An integrated alternating current charging and discharging electric drive system and electric vehicle

Abstract

The embodiment of the application provides an integrated alternating current charging and discharging electric drive system and an electric vehicle, and relates to the technical field of electric drive systems. In the electric drive system, the electric power driving assembly comprises a first power battery, a second power battery, a three-phase inverter circuit and a driving motor, the first power battery and the second power battery are connected in series, one end of the three-phase inverter circuit is connected with the first power battery, the other end of the three-phase inverter circuit is connected with the second power battery, and the driving motor is connected with the three-phase inverter circuit; the charging interface assembly comprises a charging interface, a first relay and a second relay, the charging interface is connected with the driving motor through the first relay, the charging interface is connected between the first power battery and the second power battery through the second relay, and the charging interface is connected with a preset alternating current power supply. The electric drive system can realize multiplexing of the electric power driving unit circuit, simultaneously realize the functions of electric power driving and alternating current slow charging, and achieve the technical effect of reducing the cost of the whole vehicle.

Description

Technical Field

[0001] This application relates to the field of electric drive system technology, and more specifically, to an integrated AC charging and discharging electric drive system and an electric vehicle. Background Technology

[0002] Currently, in the traditional electric vehicle electrical architecture, the electric drive unit (motor + three-phase inverter) and the AC slow charger (OBC) are two independent components. The electric drive unit operates while the vehicle is in motion, while the OBC only operates when the vehicle is parked and charging; the two operate in a time-sharing manner.

[0003] In existing technologies, conventional electric drive systems include a power battery, a three-phase inverter circuit, and a drive motor. The power battery is generally composed of multiple battery cells connected in series. The power of the electric drive unit is sufficient to meet the needs of single-phase AC slow charging. The challenge lies in how to reuse the electric drive unit circuitry to simultaneously achieve both electric drive and AC slow charging functions, thereby reducing the overall vehicle cost. Summary of the Invention

[0004] The purpose of this application is to provide an integrated AC charging and discharging electric drive system and electric vehicle, which can reuse the electric drive unit circuit and realize the functions of electric drive and AC slow charging, thereby achieving the technical effect of reducing the cost of the whole vehicle.

[0005] In a first aspect, embodiments of this application provide an integrated AC charging and discharging electric drive system, including an electric drive component and a charging interface component;

[0006] The electric drive assembly includes a first power battery, a second power battery, a three-phase inverter circuit, and a drive motor. The first power battery and the second power battery are connected in series. One end of the three-phase inverter circuit is connected to the first power battery, and the other end of the three-phase inverter circuit is connected to the second power battery. The drive motor is connected to the three-phase inverter circuit.

[0007] The charging interface assembly includes a charging interface, a first relay, and a second relay. The charging interface is connected to the drive motor through the first relay, and the charging interface is connected between the first power battery and the second power battery through the second relay. The charging interface is also connected to a preset AC power source.

[0008] In the above implementation process, the integrated AC charging and discharging electric drive system adds a charging interface component. When charging is not needed, the preset AC power supply and charging interface are disconnected; when charging is needed, the preset AC power supply and charging interface are connected. The AC power coming from the charging interface is connected at one end to the neutral point of the drive motor winding through a first relay, and at the other end to the space between the first and second power batteries through a second relay. The three-phase inverter circuit is driven and controlled by a PWM signal to control the common-mode voltage of the drive motor, thereby controlling the common-mode current of the drive motor, thus realizing AC charging of the power battery. In addition, the integrated AC charging and discharging electric drive system can also discharge the electrical energy in the power battery to the outside through the charging interface. Thus, the integrated AC charging and discharging electric drive system can reuse the electric drive unit circuit, simultaneously realizing the functions of electric drive and AC slow charging, achieving the technical effect of reducing the overall vehicle cost.

[0009] Furthermore, the electric drive system also includes a motor common-mode inductor, which is connected in series between the drive motor and the first relay.

