Power assembly compatible with heating and charging, switching circuit, vehicle, and control method

Abstract

The present application provides a power assembly, a switching circuit, a vehicle and a control method that are compatible with heating and charging. The power assembly includes a DC bus, a motor controller and a drive motor. The motor controller includes three-phase bridge arms. The DC bus includes a positive DC bus and a negative DC bus. One end of each phase bridge arm is used to connect the positive pole of the DC power supply and the positive pole of the power battery through the positive DC bus. The negative DC bus is used to connect the negative pole of the power battery through a first switch. The midpoint of one phase bridge arm in the three-phase bridge arms or the star point of the three-phase windings of the drive motor is used to connect the negative pole of the DC power supply through a second switch and connect the negative pole of the power battery through a third switch. The negative DC bus is used to connect the negative pole of the DC power supply through a fourth switch. By controlling the opening and closing of the first switch to the fourth switch, the motor controller can be switched between three different functions of battery heating, boost charging or buck charging, reducing costs and manufacturing difficulties.

Description

Technical Field

[0001] The present application relates to the field of new energy vehicles, and more specifically, to a power assembly, a switching circuit, a vehicle, and a control method that are compatible with heating and charging. Background Art

[0002] With the development and popularization of electric vehicles, the charging problem has received increasing attention.

[0003] For example, the battery, which is currently the main power source of electric vehicles, is prone to lithium plating when discharging at a large current at low temperatures, resulting in a decrease in battery capacity and even potential safety hazards for the battery. Therefore, in winter when the temperature is relatively low, the battery needs to be heated to above 0°C before starting the electric vehicle. In response to this, a battery heating solution is provided: by controlling the power battery to switch between charging and discharging through an alternating current / direct current converter (AC / DC) or the like, alternating current is generated, thereby exciting the electrochemical substances inside the battery to heat the battery from the inside.

[0004] For another example, a charging pile may have two voltage output specifications. When the voltage platform of the power battery does not match the voltage specification of the charging pile, fast charging may not be possible. In response to this, a charging voltage conversion solution is provided: the voltage output by the charging pile can be stepped up or down through a direct current / direct current converter (DC / DC) or the like, so that the voltage platform of the power battery matches the voltage specification of the charging pile.

[0005] However, in order to implement the above functions, additional devices such as AC / DC and DC / DC need to be configured, increasing the cost and manufacturing difficulty. Summary of the Invention

[0006] The present application provides a power assembly, a switching circuit, a vehicle, and a control method that are compatible with heating and charging, which can reduce the cost and manufacturing difficulty on the basis of being compatible with the battery heating solution and the charging voltage conversion solution.

[0007] In a first aspect, a power assembly that is compatible with heating and charging is provided. The power assembly includes a DC bus, a motor controller, and a drive motor. The motor controller includes three-phase bridge arms, each phase bridge arm includes an upper bridge arm switching tube and a lower bridge arm switching tube, the midpoints of the bridge arms of the three-phase bridge arms are respectively used to connect the three-phase windings of the drive motor, the DC bus includes a positive DC bus and a negative DC bus, and one end of each phase of the bridge arm is used to connect the positive electrode of the DC power supply and the positive electrode of the power battery through the positive DC bus.

[0008] The negative DC bus is used to connect to the negative electrode of the power battery through the first switch. Specifically, one end of each phase arm is used to connect one end of the DC power supply and one end of the power battery, and the other end of each phase arm is used to connect to one end of the first switch K1. The other end of K1 is used to connect to the other end of the power battery, and the midpoints of the three phase arms are used to connect to the three-phase windings of the drive motor.

[0009] In one implementation, the midpoint of one phase arm of the three-phase arm is used to connect to the negative electrode of the DC power supply through the second switch K2 and to connect to the negative electrode of the power battery through the third switch K3. Specifically, the midpoint of one phase arm of the three phase arms is used to connect to one end of the second switch K2, and the other end of K2 is used to connect to the other end of the DC power supply.

[0010] In another implementation, the star point of the three-phase windings of the drive motor is used to connect to the negative electrode of the DC power supply through the second switch K2 and to connect to the negative electrode of the power battery through the third switch K3. Specifically, the star point of the three-phase windings of the drive motor is used to connect to one end of K2, and the other end of K2 is used to connect to the other end of the DC power supply.

[0011] Moreover, the negative DC bus is used to connect to the negative electrode of the DC power supply through the fourth switch K4. Specifically, one end of K2 is also used to connect to the other end of the power battery via the third switch K3, one end of K1 is also connected to one end of the fourth switch K4, and the other end of K4 is used to connect to the other end of the DC power supply.

[0012] By arranging K1 to K4 in the powertrain as described above, when a battery heating scheme or a charging voltage conversion scheme is required, by controlling the opening and closing of K1 to K4, the motor controller can achieve the functions of AC / DC or DC / DC. That is, without additional configuration of AC / DC or DC / DC, the battery can be heated or the charging voltage can be converted. Thus, on the basis of being compatible with the battery heating scheme and the charging voltage conversion scheme, the cost and manufacturing difficulty can be reduced.

[0013] For example, in response to receiving an instruction for heating the power battery (i.e., when the power battery needs to be heated), the first switch is opened, the second switch is opened, the third switch is closed, and the fourth switch is closed.

[0014] For another example, in response to receiving an instruction for charging the power battery (i.e., when the power battery needs to be charged), the first switch is closed, the second switch is closed, the third switch is opened, and the fourth switch is opened, or the first switch is opened, the second switch is opened, the third switch is closed, and the fourth switch is closed.

[0015] Among them, charging the power battery may include the following two situations:

[0016] 1. Boost charging, that is, in response to the voltage of the DC power supply being lower than the voltage of the power battery, closing the first switch, closing the second switch, opening the third switch, and opening the fourth switch. Thereby enabling the motor controller to implement the function of DC / DC for boosting, and then completing the boosting of the current from the charging pile.

[0017] 2. Buck charging, that is, in response to the voltage of the DC power supply being higher than the voltage of the power battery, opening the first switch, opening the second switch, closing the third switch, and closing the fourth switch. Thereby enabling the motor controller to implement the function of DC / DC for bucking, and then completing the bucking of the current from the charging pile.

[0018] In addition, the powertrain is further configured to: in response to receiving an instruction for the end of power battery charging or the end of power battery heating; closing the first switch, opening the second switch, opening the third switch, and opening the fourth switch, so that the motor controller can implement the control of motor drive.

[0019] In one implementation, an inductor device is provided between the star point of the three-phase windings of the drive motor and the second switch. When the midpoints of the three bridge arms are connected to one end of K2 through the star point of the three-phase windings of the drive motor, after the three-phase windings of the drive motor are connected in parallel, they are connected in series in the circuit. Therefore, the inductance in the circuit is small. At this time, by providing an inductor device in the circuit, the value of the inductance in the circuit can be increased, thereby ensuring the effects of the battery heating scheme and the charging voltage conversion scheme.

[0020] In a possible implementation, the powertrain further includes a bus capacitor. One end of the bus capacitor is used to connect one end of the DC power supply and one end of the power battery, and the other end of the bus capacitor is used to connect one end of the first switch and one end of the fourth switch. Thus, after the mode of heating the power battery is turned on, the bus capacitor participates in the charging and discharging process of the power battery, and can improve the heating efficiency.

