A hill control method for an electric vehicle
By employing a multi-loop control method, combining speed loop, acceleration control loop, and position control loop, the problems of slippage and jerking when the golf cart is parked and started on a slope are solved, enabling the vehicle to descend evenly and start smoothly on the slope, thus improving safety and comfort.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- XIAMEN DALE NEW ENERGY VEHICLE CO LTD
- Filing Date
- 2023-11-13
- Publication Date
- 2026-07-03
AI Technical Summary
Golf carts suffer from problems such as long rolling distances, uneven deceleration, and jerking during ramp stops and starts. Traditional control methods cannot meet the requirements for safety and comfort.
A multi-loop control method is adopted, combining a speed loop, an acceleration control loop, and a position control loop. By switching control loops under different slope conditions, including speed loop + acceleration control loop, speed feedforward + position control loop, and speed loop + position loop, the vehicle can achieve uniform descent, overshoot-free parking, and slip-out-free start.
It improves the safety and comfort of golf cart operation on ramps, solves the problems of long roll distances, uneven deceleration, and jerking, and ensures the stability and smoothness of the vehicle on ramps.
Smart Images
Figure CN117584765B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of engineering control technology, specifically a slope control method for electric vehicles. Background Technology
[0002] Golf carts are currently widely used in resorts, villa areas, garden hotels, and tourist attractions, where safety and comfort are paramount. Hill-climbing is a crucial aspect of the vehicle's operation. Current golf carts commonly suffer from long roll distances when parking and starting on slopes, creating a sense of danger for the driver. They also exhibit uneven deceleration and jerking during these transitions. Traditional control methods are no longer adequate, necessitating the search for better hill-climbing control solutions. Summary of the Invention
[0003] The purpose of this invention is to provide a slope control method for electric vehicles to solve the problems mentioned in the background art.
[0004] To achieve the above objectives, the present invention provides the following technical solution: a slope control method for an electric vehicle, wherein the method is used to switch the vehicle's control loop between three states: slope descent, slope parking, or slope start.
[0005] 1) When the vehicle is descending a slope, if the accelerator input is 0, the control loop is a speed loop + acceleration control loop, and the torque command T1 = K. P1 *Δn+T i K P1 T is the speed loop proportional coefficient, Δn is the error between the given speed and the actual speed; i T is the current integral output value of the speed loop. i =K i1 *Δn+T i-1 *(1-a), K i1 T is the integral coefficient of the speed ring. i-1 is the integral output value of the previous cycle; 'a' is the absolute value of the acceleration loop output. K P2 K is the proportionality coefficient of the acceleration loop. i2 To accelerate the integral coefficient of the ring, ΔA n Let ΔA be the error between the given acceleration and the actual acceleration. j Let j be the error between the given acceleration and the actual acceleration;
[0006] 2) When the vehicle is parked on a slope, if the vehicle speed reverses, the control loop switches to the speed feedforward + position control loop, and the torque command... K P3 K is the velocity feedforward gain coefficient.P4 For the position loop integral coefficient, ΔP i The position change value is recorded after the vehicle stops, along with the current parking torque T. r =T1, start the electric brake of the motor and stop the motor output, that is, T1=0;
[0007] 3) When the vehicle is starting on a slope, the accelerator input is greater than 0. If the vehicle is in a parking position after power-on, the motor output is restored first, i.e., T... i-1 =T r Then turn off the motor electric brake, the control loop becomes a speed loop, and the torque command T1 = K. P1 *Δn+T i T i =K i1 *Δn+T i-1 If the vehicle is in a power-off parking position, the electric motor brakes are turned off, and the control loop consists of a speed loop and a position loop, with torque commands...
[0008] Furthermore, the setpoint of the acceleration control loop is determined by the current rotational speed and the current speed, and has amplitude limitations.
[0009] Furthermore, the feedback value of the acceleration control loop is the speed change value within 25ms.
[0010] Furthermore, the output limit value of the acceleration control loop is determined by the output values of the vehicle's direction of travel and the speed loop.
[0011] Furthermore, the position control loop for ramp parking is a pure integral control.
