A whole vehicle testing method and testing system for electric vehicle

Abstract

The present invention discloses a whole vehicle testing method and testing system for an electric vehicle, and belongs to the field of vehicle testing technology. In this method, the energy recovery rate of the vehicle under the energy recovery strategy is measured experimentally, and the effect of the energy recovery strategy is intuitively displayed. By comparing the energy recovery rates under different test conditions, the test control parameters are adjusted so that the test control parameters are close to the actual application scenario, which is convenient for direct use next time. In the process of performing the energy recovery test, it is tested whether the front wheel braking force and the rear wheel braking force are reasonably distributed, whether the impact of the battery current and battery temperature on the battery safety is considered when the vehicle performs energy recovery, and further whether the energy recovery strategy can ensure the safety of the driver.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle testing, and in particular to a whole vehicle testing method and testing system for an electric vehicle. Background Art

[0002] With the increasing shortage of global energy and the worsening of environmental problems, in order to implement energy conservation and emission reduction, electric vehicles are vigorously promoted to use electric energy as their power source, which is green and environmentally friendly. Electric vehicles are equipped with energy recovery functions to improve the efficiency of electric energy utilization. That is, when the vehicle is braking or sliding, the power battery meets the charging permission conditions, and the motor controller controls the drive motor to enter the charging mode, converting mechanical energy into electric energy and feeding it back to the power battery. For safety reasons, when the electric vehicle is in emergency braking, the anti-lock braking device will reduce the braking torque applied to the wheel before the wheel is about to lock, and energy recovery cannot be performed at this time. An excellent energy recovery strategy can not only improve the efficiency of electric energy utilization and increase the cruising range, but also has no negative impact on the operation of the anti-lock braking device, thereby improving the safety performance of the whole vehicle. The Chinese patent application with publication number CN111791711A discloses an energy recovery control method, device, controller and electric vehicle. The method determines whether the electric vehicle is in a sliding energy recovery mode or a braking energy recovery mode, and if so, obtains the energy recovery torque of the electric vehicle; sends the energy recovery torque to the motor controller of the electric vehicle, so that the motor controller controls the motor of the electric vehicle to charge the battery of the electric vehicle. The above method determines whether to perform energy recovery mode by judging whether the electric vehicle is in a coasting or braking posture, and does not test the impact of the energy recovery strategy on the vehicle's driving safety, battery safety and energy recovery effect. Therefore, the existing technology needs to be further improved. Summary of the invention

[0003] In order to solve the defects of the above-mentioned prior art, the present invention proposes a whole vehicle testing method and testing system for electric vehicles. The whole vehicle testing method and testing system of electric vehicles of the present invention test whether the energy recovery strategy is reasonable, whether the front wheel braking force and the rear wheel braking force are reasonably distributed, whether the impact of battery current and battery temperature on battery safety is considered when the vehicle performs energy recovery, and whether the safety of the driver can be guaranteed according to the driving condition of the vehicle.

[0004] The technical solution of the present invention is achieved in this way:

[0005] A whole vehicle testing method for an electric vehicle comprises the following steps:

[0006] Step 1: Extract a test condition from the preset condition set, and set the test control parameters, operation start time, operation end time, and test step length according to the test condition;

[0007] Step 2: The drive control module drives the motor module according to the test conditions, and the vehicle control module obtains the motor torque and motor speed from the motor module and transmits them to the transmission module;

[0008] Step 3: The transmission module calculates the vehicle speed, vehicle acceleration, and mileage based on the motor torque, motor speed, and test control parameters and transmits them to the vehicle control module;

[0009] Step 4: The vehicle control module obtains the remaining power from the battery module and the braking force from the driving module. If the vehicle acceleration and braking force are both zero, the vehicle speed is less than the speed threshold and the remaining power is less than the power threshold, go to step 6, otherwise go to step 5;

[0010] Step 5: If the braking force is less than the braking force threshold and the remaining power is less than the power threshold, the front wheel braking force is calculated according to the braking force and the braking force distribution function, and the rear wheel braking force is calculated according to the front wheel braking force and the braking force relationship function, and the process goes to step 6; otherwise, the process goes to step 8;

[0011] Step 6: The vehicle control module issues a torque command to the drive control module, and drives the motor module according to the torque command. The vehicle control module obtains the battery current, battery temperature, and remaining power from the battery module, and obtains the generated power from the motor module;

[0012] Step 7: If the battery current is less than the current threshold, the battery temperature is less than the temperature threshold, and the remaining power is less than the power threshold, return to step 6; otherwise, return to step 2;

[0013] Step 8: Get the current time from the time module. If the current time is less than the end time of the operation and the remaining power is greater than zero, return to step 2. Otherwise, generate the mileage curve and the remaining power curve and go to step 9.

