Step-down device, system and vehicle for driving electric motor

Abstract

A kind of voltage reduction device, system and vehicle of driving motor, the device includes: controller and voltage reduction circuit;Controller is connected with voltage reduction circuit, for if the demand operating voltage of first driving motor is less than the voltage of power battery, voltage reduction signal is sent to voltage reduction circuit;Voltage reduction circuit is used to respond to voltage reduction signal, and the voltage provided by power battery is reduced to demand operating voltage and then transmitted to first driving motor.By doing so, the device, the voltage provided by power battery is reduced to demand operating voltage and then transmitted to first driving motor, can guarantee that first driving motor works at high efficiency point, to reduce the energy consumption of whole vehicle.

Description

Technical Field

[0001] This disclosure relates to the field of vehicle technology, and more particularly to a step-down device, system, and vehicle for a drive motor. Background Technology

[0002] With the development of the new energy vehicle industry, more and more new energy vehicle drive motors are moving towards higher voltage platforms and higher power. The advantage of a high voltage platform is that it can increase the torque boundary of the drive motor, thereby expanding the range of its efficiency range and reducing power loss. However, under low load conditions, a high voltage platform can actually cause the motor to operate in a low-efficiency region. Summary of the Invention

[0003] A step-down device, system, and vehicle for a drive motor, which reduces the voltage provided by the power battery to the required operating voltage before transmitting it to the first drive motor, can ensure that the first drive motor operates at a high efficiency point, thereby reducing the energy consumption of the entire vehicle.

[0004] In a first aspect, this disclosure proposes a step-down device for a drive motor, the step-down device comprising: a controller and a step-down circuit; the controller is connected to the step-down circuit and is used to send a step-down signal to the step-down circuit if the required operating voltage of the first drive motor is less than the voltage of the power battery; the step-down circuit is used to respond to the step-down signal by reducing the voltage provided by the power battery to the required operating voltage and then transmitting it to the first drive motor.

[0005] The step-down device for the drive motor according to the embodiments of this disclosure reduces the voltage provided by the power battery to the required operating voltage before transmitting it to the first drive motor, thereby ensuring that the first drive motor operates at a high efficiency point and reducing the energy consumption of the entire vehicle.

[0006] Secondly, this disclosure proposes a step-down system for a drive motor, the step-down system comprising: a first motor inverter and the aforementioned step-down device for the drive motor, the step-down device being connected between a power battery and the first motor inverter.

[0007] The step-down system of the drive motor according to the embodiments of this disclosure reduces the voltage provided by the power battery to the required operating voltage before transmitting it to the first drive motor, thereby ensuring that the first drive motor operates at a high efficiency point and reducing the energy consumption of the whole vehicle.

[0008] Thirdly, this disclosure proposes a vehicle comprising a power battery, a generator, a first drive motor, and a step-down system for the drive motor, the step-down system being connected between the power battery and the first drive motor, a second motor inverter in the step-down system reusing the inverter of the generator, and an energy storage device in the step-down system reusing the coil of the generator.

[0009] According to the vehicle of the present disclosure, voltage reduction is achieved by reusing the inverter and coil of the generator, eliminating the need for additional voltage reduction circuits in the vehicle. This reduces costs and increases the reuse rate of components in the vehicle, making the voltage reduction device simple and highly feasible.

[0010] Fourthly, this disclosure proposes a vehicle comprising a power battery, a second drive motor, a first drive motor, and a step-down system for the aforementioned drive motors, wherein the step-down system is connected between the power battery and the first drive motor, the second motor inverter in the step-down system reuses the inverter of the second drive motor, and the energy storage device in the step-down system reuses the coil of the second drive motor.

[0011] According to the vehicle of the present disclosure, voltage reduction is achieved by reusing the inverter of the second drive motor and the coil of the second drive motor, without the need to add a new voltage reduction circuit in the vehicle. This reduces costs and increases the reuse rate of components in the vehicle, making the voltage reduction device simple and highly feasible.