[0012] Furthermore, the setpoint for the ramp parking position control loop is 0.
[0013] Furthermore, the power-on and power-off parking conditions are determined by the vehicle's speed and direction at the moment of starting on a slope.
[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention combines a speed control loop, an acceleration control loop, and a position control loop. Through multi-loop control and switching logic, when the vehicle is descending on a slope, it achieves a uniform descent; when the vehicle is parked on a slope, it achieves a parking without overshoot; and when starting on a slope, it achieves a start without rollback or a short rollback start. This overcomes the problems of long rollback distances during parking and starting on slopes, uneven speed reduction on slopes, and vehicle jerking during switching in the prior art, greatly improving the safety and comfort of golf cart operation on slopes. Attached Figure Description
[0015] Figure 1 This is a flowchart illustrating the output setpoint of the acceleration control loop in the slope control method for electric vehicles of the present invention. Detailed Implementation
[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0017] This embodiment provides a slope control method for an electric vehicle. The method switches the vehicle's control loop between three states: slope descent, slope parking, and slope start. For example:
[0018] When the vehicle is descending a slope, if the accelerator input is 0, the control loop is a speed loop + acceleration control loop, and the torque command T1 = K. P1 *Δn+T i K P1 T is the speed loop proportional coefficient, Δn is the error between the given speed and the actual speed; i T is the current integral output value of the speed loop. i =K i1 *Δn+T i-1 *(1-a), K i1 T is the integral coefficient of the speed ring. i-1 is the integral output value of the previous cycle; 'a' is the absolute value of the acceleration loop output. K P2 K is the proportionality coefficient of the acceleration loop. i2 To accelerate the integral coefficient of the ring, ΔA n Let ΔA be the error between the given acceleration and the actual acceleration. j Let A be the error between the given acceleration and the actual acceleration at time j. ref =n ref -n now Its upper limit is set to 2 rpm / ms, n ref Given the velocity, n now The actual rotational speed is used as the reference value. The acceleration control loop further adjusts the torque output based on the error between the desired and actual acceleration to achieve a uniform vehicle deceleration, thus controlling the vehicle to descend the slope at a constant speed. The setpoint of the acceleration control loop is determined by the current rotational speed and the current speed, and has amplitude limitations. The feedback value of the acceleration control loop is the rotational speed change within 25ms. Figure 1As shown, the system checks if the accelerator input is zero. If the input is zero, it checks the vehicle's gear. If the vehicle is in forward gear, it checks if the speed is greater than 50. If the speed is greater than 50, it checks if the speed loop output is greater than zero. If it is greater than zero, the upper limit of the acceleration loop output is 0.025, and the lower limit is -0.25. If the speed loop output is equal to or less than zero, the upper limit of the acceleration loop output is 0.25, and the lower limit is 0. If the speed is not greater than 50, both the upper and lower limits of the acceleration loop output are 0. When the vehicle is in reverse gear, if the speed is less than -50, it checks if the speed loop output is less than zero. If the speed loop output is less than zero, the acceleration... The upper limit of the speed loop output is 0.25, and the lower limit is 0.025. When the speed loop output is not less than zero, the upper limit of the acceleration loop output is 0, and the lower limit is -0.25. When the accelerator input is not zero, both the upper and lower limits of the acceleration loop output are 0. Thus, the torque command is calculated based on the outputs of the speed and acceleration loops. The speed loop adjusts the vehicle's torque output based on the difference between the desired and actual speeds to maintain the desired speed. For example, consider an electric golf cart in a ramp descent mode with zero accelerator input. The control loop consists of a speed loop and an acceleration control loop, where: the speed loop proportional coefficient is K. P1 =0.5, integral coefficient of speed ring: K i1 =0.02, Acceleration loop proportionality coefficient: K p2 =0.1, acceleration loop integral coefficient: K i2 =0.01,
[0019] Assuming a given rotational speed n ref =50rpm, actual speed n now =55 rpm, given acceleration A ref =(n ref -n now ) / 25 = -0.2 rpm / ms, assuming the current acceleration value is A fbk = -0.5 rpm / m, assuming the integral output value T of the previous cycle i-1 = -10Nm,
[0020] First, calculate the output 'a' of the acceleration loop. now ,
[0021]
[0022] Assumption Substitute into the calculation:
[0023] a now =|0.1*(-0.2-(-0.5))+0.01*(-0.2-(-0.5))+0|=0.033;
[0024] Then calculate the integral output value T of the velocity loop. i ,
[0025] T i =K i1 *Δn+T i-1 *(1-a)=0.02*(-5)-10*(1-(0.033))=-0.1-9.67=-9.57Nm
[0026] Next, the torque command T1 is calculated based on the speed error:
[0027] T1 = K P1 *Δn+T i =0.5*(-5)-9.57=-9.82Nm
[0028] Therefore, the torque command in the ramp descent state is -9.82Nm. Since the vehicle is moving downhill, the combined force of frictional resistance and gravity is needed to counteract the vehicle's inertia. The motor will generate a reverse torque accordingly to counteract the vehicle's inertia and achieve ramp descent control.
