A method for preventing runaway motors in electric vehicles

Abstract

This invention relates to a method for preventing rollback of an electric vehicle motor. By determining whether the anti-rollback function is activated, and upon activation, the method determines whether the current gear is D (Drive) or R (Reverse) and controls accordingly. If in D, it checks if the anti-rollback speed is less than a set negative speed; if so, a PI controller adjusts the speed to 0. If in R, it checks if the anti-rollback speed is greater than a set positive speed; if so, a PI controller adjusts the speed to 0. This solution does not trigger anti-rollback control during normal gear shifts; it only triggers when in R and the speed is greater than the set positive speed. This solves the problem of false triggering during rapid gear changes in parking maneuvers, i.e., when the vehicle is not completely stopped before shifting from D to R, or vice versa, causing vehicle jerking and impact.

Description

Technical Field

[0001] This invention belongs to the field of electric vehicle control technology, specifically relating to a method for preventing runaway motors in electric vehicles. Background Technology

[0002] When starting an electric vehicle on a slope, the vehicle's direction of travel may not align with the gear position as the driver releases the brake pedal and presses the accelerator. If the driver doesn't press the accelerator pedal deeply enough while driving on a slope, the vehicle may gradually decrease in speed to zero and then roll backward. To prevent this rolling backward during starts and operation on slopes, anti-rollback functionality has been added to the vehicle and motor control strategies.

[0003] The anti-rollback function ensures that when the vehicle starts, the reverse roll distance is less than a certain value. If the power is insufficient during the operation on a slope, the vehicle speed will gradually decrease to 0 and then maintain 0 speed, preventing reverse roll.

[0004] The existing anti-rollback function detects whether the anti-rollback conditions are met while the vehicle is in motion, judging by 1) the system gear position, 2) the braking status, and 3) the current motor speed. Based on these three conditions, it determines whether to enter the anti-rollback mode. Figure 1 As shown.

[0005] Triggering condition 1: The system is in D gear, the speed is ≤ a certain negative speed, the brake is ineffective, the motor anti-slip slope is triggered, the PI adjusts the motor torque to make the speed 0 rpm.

[0006] Triggering condition 2: The system is in reverse gear (R), the speed is greater than or equal to a certain positive speed, the brake is ineffective, the motor anti-slip mechanism is triggered, and the PI controller adjusts the motor torque to make the speed 0 rpm.

[0007] VCU generally allows low-speed gear shifting, that is, when the speed is below 300rpm, it allows shifting from D gear to R gear, and also allows shifting from R gear to D gear. The above anti-rollback strategy may cause false triggering during rapid gear shifting and parking (that is, when the car has not come to a complete stop and shifts from D gear to R gear, or from R gear to D gear), resulting in vehicle jerking.

[0008] For example, assuming the vehicle is currently in Drive (D) mode and the engine speed is 240 rpm, if you apply the brakes and shift to Reverse (R) mode, but the engine speed remains at 200 rpm, the Reverse anti-rollover mechanism will be triggered. After triggering, the motor will adjust the torque using a PI control to bring the target speed to 0 rpm. If you then apply the accelerator, the sudden change in motor speed will cause the vehicle to jerk and experience jolts, leading to customer complaints. Summary of the Invention

[0009] The purpose of this invention is to provide a method for preventing motor slippage in electric vehicles. Based on the existing VCU shifting strategy, the method optimizes the motor slippage prevention strategy to solve the problems of vehicle jerking and impact mentioned in the background art.

[0010] To achieve the above objectives, this application employs the following technical solution:

[0011] A method for preventing runaway motors in electric vehicles includes the following steps:

[0012] S1. Determine whether the motor anti-slip function is activated. If yes, proceed to step S2.

[0013] S2. Determine the current system gear. If the current system gear is D, proceed to step S3. If the current system gear is R, proceed to step S4.

[0014] S3. Determine if the D gear anti-slip slope meets the requirement that the entry speed is ≤ set negative speed. If so, determine if the brake is ineffective. If so, adjust the PI to make the speed 0.

[0015] S4. Determine if the R gear hill-climbing speed meets the requirement of entering the positive speed ≥ the set positive speed. If so, determine if the brake is ineffective. If so, adjust the PI to make the speed 0.

[0016] After S5, S3 or S4 are completed, determine whether the conditions for stopping or exiting the anti-slip slope are met. If so, the anti-slip slope control ends.

[0017] Furthermore, if the judgment in step S3 or step S4 is negative, then return to step S1.

[0018] Furthermore, in step S3, after the system gear is switched from D to R, if the speed in D gear is greater than or equal to the speed limit for triggering the anti-rollover mechanism in R gear, the anti-rollover gear will remain in D gear until the speed meets the condition, at which point the anti-rollover gear will be switched to R gear.

[0019] Furthermore, in step S4, after the system gear R is switched to the system gear D, if the R gear speed is less than or equal to the D gear anti-rollover trigger speed limit, the anti-rollover gear will remain in R until the speed meets the condition, at which point the anti-rollover gear will be switched to D.

[0020] Furthermore, the anti-rollover control is not triggered when switching between the normal D and R gears. It is only triggered when the gear is in R gear and the speed is greater than the set positive speed.

[0021] Compared with existing technologies, the beneficial effects of this technical solution are:

[0022] This technical solution does not trigger anti-rollover control during normal gear shifting. Anti-rollover control is only triggered when the gear is in reverse (R) and the engine speed is greater than the set positive speed. This solves the problem of false triggering during rapid gear shifting and parking, i.e., when the vehicle is not completely stopped and is shifted from D to R, or from R to D, which can cause vehicle jerking and impact. Attached Figure Description

[0023] Figure 1 This is the current anti-slip slope control logic diagram.

