Hardware-in-the-loop simulation of pressure-difference-limiting modulation of the hydraulic brake for regenerative braking control of electric vehicles

Abstract

Because of its significant impact on the cooperative regenerative braking performance of electrified vehicles, the modulation effect of a hydraulic brake is of great importance. To improve the hydraulic brake control performance further, a novel pressure-difference-limiting control method for hydraulic pressure modulation based on on–off solenoid valves is proposed. The linear relationship between the coil current and the pressure difference across the valve is obtained. The characteristics of pressure-difference-limiting modulation are simulated and analysed. Then, a cooperative regenerative braking control algorithm based on the pressure-difference-limiting modulation of the hydraulic brake is designed. Hardware-in-the-loop tests of the algorithm under typical braking procedures are carried out. The test results demonstrate the validity and feasibility of the developed regenerative braking control algorithm and indicate that the proposed pressure-difference-limiting modulation method, which has an advantage over the conventional control based on a pulse-width-modulated signal with respect to the control accuracy of the hydraulic brake pressure, has great potential to improve the braking performance of a vehicle.