[0012] Additional aspects and advantages of this disclosure will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this disclosure. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the structure of a step-down device for a drive motor according to an embodiment of the present disclosure;

[0014] Figure 2 This is a schematic diagram of the structure of a step-down device for a drive motor according to a specific embodiment of the present disclosure;

[0015] Figure 3 This is a topology diagram of the step-down device for the drive motor according to the first specific embodiment of this disclosure;

[0016] Figure 4 This is a topology diagram of the step-down device for the drive motor according to the second specific embodiment of this disclosure;

[0017] Figure 5 This is a schematic diagram of the structure of a step-down system for a drive motor according to an embodiment of the present disclosure;

[0018] Figure 6 This is a schematic diagram of the structure of a vehicle according to an embodiment of the present disclosure;

[0019] Figure 7 This is a schematic diagram of the structure of a vehicle according to another embodiment of the present disclosure. Detailed Implementation

[0020] Embodiments of this disclosure are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this disclosure, and should not be construed as limiting this disclosure.

[0021] The following is a reference appendix. Figure 1-7 This disclosure describes a step-down device, system, and vehicle for a drive motor according to embodiments of the present disclosure.

[0022] Figure 1 This is a schematic diagram of the structure of a voltage reduction device for a drive motor according to an embodiment of this disclosure. Figure 2 As shown, the step-down device 100 for driving the motor includes a controller 10 and a step-down circuit 20.

[0023] In this embodiment, the controller 10 is connected to the step-down circuit 20 and is used to send a step-down signal to the step-down circuit 20 if the required operating voltage of the first drive motor is less than the voltage of the power battery. The step-down circuit 20 is used to respond to the step-down signal, reduce the voltage provided by the power battery to the operating voltage, and then transmit it to the first drive motor.

[0024] The required operating voltage for the first drive motor is the voltage value at which the first drive motor has the highest operating efficiency, thereby ensuring that the first drive motor operates at a high efficiency point and thus reducing the energy consumption of the entire vehicle.

[0025] The controller 10 is used to acquire the operating parameters of the first drive motor and determine the required operating voltage based on the operating parameters. These operating parameters may include the operating speed n1 and / or the torque T1.

[0026] It is understandable that, with the operating parameters remaining constant, different voltages on the first drive motor result in different operating efficiencies for the first drive motor.

[0027] The controller 10 pre-stores the correspondence between parameters and voltages. The voltage corresponding to each parameter in this correspondence is the voltage value at which the first drive motor achieves the highest operating efficiency when operating according to that parameter. The controller 10 can determine the required operating voltage corresponding to the operating parameters from this correspondence. Therefore, when the first drive motor operates according to those parameters, the required operating voltage for the first drive motor is the voltage value at which the first drive motor achieves the highest operating efficiency, ensuring that the first drive motor operates at its high-efficiency point, thereby reducing the overall vehicle energy consumption.

[0028] Therefore, when the high-power drive motor is operating under low load conditions, the required high-efficiency operating voltage can be selected according to the operating parameters of the first drive motor, so that the first drive motor can work at the high-efficiency point, thereby reducing the energy consumption of the whole vehicle.

[0029] Specifically, the controller 10 can obtain the vehicle's required power P1. If the required power P1 is less than the power threshold P0, the vehicle is controlled to enter two-wheel drive mode. Then, the controller obtains the operating parameters of the first drive motor, determines the required operating voltage Ug based on the corresponding relationship of the operating parameters, and sends a step-down signal to the step-down circuit 20 when the required operating voltage Ug is less than the voltage of the power battery. The step-down circuit 20, responding to the step-down signal sent by the controller 10, reduces the voltage provided by the power battery to the required operating voltage before transmitting it to the first drive motor. Thus, when the high-power drive motor is operating under low load conditions, a high-efficiency required operating voltage can be selected based on the operating parameters of the first drive motor, allowing the first drive motor to operate at a high-efficiency point, thereby reducing the overall vehicle energy consumption.

[0030] When the vehicle is in operation, the controller 10 obtains the vehicle's required power P1 if the vehicle meets the following target conditions. The target conditions may include: the vehicle is an EV (electric vehicle, pure electric drive mode); or, if the vehicle is not an EV and the vehicle's second drive motor (i.e., the rear drive motor) is not working, then the vehicle is a four-wheel drive vehicle and the power demand is not high, and the second drive motor is idle.

