Electric vehicle and regenerative braking control method thereof
By controlling the isolating switch and regenerative braking force distribution, the coordinated work of multiple motors is optimized, and the problem of hydraulic intervention dependence of electric vehicles under the demand for large braking force is solved, regenerative braking efficiency and fuel efficiency are improved, and damage is reduced.
Patent Information
- Application Number
- CN202311588549.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2023-06-19
- Filing Date
- 2023-11-27
- Publication Date
- 2024-12-20
AI Technical Summary
When a large amount of braking force is required, electric vehicles rely on hydraulic pressure intervention, and relying solely on the main drive source motor is not enough to meet braking force requirements, resulting in inefficiency and wear of brake pads.
By controlling the engagement state of the isolating switch, the regenerative braking force distribution of multiple motors is optimized, so that the second motor can generate regenerative braking force, maximize regenerative braking force, and convert to 4WD mode if necessary to reduce hydraulic intervention.
Effectively reduces hydraulic pressure intervention, improves fuel efficiency, and reduces damage during braking, such as brake pad wear.
Smart Images
Figure CN119160003A_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to an electric vehicle and a regenerative braking control method thereof, which can improve the efficiency of regenerative braking when a large amount of braking force is required. Background Art
[0002] In view of people's increasing concern for the environment, the popularity of environmentally friendly vehicles using electric motors as a main power source has increased significantly. These environmentally friendly vehicles belong to the category of electric vehicles, of which hybrid electric vehicles (HEV) and electric vehicles (EV) are well-known representatives.
[0003] The electric motor provided in such electric vehicles can charge the battery using the wheel driving force generated by wheel deceleration. This process is generally called brake energy regeneration or regenerative braking. More specifically, when braking is required, the entire braking force or torque according to the braking requirement is calculated, and then the electric motor can be used within the entire braking force to perform regenerative braking. In this case, the deficiency obtained by subtracting the regenerative braking force generated by the entire braking force can be handled by hydraulic braking.
[0004] In addition, an electric vehicle may be provided with a plurality of electric motors, some of which serve as the main drive source and others as the auxiliary drive source. In this case, priority is given to regenerative braking by the electric motor designated as the main drive source.
[0005] Under typical operating conditions, as described above, prioritizing regenerative braking by designating a specific electric motor as the main drive source can improve overall efficiency. However, when a large braking force is required, such as during a sudden application of the brake pedal by the driver, relying solely on the main drive source electric motor may not be enough. In this case, the possibility of hydraulic force intervention becomes greater.
[0006] Therefore, a solution is needed that reduces the reliance on hydraulic force intervention and optimizes regenerative braking by effectively utilizing multiple electric motors. Summary of the invention
[0007] The present disclosure relates to an electric vehicle, and a regenerative braking control method for improving the efficiency of regenerative braking when a large amount of braking force is required.
[0008] For example, the present disclosure relates to an electric vehicle and a regenerative braking control method thereof, which reduces hydraulic pressure intervention by effectively utilizing a plurality of electric motors when a large amount of braking force is required.
[0009] According to one aspect, an electric vehicle may include: a first motor connected to a first drive wheel according to an engagement state of an isolating switch; a second motor connected to a second drive wheel; and a controller configured to control the engagement state of the isolating switch based on a required braking force before the regenerative braking force generated by the second motor reaches an upper limit during regenerative braking using the second motor, and to control the regenerative braking forces of the first motor and the second motor based on the engagement state of the isolating switch.
[0010] The controller may control the engagement state of the isolation switch regardless of the regenerative braking force generated by the second electric motor.
[0011] When the required braking force is greater than an upper limit of the regenerative braking force generated by the second electric motor, the controller may control the isolation switch to engage.
[0012] When the increase per unit time of the required braking force is greater than a predetermined value, the controller may control the isolation switch to engage.
[0013] When the isolation switch is engaged, the controller may distribute the required braking force to the first motor and the second motor. The required braking force may be preferentially distributed to the second motor so that the regenerative braking force generated by the second motor reaches an upper limit.
[0014] After the disconnect switch is engaged, the controller may perform control such that a required braking force greater than the regenerative braking force generated by the first and second motors is satisfied by hydraulic braking.
[0015] The second electric motor may be connected to the second drive wheel at all times.
[0016] According to another aspect, a regenerative braking control method for an electric vehicle, the electric vehicle including a first drive wheel connected to a first motor and a second drive wheel connected to a second motor according to an engagement state of an isolating switch, the method may include: controlling the engagement state of the isolating switch based on a required braking force during regenerative braking of the second motor; and controlling the regenerative braking force generated by the first motor and the second motor based on the engagement state of the isolating switch.
