Control method and system for hill start of electric vehicle

Abstract

The invention provides a control method and system for hill start of an electric vehicle. The control method comprises the steps that when in a hill start state, the electric vehicle continues being kept in a brake state within the preset time after it is detected that a brake pedal is loosened and a handbrake is relieved; and after the preset time, if it is detected that an accelerating pedal isstepped and the driver driving torque output by wheel-side motors of the electric vehicle is larger than the first driving torque, the pressure value of a main cylinder of an electric mechanical brakebooster for keeping the brake state of the electric vehicle is reduced gradually within the preset pressure-reduction step length so as to enable the electric vehicle to achieve hill start. By controlling hydraulic brake force and the driving torque of the motors cooperatively, the situation that the electric vehicle slips backwards at the time of hill start can be avoided, the advantage of higher response speed is achieved, and accordingly, the driver is assisted in achieving stable hill start of the electric vehicle easily.

Description

technical field [0001] The invention relates to the technical field of electric vehicles, in particular to a control method and a control system for starting an electric vehicle on a slope. Background technique [0002] When the driver drives the vehicle on a steep road or in rainy and snowy weather, the driver usually pulls up the handbrake to keep the vehicle stationary, releases the brake pedal and then quickly depresses the accelerator pedal before starting uphill. Release the handbrake while the vehicle is moving away. However, due to comfort considerations, electric vehicles have a limit on the rate of change of torque when the accelerator pedal is stepped on, and electric vehicles generally adopt a braking priority strategy. When the brake pedal returns (or the brake master cylinder has no pressure) and the handbrake is released, Only then will the torque control command be executed. The pure electric minibus or logistics vehicle has a heavier body and a larger load...

AI Technical Summary

Problems solved by technology

Therefore, it will cause the vehicle to slide backwards during the time between releasing the brake pedal and stepping on the accelerator pedal when starting uphill.

If the hill start assistance is realized through the stall function of the motor, the motor controller may be burned due to high power discharge during normal driving uphill

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