Ramp-up device control method and device in downhill state and vehicle

Abstract

The application relates to a control method and device for a range extender in a downhill state and a vehicle. The control method for the range extender in the downhill state comprises the following steps: when it is determined that the vehicle is in a downhill driving state, acquiring a current state of a brake pedal, a current state of a gear pedal and a downhill angle value of the vehicle; according to the current state of the brake pedal, the current state of the gear pedal and the downhill angle value of the vehicle, selecting a target rotating speed from a plurality of rotating speeds of the range extender of the vehicle as an actual rotating speed of the range extender; and controlling the range extender to drive a motor of the vehicle at the actual rotating speed. The control method for the range extender in the downhill state can reduce the required output power of the range extender of the vehicle, thereby avoiding energy loss caused by charging and discharging of a battery pack, and achieving the purpose of increasing fuel conversion efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electric vehicles, in particular to a range extender control method and device in a downhill state and a vehicle. BACKGROUND

[0002] At present, the power generation of the range extender is mainly determined by the accelerator pedal, the state of charge (SOC) of the battery pack and the current speed of the vehicle. Since the battery pack has internal resistance, energy loss occurs when the battery pack charges and discharges, so the charging direct current-direct current (DC-DC) control circuit and the discharging DC-DC control circuit also have energy loss, so that the range extender can achieve maximum conversion efficiency when directly driving the motor.

[0003] Therefore, how to solve the problem that the instantaneous power P1 of the gravity component of the vehicle increases due to the increase of the downhill angle, the excess power generation of the output instantaneous power P2 of the motor of the vehicle charges the battery pack, and energy loss occurs when the battery pack charges and discharges, resulting in a decrease in fuel conversion efficiency is a problem that needs to be solved by those skilled in the art. SUMMARY

[0004] Therefore, a range extender control method and device in a downhill state and a vehicle are provided to solve the problem that the instantaneous power P1 of the gravity component of the vehicle increases due to the increase of the downhill angle, the excess power generation of the output instantaneous power P2 of the motor of the vehicle charges the battery pack, and energy loss occurs when the battery pack charges and discharges, resulting in a decrease in fuel conversion efficiency.

[0005] In one aspect, a range extender control method in a downhill state is provided, which comprises: when it is determined that a vehicle is in a downhill driving state, acquiring the current state of a brake pedal, the current state of a gear pedal and the downhill angle value of the vehicle; selecting a target speed as the actual speed of the range extender from a plurality of pre-set speeds of the range extender for the vehicle according to the current state of the brake pedal, the current state of the gear pedal and the downhill angle value of the vehicle; and controlling the range extender to drive the motor of the vehicle at the actual speed.

[0006] In one of the embodiments, the selecting a target rotating speed from a plurality of pre-set rotating speeds of the range extender of the vehicle as the actual rotating speed of the range extender according to the current state of the brake pedal, the current state of the accelerator pedal and the downhill angle value of the vehicle comprises: when the accelerator pedal is currently in the non-pedal-down state and the brake pedal is currently in the pedal-down state, selecting the minimum value of the pre-set rotating speeds as the target rotating speed; or when the accelerator pedal and the brake pedal are both currently in the non-pedal-down state, selecting the minimum value of the pre-set rotating speeds as the target rotating speed.

[0007] In one of the embodiments, after the selecting the minimum value of the pre-set rotating speeds as the target rotating speed when the accelerator pedal is currently in the non-pedal-down state and the brake pedal is currently in the pedal-down state, the method further comprises: obtaining the current battery pack power of the vehicle; and when the battery pack power is greater than or equal to a pre-set power threshold, shutting down the range extender.

[0008] In one of the embodiments, before the shutting down the range extender, the method further comprises: obtaining the current driving distance of the vehicle; and determining that the driving distance is greater than or equal to a pre-set distance threshold.

[0009] In one of the embodiments, the selecting a target rotating speed from a plurality of pre-set rotating speeds of the range extender of the vehicle as the actual rotating speed of the range extender according to the current state of the brake pedal, the current state of the accelerator pedal and the downhill angle value of the vehicle further comprises: when the accelerator pedal is currently in the pedal-down state and the brake pedal is currently in the non-pedal-down state, obtaining the current driving speed of the vehicle; calculating a target power according to the downhill angle value of the vehicle and the driving speed; and matching a target rotating speed from a pre-set power-rotating speed corresponding table according to the target power.