[0029] When the vehicle is parked on a slope, if the vehicle speed reverses, the control loop switches to the speed feedforward + position control loop, and the torque command... K P3 K is the velocity feedforward gain coefficient. P4 For the position loop integral coefficient, ΔP i The position change value is recorded after the vehicle stops, along with the current parking torque T. r =T1, start the electric brake of the motor and stop the motor output, that is, T1=0. In this case, the torque command is calculated based on the current speed and position loop output. The speed feedforward adjusts the torque output based on the current speed value, and the position control loop further adjusts the torque output based on the difference between the desired position change and the actual position change, achieving overshoot-free parking and keeping the vehicle in the designated position. The position control loop for hill parking is pure integral control, and the setpoint for the position control loop for hill parking is 0. For example, if an electric golf cart reverses direction on a slope, the control loop switches to speed feedforward and position control loop, where: the speed feedforward gain coefficient K... P3 =0.2, position loop integral coefficient K P4 =0.01. Meanwhile, assuming the vehicle is parked on a slope with a rotational speed of n = 0 rpm, first, calculate the position change ΔP. i If the vehicle starts rolling downhill and rolls a distance of 1 meter, then ΔP i =1000mm,
[0030] Next, calculate the torque command T1 according to the formula:
[0031]
[0032] Therefore, the torque command is 10 Nm. Since the vehicle's control system is based on speed, and the current vehicle speed is 0, the speed feedforward output is 0. During the parking process, the position loop plays a crucial role, generating appropriate torque from the motor to keep the vehicle in the correct position. The position loop output is the torque command for the vehicle in the parking state. Due to the vehicle's gravity, this torque command is used to counteract the vehicle's weight and keep it stationary. When the vehicle comes to a complete stop, the electric brake activates, the motor stalls, and the current torque command T is recorded. r The torque command is cleared to 0.
[0033] When the vehicle starts on an incline, the accelerator input is greater than 0. If the vehicle is in a parking position after power-on, the motor output is restored first, i.e., T... i-1 =T r Then turn off the motor electric brake, the control loop becomes a speed loop, and the torque command T1 = K. P1 *Δn+T i T i =K i1 *Δn+T i-1 Based on the motor's speed, the output torque of the motor is quickly adjusted to ensure a smooth start for the vehicle, eliminating any jerking or hesitation during startup and achieving a roll-back-free start. This improves starting comfort and safety. If the vehicle is in a power-off parking position, the electric brake of the motor is deactivated. The control loop consists of a speed loop and a position loop, with torque commands... This method enables short-distance coasting starts, ensuring the vehicle maintains a stable position while the motor outputs torque. This ensures the motor's torque balances the force generated by gravity as the vehicle rolls down the slope. This prevents long-distance sliding during startup, improving parking stability and safety. Power-on and power-off parking conditions are determined by the vehicle's speed and direction at the moment of hill start. For example, in power-off parking (i.e., the vehicle is already stopped on the slope, the motor is off, and the entire vehicle is powered down), if the vehicle is powered on and the accelerator input is greater than 0, and the vehicle begins to roll backward, the control loop switches to a loop consisting of a speed loop and a position loop. Assuming a given speed n... ref =100rpm, actual vehicle speed n now = -10rpm, the integral output value T of the previous cycle i-1 = 5 Nm, position change ΔP i =100mm, proportional coefficient K of the speed ring P1 =0.1, integral coefficient K i1 =0.02, the integral coefficient K of the position loop P4 =0.1,
[0034] First, calculate the speed portion of the torque command based on the error between the given speed and the actual speed:
[0035] Δn=n ref -n now =110rpm
[0036] T1speed = K P1 *Δn+T i =0.1*110+0.02*110+5=18.2Nm;
[0037] Next, the position portion of the torque command is calculated based on the position loop:
[0038]
[0039] Finally, the torque commands from the speed loop and position loop are summed to obtain the total torque command:
[0040] T1=T1speed+T1pos=18.2+10=28.2Nm.