[0017] Control of the engagement state of the disconnect switch may be performed based on the required braking force regardless of whether the upper limit of the regenerative braking force generated by the second electric motor is reached.
[0018] In the control of the engagement state of the disconnect switch, when the required braking force is greater than an upper limit of the regenerative braking force generated by the second electric motor, the disconnect switch may be controlled to be engaged.
[0019] In the control of the engaged state of the disconnect switch, when the increase per unit time of the required braking force is greater than a predetermined value, the disconnect switch may be controlled to be engaged.
[0020] In the control of the engagement state of the isolating switch, after the isolating switch is engaged, the required braking force can be distributed to the first motor and the second motor. The required braking force can be preferentially distributed to the second motor so that the regenerative braking force generated by the second motor reaches an upper limit.
[0021] The method may further include, after the disconnect switch is engaged, performing control such that a required braking force greater than the regenerative braking force generated by the first and second motors is satisfied by hydraulic braking.
[0022] The second electric motor may be connected to the second drive wheel at all times.
[0023] According to various embodiments of the present disclosure, by pre-controlling a driving method of a vehicle using a plurality of electric motors based on a required braking force, regenerative braking may be performed more efficiently.
[0024] Specifically, in the case where a large amount of braking force is required, the possibility of hydraulic pressure intervention can be reduced by increasing the total amount of braking force. Therefore, fuel efficiency can be improved, and damage such as brake pad wear that occurs during the braking process can be reduced.
[0025] It will be understood by those skilled in the art that the effects that can be achieved by the present disclosure are not limited to those described above, and other advantages of the present disclosure will be clearly understood from the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] Figure 1 is a diagram illustrating an example of a driving method of an electric vehicle.
[0027] Figure 2 is a block diagram illustrating an example of a controller of an electric vehicle.
[0028] Figure 3A and Figure 3B is a diagram showing an example of control logic of an electric vehicle.
[0029] Figure 4 is a flowchart showing an example of a regenerative braking control process of an electric vehicle. DETAILED DESCRIPTION
[0030] Terms such as "unit" or "control unit") contained in the names of certain components (such as the motor control unit (MCU) and the hybrid control unit (HCU)) are simply terms widely used in the naming of controllers that control specific functions of the vehicle, but should not be understood as indicating general functional units.
[0031] Additionally, the term "controller" may include a communication device that communicates with another controller or sensor to control the functions managed by the controller; a memory that stores an operating system, logical instructions, input / output information, etc.; and one or more processors that perform the determinations, calculations, decisions, etc. required to perform the control functions.
[0032] An electric vehicle and a regenerative braking control method thereof are proposed to efficiently perform regenerative braking by controlling driving of the vehicle using a plurality of electric motors based on a required braking force.
[0033] Here, the vehicle driving method using multiple motors can be divided into a two-wheel drive (2WD) method, in which the driving force of the motor is transmitted to only one pair of wheels among the front and rear wheels; and a four-wheel drive (4WD) method, in which the driving force of the motor is transmitted to both the front and rear wheels.
[0034] In addition, it is assumed that the electric vehicle can be switched between the 2WD method and the 4WD method in order to effectively perform regenerative braking by controlling the driving method.
[0035] In addition, in the case where the electric vehicle is driven by the 2WD method, a pair of wheels to which the driving force of the motor is transmitted may be referred to as the main driving wheels, and another pair of wheels to which the driving force of the motor is transmitted only when the electric vehicle is driven by the 4WD method may be referred to as the auxiliary driving wheels. For example, the main driving wheels may be rear wheels, and the auxiliary driving wheels may be front wheels, but the present disclosure is not limited thereto. On the contrary, the main driving wheels and the auxiliary driving wheels may be determined in an opposite manner.
[0036] Before describing the regenerative braking control method, the electric vehicle is first described as follows.
[0037] Figure 1 is a conceptual diagram showing a driving method of an electric vehicle.
[0038] Reference Figure 1 , the electric vehicle 10 may include an isolating switch 100, a first driving wheel 210, a second driving wheel 220, a first motor 310, and a second motor 320. The isolating switch 100, the first motor 310, and the second motor 320 may be connected to a controller 400 to be described below. Figure 1 The components of the present disclosure are mainly shown, and the electric vehicle 10 may actually include a greater or lesser number of components. Hereinafter, the corresponding components will be described in detail.