[0010] In the above implementation process, an additional motor common-mode inductor is connected in series at the neutral point of the drive motor to increase the common-mode inductance.

[0011] Furthermore, the electric drive system also includes a bidirectional DC-DC converter circuit, which includes a converter inductor, a first power conversion semiconductor switch, and a second power conversion semiconductor switch. The first power conversion semiconductor switch and the second power conversion semiconductor switch are connected in series. The first power conversion semiconductor switch is connected to the first power battery, and the second power conversion semiconductor switch is connected to the second power battery. One end of the converter inductor is connected to the first power battery, and the other end of the converter inductor is connected between the first power conversion semiconductor switch and the second power conversion semiconductor switch.

[0012] In the above implementation process, by adding a bidirectional DC-DC converter circuit, the charging and discharging functions can still be achieved even when the power battery voltage is not high enough.

[0013] Furthermore, the bidirectional DC-DC converter circuit also includes a conversion relay, which is connected in series between the conversion inductor and the first power battery.

[0014] Furthermore, the voltage of the first power battery and the voltage of the preset AC power supply satisfy the following:

[0015]

[0016] Wherein, U1 is the voltage of the first power battery, U ac，rmsThe effective voltage value of the preset AC power supply.

[0017] Furthermore, the voltage of the first power battery and the voltage of the preset AC power supply satisfy the following:

[0018]

[0019] Wherein, U2 is the voltage of the first power battery, U ac，rms The effective voltage value of the preset AC power supply.

[0020] Furthermore, the electric drive assembly also includes a first drive relay, which is connected in series between the first power battery and the three-phase inverter circuit.

[0021] Furthermore, the electric drive assembly also includes a second drive relay, which is connected in series between the second power battery and the three-phase inverter circuit.

[0022] Furthermore, the electric drive assembly also includes a DC bus capacitor, which is connected to the first power battery and the second power battery respectively.

[0023] Secondly, embodiments of this application provide an electric vehicle, including an integrated AC charging and discharging electric drive system as described in any of the first aspects.

[0024] Other features and advantages disclosed in this application will be set forth in the following description, or some features and advantages may be inferred from the description or determined without doubt, or may be learned by practicing the above-described technology disclosed in this application.

[0025] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 A schematic diagram of a first integrated AC charging and discharging electric drive system provided for an embodiment of this application;

[0028] Figure 2 A schematic diagram of a second integrated AC charging and discharging electric drive system provided in an embodiment of this application;

[0029] Figure 3 A schematic diagram of a third integrated AC charging and discharging electric drive system provided in an embodiment of this application;

[0030] Figure 4 This is a simplified schematic diagram of an integrated AC charging and discharging electric drive system provided in an embodiment of this application. Detailed Implementation

[0031] The technical solutions in the embodiments of this application will now be described with reference to the accompanying drawings.

[0032] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, in the description of this application, terms such as "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0033] This application provides an integrated AC charging and discharging electric drive system and an electric vehicle, which can be applied to the electric drive system of an electric vehicle. This integrated AC charging and discharging electric drive system, by adding a charging interface component, disconnects the preset AC power supply and charging interface when charging is not needed. When charging is needed, the preset AC power supply and charging interface are connected. The AC power entering from the charging interface is connected at one end to the neutral point of the drive motor winding through a first relay, and at the other end to the connection between the first and second power batteries through a second relay. A PWM (Pulse Width Modulation) signal drives and controls the three-phase inverter circuit to control the common-mode voltage of the drive motor, thereby controlling the common-mode current of the drive motor, thus achieving AC charging of the power battery. Furthermore, this integrated AC charging and discharging electric drive system can also discharge the electrical energy in the power battery to the outside through the charging interface. Therefore, this integrated AC charging and discharging electric drive system can reuse the electric drive unit circuit, simultaneously realizing the functions of electric drive and AC slow charging, achieving the technical effect of reducing the overall vehicle cost.