[0014] Step 9: derive the end mileage and the end remaining power according to the mileage curve and the remaining power curve, and calculate and output the energy recovery rate according to the difference between the end mileage and the mileage standard value and the difference between the end remaining power and the remaining power standard value;

[0015] Step 10: If the test conditions of the condition set are extracted, determine whether the electric vehicle is qualified based on the energy recovery rates of the multiple test conditions, otherwise return to step 1.

[0016] In the present invention, in step 1, the test control parameters include wheel radius, reduction ratio, transmission efficiency, vehicle mass, remaining power function, rolling resistance, wind resistance, ramp resistance, friction coefficient, braking strength coefficient, battery internal resistance, and total power.

[0017] In the present invention, in step 3, the vehicle speed v = 2πr × n / (60i), the vehicle acceleration a = ω × i × η / (mr), and the mileage , r is the wheel radius, n is the motor speed, i is the reduction ratio, ω is the motor torque, m is the vehicle mass, η is the transmission efficiency, t1 is the start time of operation, t2 is the end time of operation, v t is the vehicle velocity varying with time t.

[0018] In the present invention, in step 4, the battery module obtains the open circuit voltage and battery temperature of the battery, and the vehicle control module substitutes the open circuit voltage U and the battery temperature T into the remaining power function to obtain the remaining power Q. The remaining power function , k is a constant coefficient, M(T)=3.4170e -5 T-2.1274e -3 .

[0019] In the present invention, in step 4, the driving module obtains the pedal opening, the braking force F=δ×η×j×(F1+F2+F3), F1 is the rolling resistance, F2 is the wind resistance, F3 is the slope resistance, δ is the pedal opening, and j is the friction coefficient.

[0020] In the present invention, in step 5, the braking force distribution function , braking force relationship function , F4 is the front wheel braking force, F5 is the rear wheel braking force, z is the braking intensity coefficient, g is the acceleration of gravity, b is the distance from the center of mass of the vehicle to the rear axle, h1 is the distance from the center of mass of the vehicle to the ground, and L is the wheelbase of the vehicle.

[0021] In the present invention, in step 9, the energy recovery rate λ=[(L2-L0) / ε+Q1-Q0] / Q3×100%, L2 is the end mileage, L0 is the mileage standard value, Q1 is the end remaining power, Q0 is the remaining power standard value, ε is the power consumption per kilometer, and Q3 is the total power.

[0022] A test system for implementing the whole vehicle test method of the electric vehicle comprises: a motor module, a drive control module, a transmission module, a battery module, a driving module, a whole vehicle control module, a time module, and a data processing module.

[0023] The motor module is connected to a torque sensor and an encoder, the torque sensor is used to measure the motor torque of the motor shaft, and the encoder is used to measure the motor speed of the motor shaft;

[0024] The drive control module is used to drive the motor module according to the test conditions;

[0025] The transmission module is used to obtain vehicle speed, vehicle acceleration, and mileage;

[0026] The battery module is connected to a voltage sensor and a temperature sensor, the voltage sensor is used to obtain the open circuit voltage of the battery, and the temperature sensor is used to obtain the battery temperature of the battery;

[0027] The driving module is connected to a pedal sensor of the electric vehicle, and the pedal sensor is used to obtain the pedal opening;

[0028] The vehicle control module is used to issue torque instructions to the drive control module;

[0029] The time module is used to obtain the current time;

[0030] The data processing module is used to calculate vehicle speed, vehicle acceleration, mileage, front wheel braking force, rear wheel braking force, remaining power, braking force, and energy recovery rate.