[0039] First, the first motor 310 may be connected to the first driving wheel 210 according to the engagement state of the disconnector 100. When the first motor 310 and the first driving wheel 210 are connected, the driving force from the first motor 310 may be transmitted to the first driving wheel 210.
[0040] In addition, the second motor 320 may be connected to the second driving wheel 220 to provide driving force to the second driving wheel 220. The second motor 320 and the second driving wheel 220 may be connected through the second driving shaft 202.
[0041] The isolating switch 100 may connect or disconnect the first driving wheel 210 and the first motor 310 according to the engagement state. More specifically, when the isolating switch 100 is engaged, the first driving wheel 210 and the first motor 310 may be connected to each other so that the driving force of the first motor 310 may be transmitted to the first driving wheel 210. When the isolating switch 100 is not engaged, the first driving wheel 210 and the first motor 310 may be disconnected so that the driving force of the first motor 310 is not transmitted to the first driving wheel 210.
[0042] In order to control the connection or disconnection between the first driving wheel 210 and the first motor 310, the disconnector 100 may be provided on the side of the first driving wheel 210. More specifically, the disconnector 100 may be attached to the reducer on the first driving shaft 201. The disconnector 100 may control the connection or disconnection of the first motor 310 with the first driving wheel 210 connected to the first driving shaft 201 by connecting or disconnecting the first motor 310 with the first driving shaft 201.
[0043] Unlike the first motor 310 and the first driving wheel 210, the second motor 320 and the second driving wheel 220 may be always connected. Therefore, the disconnector 100 may not be provided on the second driving wheel 220 side.
[0044] In this manner, by controlling the engagement state of the disconnect switch 100 that determines whether the first drive wheel 210 and the first motor 310 are connected or disconnected, the driving method of the vehicle can be switched from 2WD to 4WD or from 4WD to 2WD.
[0045] In addition, even in 2WD, the second drive wheel 220 is always connected to the second motor 320 to receive the driving force, so the second drive wheel 220 can be called a main drive wheel. In 4WD, the first drive wheel 210 is connected to the first motor 310 through the isolation switch 100 to receive the driving force, so the first drive wheel 210 can be called an auxiliary drive wheel.
[0046] On the other hand, the electric vehicle 10 may be provided with a controller 400 to control the disconnect switch 100, the first motor 310 and the second motor 320 as described above. Figures 2 to 3B The controller 400 is described in detail.
[0047] Figure 2 is a block diagram showing the configuration of a controller of an electric vehicle.
[0048] Reference Figure 2The controller 400 may include an isolating switch controller 410 , a regenerative braking force controller 420 , and a hydraulic pressure controller 430 . Figure 2 Components related to the description of the embodiments of the present disclosure are mainly shown, and the controller 400 may actually include a greater or lesser number of components. Hereinafter, the respective components of the controller 400 will be described in detail.
[0049] First, during regenerative braking by the second motor 320 , before the regenerative braking force generated by the second motor 320 reaches an upper limit, the isolator switch controller 410 may control the engagement state of the isolator switch 100 based on the required braking force.
[0050] In this case, the upper limit of the regenerative braking force generated by the second motor 320 may be predetermined or may be obtained from a brake controller, an upper controller, etc. provided in the vehicle. In addition, the required braking force may be determined according to the depression amount of the brake pedal. The required braking force may be determined by receiving a measurement result from a brake pedal sensor, etc., or may be obtained from a brake controller, an upper controller, etc.
[0051] Specifically, the isolating switch controller 410 may control the engagement state of the isolating switch 100 regardless of the regenerative braking force generated by the second motor 320. That is, when the required braking force satisfies a predetermined condition, the isolating switch controller 410 controls the engagement state of the isolating switch 100. In this case, it may be determined whether the isolating switch 100 is engaged regardless of the regenerative braking force generated by the second motor 320.
[0052] Before the regenerative braking force generated by the second motor 320 reaches the upper limit, the disconnect switch controller 410 controls the engagement state of the disconnect switch 100. Therefore, before the hydraulic force intervenes, the vehicle driving method using the plurality of motors 310 and 320 can be converted and prepared in advance so that regenerative braking can be effectively performed.
[0053] In addition, the regenerative braking force controller 420 may control the regenerative braking forces of the first motor 310 and the second motor 320 based on the engagement state of the isolation switch 100 .