[0034] Please see Figure 1 , Figure 1 This is a schematic diagram of a first integrated AC charging and discharging electric drive system provided in an embodiment of this application. The integrated AC charging and discharging electric drive system includes a power drive component and a charging interface component.

[0035] For example, the electric drive assembly includes a first power battery U1, a second power battery U2, a three-phase inverter circuit, and a drive motor M. The first power battery U1 and the second power battery U2 are connected in series. One end of the three-phase inverter circuit is connected to the first power battery U1, and the other end of the three-phase inverter circuit is connected to the second power battery U2. The drive motor M is connected to the three-phase inverter circuit.

[0036] In some implementations, the three-phase inverter circuit includes six power switch modules Q1 to Q6 (six semiconductor power switches and six anti-parallel diodes), connected as follows: Figure 1 As shown; the semiconductor power switching device can be an IGBT (Insulated Gate Bipolar Transistor) or a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor).

[0037] For example, the charging interface assembly includes a charging interface, a first relay K1 and a second relay K2. The charging interface is connected to the drive motor M through the first relay K1, and the charging interface is connected between the first power battery U1 and the second power battery U2 through the second relay K2. The charging interface is also connected to a preset AC power supply.

[0038] In some implementations, the charging interface is connected to the midpoint of the battery pack via a second relay K2, and the voltages of the first power battery U1 and the second power battery U2 are equal.

[0039] For example, this integrated AC charging and discharging electric drive system, by adding a charging interface component, disconnects the preset AC power supply and the charging interface when charging is not needed; when charging is needed, it connects the preset AC power supply and the charging interface. The AC power coming from the charging interface is connected at one end to the neutral point of the drive motor M winding through a first relay K1, and at the other end to the space between the first power battery U1 and the second power battery U2 through a second relay K2. The three-phase inverter circuit is driven and controlled by a PWM signal to control the common-mode voltage of the drive motor M, thereby controlling the common-mode current of the drive motor M, thus realizing AC charging of the power battery. In addition, this integrated AC charging and discharging electric drive system can also discharge the electrical energy in the power battery to the outside through the charging interface. Thus, this integrated AC charging and discharging electric drive system can reuse the electric drive unit circuit, simultaneously realizing the functions of electric drive and AC slow charging, achieving the technical effect of reducing the overall vehicle cost.

[0040] Optionally, the preset AC power supply can be a single-phase AC source, such as a regular AC slow charging station; the first relay K1 and the second relay K2 are used to disconnect the high-voltage circuit and the charging interface when charging is not required; the single-phase AC power coming from the charging interface is connected at one end to the neutral point of the drive motor M winding through the first relay K1, and at the other end to the connection between the first power battery U1 and the second power battery U2 through the second relay K2.

[0041] For example, the voltage of the first power battery and the voltage of the preset AC power supply satisfy:

[0042]

[0043] Where U1 is the voltage of the first power battery, U ac，rms This is the preset effective voltage value of the AC power supply;

[0044] For example, the voltage of the first power battery and the voltage of the preset AC power supply satisfy:

[0045]

[0046] Where U2 is the voltage of the first power battery, U ac，rms This is the preset effective voltage value of the AC power supply.

[0047] In some implementations, the common-mode inductance of the drive motor M may be too small. In this case, an additional motor common-mode inductor Ln can be connected in series at the neutral point of the drive motor M; please refer to [link to relevant documentation]. Figure 2 , Figure 2 This is a schematic diagram of a second integrated AC charging and discharging electric drive system provided in an embodiment of this application.

[0048] For example, the electric drive system also includes a motor common mode inductor Ln, which is connected in series between the drive motor M and the first relay K1.

[0049] For example, the electric drive assembly also includes a first drive relay Kp, which is connected in series between the first power battery U1 and the three-phase inverter circuit.

[0050] For example, the electric drive assembly also includes a second drive relay Kn, which is connected in series between the second power battery U2 and the three-phase inverter circuit.