[0031] The whole vehicle testing method and testing system for electric vehicles implemented in the present invention have the following beneficial effects: The present invention measures the energy recovery rate of the vehicle under the energy recovery strategy through experiments, and intuitively displays the effect of the energy recovery strategy. By comparing the energy recovery rates under different test conditions, the test control parameters are adjusted so that the test control parameters are close to the actual application scenario, which is convenient for direct use next time. In the process of energy recovery testing, it is tested whether the front wheel braking force and the rear wheel braking force are reasonably distributed, whether the battery current and battery temperature are considered to the battery safety when the vehicle performs energy recovery, and further whether the energy recovery strategy can ensure the safety of the driver. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a flow chart of the whole vehicle testing method of the electric vehicle of the present invention;

[0033] Figure 2 It is a curve diagram of the remaining power and the open circuit voltage of the present invention;

[0034] Figure 3 is a schematic diagram of physical parameters of the vehicle of the present invention;

[0035] Figure 4 is a schematic diagram of the braking force distribution function of the present invention;

[0036] Figure 5 is a schematic diagram of a mileage curve of the present invention;

[0037] Figure 6 is a schematic diagram of a remaining power curve of the present invention;

[0038] Figure 7 The block diagram of the test system for implementing the whole vehicle test method of electric vehicles according to the present invention. DETAILED DESCRIPTION

[0039] In order to more clearly understand the purpose, technical solutions and advantages of the present application, the present application is described and illustrated below in conjunction with the accompanying drawings and embodiments.

[0040] During the test experiment, the test control parameters were set for different test conditions for multiple experiments to improve the rationality of the test control parameter settings. During the energy recovery test, the main test was whether the energy recovery strategy was reasonable and whether the front wheel braking force and the rear wheel braking force were reasonably distributed. During the energy recovery test, it was further tested whether the impact of battery current and battery temperature on battery safety was considered when the vehicle was recovering energy. The current threshold is generally the rated current of the battery power generation. When the battery current is less than the current threshold, the safety of the battery charging is guaranteed. The temperature threshold is generally the short-circuit temperature of the circuit wire. When the battery temperature is less than the temperature threshold, the safety of the circuit during charging is guaranteed. Embodiment 1

[0041] like Figures 1 to 6 As shown, the whole vehicle testing method and testing system of the electric vehicle of the present invention include the following steps.

[0042] Step 1: Extract a test condition from the preset condition set, and set the test control parameters, operation start time, operation end time, and test step length according to the test condition. The vehicle control module is connected to the motor module, drive control module, transmission module, battery module, driving module, and time module respectively, and the drive control module is connected to the motor module. Different test conditions correspond to different test control parameters, and the corresponding operation start time and operation end time are different. Typical test conditions include the new European automobile regulation cycle condition and the US urban test cycle condition. The test control parameters include wheel radius, reduction ratio, transmission efficiency, vehicle mass, remaining power function, rolling resistance, wind resistance, ramp resistance, friction coefficient, braking strength coefficient, battery internal resistance, and total power.

[0043] Step 2: The drive control module drives the motor module according to the test conditions, and the vehicle control module obtains the motor torque and motor speed from the motor module and transmits them to the transmission module. The motor module is connected to the torque sensor and encoder. The torque sensor is used to measure the motor torque of the motor shaft, and the encoder is used to measure the motor speed of the motor shaft. The motor shaft is part of the motor, and real-time data is obtained by connecting to the motor through the torque sensor and encoder.

[0044] Step 3: The transmission module calculates the vehicle speed, vehicle acceleration, and mileage based on the motor torque, motor speed, and test control parameters and transmits them to the vehicle control module. Vehicle speed v = 2πr × n / (60i), vehicle acceleration a = ω × i × η / (mr), mileage , r is the wheel radius, n is the motor speed, i is the reduction ratio, ω is the motor torque, m is the vehicle mass, η is the transmission efficiency, t1 is the start time of operation, t2 is the end time of operation, v t is the vehicle velocity varying with time t.