[0021] In the embodiments of the present application, the powertrain includes a controller, and the control device includes at least one of the battery management device of the power battery, the motor controller, or the vehicle controller. The controller is configured to: in response to at least one instruction, the instruction includes an instruction for power battery heating, an instruction for power battery charging, an instruction for the end of power battery charging, or an instruction for the end of power battery heating; control the opening and closing of the first switch, the second switch, the third switch, and the fourth switch.

[0022] In an embodiment of the present application, after the mode of heating the power battery by the motor controller is turned on, in one period, the upper-bridge-arm switch tube and the lower-bridge-arm switch tube are controlled to open and close with a first duty cycle; in another period, the upper-bridge-arm switch tube and the lower-bridge-arm switch tube are controlled to open and close with a second duty cycle, wherein the heating power in the one period is greater than the heating power in the another period, and the first duty cycle is greater than the second duty cycle. Thus, it is possible to meet the requirements of different heating powers by varying the duty cycle.

[0023] In a second aspect, a switching circuit for a powertrain is provided. The powertrain includes a DC bus, a motor controller, and a drive motor. The motor controller includes a three-phase bridge arm. Each phase of the bridge arm includes an upper-bridge-arm switch tube and a lower-bridge-arm switch tube, and the midpoints of the bridge arms of the three-phase bridge arm are respectively used to connect the three-phase windings of the drive motor. The DC bus includes a positive DC bus and a negative DC bus, and one end of each phase of the bridge arm is used to connect the positive pole of the DC power supply and the positive pole of the power battery through the positive DC bus.

[0024] The switching circuit includes: a first switch, a second switch, a third switch, and a fourth switch.

[0025] The first switch is used to connect the negative DC bus and the negative pole of the power battery.

[0026] The second switch and the third switch are respectively used to connect the negative pole of the DC power supply and the midpoint of one phase of the three-phase bridge arm, the negative pole of the power battery and the midpoint of one phase of the three-phase bridge arm, or the second switch and the third switch are respectively used to connect the negative pole of the DC power supply and the star point of the three-phase windings of the drive motor, the negative pole of the power battery and the star point of the three-phase windings of the drive motor;

[0027] The fourth switch is used to connect the negative DC bus and the negative pole of the DC power supply.

[0028] In one implementation, when the first switch is closed, the second switch is open, the third switch is open, and the fourth switch is open, the motor controller is used to drive the drive motor;

[0029] In another implementation, when the first switch is open, the second switch is open, the third switch is closed, and the fourth switch is open, the powertrain is used to heat the battery.

[0030] In yet another implementation, when the first switch is closed, the second switch is closed, the third switch is open, and the fourth switch is open, or when the first switch is open, the second switch is open, the third switch is closed, and the fourth switch is closed, the powertrain is used to receive power from the DC power supply to charge the power battery.

[0031] Specifically, when the first switch is closed, the second switch is closed, the third switch is open, and the fourth switch is open, the power assembly is used to boost the power supply of the DC power source and then charge the power battery.

[0032] And when the first switch is open, the second switch is open, the third switch is closed, and the fourth switch is closed, the power assembly is used to step down the power supply of the DC power source and then charge the power battery.

[0033] In a third aspect, a vehicle is provided, which includes: a power battery, wheels, and a power assembly as in the first aspect and any possible implementation thereof.

[0034] Alternatively, the vehicle includes a power battery, wheels, a power assembly, and a switch circuit as in the second aspect and any possible implementation thereof.

[0035] Wherein, the power assembly is used to receive power supply from the power battery and drive the wheels.

[0036] In a possible implementation, the vehicle includes a power battery heating mode and a power battery charging mode.

[0037] For example, in response to the user triggering the power battery heating mode, the vehicle is used to control the first switch to be open, the second switch to be open, the third switch to be closed, and the fourth switch to be open.

[0038] For another example, in response to the user triggering the power battery charging mode, the vehicle is used to control the first switch to be closed, the second switch to be closed, the third switch to be open, and the fourth switch to be open, or control the first switch to be open, the second switch to be open, the third switch to be closed, and the fourth switch to be closed.

[0039] And in response to the user ending the power battery heating mode or the power battery charging mode, the vehicle is used to control the first switch to be closed, the second switch to be open, the third switch to be open, and the fourth switch to be open.

[0040] In a fourth aspect, a control method for a power assembly. The power assembly includes a first switch, a second switch, a third switch, a fourth switch, a DC bus, a motor controller, and a drive motor. The motor controller includes three-phase bridge arms, each phase bridge arm includes an upper bridge arm switch tube and a lower bridge arm switch tube. The midpoints of the bridge arms of the three-phase bridge arms are respectively used to connect the three-phase windings of the drive motor. The DC bus includes a positive DC bus and a negative DC bus. One end of each phase of the bridge arm is used to connect the positive pole of the DC power source and the positive pole of the power battery through the positive DC bus.

[0041] The method includes:

[0042] In response to receiving a power battery heating instruction, control the first switch to disconnect the connection between the negative DC bus and the negative electrode of the power battery, control the second switch to disconnect the connection between the midpoint of one phase of the three-phase bridge arm and the negative electrode of the DC power supply or the negative electrode of the power battery, control the third switch to conduct the connection between the negative electrode of the power battery and the star point of the three-phase windings of the drive motor, and control the fourth switch to disconnect the connection between the negative DC bus and the negative electrode of the DC power supply;

[0043] In response to receiving a power battery charging instruction, control the first switch to conduct the connection between the negative DC bus and the negative electrode of the power battery, control the second switch to conduct the connection between the midpoint of one phase of the three-phase bridge arm and the negative electrode of the DC power supply or the negative electrode of the power battery, control the third switch to disconnect the connection between the negative electrode of the power battery and the star point of the three-phase windings of the drive motor, and control the fourth switch to disconnect the connection between the negative DC bus and the negative electrode of the power battery. Alternatively, control the first switch to disconnect the connection between the negative DC bus and the negative electrode of the power battery, control the second switch to disconnect the connection between the midpoint of one phase of the three-phase bridge arm and the negative electrode of the DC power supply or the negative electrode of the power battery, control the third switch to conduct the connection between the negative electrode of the power battery and the star point of the three-phase windings of the drive motor, and control the fourth switch to conduct the connection between the negative DC bus and the negative electrode of the DC power supply.

[0044] Moreover, the method further includes: in response to the end of the power battery heating mode or the end of the power battery charging mode, control the first switch to conduct the connection between the negative DC bus and the negative electrode of the power battery, control the second switch to disconnect the connection between the midpoint of one phase of the three-phase bridge arm and the negative electrode of the DC power supply or the negative electrode of the power battery, control the third switch to disconnect the connection between the negative electrode of the power battery and the star point of the three-phase windings of the drive motor, and control the fourth switch to disconnect the connection between the negative DC bus and the negative electrode of the DC power supply.