[0024] Figure 2 This is the anti-slippage control logic diagram of the present invention. Detailed Implementation

[0025] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings. The following embodiments are merely exemplary and can only be used to explain and illustrate the technical solution of the present invention, and should not be construed as limiting the technical solution of the present invention.

[0026] When the vehicle is running, the vehicle controller controls the motor's forward and reverse rotation through positive and negative torque. The system gears are primarily used for additional functions such as determining the trigger conditions for the anti-slip function and determining the gear torque.

[0027] To address the issue of accidental triggering of the anti-rollover function during rapid gear shifting, this technical solution involves processing the system gear selection to determine the appropriate anti-rollover function gear.

[0028] The trigger speed condition (limit) for the anti-rollback function in D / R gears is applied to the anti-rollback gear switching logic, which rigorously implements the anti-rollback gear judgment and solves the problem of false triggering.

[0029] like Figure 2 As shown, this application relates to a method for preventing runaway motors in electric vehicles, comprising the following steps:

[0030] S1. Determine whether the motor anti-rollover function is activated. If yes, proceed to step S2. The condition for determining whether the motor anti-rollover function is activated in this technical solution is the rotation speed of the electric vehicle. The motor anti-rollover function is activated when the rotation speed of the electric vehicle reaches the set range.

[0031] S2. Determine the current system gear. If the current system gear is D, proceed to step S3. If the current system gear is R, proceed to step S4.

[0032] S3. Determine if the D gear anti-rollover speed meets the requirement of entering the negative speed. If so, determine if the brake is ineffective. If so, adjust the PI to make the speed 0. Specifically, after the system gear is switched from D to R, if the D gear speed is greater than or equal to the R gear anti-rollover trigger speed limit, the anti-rollover gear will remain in D until the speed meets the condition, at which point the anti-rollover gear will be switched to R.

[0033] S4. Determine if the R gear rollover meets the requirement of entering speed ≥ set positive speed. If so, determine if the brake is ineffective. If so, adjust the PI to make the speed 0. Specifically, after the system gear is switched from R to D, if the R gear speed is ≤ D gear anti-rollover trigger speed limit, the anti-rollover gear will remain in R until the speed meets the condition, and then the anti-rollover gear will be switched to D.

[0034] After S5, S3 or S4 are completed, determine whether the conditions for stopping or exiting the anti-slip slope are met. If so, the anti-slip slope control ends.

[0035] If the judgment in step S3 or step S4 is negative, return to step S1 and re-determine whether the anti-slip slope function has been activated.

[0036] By adding a gear control strategy for the anti-slip function, the anti-slip control is not triggered when switching between the normal D and R gears. It is only triggered when the gear is in R gear and the speed is greater than the set positive speed (the R gear anti-slip trigger speed).

[0037] This technical solution can effectively solve the problem of accidental triggering during rapid gear shifts and effectively avoid the problem of jerking.

[0038] Compared with existing technologies, this technology solves the problem of accidental triggering during rapid gear shifting and parking maneuvers (i.e., shifting from D to R before the vehicle has come to a complete stop, or from R to D), which causes vehicle jerking and impact.

[0039] The above are preferred embodiments of the present invention. The basic principles and advantages of the present invention have been shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are only illustrative of the principles of the present invention. Various changes and modifications can be made to the present invention without departing from the spirit and scope of the present invention. All such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preventing hill hold control of an electric motor for an electric vehicle, characterized by, The method comprises the following steps: S1, judging whether to start the motor anti-slip function, if yes, entering step S2; S2, judging the current system gear, if the current system gear is D gear, entering step S3, if the current system gear is R gear, entering step S4; S3, after the system gear D gear is switched to the system gear R gear, if the R gear speed is greater than the R gear anti-slip triggering speed limit, the anti-slip gear is still maintained as D gear, judging whether the D gear anti-slip meets the entering speed less than the set negative speed, if yes, judging whether the brake is invalid, if yes, PI adjustment is made to make the speed 0, if the R gear speed is less than the R gear anti-slip triggering speed limit, the anti-slip gear is switched to R gear, and R gear anti-slip judgment is performed, judging whether the R gear anti-slip meets the entering speed greater than the set positive speed, if yes, judging whether the brake is invalid, if yes, PI adjustment is made to make the speed 0; S4, after the system gear R gear is switched to the system gear D gear, if the D gear speed is less than the D gear anti-slip triggering speed limit, the anti-slip gear is still maintained as R gear, judging whether the R gear anti-slip meets the entering speed greater than the set positive speed, if yes, judging whether the brake is invalid, if yes, PI adjustment is made to make the speed 0, if the D gear speed is greater than the D gear anti-slip triggering speed limit, the anti-slip gear is switched to D gear, and D gear anti-slip judgment is performed, judging whether the D gear anti-slip meets the entering speed less than the set negative speed, if yes, judging whether the brake is invalid, if yes, PI adjustment is made to make the speed 0; S5, after step S3 or step S4 is ended, judging whether the anti-slip stop or exit condition is met, if yes, the anti-slip control is ended.

2. The motor anti-slip control method for an electric vehicle according to claim 1, characterized by, If the judgment in step S3 or step S4 is no, returning to step S1.

3. The control method of claim 1, wherein In the conventional gear D gear and gear R gear switching, the anti-slip control is not triggered, only when the gear R gear and the speed is greater than the set positive speed, the anti-slip control can be triggered.

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