[0054] More specifically, when the isolation switch 100 is engaged, the regenerative braking force controller 420 may allocate the required braking force to the first motor 310 and the second motor 320. In this case, the required braking force may be allocated to the second motor 320 with priority, so that the regenerative braking force generated by the second motor 320 reaches an upper limit. Specifically, when the second drive wheel 220 connected to the second motor 320 is the main drive wheel, the efficiency of the regenerative braking may be improved by allocating the required braking force to the second motor 320 with priority.
[0055] After the isolation switch 100 is engaged, the hydraulic pressure controller 430 may perform control so that a required braking force exceeding the regenerative braking force generated by the first motor 310 and the second motor 320 may be satisfied by hydraulic braking.
[0056] In other words, in the engaged state of the disconnect switch 100, the sum of the regenerative braking force generated by the first motor 310, the regenerative braking force generated by the second motor 320, and the hydraulic braking force is the same as the required braking force. The regenerative braking may be controlled so that the hydraulic braking force is minimized. The regenerative braking may also be controlled so that the regenerative braking force generated by the motor (e.g., the second motor 320) connected to the main drive wheel as described above is maximized while minimizing the hydraulic braking force.
[0057] In addition, reference will be made to Figure 3A and Figure 3B A driving method and a specific regenerative braking control method are described in more detail.
[0058] Figure 3A and Figure 3B is a diagram showing the control logic of an electric vehicle.
[0059] Figure 3A and Figure 3B These can be understood as diagrams each having time on the horizontal axis and torque or control signal on the vertical axis.
[0060] First, refer to Figure 3A When the required braking force Tq_r is greater than the upper limit Max Tq_2 of the regenerative braking force Tq_2 generated by the second motor 320 , the isolation switch controller 410 may control the isolation switch 100 to be engaged.
[0061] More specifically, at a time point t1 when the required braking force Tq_r is greater than the upper limit Max Tq_2 of the regenerative braking force Tq_2 generated by the second motor 320, the disconnect switch controller 410 may generate an engagement request to engage the disconnect switch 100. The disconnect switch 100 is engaged in response to the engagement request, and before a time point t2 when the regenerative braking force Tq_2 generated by the second motor 320 reaches the upper limit Max Tq_2, the driving method Md of the vehicle may be switched from the 2WD method to the 4WD method.
[0062] Next, refer to Figure 3B When the increase per unit time of the required braking force Tq_r is greater than a predetermined value, the isolating switch controller 410 may control the isolating switch 100 to engage.
[0063] More specifically, at a time point t1' when the increase per unit time of the required braking force Tq_r is greater than a predetermined value, the disconnect switch controller 410 may generate an engagement request to engage the disconnect switch 100. The disconnect switch is engaged in response to the engagement request, and before a time point t2' when the regenerative braking force Tq_2 generated by the second motor 320 reaches the upper limit Max Tq_2, the driving method Md of the vehicle may be switched from the 2WD method to the 4WD method.
[0064] Reference Figure 3A and Figure 3B In both cases, when the driving method Md of the vehicle is the 2WD method, the regenerative braking force controller 420 may perform control so that the regenerative braking force Tq_2 generated by the second motor 320 is as close as possible to the required braking force Tq_r. Here, when the regenerative braking force Tq_2 generated by the second motor 320 is insufficient to cover the entire required braking force Tq_r, the hydraulic pressure controller 430 may perform control so that the hydraulic braking force Tq_h exceeds the required braking force Tq_r by the same amount.
[0065] When the driving method Md of the vehicle is the 4WD method, the regenerative braking force controller 420 may perform control so that the regenerative braking force Tq_1 generated by the first motor 310 and the regenerative braking force Tq_2 generated by the second motor 320 are as close to the required braking force Tq_r as possible. Also in this case, the excess amount of the required braking force Tq_r can be satisfied by the hydraulic braking force Tq_h. In addition, the regenerative braking force controller 420 may control the regenerative braking force Tq_1 generated by the first motor 310 and the regenerative braking force Tq_2 generated by the second motor 320 by distributing the required braking force Tq_r to the first motor 310 and the second motor 320 so that the regenerative braking force Tq_1 generated by the first motor 310 reaches the upper limit.
[0066] In addition, when the engagement state of the disconnect switch 100 is controlled based on the regenerative braking force Tq_2 generated by the second motor 320, the disconnect switch 100 may be engaged after the regenerative braking force Tq_2 generated by the second motor 320 actually reaches the upper limit Max Tq_2. In this case, the regenerative braking using the first motor 310 cannot be performed before the driving method Md is converted to the 4WD method, and the hydraulic braking force Tq_h increases to cope with the required braking force Tq_r greater than the upper limit Max Tq_2 of the regenerative braking force Tq_2 generated by the second motor 320.