[0045] For the technical effects of the solutions provided in the second to fourth aspects as described above, reference may be made to the corresponding description in the first aspect, and details will not be repeated. Description of the Drawings

[0046] Figure 1 is a schematic structural diagram of a vehicle provided by an embodiment of the present application;

[0047] Figure 2 is a schematic structural diagram of an example of a powertrain provided by an embodiment of the present application;

[0048] Figure 3 is Figure 2 a schematic diagram of the current flow direction during the battery discharge process of the powertrain shown in the battery heating mode;

[0049] Figure 4 isFigure 2 Schematic diagram of current flow during the battery charging process of the powertrain shown in the battery heating mode;

[0050] Figure 5 is Figure 2 Schematic diagram of current flow during the field excitation process of the powertrain shown in the boost charging mode;

[0051] Figure 6 is Figure 2 Schematic diagram of current flow during the freewheeling process of the powertrain shown in the boost charging mode;

[0052] Figure 7 is Figure 2 Schematic diagram of current flow during the field excitation process of the powertrain shown in the buck charging mode;

[0053] Figure 8 is Figure 2 Schematic diagram of current flow during the freewheeling process of the powertrain shown in the buck charging mode;

[0054] Figure 9 Schematic diagram of the structure of another example of the powertrain provided by the embodiments of the present application;

[0055] Figure 10 is Figure 9 Schematic diagram of current flow during the battery discharging process of the powertrain shown in the battery heating mode;

[0056] Figure 11 is Figure 9 Schematic diagram of current flow during the battery charging process of the powertrain shown in the battery heating mode;

[0057] Figure 12 is Figure 9 Schematic diagram of current flow during the field excitation process of the powertrain shown in the boost charging mode;

[0058] Figure 13 is Figure 9 Schematic diagram of current flow during the freewheeling process of the powertrain shown in the boost charging mode;

[0059] Figure 14 is Figure 9 Schematic diagram of current flow during the field excitation process of the powertrain shown in the buck charging mode;

[0060] Figure 15 is Figure 9 Schematic diagram of current flow during the freewheeling process of the powertrain shown in the buck charging mode;

[0061] Figure 16It is a schematic structural diagram of another example of the powertrain provided by an embodiment of the present application;

[0062] Figure 17 It is a schematic structural diagram of yet another example of the powertrain provided by an embodiment of the present application;

[0063] Figure 18 It is a schematic structural diagram of yet another example of the powertrain provided by an embodiment of the present application;

[0064] Figure 19 It is a schematic structural diagram of yet another example of the powertrain provided by an embodiment of the present application. Detailed implementation manners

[0065] Next, the technical solutions in the present application will be described with reference to the accompanying drawings.

[0066] Please refer to Figure 1 , Figure 1 It is a schematic diagram of a vehicle scenario provided by an embodiment of the present application. In the implementation of the present application, the vehicle is described by taking an electric vehicle as an example. In the implementation of the present application, the vehicle can be a pure electric vehicle, a hybrid vehicle or a plug-in hybrid vehicle.

[0067] As Figure 1 shown, the vehicle includes a power battery 101 and a powertrain 102. The power battery 101 is connected to the powertrain 102. When the vehicle is not connected to a power source, the power battery 101 supplies power to the powertrain 102. When the vehicle is connected to a power source, the power source can charge the power battery 101 through the powertrain 102.

[0068] Please refer to Figure 2 , Figure 2 It is a schematic structural diagram of an example of a powertrain provided by an embodiment of the present application. As Figure 2 shown, the powertrain 102 may include a drive motor 1021 and a motor controller 1022. The motor controller 1022 includes an inverter circuit. The inverter circuit includes three-phase bridge arms, each phase bridge arm includes an upper bridge arm and a lower bridge arm, each phase bridge arm includes a switching tube, and the position between the upper bridge arm and the lower bridge arm of the same phase bridge arm is called the bridge arm midpoint. The drive motor may include three-phase windings, and the bridge arm midpoints of the three-phase bridge arms are respectively connected to the three-phase windings of the drive motor. The bridge arm midpoints of the three-phase bridge arms respectively output three-phase currents to supply power to the three-phase windings of the drive motor 1021.

[0069] As Figure 2As shown in the figure, the inverter circuit includes leg 1, leg 2, and leg 3. Among them, leg 1 of the inverter circuit includes switch tube T1 (i.e., the upper leg of leg 1) and switch tube T2 (i.e., the lower leg of leg 1). Leg 2 of the inverter circuit includes switch tube T3 (i.e., the upper leg of leg 2) and switch tube T4 (i.e., the lower leg of leg 2). Leg 3 of the inverter circuit includes switch tube T5 (i.e., the upper leg of leg 3) and switch tube T6 (i.e., the lower leg of leg 3).

[0070] The midpoint of leg 2 of the inverter circuit is coupled to winding N1 of the drive motor and outputs a phase current to winding N1 of the drive motor. The midpoint of leg 1 of the inverter circuit is coupled to winding N2 of the drive motor and outputs a phase current to winding N2 of the drive motor. The midpoint of leg 3 of the inverter circuit is coupled to winding N3 of the drive motor and outputs a phase current to winding N3 of the drive motor.

[0071] It should be noted that "coupled" in the embodiments of this application means directly or indirectly connected. For example, when A is coupled to B, it can be either that A is directly connected to B, or that A and B are indirectly connected through one or more other electrical components. For example, it can be that A is directly connected to C and C is directly connected to B, so that A and B are connected through C. Hereinafter, the description of the same or similar situations is omitted.

[0072] When charging the power battery, the powertrain in the embodiments of this application can be coupled between the DC power supply and the power battery 102. Specifically, the powertrain includes a positive interface and a negative interface. The positive interface is used to connect to the positive pole of the DC power supply, and the negative interface is used to connect to the negative pole of the DC power supply.

[0073] Among them, the powertrain includes a positive DC bus for connecting the positive pole of the DC power supply and the positive pole of the power battery, and the powertrain includes a negative DC bus for connecting the negative pole of the DC power supply and the negative pole of the power battery.

[0074] In this case, one end of each phase leg is used to connect to the positive pole of the DC power supply and the positive pole of the power battery through the positive DC bus.

[0075] The negative DC bus is used to connect to the negative pole of the power battery through the first switch (denoted as switch K1).

[0076] The midpoint of one phase leg among the three-phase legs is used to connect to the negative pole of the DC power supply through the second switch (denoted as switch K2) and connect to the negative pole of the power battery through the third switch (denoted as switch K3).

[0077] The negative DC bus is used to connect to the negative pole of the DC power supply through the fourth switch (denoted as switch K4).

[0078] That is, the positive interface couples one end of the switching tubes corresponding to the upper bridge arms in each bridge arm, and the positive interface couples one end of the bus capacitor 1023, and the positive interface couples the positive electrode of the power battery 101.

[0079] In addition, the negative interface couples one end of switch K2, and the negative interface couples one end of switch K4.

[0080] The other end of switch K2 couples to the midpoint of bridge arm 2, and the other end of switch K2 couples to one end of switch K3. The other end of switch K3 couples to the negative electrode of the power battery 101.

[0081] The other end of switch K4 couples to one end of switch K1, and the other end of switch K4 couples to the other end of the bus capacitor 1023.

[0082] The other end of switch K1 couples to the negative electrode of the power battery 101.

[0083] It should be noted that each of the switching tubes T1 - T6 in each bridge arm can be a Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET), an Insulated Gate Bipolar Transistor (IGBT), and its parallel diode, etc.

[0084] And, in the embodiment of the present application, the motor controller 1022 can control the opening and closing (or conduction and cutoff) of each of the above-mentioned switching tubes T1 - T6.