[0031] It should be noted that when the vehicle is in EV mode and the required power P1 is greater than or equal to the power threshold P0, or when the vehicle is not in EV mode and the second drive motor of a four-wheel drive vehicle is working, the controller 10 controls the vehicle to be in four-wheel drive mode without voltage reduction and controls it according to the vehicle torque distribution strategy.

[0032] See Figure 2 The step-down circuit 20 may include a second motor inverter 21, an energy storage device 22, and a switching circuit 23. The second motor inverter 21 is connected to the first terminals of the power battery 301 and the energy storage device 22, respectively. The first terminal of the switching circuit 23 is connected to the second terminal of the energy storage device 22, the second terminal of the switching circuit 23 is connected to the first motor inverter 201 of the first drive motor 303, and the third terminal of the switching circuit 23 is connected to the power battery 301.

[0033] Specifically, the first end of the second motor inverter 21 is used to connect to the power battery 301, and the second end of the second motor inverter 21 is connected to the first end of the energy storage device 22.

[0034] In this example, in response to the step-down signal, the second motor inverter 21 switches the circuit 23 to the first switching state, and the energy storage device 22 is connected to the first motor inverter 201 to reduce the voltage provided by the power battery 301 to the required operating voltage.

[0035] Specifically, the second motor inverter 21 is used to receive the step-down signal sent by the controller 10. In response to the step-down signal, the control switch circuit 23 is in a first switching state to connect the energy storage device 22 and the first motor inverter 201, and repeatedly executes the charging and discharging process of the energy storage device 22 to reduce the voltage provided by the power battery 301 to the required operating voltage. The charging and discharging process of the energy storage device 22 includes: controlling the power battery 301 to supply power to the energy storage device 22 and the first drive motor 303 in a first time period, and controlling the energy storage device 22 to supply power to the first drive motor 303 in a second time period. The second time period is after the first time period.

[0036] It should be noted that the second motor inverter 21 can be either the generator inverter or the second drive motor inverter, and the energy storage device 22 can be either the generator coil or the second drive motor coil. Specifically, if the vehicle is an EV, the generator inverter and generator coil will be idle and can therefore be reused. If the vehicle is not an EV and the second drive motor is not operating, the second drive motor inverter and the second drive motor coil will be idle, and thus the second drive motor inverter and the second drive motor can be reused.

[0037] As a first example, see Figure 3 The switching circuit 23 may include a first switch S1 and a second switch S2; wherein the first switch S1 is connected between the power battery 301 and the first motor inverter 201; and the second switch S2 is connected between the first motor inverter 201 and the energy storage device 22.

[0038] Specifically, the control terminal of the first switch S1 is connected to the second motor inverter 21, the first terminal of the first switch S1 is connected to the output terminal of the power battery 301, and the second terminal of the first switch S1 is connected to both the first motor inverter 201 and the first terminal of the second switch S2; the control terminal of the second switch S2 is connected to the second motor inverter 21, and the second terminal of the second switch S2 is connected to the second terminal of the energy storage device 22. The state of the first switch can include: the first switch S1 is open, and the second switch S2 is closed.

[0039] Specifically, the second motor inverter 21 can be a generator inverter, and the energy storage device 22 can be a generator coil. In the case of an EV (electric vehicle), the generator inverter and generator coil are idle and can be reused. The second motor inverter 21 receives a step-down signal from the controller 10. In response to the step-down signal, the second motor inverter 21 controls the switching circuit 23 to be in a first switching state (i.e., first switch S1 is open, second switch S2 is closed) to enable conduction between the energy storage device 22 and the first motor inverter 201, and repeatedly executes the charging and discharging process of the energy storage device 22 to reduce the voltage provided by the power battery 301 to the required operating voltage. See also... Figure 3 The step-down circuit 20 may also include a capacitor C1.

[0040] The charging and discharging process of the energy storage device 22 includes:

[0041] During the first time period, the controllable switches V1, V2, and V3 in the second motor inverter 21 are turned on. Current flows from the positive terminal of the power battery 301 through the controllable switches V1, V2, and V3 to the coils L1, L2, and L3 of the energy storage device 22, then through two phases of the first motor inverter 201 to the first drive motor 303, and finally back to the negative terminal of the power battery 301 through one phase of the first motor inverter 201. Thus, the power battery 301 supplies power to the energy storage device 22 and the first drive motor 303.