[0010] In one of the embodiments, the calculating a target power according to the downhill angle value of the vehicle and the driving speed comprises: calculating a reference power of the range extender by a formula ; determining the target power according to the reference power; wherein P4 is the reference power of the range extender, k is a pre-set coefficient, m is the mass of the vehicle, g is the gravity acceleration, v is the current driving speed of the vehicle, and a is the downhill angle value of the vehicle.

[0011] In one of the embodiments, the determining the target power according to the reference power comprises: when receiving an instruction of starting the power-saving mode, matching the reference power with the pre-set power-rotating speed corresponding table, and selecting a power closest to the reference power from the powers less than the reference power in the power-rotating speed corresponding table as the target power.

[0012] In one of the embodiments, the determining the target power according to the reference power comprises: obtaining a current residual power value of a battery pack of the vehicle; when the residual power value is less than a preset power value, matching the reference power with the preset power and speed corresponding relation table, selecting a power greater than the reference power from the preset power and speed corresponding relation table, and selecting a power closest to the reference power as the target power.

[0013] In another aspect, a range extender control device in a downhill state is also provided, which comprises an obtaining unit, a determining unit and a control unit. When it is determined that a vehicle is in a downhill driving state, the obtaining unit is configured to obtain a current state of a brake pedal, a current state of a gear lever pedal and a downhill angle value of the vehicle. The determining unit is configured to select a target speed from a plurality of pre-set speeds of a range extender of the vehicle as an actual speed of the range extender according to the current state of the brake pedal, the current state of the gear lever pedal and the downhill angle value of the vehicle. The control unit is configured to control the range extender to drive a motor of the vehicle at the actual speed.

[0014] In another aspect, a vehicle is also provided, which comprises the range extender control device in a downhill state described above.

[0015] The range extender control method, device and vehicle described above can reduce the output power required by the range extender of the vehicle, thereby avoiding energy loss caused by charging and discharging of a battery pack, and achieving the purpose of increasing fuel conversion efficiency, by selecting a target speed from a plurality of pre-set speeds of a range extender of the vehicle as an actual speed of the range extender according to a current state of a brake pedal, a current state of a gear lever pedal and a downhill angle value of the vehicle, and controlling the range extender to drive a motor of the vehicle at the actual speed. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 A working principle diagram of the range extender disclosed in the embodiments of the present application;

[0017] Figure 2 A flowchart of a range extender control method in a downhill state disclosed in the embodiments of the present application;

[0018] Figure 3 A flowchart of step S20 in the range extender control method in a downhill state shown in Figure 2

[0019] Figure 4 Figure 3 ​​The flowchart of step S23 in the range extender control method under downhill conditions is shown.

[0020] Figure 5 for Figure 2 The flowchart of step S30 in the range extender control method under downhill conditions is shown.

[0021] Figure 6 This is a schematic diagram of the structure of a range extender control device in a downhill state disclosed in an embodiment of this application;

[0022] Figure 7 This is a schematic diagram of the structure of a vehicle disclosed in an embodiment of this application. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0024] It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show components relevant to the present invention and are not drawn according to the actual number, shape, and size of components in implementation. In actual implementation, the form, quantity, and proportion of each component can be arbitrarily changed, and the component layout may be more complex. The structures, proportions, sizes, etc., depicted in the accompanying drawings are only for illustrative purposes to aid those skilled in the art and are not intended to limit the implementation conditions of the present invention. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effects and objectives of the present invention, should still fall within the scope of the technical content disclosed in the present invention. Furthermore, the terms such as "upper," "lower," "left," "right," "middle," and "one" used in this specification are only for clarity of description and are not intended to limit the scope of the present invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the present invention.

[0025] Currently, the power generation of the range extender is mainly determined by the accelerator pedal, the state of charge (SOC) of the battery pack and the current speed of the vehicle. Since the battery pack has internal resistance, energy loss occurs when the battery pack is charged and discharged, so the charging direct current-direct current (DC-DC) control circuit and the discharging DC-DC control circuit also have energy loss, so that the range extender power generation directly drives the motor to achieve maximum conversion efficiency. Therefore, how to solve the problem that due to the increase of the downhill angle, the gravity component instantaneous power P1 of the vehicle increases, and the excess power generation of the output instantaneous power P2 of the motor of the vehicle charges the battery pack, and energy loss occurs when the battery pack is charged and discharged, thereby causing the fuel conversion efficiency to decrease is a problem that those skilled in the art need to solve.