[0085] And, each of the switches K1 - K4 can be various switches such as MOSFET, IGBT, diode, or relay, etc.

[0086] In addition, in the embodiment of the present application, the opening and closing of each of the above-mentioned switches K1 - K4 can be controlled by a controller.

[0087] Among them, the controller can be the motor controller 1022.

[0088] Or, the controller can also be a battery management system (BMS) in the vehicle.

[0089] Or, the controller can also be an electronic control device such as a vehicle control unit (VCU) in the vehicle.

[0090] For example, there is a signal connection between the controller and each of the switches K1 to K4, so that the controller can send control signals to the switches through this signal connection, and then control the opening and closing of each of the switches K1 to K4.

[0091] The powertrain provided by the embodiment of the present application can achieve, by controlling the opening and closing of the above-mentioned K1 to K4 and controlling the above-mentioned switching tubes T1 to T6D:

[0092] Mode 1: The powertrain discharges the power battery to heat the power battery;

[0093] Mode 2: The powertrain boosts the voltage of the DC power supply and charges the power battery;

[0094] Mode 3: The powertrain steps down the voltage of the DC power supply and charges the power battery;

[0095] Mode 4: The powertrain receives power supply from the power battery and outputs alternating current to the drive motor.

[0096] Next, the operation of the vehicle and the powertrain provided by the embodiment of the present application in each mode will be described.

[0097] Mode 1: The powertrain discharges the power battery to heat the power battery;

[0098] For example, when the outside temperature is too low, or when the temperature of the power battery is too low, the battery needs to be heated. In this case, the controller responds to the battery heating command and sends control signals to each of the switches K1 to K4, so that K1, K2, and K4 are disconnected, and K3 is closed. Thus, the circuit connection of the powertrain is switched to the structure corresponding to Mode 1. Furthermore, the motor controller 1022 can control the above-mentioned switching tubes T1 to T6 to conduct or cut off in the following manner to complete the heating of the power battery 101.

[0099] Specifically, the motor controller 1022 can use pulse width modulation (PWM) control technology to control the above-mentioned switching tubes T1 to T6, so that a series of pulses with equal amplitudes but unequal widths are obtained at the output end, that is, PWM waves, and use PWM waves to replace the sinusoidal AC voltage. Modulating the widths of the pulses according to certain rules can change both the magnitude of the output voltage of the inverter circuit and the output frequency.

[0100] The above PWM control includes multiple PWM cycles, and each PWM cycle includes an excitation stage and a freewheeling stage. Hereinafter, for the convenience of description, the control process of one PWM cycle will be described.

[0101] Specifically, after K1, K2, and K4 are disconnected and K3 is closed, the motor controller 1022 controls T1 and T5 to conduct (other switching tubes are cut off). In this case, as Figure 3 shown, the current flowing out from the positive electrode of the power battery 101 passes through T1 and flows into the winding N2. Moreover, the current flowing out from the positive electrode of the power battery 101 passes through T5 and flows into the winding N3. And the current flowing out from the winding N2 and the winding N3 converges to the winding N1, and then flows into the battery negative electrode through the closed K3. Thus, the discharge of the power battery 101 and the charging of the windings N1 - N3 are completed. Furthermore, the excitation stage of the PWM is completed.

[0102] After that, continue to keep K1, K2, and K4 disconnected and K3 closed. The motor controller 1022 controls T2 and T6 to conduct (other switching tubes are cut off). In this case, as Figure 4 shown, the electric energy stored in the windings N1 - N3 outputs current. This current flows from the winding N1 through the closed switch K3 into the battery negative electrode. The current flowing out from the battery positive electrode flows into the winding N3 through the wireless capacitor and T6. And the current flowing out from the battery positive electrode flows into the winding N2 through the wireless capacitor and T2. Thus, the charging of the power battery 101 and the discharge of the windings N1 - N3 are completed. Furthermore, the freewheeling stage of the PWM is completed.

[0103] Therefore, due to the different current directions in the above-mentioned excitation stage and freewheeling stage, a high-frequency alternating current is formed, and then a high-frequency transformed magnetic field is formed. The substances inside the battery generate eddy currents in this high-frequency magnetic field and convert electrical energy into heat energy, thereby achieving the purpose of heating.

[0104] The above examples list the way that arm 1 and arm 3 work simultaneously during the PWM control process. It is also possible to only make one of arm 1 and arm 3 work. That is, during the PWM control process, it is possible to only make the switching tubes of one of arm 1 and arm 3 conduct and turn off in the above-mentioned manner, and keep the switching tubes of the other arm in the cut-off state.

[0105] In addition, in the embodiments of the present application, the duty cycle of the switching tube (i.e., the conduction time and the cut-off time) can be changed according to the heating power requirements during the actual use process. For example, the higher the required heating power, the larger the duty cycle of the switching tube can be made.

[0106] Moreover, in the embodiment of the present application, when the battery is heated to a preset temperature, the powertrain can also exit Mode 1, causing the motor controller 1022 to switch to the mode of driving and controlling the motor. That is, in response to a battery heating end instruction (or, a motor driving instruction), the controller sends control signals to each of the switches K1-K4, causing K1 to close and K2, K3, and K4 to open. Thus, the circuit connection of the powertrain is switched to the structure corresponding to the mode of driving the motor. Furthermore, the motor controller 1022 can control the conduction or cutoff of each of the above-mentioned switching tubes T1-T6 to complete the driving of the motor, or rather, the control of the torque output by the motor. Among them, this control process can be similar to the prior art. To avoid repetition, its detailed description is omitted here.

[0107] Mode 2: The powertrain boosts the voltage of the DC power supply and charges the power battery.

[0108] For example, when it is necessary to charge the power battery, if the voltage provided by the DC power supply is lower than the current voltage of the power battery, charging the power battery cannot be achieved. In this case, in response to a charging instruction (such as a boost charging instruction), the controller sends control signals to each of the switches K1-K4, causing K1 and K2 to close and K3 and K4 to open. Thus, the circuit connection of the powertrain is switched to the structure corresponding to Mode 2. Furthermore, the motor controller 1022 can control the conduction or cutoff of each of the above-mentioned switching tubes T1-T6 in the following manner to complete the boosting of the voltage from the DC power supply and thereby achieve the charging of the battery.

[0109] Specifically, after K1 and K2 are closed and K3 and K4 are open, the motor controller 1022 controls T1 and T5 to conduct (the other switching tubes are cutoff). In this case, as Figure 5 shown, the current flowing out from the positive pole of the DC power supply passes through T1 and flows into winding N2. Moreover, the current flowing out from the positive pole of the power battery 101 passes through T5 and flows into winding N3. And the current flowing out from windings N2 and N3 converges to winding N1 and then flows into the negative pole of the DC power supply via the closed K2. Thus, the charging of windings N1-N3 is completed. Furthermore, the excitation stage of PWM is completed.

[0110] Thereafter, while maintaining the state where K1 and K2 are closed and K3 and K4 are open, the motor controller 1022 controls T2 and T6 to conduct (the other switching tubes are cutoff). In this case, as Figure 6As shown, the current flowing out from the positive pole of the DC power supply flows into the positive pole of the power battery 101. And the current flows from the negative pole of the power battery 101 through the closed switch K1 into the conducting T6, and then into the winding N3. Further, the current flows from the negative pole of the power battery 101 through the closed switch K1 into the conducting T2, and then into the winding N2. And the current flowing out from the winding N2 and the winding N3 converges to the winding N1, and then flows into the negative pole of the DC power supply through the closed K2.