[0042] During the second time period, the controllable switches V1, V2, and V3 in the second motor inverter 21 are turned off, and the coils L1, L2, and L3 of the energy storage device 22 discharge. The current flows through the freewheeling diodes VD1, VD2, and VD3 in the second motor inverter 21, the capacitor C1, and two phase arms of the first motor inverter 201 to the first drive motor 303, and then returns to the coils L1, L2, and L3 of the energy storage device 22 through one phase arm of the first motor inverter 201. Thus, the first drive motor 303 is powered through the energy storage device 22.

[0043] Therefore, by reusing the inverter and coil of the generator to achieve voltage reduction, the energy consumption of the entire vehicle is reduced.

[0044] It should be noted that the second motor inverter 21 may also include controllable switches V4, V5, and V6, and freewheeling diodes VD4, VD5, and VD6, which control the controllable switches V4, V5, and V6 and the freewheeling diodes VD4, VD5, and VD6 to turn off during the charging and discharging process of the energy storage device 22.

[0045] As a second example, see Figure 4 The switching circuit 23 may also include a third switch S3. The third switch S3 is connected between the power battery 301 and the first motor inverter 201.

[0046] Specifically, the control terminal of the third switch S3 is connected to the second motor inverter 21, the first terminal of the third switch S3 is used to connect to the output terminal of the power battery 301, and the second terminal of the third switch S3 is connected to the first motor inverter 201.

[0047] In this example, the first switch state may also include the third switch S3 being open, and the second switch state may also include the third switch S3 being closed.

[0048] Specifically, the second motor inverter 21 can be the inverter of the second drive motor (i.e., the electronic control unit of the second drive motor), and the energy storage device 22 can be the coil of the second drive motor. When the vehicle is not an EV and the second drive motor is not operating, the inverter and coil of the second drive motor can be reused when both are idle. After receiving the step-down signal from the controller 10, the second motor inverter 21 can respond to the step-down signal by controlling the switching circuit 23 to be in a first switching state (i.e., the first switch S1 is open, the second switch S2 is closed, and the third switch S3 is open) to enable conduction between the energy storage device 22 and the first motor inverter 201, and repeatedly execute the charging and discharging process of the energy storage device 22 to reduce the voltage of the power battery 301 to the required operating voltage. See also... Figure 4 The step-down circuit 20 may also include a capacitor C1.

[0049] The charging and discharging process of the energy storage device 22 includes:

[0050] During the first time period, the controllable switches V1, V2, and V3 in the second motor inverter 21 are turned on. Current flows from the positive terminal of the power battery 301 through the controllable switches V1, V2, and V3 to the coils L1, L2, and L3 of the energy storage device 22, then through two phases of the first motor inverter 201 to the first drive motor 303, and finally back to the negative terminal of the power battery 301 through one phase of the first motor inverter 201. Thus, the power battery 301 supplies power to the energy storage device 22 and the first drive motor 303.

[0051] During the second time period, the controllable switches V1, V2, and V3 in the second motor inverter 21 are turned off, and the coils L1, L2, and L3 of the energy storage device 22 discharge. The current flows through the freewheeling diodes VD1, VD2, and VD3 in the second motor inverter 21, the capacitor C1, and two phase arms of the first motor inverter 201 to the first drive motor 303, and then returns to the coils L1, L2, and L3 of the energy storage device 22 through one phase arm of the first motor inverter 201. Thus, the first drive motor 303 is powered through the energy storage device 22.

[0052] Therefore, by reusing the inverter of the second drive motor and the coil of the second drive motor to achieve voltage reduction, the energy consumption of the whole vehicle is reduced.

[0053] It should be noted that the second motor inverter 21 may also include controllable switches V4, V5, and V6, and freewheeling diodes VD4, VD5, and VD6, which control the controllable switches V4, V5, and V6 and the freewheeling diodes VD4, VD5, and VD6 to turn off during the charging and discharging process of the energy storage device 22.