[0026] Based on this, the present application hopes to provide a solution to the above technical problems, which can solve the problem that due to the increase of the downhill angle, the gravity component instantaneous power P1 of the vehicle increases, and the excess power generation of the output instantaneous power P2 of the motor of the vehicle charges the battery pack, and energy loss occurs when the battery pack is charged and discharged, thereby causing the fuel conversion efficiency to decrease. The detailed content will be described in the subsequent embodiments.

[0027] The present application discloses a range extender control method in a downhill state, a range extender control device in a downhill state and a vehicle with the range extender control device in a downhill state.

[0028] Please refer to Figure 1 which is the working principle diagram of the range extender disclosed in the embodiment of the present application. The range extender power generation drives the motor in two paths, one of which is to charge and discharge the battery pack to the motor, and the other is to directly drive the motor by the range extender power generation. When the vehicle is driving, the more the range extender power generation directly drives the motor, the higher the fuel conversion efficiency.

[0029] Please refer to Figure 2 which is a flowchart of the range extender control method in a downhill state disclosed in the embodiment of the present application. In the present application, the flowchart of the range extender control method in a downhill state includes at least the following steps.

[0030] S10, when it is determined that the vehicle is in a downhill driving state, the current state of the brake pedal, the current state of the accelerator pedal and the downhill angle value of the vehicle are obtained.

[0031] S20, selecting a target rotating speed from a plurality of rotating speeds pre-set for the range extender of the vehicle as the actual rotating speed of the range extender according to the current state of the brake pedal, the current state of the accelerator pedal and the vehicle downhill angle value.

[0032] S30, controlling the range extender to drive the motor of the vehicle at the actual rotating speed.

[0033] Please refer to Figure 3 In the embodiment of the present application, the step S20 at least includes the following steps.

[0034] S21, when the accelerator pedal is currently in the non-pedal-down state and the brake pedal is currently in the pedal-down state, selecting the minimum value of the pre-set rotating speeds as the target rotating speed.

[0035] In the embodiment of the present application, when the accelerator pedal is in the non-pedal-down state and the brake pedal is in the pedal-down state, the instantaneous power P2 of the motor of the range extended vehicle is 0, the instantaneous power P1 of the gravity component is greater than the total power P3 of the vehicle, and thus the minimum value of the pre-set rotating speeds is selected as the target rotating speed, which can avoid the energy loss caused by the charging and discharging of the battery pack, so as to achieve the purpose of increasing the fuel conversion efficiency. When the accelerator pedal is currently in the non-pedal-down state and the brake pedal is currently in the pedal-down state, the minimum value of the pre-set rotating speeds is selected as the target rotating speed. Specifically, the current battery pack power of the vehicle and the current driving distance of the vehicle are obtained, when the battery pack power is greater than or equal to a preset power threshold and it is determined that the driving distance is greater than or equal to a preset distance threshold, the range extender is turned off; when the battery pack power is less than the preset power threshold or it is determined that the driving distance is less than the preset distance threshold, the minimum value of the pre-set rotating speeds is kept as the target rotating speed.

[0036] In the embodiment of the present application, the preset distance threshold can be 100 meters.

[0037] S22, when the accelerator pedal and the brake pedal are currently in the non-pedal-down state, selecting the minimum value of the pre-set rotating speeds as the target rotating speed.

[0038] In the embodiment of the present application, when the accelerator pedal and the brake pedal are currently in the non-pedal-down state, the instantaneous power P2 of the motor of the range extended vehicle is 0, the instantaneous power P1 of the gravity component is equal to the total power P3 of the vehicle, and thus the minimum value of the pre-set rotating speeds is selected as the target rotating speed, which can avoid the energy loss caused by the charging and discharging of the battery pack, so as to achieve the purpose of increasing the fuel conversion efficiency.

[0039] S23, when the electric pedal is currently in a depressed state and the brake pedal is currently not depressed, selecting a target rotating speed from a plurality of pre-set rotating speeds of the range extender of the vehicle as the actual rotating speed of the range extender.

[0040] In the embodiment of the present application, when the electric pedal is in a depressed state and the brake pedal is not depressed, the total power P3 of the vehicle is greater than the sum of the instantaneous power P2 of the motor output of the extended range vehicle and the instantaneous power P1 of the gravity component; therefore, at this time, a reasonable control mode of the output power and the rotating speed of the range extender is adopted, so as to avoid the energy loss caused by the charging and discharging of the battery pack, thereby achieving the purpose of increasing the fuel conversion efficiency.