[0111] In addition, the electric energy stored in the windings N1 - N3 can output current and flow into the power battery through the above path. Further, the freewheeling stage of the PWM is completed. Thereby, the charging voltage of the power battery is increased.

[0112] The above lists the way that the arm 1 and the arm 3 work simultaneously during the PWM control process. It is also possible to make only one of the arm 1 and the arm 3 work. That is, during the PWM control process, it is possible to make only the switching tubes of one of the arm 1 and the arm 3 conduct and turn off in the above manner, and keep the switching tubes of the other party in the cut-off state.

[0113] And, in the embodiment of the present application, when the battery charging is completed, the powertrain can also exit this mode 2, and make the motor controller 1022 switch to the mode of driving and controlling the motor. That is, the controller responds to the battery heating end instruction (or, the motor driving instruction), and sends control signals to each of the switches K1 - K4, makes K1 closed, and makes K2, K3, and K4 open. Thus, the circuit connection of the powertrain is switched to the structure corresponding to the mode of driving the motor. Further, the motor controller 1022 can control the conduction or cut-off of each of the above switching tubes T1 - T6 to complete the driving of the motor, or rather, the control of the torque output by the motor. Among them, this control process can be similar to the prior art. To avoid repetition, its detailed description is omitted here.

[0114] Mode 3: The powertrain steps down the voltage of the DC power supply and charges the power battery;

[0115] For example, when it is necessary to charge the power battery, if the voltage provided by the DC power supply is higher than the current voltage of the power battery, it is impossible to achieve fast charging of the power battery. In this case, the controller responds to the charging instruction (for example, the step-down charging instruction) and sends control signals to each of the switches K1 - K4, makes K1 and K2 open, and makes K3 and K4 closed. Thus, the circuit connection of the powertrain is switched to the structure corresponding to mode 3. Further, the motor controller 1022 can control the conduction or cut-off of each of the above switching tubes T1 - T6 in the following manner to complete the step-down of the voltage from the DC power supply, and further achieve the charging of the battery.

[0116] Specifically, after K1 and K2 are disconnected and K3 and K4 are closed, the motor controller 1022 controls T2 and T6 to conduct (other switching tubes are cut off). In this case, as Figure 7 shown, the current flowing out from the positive pole of the DC power supply, for example, the positive pole of the power battery 101, and the current flowing out from the negative pole of the power battery 101 flows into the winding N1 through the closed switch K3, and then flows into the windings N2 and N3 respectively. The current flowing out from the winding N2 flows through T2 and K4 into the negative pole of the DC power supply, and the current flowing out from the winding N3 flows through T6 and K4 into the negative pole of the DC power supply. Thus, the charging of the windings N1 to N3 is completed. Furthermore, the exciting stage of the PWM is completed.

[0117] After that, the state where K1 and K2 are disconnected and K3 and K4 are closed is continuously maintained, and the motor controller 1022 controls T1 and T5 to conduct (other switching tubes are cut off). In this case, as Figure 8 shown, the electric energy stored in the windings N1 to N3 flows out from the windings N2 and N3 respectively. The current flowing out from the winding N2 flows into the positive pole of the power battery 101 through T1, the current flowing out from the winding N3 flows into the positive pole of the power battery 101 through T5, and the current flowing out from the negative pole of the power battery 101 flows into the winding N1 through the closed switch K3. Furthermore, the freewheeling stage of the PWM is completed. Since the DC power supply only supplies power to the power battery during the exciting stage, step-down charging is achieved.

[0118] Mode 4: The powertrain receives power from the power battery and outputs alternating current to the drive motor;

[0119] In the embodiment of the present application, when the battery charging is completed, the powertrain can also exit this Mode 3, and the motor controller 1022 is switched to Mode 4, which is a mode for driving and controlling the motor.

[0120] In one embodiment, in response to a battery heating end instruction (or, a motor driving instruction), the controller sends control signals to each of the switches K1 to K4, closes K1, and disconnects K2, K3, and K4, so that the circuit connection of the powertrain is switched to the structure corresponding to the mode of driving the motor. The motor controller 1022 can control the conduction or cut-off of each of the above-mentioned switching tubes T1 to T6 to complete the driving of the motor, or rather, the control of the torque output by the motor. Among them, this control process can be similar to the prior art, and for the sake of avoiding repetition, its detailed description is omitted here.

[0121] The above lists the way that arm 1 and arm 3 work simultaneously during the PWM control process. It is also possible to only make one of arm 1 and arm 3 work. That is, during the PWM control process, it is possible to only make the switching tubes of one of arm 1 and arm 3 conduct and turn off in the above manner, and keep the switching tubes of the other arm in the cut-off state.

[0122] Please refer to Figure 9 , Figure 9 which is another schematic structural diagram of a powertrain provided by an embodiment of the present application. Different from the circuit structure shown in Figure 2 :

[0123] The other end of switch K2 is coupled to the star point of motor 1021, and one end of switch K3 is coupled to this star point.

[0124] Figure 10 shows Figure 9 the current direction in the excitation stage of the above-mentioned mode 1 under the circuit structure. As shown in Figure 10 , after K1, K2, and K4 are turned off and K3 is turned on, the motor controller 1022 controls T1 and T5 to conduct (other switching tubes are turned off). In this case, as shown in Figure 3 , the current flowing out from the positive pole of the power battery 101 flows through T1 into winding N2, and the current flowing out from the positive pole of the power battery 101 flows through T5 into winding N3. And the current flowing out from winding N2 and winding N3 converges to winding N1, and then flows into the battery negative pole through the closed K3. Thus, the discharge of the power battery 101 and the charging of windings N1 to N3 are completed. Furthermore, the excitation stage of PWM is completed.

[0125] Figure 11 shows Figure 9 the current direction in the freewheeling stage of the above-mentioned mode 1 under the circuit structure. As shown in Figure 11 , continue to maintain the state where K1, K2, and K4 are turned off and K3 is turned on. The motor controller 1022 controls T2 and T6 to conduct (other switching tubes are turned off). In this case, as shown in Figure 4 , the electrical energy stored in windings N1 to N3 outputs current. This current flows from winding N1 through the closed switch K3 into the battery negative pole. The current flowing out from the battery positive pole flows through the wireless capacitor and T6 into winding N3, and the current flowing out from the battery positive pole flows through the wireless capacitor and T2 into winding N2. Thus, the charging of the power battery 101 and the discharge of windings N1 to N3 are completed. Furthermore, the freewheeling stage of PWM is completed.

[0126] Figure 12 shows Figure 9 the current direction in the excitation stage of the above-mentioned mode 2 under the circuit structure. As shown in Figure 12 , after K1 and K2 are turned on and K3 and K4 are turned off, the motor controller 1022 controls T1 and T5 to conduct (other switching tubes are turned off). In this case, as shown in Figure 5As shown, the current flowing out from the positive electrode of the DC power supply passes through T1 and flows into winding N2. Also, the current flowing out from the positive electrode of the power battery 101 passes through T5 and flows into winding N3. And the currents flowing out from winding N2 and winding N3 converge to winding N1, and then flow into the negative electrode of the DC power supply via the closed K2. Thus, the charging of windings N1 to N3 is completed. Furthermore, the excitation stage of PWM is completed.