[0051] For example, the electric drive assembly also includes a DC bus capacitor Cdc, which is connected to the first power battery U1 and the second power battery U2 respectively.

[0052] For example, combined Figures 1 to 2The integrated AC charging and discharging electric drive system provided in this application embodiment closes the first drive relay Kp, the second drive relay Kn, the first relay K1, and the second relay K2 when charging is required. Then, the six power switch modules Q1 to Q6 of the three-phase inverter circuit are controlled by PWM to control the common mode voltage of the drive motor M, and then control the common mode current of the drive motor M, so as to realize AC charging of the batteries (first power battery U1 and second power battery U2).

[0053] In addition to AC charging, this integrated AC charging and discharging electric drive system can also discharge the energy from the power battery to the external environment through the AC charging interface. In this case, the first drive relay Kp, the second drive relay Kn, the first relay K1, and the second relay K2 are closed, controlling the six power switching modules Q1 to Q6 of the three-phase inverter to operate under PWM drive, thereby controlling the common-mode voltage of the drive motor M, and consequently controlling the common-mode current of the drive motor M. The difference is that the phase of the common-mode current relative to the AC voltage is in an external discharge state. This external discharge state can be either feeding energy back to the grid or driving ordinary household appliances; it is not limited here.

[0054] In some implementations, if the battery voltage is insufficient (e.g., the minimum battery voltage is less than 750V), a bidirectional DC-DC converter circuit can be added; please refer to [link to relevant documentation]. Figure 3 , Figure 3 This is a schematic diagram of a third integrated AC charging and discharging electric drive system provided in an embodiment of this application.

[0055] For example, the electric drive system further includes a bidirectional DC-DC converter circuit, which includes a converter inductor Lb, a first power conversion semiconductor switch Q7, and a second power conversion semiconductor switch Q8. The first power conversion semiconductor switch Q7 and the second power conversion semiconductor switch Q8 are connected in series. The first power conversion semiconductor switch Q7 is connected to the first power battery U1, and the second power conversion semiconductor switch Q8 is connected to the second power battery U2. One end of the converter inductor Lb is connected to the first power battery U1, and the other end of the converter inductor Lb is connected between the first power conversion semiconductor switch Q7 and the second power conversion semiconductor switch Q8.

[0056] For example, the bidirectional DC-DC converter circuit also includes a converter relay Kac, which is connected in series between the converter inductor Lb and the first power battery U1.

[0057] In some implementations, when charging or discharging is required, the switching relay Kac and the second drive relay Kn are closed, while the first drive relay Kp remains open. The bidirectional DC-DC converter circuit raises the relatively low battery voltage to a higher DC bus voltage (Udc, i.e., the voltage across the DC bus capacitor Cdc), thus ensuring that the DC bus voltage Udc meets the requirements for single-phase AC charging or discharging. During normal motor drive, the switching relay Kac, the first drive relay K1, and the second drive relay K2 are open, while the first drive relay Kp and the second drive relay Kn are closed. The bidirectional DC-DC converter circuit does not operate, and the three-phase inverter circuit operates according to normal motor drive requirements. At this time, the battery voltage should meet the following requirements:

[0058]

[0059]

[0060] For example, Figure 3 The integrated AC charging and discharging electric drive system shown can control all upper bridge arms and all lower bridge arms of the three-phase inverter circuit to switch simultaneously during single-phase charging and discharging, i.e., Q1, Q2, Q3 (upper bridge) synchronous switches, Q2, Q4, Q6 (lower bridge) synchronous switches, or the three bridge arms can be driven by three-phase interleaved PWM, thereby further reducing common-mode current ripple.

[0061] Please see Figure 4 , Figure 4 This is a simplified schematic diagram of an integrated AC charging and discharging electric drive system provided in an embodiment of this application.

