Research on the Estimation Algorithm of Wheel Cylinder Pressure for Regenerative Braking System of Plug-in Hybrid Vehicle

摘要

Nowadays, regenerative braking system (RBS) is widely used in the electric vehicles. When the pressure sensor could not provide the accurate information to the control system, the RBS would be in failure state. So the redundancy estimation algorithm related to wheel cylinder pressure is necessary. In this paper, an estimation algorithm of wheel cylinder pressure based on the pulse signal from wheel speed sensor is proposed, there are two points proposed to achieve the wheel cylinder pressure estimation. One is the estimation of the vehicle speed according to the pulse signal of wheel speed sensor, where the estimation algorithm is improved to solve the problem that vehicle speed estimated by ABS is not that accurate at low speed. The other one is the estimation of the wheel cylinder pressure in the situation that ABS is not triggered, where it is based on the condition of braking force distribution, the equation of kinetics and the deceleration characters of traditional braking system. At last, the estimation algorithm of wheel cylinder pressure has been verified by road tests in sliding process in the target pure electric vehicle. The result shows the vehicle speed estimated is more accurate than before, particularly the stage of low speed, And also the front and rear wheel cylinder pressure estimated is in accordance with the observed value.