[0127] Figure 13 As shown Figure 9 shows the current flow direction in the freewheeling stage of the above-mentioned Mode 2 under the circuit structure, as Figure 13 shown, continue to keep K1 and K2 closed and K3 and K4 open. The motor controller 1022 controls T2 and T6 to conduct (other switching tubes are cut off). In this case, as Figure 6 shown, the current flowing out from the positive electrode of the DC power supply flows into the positive electrode of the power battery 101. Also, the current flows from the negative electrode of the power battery 101 through the closed switch K1 into the conducting T6, and then into winding N3. And the current flows from the negative electrode of the power battery 101 through the closed switch K1 into the conducting T2, and then into winding N2. And the currents flowing out from winding N2 and winding N3 converge to winding N1, and then flow into the negative electrode of the DC power supply via the closed K2. Furthermore, the excitation stage of PWM is completed.

[0128] Figure 14 As shown Figure 9 shows the current flow direction in the excitation stage of the above-mentioned Mode 3 under the circuit structure, as Figure 14 shown, after K1 and K2 are open and K3 and K4 are closed, the motor controller 1022 controls T2 and T6 to conduct (other switching tubes are cut off). In this case, as Figure 7 shown, the current flowing out from the positive electrode of the DC power supply, for example, the positive electrode of the power battery 101, and the current flowing out from the negative electrode of the power battery 101 passes through the closed switch K3 and flows into winding N1, and then flows into windings N2 and N3 respectively. The current flowing out from winding N2 passes through T2 and K4 and flows into the negative electrode of the DC power supply. The current flowing out from winding N3 passes through T6 and K4 and flows into the negative electrode of the DC power supply. Thus, the charging of windings N1 to N3 is completed. Furthermore, the excitation stage of PWM is completed.

[0129] Figure 15 As shown Figure 9 shows the current flow direction in the freewheeling stage of the above-mentioned Mode 3 under the circuit structure, as Figure 15 shown, continue to keep K1 and K2 open and K3 and K4 closed. The motor controller 1022 controls T1 and T5 to conduct (other switching tubes are cut off). In this case, as Figure 8As shown, the electric energy stored in windings N1 to N3 flows out from windings N2 and N3 respectively. The current flowing out from winding N2 flows into the positive electrode of power battery 101 via T1, and the current flowing out from winding N3 flows into the positive electrode of power battery 101 via T5. The current flowing out from the negative electrode of power battery 101 flows into winding N1 through the closed switch K3. Furthermore, the freewheeling stage of PWM is completed. Since the DC power supply only supplies power to the power battery during the excitation stage, step-down charging is achieved.

[0130] It should be noted that Figures 10 to 15 the control processes corresponding to the current directions shown are respectively similar to Figures 3 to 8 the control processes corresponding to the current directions shown. For the sake of avoiding repetition, their detailed descriptions are omitted here.

[0131] It should be understood that the above Figure 2 and Figure 9 the circuit structures capable of realizing the switching between the above-mentioned Mode 1 to Mode 3 shown are only for illustrative purposes, and the present application is not limited thereto. For example, Figure 2 and Figure 9 show a scheme where switches K1 to K4 are arranged on the negative busbar, but the present application is not limited thereto. For example, as Figure 16 and Figure 17 shown, switches K1 to K4 are arranged on the positive busbar. And, Figure 16 the control processes and current directions under the structure shown are similar to those Figures 3 to 8 shown above, Figure 17 the control processes and current directions under the structure shown are similar to those Figures 10 to 15 shown above. Here, for the sake of avoiding repetition, their detailed descriptions are omitted.

[0132] In addition, when the powertrain has Figure 9 the structure shown, when entering the control of the above-mentioned Mode 1 to Mode 3, windings N1 to N3 are equivalent to being connected in parallel, and the inductance value in the circuit is less than the inductance value of each winding. In order to ensure that the inductance value in the circuit meets the requirements of the above three modes, an inductor component can be set in the circuit. And, as Figure 18 shown, the inductor component is connected in series with the parallel-connected windings N1 to N3. In addition, Figure 18 the setting position of the inductor component shown is only for illustrative purposes, and the setting position of the inductor component can be changed arbitrarily as long as it is ensured that the inductor component is connected in series with the parallel-connected windings N1 to N3.

[0133] It should be noted that when the powertrain has Figure 2When in the structure shown, when entering the control of the above-mentioned Mode 1 to Mode 3, windings N1 to N3 generate currents for exciting the motor to output torque. In this regard, when the vehicle enters the control of the above-mentioned Mode 1 to Mode 3, it can control the braking system to show braking forces to each wheel so that each wheel is locked, thereby being able to avoid the vehicle from moving when performing the control of the above-mentioned Mode 1 to Mode 3.

[0134] In addition, as above Figures 2 to 18 The circuit structure shown is equipped with a bus capacitor, but the present application is not limited thereto. For example, as Figure 19 shown, a switch K5 can also be set to replace the bus capacitor. In this case, for example, the switch K5 is in the normally open state. When it is necessary to execute Figure 4 or Figure 11 the control shown, the switch K5 is closed.

[0135] The embodiment of the present application also provides a switching circuit for a powertrain. Among them, the powertrain includes a DC bus, a motor controller, and a drive motor. The motor controller includes three-phase bridge arms. Each phase bridge arm includes an upper bridge arm switching tube and a lower bridge arm switching tube. The midpoints of the bridge arms of the three-phase bridge arms are respectively used to connect the three-phase windings of the drive motor. The DC bus includes a positive DC bus and a negative DC bus. One end of each phase of the bridge arm is used to connect the positive pole of the DC power supply and the positive pole of the power battery through the positive DC bus.

[0136] The switching circuit provided by the embodiment of the present application includes a first switch, a second switch, a third switch, and a fourth switch. The first switch is used to connect the negative DC bus and the negative pole of the power battery. The second switch and the third switch are respectively used to connect the negative pole of the DC power supply and the midpoint of a phase bridge arm in the three-phase bridge arm, the negative pole of the power battery and the midpoint of a phase bridge arm in the three-phase bridge arm, or the second switch and the third switch are respectively used to connect the negative pole of the DC power supply and the star point of the three-phase windings of the drive motor, the negative pole of the power battery and the star point of the three-phase windings of the drive motor. The fourth switch is used to connect the negative DC bus and the negative pole of the DC power supply.

[0137] In one embodiment, when the first switch is closed, the second switch is open, the third switch is open, and the fourth switch is open, the motor controller is used to drive the drive motor;

[0138] In one embodiment, when the first switch is open, the second switch is open, the third switch is closed, and the fourth switch is open, the powertrain is used to heat the battery.

[0139] In one embodiment, when the first switch is closed, the second switch is closed, the third switch is open, and the fourth switch is open, or when the first switch is open, the second switch is open, the third switch is closed, and the fourth switch is closed, the power assembly is used to receive power from the DC power supply to charge the power battery.

[0140] In one embodiment, when the first switch is closed, the second switch is closed, the third switch is open, and the fourth switch is open, the power assembly is used to boost-convert the power supplied by the DC power supply and then charge the power battery.

