Energy recovery of four-wheel hub motor driven vehicle in steering-braking condition

The factors that affect the efficiency of braking energy recovery is a crucial and worthy research problem for the four-wheel hub motor driven (FWHMD) electric vehicle (EV). This paper presents an energy classification statistical method by integrating the direct current (DC) of the power battery and considering the efficiency of the permanent magnet synchronous motor (PMSM). According to the characteristics of DC, the energy recovered and consumed by the motor during regenerative braking is divided into total recovered energy, net recovered energy and dissipated energy. Then, the influence of steering resistance on braking energy recovery of the steering braking is analyzed by using the proposed energy statistical method and combining Carsim and Matlab/Simulink co-simulation. Firstly, a closed-loop coupling model combined with the PMSM and vehicle dynamics is established. Secondly, the braking energy recovery only the PMSM engaged is simulated for different brake strengths under steering-braking conditions, also the stability of the vehicle is analyzed and the recovery energy is counted. Lastly, the energy recovered is compared with the recovery energy by longitudinal braking under the same braking strength. The results show that the energy recovery of the steering regenerative braking conditions with braking strengths of 0.1 and 0.2 is 4.10% and 1.90% less than that of the longitudinal braking conditions with the same braking strengths, respectively, and the steering resistance is constant. The reduction of the recovery energy is only related to the braking time. Meanwhile, the research in this paper provides a reference significance for the research of braking energy recovery strategies for FWHMD vehicles.