[0045] Step 4: The vehicle control module obtains the remaining power from the battery module and the braking force from the driving module. If the vehicle acceleration and braking force are both zero, the vehicle speed is less than the speed threshold, and the remaining power is less than the power threshold, go to step 6, otherwise go to step 5. The battery module is connected to the voltage sensor to obtain the open circuit voltage of the battery, and is connected to the temperature sensor to obtain the battery temperature of the battery. The remaining power is related to the open circuit voltage and the battery temperature. Figure 2 The figure is a curve diagram of the remaining power and open circuit voltage at a battery temperature of 30°C. The horizontal axis is the open circuit voltage in V, and the vertical axis is the remaining power, which is a dimensionless proportional value between 0 and 1. It expresses the proportion of the current power to the full power state, not a specific physical quantity. The open circuit voltage is divided into four sections [0, 2.65], [2.65, 3.2], [3.2, 3.35], [3.35, 3.42] for curve fitting to obtain the remaining power function at a battery temperature of 30°C. The vehicle control module substitutes the open circuit voltage U and the battery temperature T into the remaining power function to obtain the remaining power Q. Because the remaining power function is a fitting function, the open circuit voltage U and the battery temperature T are only substituted with numerical values, not units, and the remaining power function , k is a constant coefficient, M(T)=3.4170e -5 T-2.1274e -3 The driving module is connected to the pedal sensor of the electric vehicle to obtain the pedal opening, and the braking force F=δ×η×j×(F1+F2+F3), where F1 is the rolling resistance, F2 is the wind resistance, F3 is the slope resistance, δ is the pedal opening, and j is the friction coefficient. If the vehicle acceleration and braking force are both zero, the vehicle enters the gliding state. At this time, part of the kinetic energy can be converted into electrical energy and stored in the battery through the battery module. The vehicle speed is less than the speed threshold to ensure the safety of the vehicle. There is no need to apply additional braking force to decelerate, and the remaining power is less than the power threshold to meet the battery charging requirements.

[0046] Step 5: If the braking force is less than the braking force threshold and the remaining power is less than the power threshold, the front wheel braking force is calculated according to the braking force and the braking force distribution function, and the rear wheel braking force is calculated according to the front wheel braking force and the braking force relationship function, and then the process goes to step 6; otherwise, the process goes to step 8. Figure 3 As shown in , the front wheel braking force and the rear wheel braking force are calculated based on the physical parameters of the vehicle. Figure 4 As shown, the horizontal axis is the front wheel braking force, and the vertical axis is the rear wheel braking force, both in N, and the curve is fitted piecewise. Braking force distribution function , braking force relationship function , F4 is the front wheel braking force, F5 is the rear wheel braking force, z is the braking intensity coefficient, g is the acceleration of gravity, b is the distance from the center of mass of the vehicle to the rear axle, h1 is the distance from the center of mass of the vehicle to the ground, and L is the wheelbase of the vehicle. When the braking force is greater than the braking force threshold, the vehicle brakes suddenly, and energy recovery cannot be performed while ensuring the safe driving of the vehicle. The front wheel braking force is mainly electric braking force, which will convert part of the vehicle's kinetic energy into electrical energy. The rear wheel braking force is mainly mechanical braking force, which relies on frictional heat generation to convert part of the vehicle's kinetic energy into thermal energy. When the braking force is not zero, redistributing the front wheel braking force and the rear wheel braking force according to the size of the braking force can further increase energy recovery.

[0047] Step 6: The vehicle control module issues a torque command to the drive control module, and drives the motor module according to the torque command. The vehicle control module obtains the battery current, battery temperature, and remaining power from the battery module, and obtains the power generation from the motor module. The torque command is used to specify the output torque that the motor module should generate. The vehicle control module issues a torque command to the drive control module, and the drive control module controls the motor module to enter the power generation state. At this time, the vehicle speed is reduced, and part of the kinetic energy is converted into electrical energy and stored in the battery through the battery module. Battery current I=U / R, power generation P=U 2 / R, R is the internal resistance of the battery.

[0048] Step 7: If the battery current is less than the current threshold, the battery temperature is less than the temperature threshold, and the remaining power is less than the power threshold, return to step 6, otherwise return to step 2. The current threshold is generally the rated current of the battery power generation. When the battery current is less than the current threshold, the safety of the battery charging is guaranteed. The temperature threshold is generally the short-circuit temperature of the circuit wire of 250°C. When the battery temperature is less than the temperature threshold, the safety of the circuit during charging is guaranteed. When the conditions for energy recovery are not met, return to step 2 and continue to let the drive control module control the motor module according to the test conditions.