[0041] Please refer to Figure 4 In the embodiment of the present application, the step S23 can include the following sub-steps.

[0042] S231, acquiring the current driving speed of the vehicle.

[0043] S232, calculating the target power according to the downhill angle value of the vehicle and the driving speed.

[0044] In the embodiment of the present application, specifically, the gravity traction force of the vehicle when downhill is F1, which is calculated by formula (1):

[0045] F1=mgsinα Formula (1)

[0046] Wherein, m is the mass of the vehicle, g is the acceleration of gravity, v is the current driving speed of the vehicle when downhill, and a is the downhill angle value of the vehicle. Therefore, the instantaneous power of the gravity component of the vehicle when downhill is P1, which is calculated by formula (2):

[0047] P1=mgvsinα Formula (2)

[0048] The output instantaneous power of the motor of the vehicle is P2, which can be directly read. The total power of the vehicle is P3, which is calculated by formula (3):

[0049] P3=P1+P2 Formula (3)

[0050] According to formula (2) and formula (3), the following is obtained:

[0051] P3=mgvsinα+P2 Formula (4)

[0052] According to formula (4), the following is obtained:

[0053] P2=P3-mgvsinα Formula (5)

[0054] The reference power of the range extender is P4, and P2=kP4, where k is a preset coefficient, and k can be calibrated according to the motor efficiency and a direct current-direct current (DC-DC). The reference power of the range extender is calculated according to P3=mgv and formula (5):

[0055]

[0056] In the embodiment of the present application, the target power is determined according to the reference power. Specifically, when the instruction of starting the power saving mode is received, the reference power is matched with the preset power-speed corresponding relationship table, and a power closest to the reference power is selected as the target power from the power smaller than the reference power in the power-speed corresponding relationship table.

[0057] In the embodiment of the present application, the current residual power value of the battery pack of the vehicle is obtained, and when the residual power value is smaller than a preset power value, the reference power is matched with the preset power-speed corresponding relationship table, and a power closest to the reference power is selected as the target power from the power greater than the reference power in the preset power-speed corresponding relationship table.

[0058] S233, a target speed is matched from the preset power-speed corresponding relationship table according to the target power.

[0059] In the embodiment of the present application, specifically, the range extender can match the power required by the motor according to the actual speed, but the output instantaneous power P2 of the motor of the vehicle is a variable value, and the internal combustion engine must be at a specific speed to achieve the best thermal efficiency, which may cause the efficiency of the range extender to decrease instead. Therefore, a plurality of working gears of the range extender with the best thermal efficiency are calibrated, and a preset power-speed corresponding relationship table is established, where each working gear of the range extender corresponds to a speed interval. Taking the number of working gears of the range extender with the best thermal efficiency as N as an example, when the working gear of the range extender is 1 gear, the speed of the range extender of the vehicle is 2000 revolutions, and the corresponding power is A; when the working gear of the range extender is 2 gear, the speed of the range extender of the vehicle is 2300 revolutions, and the corresponding power is B; and when the working gear of the range extender is N gear, the speed of the range extender of the vehicle is 5000 revolutions, and the corresponding power is Z. Since the speed and power of the internal combustion engine are not in a linear relationship, an appropriate best gear number D can be obtained by table lookup, and the range of D can be 0-N, and each working gear of the range extender corresponds to a speed interval.

[0060] Please refer to Figure 5 In the embodiment of the present application, the step S30 can include the following sub-steps.

[0061] S31, start timing when it is determined that the vehicle meets a pre-designed condition.

[0062] In the embodiments of the present application, specifically, the pre-designed condition is that the vehicle is in a bumpy road driving state, and the target power and the target speed are different from the current power and the current speed of the range extender, and the target speed is selected as the actual speed of the range extender.

[0063] S32, after the target timing duration arrives, control the range extender to drive the motor of the vehicle at the actual speed.

[0064] In summary, in the range extender control method in the downhill state of the present application, the current state of the brake pedal, the current state of the accelerator pedal and the downhill angle value of the vehicle are obtained, a target speed is selected as the actual speed of the range extender from a plurality of pre-set speeds of the range extender for the vehicle according to the current state of the brake pedal, the current state of the accelerator pedal and the downhill angle value of the vehicle, and the range extender is controlled to drive the motor of the vehicle at the actual speed, which can reduce the output power required by the range extender of the vehicle, thereby avoiding energy loss caused by charging and discharging of the battery pack, and achieving the purpose of increasing fuel conversion efficiency.