[0067] In contrast, according to the control in accordance with the embodiment of the present disclosure, the engagement request time points t1 and t1' of the disconnect switch 100 may precede the time points t2 and t2' at which the regenerative braking force Tq_2 generated by the second motor 320 actually reaches the upper limit Max Tq_2. Therefore, once the upper limit Max Tq_2 of the regenerative braking force Tq_2 generated by the second motor 320 is reached, the first motor 310 may intervene in the regenerative braking, and a portion of the required braking force Tq_r exceeding the upper limit Max Tq_2 of the regenerative braking force Tq_2 generated by the second motor 320 may be satisfied by the regenerative braking force Tq_1 generated by the first motor 310, thereby reducing the hydraulic braking force Tq_h.
[0068] Hereinafter, the control process of the above-mentioned regenerative braking will be described with reference to a flowchart.
[0069] Figure 4 is a flowchart showing a regenerative braking control process of an electric vehicle.
[0070] Reference Figure 4 When a braking request is generated in S410 , the disconnect switch controller 410 may compare the required braking force Tq_r with an upper limit Max Tq_2 of the regenerative braking force Tq_2 generated by the second motor 320 in S420 .
[0071] When the required braking force Tq_r is greater than the upper limit Max Tq_2 of the regenerative braking force Tq_2 generated by the second motor 320 ("Yes" in S420), the isolation switch controller 410 may determine that regenerative braking by the first motor 310 is necessary, and in S440 may control the isolation switch 100 to engage, thereby converting the driving method of the vehicle to 4WD.
[0072] In the 4WD state, the regenerative braking force controller 420 may distribute the required braking force Tq_r to the first motor 310 and the second motor 320. In this regard, the regenerative braking force controller 420 may determine the regenerative braking force Tq_1 of the first motor 310 in S450.
[0073] For example, the regenerative braking force controller 420 may determine the regenerative braking force when the regenerative braking force Tq_2 generated by the second motor 320 reaches the upper limit as the regenerative braking force Tq_1 generated by the first motor 310. In this case, the value of the regenerative braking force Tq_2 generated by the second motor 320 may be greater than the value of the regenerative braking force Tq_1 generated by the first motor 310.
[0074] In S460 , the first motor 310 and the second motor 320 perform regenerative braking in response to the distribution of the required braking force Tq_r.
[0075] In this case, when braking is not completed (No in S470), the regenerative braking force Tq_1 generated by the first motor 310 is continuously determined in response to changes in the required braking force Tq_r (advancing to S450). When braking is completed (Yes in S470), the regenerative braking control process ends.
[0076] In addition, differently, even in the case where the required braking force Tq_r is not greater than the upper limit Max Tq_2 of the regenerative braking force Tq_2 generated by the second motor 320 ("No" in S420), when the change ΔTq_r / s per unit time of the required braking force is greater than a predetermined value X in S430, the isolation switch controller 410 can control the isolation switch 100 to engage, thereby converting the driving method of the vehicle to the 4WD method in S440.
[0077] When the isolating switch engagement condition is not satisfied ("No" in S430), that is, when it is determined that regenerative braking is not required by the first motor 310, the isolating switch 100 may be controlled not to be engaged, and regenerative braking may be performed using the second motor 320 by controlling the electric vehicle 10 to maintain the 2WD state in S480. In this case, when braking is not completed ("No" in S490), it is determined whether to control the isolating switch 100 to be engaged (advancing to S420). When braking is completed ("Yes" in S490), the regenerative braking control process ends.
[0078] According to various embodiments of the present disclosure as described above, by controlling the vehicle driving method using a plurality of electric motors in advance based on the required braking force, regenerative braking may be performed more efficiently.
[0079] Specifically, in the case where a large amount of braking force is required, the possibility of hydraulic pressure intervention can be reduced, thereby improving fuel efficiency. In addition, damage such as brake pad wear that occurs during the braking process can be reduced.
[0080] In addition, the present disclosure as described above can be implemented as a computer-readable code in a program recording medium. Computer-readable media may include all types of recording devices in which data readable by a computer system is stored. Examples of computer-readable media include hard disk drives (HDDs), solid-state disks (SSDs), silicon disk drives (SDDs), read-only memories (ROMs), random access memories (RAMs), compact disk read-only memories (CD-ROMs), magnetic tapes, floppy disks, optical data storage devices, etc.