[0049] Step 8: Get the current time from the time module. If the current time is less than the end time of the operation and the remaining power is greater than zero, return to step 2. Otherwise, generate the mileage curve and the remaining power curve and go to step 9. If the current time is less than the end time of the operation and the remaining power is greater than zero, the test is not over, exit the energy recovery process, and return to step 2.

[0050] Step 9: Determine the end mileage and the end remaining power according to the mileage curve and the remaining power curve, and calculate and output the energy recovery rate according to the difference between the end mileage and the standard mileage value and the difference between the end remaining power and the standard remaining power value. Figure 5 This is the mileage curve under the ECE working cycle. The horizontal axis is time and the vertical axis is mileage. It can be seen from the figure that the end mileage is 175km. Figure 6The remaining power at the end of the ECE operating cycle, the horizontal axis is time, and the vertical axis is the remaining power. It can be seen from the figure that the remaining power at the end is 0.22. Under the ECE operating cycle, the mileage standard value and the remaining power standard value can generally be obtained by specific experimental measurements. The general mileage standard value is 110km, and the remaining power standard value is 0.2. Energy recovery rate λ=[(L2-L0) / ε+Q1-Q0] / Q3×100%, L2 is the end mileage, L0 is the mileage standard value, Q1 is the end remaining power, Q0 is the remaining power standard value, ε is the power consumption per kilometer, and Q3 is the total power.

[0051] Step 10: If the test conditions of the condition set are extracted, determine whether the electric vehicle is qualified based on the energy recovery rates of multiple test conditions, otherwise return to step 1. The more test conditions in the condition set, the more reasonable the test experiment. The correctness of the test experiment is verified by comparing the energy recovery rates under different test conditions, and the test control parameters are adjusted to make the test control parameters close to the actual application scenario. There are many methods for determining whether an electric vehicle is qualified based on the energy recovery rates of multiple test conditions. In this embodiment, whether the electric vehicle is qualified is determined based on whether the energy recovery rate of the smallest test condition is greater than a threshold. Embodiment 2

[0052] like Figure 7 As shown, the present invention implements the test system of the whole vehicle test method of the electric vehicle, including: a motor module, a drive control module, a transmission module, a battery module, a driving module, a whole vehicle control module, a time module, and a data processing module. The motor module is connected to a torque sensor and an encoder, the torque sensor is used to measure the motor torque of the motor shaft, and the encoder is used to measure the motor speed of the motor shaft. The drive control module is used to drive the motor module according to the test conditions. The transmission module is used to obtain the vehicle body speed, the vehicle body acceleration, and the mileage. The battery module is connected to a voltage sensor and a temperature sensor, the voltage sensor is used to obtain the open circuit voltage of the battery, and the temperature sensor is used to obtain the battery temperature of the battery. The driving module is connected to the pedal sensor of the electric vehicle, and the pedal sensor is used to obtain the pedal opening. The whole vehicle control module is used to issue a torque instruction to the drive control module. The time module is used to obtain the current time. The data processing module is used to calculate the vehicle body speed, vehicle body acceleration, mileage, front wheel braking force, rear wheel braking force, remaining power, braking force, and energy recovery rate.

[0053] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A whole vehicle testing method for an electric vehicle, characterized in that: The following steps are involved: Step 1: Extract a test condition from the preset condition set, and set the test control parameters, operation start time, operation end time, and test step length according to the test condition; Step 2: The drive control module drives the motor module according to the test conditions, and the vehicle control module obtains the motor torque and motor speed from the motor module and transmits them to the transmission module; Step 3: The transmission module calculates the vehicle speed, vehicle acceleration, and mileage based on the motor torque, motor speed, and test control parameters and transmits them to the vehicle control module; Step 4: The vehicle control module obtains the remaining power from the battery module and the braking force from the driving module. If the vehicle acceleration and braking force are both zero, the vehicle speed is less than the speed threshold and the remaining power is less than the power threshold, go to step 6, otherwise go to step 5; Step 5: If the braking force is less than the braking force threshold and the remaining power is less than the power threshold, the front wheel braking force is calculated according to the braking force and the braking force distribution function, and the rear wheel braking force is calculated according to the front wheel braking force and the braking force relationship function, and the process goes to step 6; otherwise, the process goes to step 8; Step 6: The vehicle control module issues a torque command to the drive control module, and drives the motor module according to the torque command. The vehicle control module obtains the battery current, battery temperature, and remaining power from the battery module, and obtains the generated power from the motor module; Step 7: If the battery current is less than the current threshold, the battery temperature is less than the temperature threshold, and the remaining power is less than the power threshold, return to step 6; otherwise, return to step 2; Step 8: Get the current time from the time module. If the current time is less than the end time of the operation and the remaining power is greater than zero, return to step 2. Otherwise, generate the mileage curve and the remaining power curve and go to step 9. Step 9: derive the end mileage and the end remaining power according to the mileage curve and the remaining power curve, and calculate and output the energy recovery rate according to the difference between the end mileage and the mileage standard value and the difference between the end remaining power and the remaining power standard value; Step 10: If the test conditions of the condition set are extracted, determine whether the electric vehicle is qualified based on the energy recovery rates of the multiple test conditions, otherwise return to step 1.