[0062] For example, regardless of the above scheme, if the upper bridge (Q1, Q2, Q3) of the three-phase inverter circuit is switched synchronously, the three-phase inverter circuit along with the drive motor M can be simplified as follows: Figure 4 The circuit shown is illustrated. Ln is the equivalent common-mode inductance (including the common-mode inductance of the drive motor M itself and any additional inductance added in series). QH and QL are the equivalent upper and lower bridge switches.

[0063] In this system, QH and QL conduct in a complementary manner. By controlling the proportion of QH that is active, the current flowing through Ln can be controlled, thereby achieving single-phase charging or discharging. This is a principle that engineers in the field of power electronics can understand, and will not be elaborated upon here.

[0064] Exemplary, embodiments of this application provide an electric vehicle, including as follows Figures 1 to 4 The integrated AC charging and discharging electric drive system shown is illustrated.

[0065] In the several embodiments provided in this application, it should be understood that the functional modules in each embodiment can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0066] The above description is merely an embodiment of this application and is not intended to limit the scope of protection of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application. It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0067] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0068] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

Claims

1. An integrated AC charging and discharging electric drive system, characterized in that, Includes electric drive components and charging interface components; The electric drive assembly includes a first power battery, a second power battery, a three-phase inverter circuit, and a drive motor. The first power battery and the second power battery are connected in series. One end of the three-phase inverter circuit is connected to the first power battery, and the other end of the three-phase inverter circuit is connected to the second power battery. The drive motor is connected to the three-phase inverter circuit. The charging interface assembly includes a charging interface, a first relay, and a second relay. The charging interface is connected to the drive motor through the first relay, and the charging interface is connected between the first power battery and the second power battery through the second relay. The charging interface is also connected to a preset AC power source. The electric drive system also includes a motor common mode inductor, which is connected in series between the drive motor and the first relay; The voltage of the first power battery and the voltage of the preset AC power supply satisfy the following: ； Wherein, U1 is the voltage of the first power battery, U ac，rms The effective voltage value of the preset AC power supply; The three-phase inverter circuit is configured such that, in AC charging and discharging mode, all upper bridge arm power switches are switched on and off synchronously, and all lower bridge arm power switches are switched on and off synchronously, so as to excite the common mode inductor of the drive motor, and filter and store the AC charging and discharging current together through the common mode inductor of the motor.

2. The integrated AC charging and discharging electric drive system according to claim 1, characterized in that, The electric drive system further includes a bidirectional DC-DC converter circuit, which includes a converter inductor, a first power conversion semiconductor switch, and a second power conversion semiconductor switch. The first power conversion semiconductor switch and the second power conversion semiconductor switch are connected in series. The first power conversion semiconductor switch is connected to the first power battery, and the second power conversion semiconductor switch is connected to the second power battery. One end of the converter inductor is connected to the first power battery, and the other end of the converter inductor is connected between the first power conversion semiconductor switch and the second power conversion semiconductor switch.

3. The integrated AC charging and discharging electric drive system according to claim 2, characterized in that, The bidirectional DC-DC converter circuit also includes a converter relay, which is connected in series between the converter inductor and the first power battery.

4. The integrated AC charging and discharging electric drive system according to claim 1, characterized in that, The voltage of the first power battery and the voltage of the preset AC power supply satisfy the following: ； Wherein, U2 is the voltage of the first power battery, U ac，rms The effective voltage value of the preset AC power supply.

5. The integrated AC charging and discharging electric drive system according to claim 1, characterized in that, The electric drive assembly also includes a first drive relay, which is connected in series between the first power battery and the three-phase inverter circuit.

6. The integrated AC charging and discharging electric drive system according to claim 1 or 5, characterized in that, The electric drive assembly also includes a second drive relay, which is connected in series between the second power battery and the three-phase inverter circuit.

7. The integrated AC charging and discharging electric drive system according to claim 1, characterized in that, The electric drive assembly also includes a DC bus capacitor, which is connected to the first power battery and the second power battery respectively.

8. An electric vehicle, characterized in that, Includes the integrated AC charging and discharging electric drive system as described in any one of claims 1 to 7.

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