[0065] It should be understood that, although Figures 2 to 5 The steps in the flowchart of the range extender control method in the downhill state of the present application are displayed in sequence according to the arrows, but these steps are not necessarily executed in sequence according to the arrows. Unless otherwise specified herein, the execution of these steps has no strict order limitation, and these steps can be executed in other orders. Moreover, Figures 2 to 5 At least part of the steps in the range extender control method in the downhill state of the present application can include a plurality of sub-steps or a plurality of stages, which are not necessarily executed at the same time, but can be executed at different times, and the execution order of these sub-steps or stages is not necessarily sequential, but can be alternately executed with other steps or at least part of the sub-steps or stages of other steps.

[0066] Please refer to Figure 6 which is a structural schematic diagram of a range extender control device in a downhill state disclosed by the embodiments of the present application. The present application provides a range extender control device 100 in a downhill state, which can at least include an acquisition unit 110, a determination unit 120 and a control unit 130. The acquisition unit 110 is connected with the determination unit 120, and the determination unit 120 is connected with the control unit 130.

[0067] When it is determined that the vehicle is in a downhill driving state, the pedal state acquisition unit 110 is configured to acquire a current state of a brake pedal of the vehicle, a current state of a gear pedal of the vehicle, and a downhill angle value of the vehicle.

[0068] The determination unit 120 is configured to select a target rotating speed from a plurality of rotating speeds of a range extender of the vehicle as an actual rotating speed of the range extender according to the current state of the brake pedal, the current state of the gear pedal, and the downhill angle value of the vehicle. When the gear pedal is in an unpressed state and the brake pedal is in a pressed state, a minimum value of the plurality of rotating speeds is selected as the target rotating speed. Specifically, a current battery pack power of the vehicle and a current driving distance of the vehicle are acquired. When the battery pack power is greater than or equal to a preset power threshold and it is determined that the driving distance is greater than or equal to a preset distance threshold, the range extender is turned off.

[0069] When the battery pack power is less than the preset power threshold or it is determined that the driving distance is less than the preset distance threshold, the minimum value of the plurality of rotating speeds is maintained as the target rotating speed. When the gear pedal and the brake pedal are both in the unpressed state, the minimum value of the plurality of rotating speeds is selected as the target rotating speed.

[0070] When the gear pedal is in the pressed state and the brake pedal is in the unpressed state, a target rotating speed is selected from the plurality of rotating speeds of the range extender of the vehicle as the actual rotating speed of the range extender. In an embodiment of the present application, a current driving speed of the vehicle is acquired, a target power is calculated according to the downhill angle value of the vehicle and the driving speed, and the target rotating speed is matched from a preset power-rotating speed corresponding table according to the target power.

[0071] The control unit 130 is configured to control the range extender to drive a motor of the vehicle at the actual rotating speed. In an embodiment of the present application, when it is determined that the vehicle satisfies a preset time condition, timing is started, wherein the preset time condition is that the vehicle is in a rough road driving state, and the target power and the target rotating speed are different from a current power and a current rotating speed of the range extender, and the target rotating speed is selected as the actual rotating speed of the range extender. After a target timing duration is reached, the range extender is controlled to drive the motor of the vehicle at the actual rotating speed.

[0072] In summary, in the range extender control device in the downhill state of the application, when it is determined that the vehicle is in the downhill driving state, the pedal state acquisition unit 110 acquires the current state of the brake pedal of the vehicle, the current state of the gear pedal, and the downhill angle value of the vehicle. The determination unit 120 selects a target speed as the actual speed of the range extender from a plurality of pre-set speeds of the range extender of the vehicle according to the current state of the brake pedal, the current state of the gear pedal, and the downhill angle value of the vehicle. The control unit 130 drives the motor of the vehicle by controlling the range extender at the actual speed, which can reduce the output power required by the range extender of the vehicle, thereby avoiding energy loss caused by charging and discharging of the battery pack, and further achieving the purpose of increasing fuel conversion efficiency.

[0073] Please refer to Figure 7 which is a structural schematic diagram of a vehicle disclosed by an embodiment of the application. The application also provides a vehicle 10, which comprises Figure 6 the range extender control device 100 in the downhill state in the illustrated embodiment.

[0074] The technical features of the above embodiments can be combined arbitrarily. In order to make the description simple, all possible combinations of the technical features in the above embodiments are not described, but as long as the combinations of the technical features do not exist, they should be considered as the scope of the description.