[0054] See Figure 4 The vehicle 400 may also include an inverter of the generator 302 and a coil of the generator 302. The first end of the inverter of the generator 302 is connected to the power battery 301 and the switching circuit 23 respectively, and the second end of the inverter of the generator 302 is connected to the first end of the coil of the generator 302.

[0055] As an example, the controller 10 is also configured to send a shutdown signal to the buck circuit 20 if the required operating voltage is greater than or equal to the voltage of the power battery 301; in response to the shutdown signal, the second motor inverter 21 in the buck circuit 20 switches the circuit 23 to a second switching state, and the power battery 301 and the first motor inverter 201 are connected to transmit the voltage provided by the power battery 301 to the first motor inverter 201.

[0056] Specifically, when the required operating voltage Ug is greater than or equal to the voltage of the power battery 301, the controller 10 sends a shutdown signal to the buck circuit 20. In response to the shutdown signal sent by the controller 10, the second motor inverter 21 in the buck circuit 20 controls the switching circuit 23 to be in a second switching state (i.e., the first switch S1 is closed and the second switch S2 is open), thus connecting the power battery 301 and the first motor inverter 201 to transmit the voltage provided by the power battery 301 to the first motor inverter 201. It should be noted that the controller 10 can also send a shutdown signal to the buck circuit 20 when the required power P1 increases instantaneously. Therefore, by sending a shutdown signal to the buck circuit when the required operating voltage is greater than or equal to the voltage of the power battery, the buck converter can be disconnected when the circuit does not need to step down the voltage.

[0057] In summary, the step-down device for the drive motor reduces voltage by adding a step-down circuit at the front end of the first drive motor. By determining the required high-efficiency operating voltage based on the operating parameters of the first drive motor, the device enables the first drive motor to operate at its high-efficiency point when the high-power drive motor is operating under low load conditions, thereby reducing the overall vehicle energy consumption.

[0058] Furthermore, by reusing the inverter and coil of the generator, or the inverter and coil of the second drive motor, voltage reduction can be achieved, thereby eliminating the need to add a new voltage reduction circuit in the vehicle. This reduces costs and increases the reuse rate of components in the vehicle, making the voltage reduction device simple and highly feasible.

[0059] Figure 4 This is a schematic diagram of the structure of a step-down system for a drive motor according to an embodiment of this disclosure. Figure 4 As shown, the step-down system 200 for the drive motor includes: a first motor inverter 201 and the aforementioned step-down device 100 for the drive motor, wherein the step-down device 100 for the drive motor is connected between the power battery 301 and the first motor inverter 201.

[0060] It should be noted that for other specific embodiments of the step-down system 200 of the drive motor in this disclosure, please refer to the specific embodiments of the step-down device 100 of the drive motor in this disclosure.

[0061] Therefore, the step-down system of the drive motor in this embodiment of the present disclosure can ensure that the first drive motor operates at a high efficiency point by reducing the voltage provided by the power battery to the required operating voltage and then transmitting it to the first drive motor, thereby reducing the energy consumption of the whole vehicle.

[0062] Figure 5 This is a schematic diagram of the structure of a vehicle according to an embodiment of this disclosure. Figure 6 As shown, the vehicle 300 includes a power battery 301, a generator 302, a first drive motor 303, and a step-down system 200 for the drive motor. The step-down system 200 for the drive motor is connected between the power battery 301 and the first drive motor 303. The second motor inverter 21 in the step-down system 200 for the drive motor reuses the inverter of the generator 302, and the energy storage device 22 in the step-down system 200 for the drive motor reuses the coil of the generator 302.

[0063] Therefore, the vehicle in this embodiment of the present disclosure achieves voltage reduction by reusing the inverter and coil of the generator, eliminating the need to add a new voltage reduction circuit in the vehicle. This reduces costs and increases the reuse rate of components in the vehicle, making the voltage reduction device simple and highly feasible.

[0064] Figure 6 This is a schematic diagram of the structure of a vehicle according to an embodiment of this disclosure. Figure 6As shown, the vehicle 400 includes a power battery 301, a second drive motor 401, a first drive motor 303, and a step-down system 200 for the aforementioned drive motors. The step-down system 200 is connected between the power battery 301 and the first drive motor 303. The second motor inverter 21 in the step-down system 200 reuses the inverter of the second drive motor 401, and the energy storage device 22 in the step-down system 200 reuses the coil of the second drive motor 401.