[0141] In one embodiment, when the first switch is open, the second switch is open, the third switch is closed, and the fourth switch is closed, the power assembly is used to step-down convert the power supplied by the DC power supply and then charge the power battery.

[0142] It should be noted that the embodiments of the present application also provide a vehicle. In one embodiment, the vehicle includes a power battery, wheels, and the power assembly as described above. In one embodiment, the vehicle includes a power battery, wheels, a power assembly, and the switch circuit as described above.

[0143] In the embodiments of the present application, the power assembly is used to receive power from the power battery and drive the wheels. In one embodiment, the vehicle includes a power battery heating mode and a power battery charging mode.

[0144] In one embodiment, in response to the user triggering the power battery heating mode, the vehicle is used to control the first switch to open, the second switch to open, the third switch to close, and the fourth switch to open.

[0145] In one embodiment, in response to the user triggering the power battery charging mode, the vehicle is used to control the first switch to close, the second switch to close, the third switch to open, and the fourth switch to open, or control the first switch to open, the second switch to open, the third switch to close, and the fourth switch to close.

[0146] In one embodiment, in response to the user ending the power battery heating mode or the power battery charging mode, the vehicle is used to control the first switch to close, the second switch to open, the third switch to open, and the fourth switch to open.

[0147] In the embodiments of the present application, the power assembly can respond to the user triggering the power battery heating mode, the user triggering the power battery charging mode, or the user ending the power battery heating mode or the power battery charging mode.

[0148] In one embodiment, when the user triggers the power battery heating mode, the powertrain receives an instruction to heat the power battery. When the user triggers the power battery charging mode, the powertrain receives an instruction to charge the power battery. When the user ends the power battery heating mode or the power battery charging mode, the powertrain receives an instruction to end the power battery charging or an instruction to end the power battery heating.

[0149] The embodiment of the present application also provides a control method for the powertrain. The powertrain includes a first switch, a second switch, a third switch, a fourth switch, a DC bus, a motor controller, and a drive motor. The motor controller includes three-phase bridge arms, and each phase bridge arm includes an upper bridge arm switch tube and a lower bridge arm switch tube. The midpoints of the bridge arms of the three-phase bridge arms are respectively used to connect the three-phase windings of the drive motor. The DC bus includes a positive DC bus and a negative DC bus. One end of each phase of the bridge arm is used to connect the positive electrode of the DC power supply and the positive electrode of the power battery through the positive DC bus.

[0150] The method provided by the embodiment of the present application includes: in response to receiving an instruction to heat the power battery, controlling the first switch to disconnect the connection between the negative DC bus and the negative electrode of the power battery, controlling the second switch to disconnect the connection between the midpoint of one phase bridge arm of the three-phase bridge arm and the negative electrode of the DC power supply or the negative electrode of the power battery, controlling the third switch to conduct the connection between the negative electrode of the power battery and the star point of the three-phase windings of the drive motor, and controlling the fourth switch to disconnect the connection between the negative DC bus and the negative electrode of the DC power supply;

[0151] The method provided by the embodiment of the present application further includes: in response to receiving an instruction to charge the power battery, controlling the first switch to conduct the connection between the negative DC bus and the negative electrode of the power battery, controlling the second switch to conduct the connection between the midpoint of one phase bridge arm of the three-phase bridge arm and the negative electrode of the DC power supply or the negative electrode of the power battery, controlling the third switch to disconnect the connection between the negative electrode of the power battery and the star point of the three-phase windings of the drive motor, and controlling the fourth switch to disconnect the connection between the negative DC bus and the negative electrode of the power battery, or controlling the first switch to disconnect the connection between the negative DC bus and the negative electrode of the power battery, controlling the second switch to disconnect the connection between the midpoint of one phase bridge arm of the three-phase bridge arm and the negative electrode of the DC power supply or the negative electrode of the power battery, controlling the third switch to conduct the connection between the negative electrode of the power battery and the star point of the three-phase windings of the drive motor, and controlling the fourth switch to conduct the connection between the negative DC bus and the negative electrode of the DC power supply.

[0152] The method provided by the embodiment of the present application further includes: in response to the end of the power battery heating mode or the end of the power battery charging mode, controlling the first switch to conduct the connection between the negative DC bus and the negative electrode of the power battery, controlling the second switch to disconnect the connection between the midpoint of one phase of the three-phase bridge arm and the negative electrode of the DC power supply or the negative electrode of the power battery, controlling the third switch to disconnect the connection between the negative electrode of the power battery and the star point of the three-phase windings of the drive motor, and controlling the fourth switch to disconnect the connection between the negative DC bus and the negative electrode of the DC power supply.

[0153] Those of ordinary skill in the art can realize that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. Professional technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of this application.

[0154] Those skilled in the art can clearly understand that for the convenience and conciseness of description, the specific working processes of the systems, devices, and units described above can refer to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0155] In several embodiments provided by the present application, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the units is only a logical function division, and there can be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed mutual coupling or direct coupling or communication connection can be through some interfaces, and the indirect coupling or communication connection of the devices or units can be in an electrical, mechanical, or other form.

[0156] The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they can be located in one place, or can be distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0157] The above is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present application, and all should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A power assembly compatible with heating and charging, characterized in that, The powertrain includes a DC bus, a switching circuit, a motor controller, and a drive motor. The motor controller includes three-phase bridge arms, and each phase bridge arm includes an upper bridge arm switching tube and a lower bridge arm switching tube. The midpoints of the bridge arms of the three-phase bridge arms are respectively used to connect the three-phase windings of the drive motor. The DC bus includes a positive DC bus and a negative DC bus. One end of each phase bridge arm is used to connect the positive pole of the DC power supply and the positive pole of the power battery through the positive DC bus. The switching circuit is used to control the powertrain to heat the power battery or charge the power battery. The switching circuit includes a first switch, a second switch, a third switch, and a fourth switch, where: The first switch is used to connect the negative DC bus and the negative pole of the power battery; The second switch and the third switch are respectively used to connect the negative pole of the DC power supply and the midpoint of one phase bridge arm of the three-phase bridge arm, the negative pole of the power battery and the midpoint of one phase bridge arm of the three-phase bridge arm, or the second switch and the third switch are respectively used to connect the negative pole of the DC power supply and the star point of the three-phase windings of the drive motor, the negative pole of the power battery and the star point of the three-phase windings of the drive motor; The fourth switch is used to connect the negative DC bus and the negative pole of the DC power supply; When the first switch in the switching circuit is off, the second switch is off, the third switch is on, and the fourth switch is off, the powertrain is used to heat the battery; when the first switch in the switching circuit is on, the second switch is on, the third switch is off, and the fourth switch is off, or when the first switch in the switching circuit is off, the second switch is off, the third switch is on, and the fourth switch is on, the powertrain is used to receive power supply from the DC power supply to charge the power battery.

2. The power assembly according to claim 1, characterized in that, The powertrain is used to: In response to receiving an instruction to heat the power battery, turn off the first switch, turn off the second switch, turn on the third switch, and turn off the fourth switch.

3. The power assembly according to claim 1, characterized in that, The powertrain is used to: In response to receiving an instruction to charge the power battery; Turn on the first switch, turn on the second switch, turn off the third switch, and turn off the fourth switch, or turn off the first switch, turn off the second switch, turn on the third switch, and turn on the fourth switch.