[0075] The above embodiments only express several implementation manners of the application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be pointed out that for ordinary skilled persons in the art, without departing from the concept of the application, a number of modifications and improvements can be made, which are all within the protection scope of the application. Therefore, the protection scope of the patent of the application should be subject to the appended claims.

Claims

1. A method for controlling a range extender in a downhill state, characterized in that, The method comprises the following steps: When it is determined that the vehicle is in a downhill driving state, the current state of a brake pedal of the vehicle, the current state of a gear pedal of the vehicle and a downhill angle value of the vehicle are obtained; According to the current state of the brake pedal, the current state of the gear pedal and the downhill angle value of the vehicle, one target rotating speed is selected from a plurality of rotating speeds of a range extender of the vehicle as an actual rotating speed of the range extender; The range extender is controlled to drive an electric motor of the vehicle at the actual rotating speed; The method further comprises the following steps: When the current state of the gear pedal is in a pressed state and the current state of the brake pedal is in an unpressed state, a current driving speed of the vehicle is obtained; According to the downhill angle value of the vehicle and the driving speed, a reference power of the range extender is calculated; A current residual power value of a battery pack of the vehicle is obtained; when the residual power value is less than a preset power value, the reference power is matched with a preset power-rotating speed corresponding table, and a power closest to the reference power is selected as a target power from powers greater than the reference power in the power-rotating speed corresponding table; The target rotating speed is matched from the preset power-rotating speed corresponding table according to the target power.

2. The method of claim 1, wherein, The method further comprises the following steps: When the current state of the gear pedal is in an unpressed state and the current state of the brake pedal is in a pressed state, a minimum value of the preset rotating speeds is selected as the target rotating speed; or When the current state of the gear pedal and the current state of the brake pedal are both in an unpressed state, a minimum value of the preset rotating speeds is selected as the target rotating speed.

3. The method of claim 2, wherein, The method further comprises the following steps after the minimum value of the preset rotating speeds is selected as the target rotating speed when the current state of the gear pedal is in an unpressed state and the current state of the brake pedal is in a pressed state: A current battery pack power of the vehicle is obtained; When the battery pack power is greater than or equal to a preset power threshold, the range extender is turned off.

4. The method of claim 3, wherein, The method further comprises the following steps before the range extender is turned off: A current driving distance of the vehicle is obtained; It is determined that the driving distance is greater than or equal to a preset distance threshold.

5. The method of controlling a range extender in a downhill state according to claim 1, wherein The calculation formula of the reference power is ; The reference power of the range extender is determined according to the following formula: P4=k*m*g*v*alpha, wherein P4 is the reference power of the range extender, k is a preset coefficient, m is the mass of the vehicle, g is the acceleration of gravity, v is the current driving speed of the vehicle, and alpha is the downhill angle value of the vehicle.

6. The method of controlling a range extender in a downhill state according to claim 5, wherein The target power is determined according to the reference power, and the method further comprises the following steps: When receiving the instruction of starting the power saving mode, the reference power is matched with the preset power and rotating speed corresponding relation table, and a power closest to the reference power is selected as the target power from the power less than the reference power in the power and rotating speed corresponding relation table.

7. A range extender control device in a downhill state, characterized by, The range extender control device in the downhill state comprises an acquisition unit, a determination unit and a control unit, wherein, The acquisition unit is configured to acquire a current state of a brake pedal, a current state of a gear pedal and a downhill angle value of the vehicle when it is determined that the vehicle is in a downhill driving state; The determination unit is configured to select a target rotating speed as an actual rotating speed of the range extender from a plurality of rotating speeds of the range extender of the vehicle which are set in advance according to the current state of the brake pedal, the current state of the gear pedal and the downhill angle value of the vehicle; The control unit is configured to control the range extender to drive the motor of the vehicle at the actual rotating speed. The determination unit is specifically configured to acquire a current driving speed of the vehicle when the current state of the gear pedal is in a pressed state and the current state of the brake pedal is in an unpressed state, calculate a reference power of the range extender according to the downhill angle value of the vehicle and the driving speed, acquire a current residual power value of a battery pack of the vehicle, select a power closest to the reference power as a target power from the power greater than the reference power in a preset power and rotating speed corresponding relation table when the residual power value is less than a preset power value, and match the target power with the preset power and rotating speed corresponding relation table to match a target rotating speed from the preset power and rotating speed corresponding relation table according to the target power.

8. A vehicle characterized by comprising: The vehicle comprises the range extender control device in the downhill state according to claim 7.

Images