch is closed, the relay switches to normally closed contact a, one end of the first phase winding, the second phase winding, and the third phase winding are short-circuited to form a neutral point, and the other end of the first phase winding, the second phase winding, and the third phase winding are respectively connected to the midpoint of the first phase bridge arm, the second phase bridge arm, and the third phase bridge arm, and the permanent magnet motor is driven by the battery.

[0041] In charging / VG mode, the switching switch is turned on, the relay switches to normally open contact b, one end of the first phase winding and the second phase winding are connected to the single-phase power supply, and the other end is connected to the midpoint of the first phase bridge arm and the second phase bridge arm respectively, forming an H-bridge converter. One end of the third phase winding is connected to the positive terminal of the DC bus through the relay, and the other end is connected to the midpoint of the third phase bridge arm, forming a DC / DC converter.

[0042] In charging mode, the H-bridge converter is used as a rectifier to convert AC power from the grid into DC power, and the DC / DC converter is used as a Buck converter to adjust the rectified DC power to a suitable charging voltage level.

[0043] In V2G mode, the DC / DC converter is used as a Boost converter to regulate the battery voltage to a suitable grid-connected voltage level, and the H-bridge converter is used as an inverter to convert DC power into AC power for feeding into the grid.

[0044] When the system operates in electric drive mode, it uses a field-oriented control strategy to drive the motor.

[0045] When the system is operating in charging mode, a dual closed-loop control strategy of outer loop of bus voltage and inner loop of grid current is used to control the rectifier, and a dual closed-loop control strategy of outer loop of charging current and inner loop of charging voltage is used to control the Buck converter.

[0046] When the system operates in V2G mode, a dual closed-loop control strategy of outer loop of bus voltage and inner loop of discharge current is used to control the Boost converter, and a single closed-loop control strategy of grid current is used to control the inverter.

[0047] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A control method for a multi-functional integrated system of electric drive, charging, and V2G for electric vehicles, characterized in that, A multi-functional integrated system for electric drive, charging and V2G for electric vehicles, the system comprising: a three-phase permanent magnet motor drive system consisting of a three-phase permanent magnet motor (1), a three-phase voltage-source inverter (2), a capacitor (6) and a battery (7), characterized in that it further comprises a switching switch (3) and a relay (4); The switching switch (3) is connected to the middle of one tap of the winding of the three-phase permanent magnet motor (1); One end of the relay (4) is connected to the positive terminal of the battery and capacitor, and the other end includes a normally closed contact. a With a normally open contact b The normally closed contact a Connected to the positive DC side of the three-phase voltage source inverter (2), normally open contact b Connect to one end of one phase winding of a three-phase permanent magnet motor (1); The negative terminals of the capacitor (6) and the battery (7) are connected to the negative terminal of the DC side of the three-phase voltage-source inverter (2); It also includes a single-phase power supply (5), which is connected in series between the first phase winding (1-1) and the second phase winding (1-2) of the three-phase permanent magnet motor (1); The normally open contact b The third phase winding (1-3) is connected to the three-phase permanent magnet motor (1); The three-phase voltage source inverter (2) includes three phase arms, namely the first phase arm (2-1), the second phase arm (2-2), and the third phase arm (2-3). The method includes: In electric drive mode, the switch (3) is closed, and the relay (4) switches to the normally closed contact. a One end of the first phase winding (1-1), the second phase winding (1-2), and the third phase winding (1-3) are short-circuited to form a neutral point. The other ends of the first phase winding (1-1), the second phase winding (1-2), and the third phase winding (1-3) are respectively connected to the midpoints of the first phase bridge arm (2-1), the second phase bridge arm (2-2), and the third phase bridge arm (2-3). The permanent magnet motor is powered by the storage battery (7). In charging / V2G mode, the switch (3) is turned on and the relay (4) is switched to the normally open contact. b The first phase winding (1-1) and the second phase winding (1-2) are connected at one end to a single-phase power supply (5), and at the other end to the midpoint of the first phase bridge arm (2-1) and the second phase bridge arm (2-2) respectively, forming an H-bridge converter. One end of the third phase winding (1-3) is connected to the positive terminal of the DC bus through a relay (4), and at the other end is connected to the midpoint of the third phase bridge arm (2-3), forming a DC / DC converter. In charging mode, the H-bridge converter is used as a rectifier to convert AC power from the grid into DC power, and the DC / DC converter is used as a Buck converter to adjust the rectified DC power to a suitable charging voltage level. In V2G mode, the DC / DC converter is used as a Boost converter to regulate the battery voltage to a suitable grid-connected voltage level, and the H-bridge converter is used as an inverter to convert DC power into AC power for feeding into the grid.

2. The control method for the multi-functional integrated system of electric drive, charging, and V2G for electric vehicles according to claim 1, characterized in that, When the system operates in electric drive mode, it uses a field-oriented control strategy to drive the motor.

3. The control method for the multi-functional integrated system of electric drive, charging, and V2G for electric vehicles according to claim 1, characterized in that, When the system is operating in charging mode, a dual closed-loop control strategy of outer loop of bus voltage and inner loop of grid current is used to control the rectifier, and a dual closed-loop control strategy of outer loop of charging current and inner loop of charging voltage is used to control the Buck converter.

4. The control method for the multi-functional integrated system of electric drive, charging, and V2G for electric vehicles according to claim 1, characterized in that, When the system operates in V2G mode, a dual closed-loop control strategy of outer loop of bus voltage and inner loop of discharge current is used to control the Boost converter, and a single closed-loop control strategy of grid current is used to control the inverter.

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