[0065] Therefore, the vehicle in this embodiment of the present disclosure achieves voltage reduction by reusing the inverter of the second drive motor and the coil of the second drive motor, without the need to add a new voltage reduction circuit in the vehicle. This reduces costs and increases the reuse rate of components in the vehicle, making the voltage reduction device simple and highly feasible.

[0066] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this disclosure. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0067] In the description of this disclosure, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this disclosure and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this disclosure.

[0068] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this disclosure, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0069] In this disclosure, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this disclosure according to the specific circumstances.

[0070] In this disclosure, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0071] Although embodiments of the present disclosure have been shown and described above, it is to be understood that the above embodiments are exemplary and should not be construed as limiting the present disclosure. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present disclosure.

Claims

1. A voltage reduction device for a drive motor, characterized in that, The step-down device includes: a controller and a step-down circuit; The controller is connected to the step-down circuit and is used to send a step-down signal to the step-down circuit if the required operating voltage of the first drive motor is less than the voltage of the power battery. The step-down circuit is used to respond to the step-down signal, reduce the voltage provided by the power battery to the required operating voltage, and then transmit it to the first drive motor; The step-down circuit includes a second motor inverter, an energy storage device, and a switching circuit. The second motor inverter is connected to the first end of the power battery and the energy storage device, respectively. The first terminal of the switching circuit is connected to the second terminal of the energy storage device, the second terminal of the switching circuit is connected to the first motor inverter of the first drive motor, and the third terminal of the switching circuit is connected to the power battery. In response to the step-down signal, the switching circuit is in a first switching state, and the energy storage device is connected to the first motor inverter to reduce the voltage provided by the power battery to the required operating voltage.

2. The voltage reduction device for the drive motor according to claim 1, characterized in that, The controller is further configured to send a shutdown signal to the buck circuit if the required operating voltage is greater than or equal to the voltage of the power battery. In response to the shutdown signal, the switching circuit is in a second switching state, and the power battery is connected to the first motor inverter to transmit the voltage provided by the power battery to the first motor inverter.

3. The voltage reduction device for the drive motor according to claim 2, characterized in that, The switching circuit includes a first switch and a second switch; The first switch is connected between the power battery and the first motor inverter. The second switch is connected between the first motor inverter and the energy storage device; The first switch state includes: the first switch is open and the second switch is closed; The second switch state includes: the first switch is closed and the second switch is open.

4. The voltage reduction device for the drive motor according to claim 1, characterized in that, The second motor inverter is either an inverter for a generator or an inverter for a second drive motor, and the energy storage device includes the coil of the generator or the coil of the second drive motor.

5. The voltage reduction device for the drive motor according to claim 3, characterized in that, The switching circuit also includes a third switch; The third switch is connected between the power battery and the first motor inverter. The first switch state also includes the third switch being open, and the second switch state also includes the third switch being closed.

6. The voltage reduction device for the drive motor according to any one of claims 1 to 5, characterized in that, The controller is used to acquire the operating parameters of the first drive motor and determine the required operating voltage based on the operating parameters.

7. A step-down system for a drive motor, characterized in that, The step-down system includes: a first motor inverter and a step-down device for the drive motor according to any one of claims 1 to 6, wherein the step-down device is connected between the power battery and the first motor inverter.

8. A vehicle, characterized in that, The vehicle includes a power battery, a generator, a first drive motor, and a step-down system for the drive motor as described in claim 7. The step-down system is connected between the power battery and the first drive motor. The second motor inverter in the step-down system reuses the inverter of the generator, and the energy storage device in the step-down system reuses the coil of the generator.

9. A vehicle, characterized in that, The vehicle includes a power battery, a second drive motor, a first drive motor, and a step-down system for the drive motor as described in claim 7. The step-down system is connected between the power battery and the first drive motor. The second motor inverter in the step-down system reuses the inverter of the second drive motor, and the energy storage device in the step-down system reuses the coil of the second drive motor.

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