[0041] Therefore, when starting on a slope, the vehicle will roll backward because the force of gravity on the slope is greater than the power of the motor when it starts. At this time, the torque command is 28.2 Nm, in which the position loop plays a key role in preventing the vehicle from rolling backward by generating appropriate torque from the motor.
[0042] This invention combines a speed control loop, an acceleration control loop, and a position control loop. Through multi-loop control and switching logic, it achieves uniform descent when the vehicle is descending a slope, overshoot-free parking when the vehicle is parked on a slope, and no-rollback or short-distance rollback start when starting on a slope. This overcomes the problems of long rollback distances during slope parking and starting, uneven speed reduction on slopes, and vehicle jerking during switching in the prior art, greatly improving the safety and comfort of golf cart operation on slopes.
[0043] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A hill control method for an electric vehicle, characterized by, The method is used to switch the vehicle's control loop between three states: ramp descent, ramp parking, or ramp start. 1) When the vehicle is descending a slope, if the accelerator input is 0, the control loop is a speed loop + acceleration control loop, and the torque command T1 = K. P1 *Δn+T i K P1 T is the speed loop proportional coefficient, Δn is the error between the given speed and the actual speed; i T is the current integral output value of the speed loop. i =K i *Δn+T i-1 *(1-a), K i T is the integral coefficient of the speed ring. i-1 This is the integral output value of the previous cycle; 'a' is the absolute value of the acceleration loop output. K P2 K is the proportionality coefficient of the acceleration loop. i2 To accelerate the integral coefficient of the ring, ΔA n Let ΔA be the error between the given acceleration and the actual acceleration. j Let j be the error between the given acceleration and the actual acceleration; 2) When the vehicle is on a slope, if the vehicle speed is reversed, the control loop switches to speed feedforward + position control loop, torque instruction K P3 K P4 K i K r K 3) When the vehicle is starting on a slope, the accelerator input is greater than 0. If the vehicle is in a parking position after power-on, the motor output is restored first, i.e., T... i-1 =T r Then turn off the motor electric brake, the control loop becomes a speed loop, and the torque command T1 = K. P1 *Δn+T i T i =K i1 *Δn+T i-1 If the vehicle is in a power-off parking position, the electric motor brakes are turned off, and the control loop consists of a speed loop and a position loop, with torque commands... T i =K i1 *Δn+T i-1 .
2. The hill control method of the electric vehicle according to claim 1, characterized by: The setpoint of the acceleration control loop is determined by the current rotational speed and the current speed, and has amplitude limitations.
3. The hill control method of the electric vehicle according to claim 2, characterized by: The feedback value of the acceleration control loop is the speed change value within 25ms.
4. The hill control method of the electric vehicle according to claim 2, characterized by: The output limit value of the acceleration control loop is determined by the output values of the vehicle's direction of travel and the speed loop.
5. The hill control method of the electric vehicle according to claim 1, characterized by: The position control loop for parking on the ramp is a pure integral control.
6. The hill control method of the electric vehicle according to claim 1, characterized by: The setpoint for the ramp parking position control loop is 0.
7. The hill control method of the electric vehicle according to claim 1, characterized by: The power-on and power-off parking conditions are determined by the vehicle's speed and direction at the moment of starting on a slope.