2. The whole vehicle testing method of an electric vehicle according to claim 1, characterized in that: In step 1, the test control parameters include wheel radius, reduction ratio, transmission efficiency, vehicle mass, remaining power function, rolling resistance, wind resistance, ramp resistance, friction coefficient, braking strength coefficient, battery internal resistance, and total power.

3. The whole vehicle testing method of an electric vehicle according to claim 1, characterized in that: In step 3, the vehicle speed v = 2πr × n / (60i), the vehicle acceleration a = ω × i × η / (mr), and the mileage , r is the wheel radius, n is the motor speed, i is the reduction ratio, ω is the motor torque, m is the vehicle mass, η is the transmission efficiency, t1 is the start time of operation, t2 is the end time of operation, v t is the vehicle velocity varying with time t.

4. The whole vehicle testing method of an electric vehicle according to claim 1, characterized in that: In step 4, the battery module obtains the open circuit voltage and battery temperature of the battery, and the vehicle control module substitutes the open circuit voltage U and battery temperature T into the remaining power function to obtain the remaining power Q. The remaining power function , k is a constant coefficient, M(T)=3.4170e -5 T-2.1274e -3 .

5. The whole vehicle testing method of an electric vehicle according to claim 3, characterized in that: In step 4, the driving module obtains the pedal opening, the braking force F=δ×η×j×(F1+F2+F3), F1 is the rolling resistance, F2 is the wind resistance, F3 is the slope resistance, δ is the pedal opening, and j is the friction coefficient.

6. The whole vehicle testing method of an electric vehicle according to claim 5, characterized in that: In step 5, the braking force distribution function , braking force relationship function , F4 is the front wheel braking force, F5 is the rear wheel braking force, z is the braking intensity coefficient, g is the acceleration of gravity, b is the distance from the center of mass of the vehicle to the rear axle, h1 is the distance from the center of mass of the vehicle to the ground, and L is the wheelbase of the vehicle.

7. The whole vehicle testing method of an electric vehicle according to claim 1, characterized in that: In step 9, the energy recovery rate λ=[(L2-L0) / ε+Q1-Q0] / Q3×100%, L2 is the end mileage, L0 is the mileage standard value, Q1 is the end remaining power, Q0 is the remaining power standard value, ε is the power consumption per kilometer, and Q3 is the total power.

8. A test system for implementing the whole vehicle test method of electric vehicle according to claim 1, characterized in that: include: Motor module, drive control module, transmission module, battery module, driving module, vehicle control module, time module, data processing module, The motor module is connected to a torque sensor and an encoder, the torque sensor is used to measure the motor torque of the motor shaft, and the encoder is used to measure the motor speed of the motor shaft; The drive control module is used to drive the motor module according to the test conditions; The transmission module is used to obtain vehicle speed, vehicle acceleration, and mileage; The battery module is connected to a voltage sensor and a temperature sensor, the voltage sensor is used to obtain the open circuit voltage of the battery, and the temperature sensor is used to obtain the battery temperature of the battery; The driving module is connected to a pedal sensor of the electric vehicle, and the pedal sensor is used to obtain the pedal opening; The vehicle control module is used to issue torque instructions to the drive control module; The time module is used to obtain the current time; The data processing module is used to calculate the front wheel braking force, rear wheel braking force, remaining power, braking force, and energy recovery rate.

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