Temperature Compensation Control Strategy of Assist Mode for Hydraulic Hub-Motor Drive Vehicle

Based on the traditional heavy commercial vehicle, hydraulic hub-motor drive vehicle (HHMDV) is equipped with a hydraulic hub-motor auxiliary drive system, which makes the vehicle change from the rear-wheel drive to the four-wheel drive to improve the traction performance on low-adhesion road. In the typical operating mode of the vehicle, the leakage of the hydraulic system increases because of the oil temperature rising, this makes the control precision of the hydraulic system drop. Therefore, a temperature compensation control strategy for the assist mode is proposed in this paper. According to the principle of flow continuity, considering the loss of the system and the expected wheel speed, the control strategy of multifactor target pump displacement based on temperature compensation is derived. The control strategy is verified by the co-simulation platform of MATLAB/Simulink and AMESim. The simulation results show that the temperature compensation control strategy compensates the flow loss of the hydraulic system, ensures the power output, and meets the requirement of the actual expected wheel speed. At the same time, the maximum grades of the vehicle under temperature compensation control strategy are all improved at different initial temperatures, and the maximum promotion ratio reaches 14.5%. The study in this paper improves the traction performance and promotes the environmental adaptability of HHMDV.