Claims
1. An electric vehicle, include: a first electric motor configured to be connected to the first drive wheel based on an engaged state of the isolating switch; a second electric motor connected to a second drive wheel; as well as The controller is configured as: when the second electric motor performs regenerative braking, before the regenerative braking force generated by the second electric motor reaches an upper limit, controlling the engagement state of the disconnect switch based on a required braking force, and The regenerative braking forces of the first and second electric motors are controlled based on the engagement state of the isolation switch.
2. The electric vehicle according to claim 1, in, The controller is configured to control an engagement state of the isolation switch regardless of the regenerative braking force generated by the second electric motor.
3. The electric vehicle according to claim 1, in, The controller is configured to control the disconnect switch to engage based on the required braking force being greater than the upper limit of the regenerative braking force of the second electric motor.
4. The electric vehicle according to claim 1, in, The controller is configured to control the isolation switch to engage based on a rate of increase of the required braking force being greater than a predetermined value.
5. The electric vehicle according to claim 1, in, The controller is configured to distribute the desired braking force to the first motor and the second motor based on the isolator switch being engaged, and The required braking force is distributed to the second electric motor so that the regenerative braking force generated by the second electric motor reaches the upper limit.
6. The electric vehicle according to claim 1, in, The controller is configured to control the desired braking force provided by hydraulic braking based on the isolator switch engagement, the desired braking force being greater than a regenerative braking force generated by the first and second motors.
7. The electric vehicle according to claim 1, in, The second electric motor is configured to maintain a continuous connection with the second drive wheel.
8. A regenerative braking control method for an electric vehicle, the electric vehicle comprising a first drive wheel connected to a first motor and a second drive wheel connected to a second motor based on an engagement state of an isolating switch, the method include: controlling the engagement state of the disconnect switch based on a required braking force when the second electric motor performs regenerative braking; as well as Regenerative braking forces generated by the first and second electric motors are controlled based on an engagement state of the isolating switch.
9. The method according to claim 8, in, Control of the engagement state of the disconnect switch is performed based on the required braking force regardless of whether an upper limit of the regenerative braking force generated by the second electric motor is reached.
10. The method according to claim 8, in, Controlling the engagement state of the disconnect switch includes controlling the disconnect switch to engage based on the required braking force being greater than an upper limit of a regenerative braking force generated by the second electric motor.
11. The method according to claim 8, in, Controlling the engagement state of the isolating switch includes controlling the isolating switch to engage based on a rate of increase of the required braking force being greater than a predetermined value.
12. The method according to claim 8, in, controlling the engagement state of the isolator switch includes distributing the desired braking force to the first motor and the second motor based on the isolator switch engagement, and The required braking force is distributed to the second electric motor so that the regenerative braking force generated by the second electric motor reaches an upper limit.
13. The method according to claim 8, further comprising: include: The desired braking force provided by hydraulic braking is controlled based on the isolator switch engagement, the desired braking force being greater than regenerative braking forces generated by the first and second electric motors.
14. The method according to claim 8, in, The second electric motor is configured to maintain a continuous connection with the second drive wheel.
15. A non-transitory computer-readable recording medium storing a program, in, Execution of the program causes one or more computers to perform operations including: When the second electric motor performs regenerative braking, controlling an engagement state of the disconnect switch based on a required braking force; and Regenerative braking forces generated by the first electric motor and the second electric motor are controlled based on an engagement state of the isolating switch.
16. The non-transitory computer-readable recording medium according to claim 15, in, Controlling the engagement state of the disconnect switch is performed based on the required braking force regardless of whether an upper limit of the regenerative braking force generated by the second electric motor is reached.
17. The non-transitory computer-readable recording medium according to claim 15, in, Controlling the engagement state of the disconnect switch includes controlling the disconnect switch to engage based on the required braking force being greater than an upper limit of a regenerative braking force generated by the second electric motor.
18. The non-transitory computer-readable recording medium according to claim 15, in, Controlling the engagement state of the isolating switch includes controlling the isolating switch to engage based on a rate of increase of the required braking force being greater than a predetermined value.
19. The non-transitory computer-readable recording medium according to claim 15, in, controlling the engagement state of the isolator switch includes distributing the desired braking force to the first motor and the second motor based on the isolator switch engagement, and The required braking force is distributed to the second electric motor so that the regenerative braking force generated by the second electric motor reaches an upper limit.
20. The non-transitory computer-readable recording medium according to claim 15, in, The operations also include controlling the desired braking force provided by hydraulic braking based on the isolator switch engagement, the desired braking force being greater than the regenerative braking force generated by the first and second motors.