4. The power assembly according to claim 1, characterized in that, The powertrain is used to: In response to the voltage of the DC power supply being higher than the voltage of the power battery, turn off the first switch, turn off the second switch, turn on the third switch, and turn on the fourth switch; Or In response to the voltage of the DC power supply being lower than the voltage of the power battery, turn on the first switch, turn on the second switch, turn off the third switch, and turn off the fourth switch.

5. The power assembly according to any one of claims 2 to 4, characterized in that, The powertrain is used to: In response to receiving an instruction to end charging the power battery or end heating the power battery; Turn on the first switch, turn off the second switch, turn off the third switch, and turn off the fourth switch.

6. The power assembly according to any one of claims 1 to 4, characterized in that, The powertrain includes a controller, and the controller includes at least one of the battery management device of the power battery, the motor controller, or the vehicle controller. The controller is configured to: Respond to at least one instruction, where the instruction includes an instruction for heating the power battery, an instruction for charging the power battery, an instruction for ending the charging of the power battery, or an instruction for ending the heating of the power battery; Control the opening and closing of the first switch, the second switch, the third switch, and the fourth switch.

7. A switching circuit for a power assembly, characterized in that, The powertrain includes a DC bus, a motor controller, and a drive motor. The motor controller includes three-phase bridge arms, and each phase bridge arm includes an upper bridge arm switch tube and a lower bridge arm switch tube. The midpoints of the bridge arms of the three-phase bridge arms are respectively used to connect the three-phase windings of the drive motor. The DC bus includes a positive DC bus and a negative DC bus. One end of each phase bridge arm is used to connect the positive pole of the DC power supply and the positive pole of the power battery through the positive DC bus. The switching circuit is used to control the powertrain to heat the power battery or charge the power battery. The switching circuit includes: A first switch, which is used to connect the negative DC bus and the negative pole of the power battery; A second switch and a third switch, where the second switch and the third switch are respectively used to connect the negative pole of the DC power supply and the midpoint of one phase bridge arm of the three-phase bridge arm, the negative pole of the power battery and the midpoint of one phase bridge arm of the three-phase bridge arm, or the second switch and the third switch are respectively used to connect the negative pole of the DC power supply and the star point of the three-phase windings of the drive motor, the negative pole of the power battery and the star point of the three-phase windings of the drive motor; A fourth switch, which is used to connect the negative DC bus and the negative pole of the DC power supply; When the first switch in the switching circuit is open, the second switch is open, the third switch is closed, and the fourth switch is open, the powertrain is used to heat the battery; when the first switch in the switching circuit is closed, the second switch is closed, the third switch is open, and the fourth switch is open, or when the first switch in the switching circuit is open, the second switch is open, the third switch is closed, and the fourth switch is closed, the powertrain is used to receive power from the DC power supply to charge the power battery.

8. The switching circuit according to claim 7, characterized in that, When the first switch is closed, the second switch is open, the third switch is open, and the fourth switch is open, the motor controller is used to drive the drive motor.

9. The switching circuit according to claim 7 or 8, characterized in that, In response to receiving an instruction for charging the power battery; The first switch is closed, the second switch is closed, the third switch is open, and the fourth switch is open, or the first switch is open, the second switch is open, the third switch is closed, and the fourth switch is closed.

10. The switching circuit according to claim 9, characterized in that, When the first switch is closed, the second switch is closed, the third switch is open, and the fourth switch is open, the powertrain is used to boost the power supply from the DC power supply and then charge the power battery; Or The first switch is off, the second switch is off, the third switch is on, the fourth switch is on, and the power assembly is used to step down the power supply of the DC power supply and then charge the power battery.

11. A vehicle, characterized in that, The vehicle includes: A power battery, wheels, and a power assembly as described in any one of claims 1 to 6; or, a power battery, wheels, a power assembly, and a switch circuit as described in any one of claims 7 to 10; Wherein, the power assembly is used to receive the power supply from the power battery and drive the wheels.

12. The vehicle according to claim 11, characterized in that, The vehicle includes a power battery heating mode and a power battery charging mode, and the vehicle is used for: In response to the user triggering the power battery heating mode, controlling the first switch to be off, the second switch to be off, the third switch to be on, and the fourth switch to be off; In response to the user triggering the power battery charging mode, controlling the first switch to be on, the second switch to be on, the third switch to be off, the fourth switch to be off, or controlling the first switch to be off, the second switch to be off, the third switch to be on, and the fourth switch to be on.

13. The vehicle according to claim 12, characterized in that, The vehicle is used for: In response to the user ending the power battery heating mode or the power battery charging mode, controlling the first switch to be on, the second switch to be off, the third switch to be off, and the fourth switch to be off.

14. A control method for a powertrain, characterized in that, The power assembly includes a first switch, a second switch, a third switch, a fourth switch, a DC bus, a motor controller, and a drive motor. The motor controller includes three-phase bridge arms, and each phase bridge arm includes an upper-bridge-arm switch tube and a lower-bridge-arm switch tube. The midpoints of the bridge arms of the three-phase bridge arms are respectively used to connect the three-phase windings of the drive motor. The DC bus includes a positive DC bus and a negative DC bus. One end of each phase of the bridge arm is used to connect the positive pole of the DC power supply and the positive pole of the power battery through the positive DC bus. The method includes: In response to receiving a power battery heating instruction, controlling the first switch to disconnect the connection between the negative DC bus and the negative pole of the power battery, controlling the second switch to disconnect the connection between the midpoint of one phase bridge arm of the three-phase bridge arm and the negative pole of the DC power supply or the negative pole of the power battery, controlling the third switch to conduct the connection between the negative pole of the power battery and the star point of the three-phase windings of the drive motor, and controlling the fourth switch to disconnect the connection between the negative DC bus and the negative pole of the DC power supply; In response to receiving a power battery charging instruction, control the first switch to conduct the connection between the negative DC bus and the negative electrode of the power battery, control the second switch to conduct the connection between the midpoint of one phase arm of the three-phase bridge arm and the negative electrode of the DC power supply or the negative electrode of the power battery, control the third switch to disconnect the connection between the negative electrode of the power battery and the star point of the three-phase windings of the drive motor, control the fourth switch to disconnect the connection between the negative DC bus and the negative electrode of the power battery, or control the first switch to disconnect the connection between the negative DC bus and the negative electrode of the power battery, control the second switch to disconnect the connection between the midpoint of one phase arm of the three-phase bridge arm and the negative electrode of the DC power supply or the negative electrode of the power battery, control the third switch to conduct the connection between the negative electrode of the power battery and the star point of the three-phase windings of the drive motor, and control the fourth switch to conduct the connection between the negative DC bus and the negative electrode of the DC power supply.

15. The control method according to claim 14, characterized in that, The method further includes: In response to the end of the power battery heating mode or the end of the power battery charging mode, control the first switch to conduct the connection between the negative DC bus and the negative electrode of the power battery, control the second switch to disconnect the connection between the midpoint of one phase arm of the three-phase bridge arm and the negative electrode of the DC power supply or the negative electrode of the power battery, control the third switch to disconnect the connection between the negative electrode of the power battery and the star point of the three-phase windings of the drive motor, and control the fourth switch to disconnect the connection between the negative DC bus and the negative electrode of the DC power supply.

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