Hybrid Electrical Vehicle Motor Drive System Speed Sensorless Study

Hybrid electrical vehicle motor drive system is key technology for vehicle security and accurate control. The motor speed measurement is very important for drive system. The common speed measurement device for vehicle is rotary transformer or hall sensor which not only increases the system cost but also degrades the reliability of the system.This paper sets hybrid electrical vehicle as research object, the speed identification issue is discussed through simulation and experiment. The vehicle drive system needs quick response and strong robustness to nonlinear, and the direct torque control is used for the inductive motor control. The Model reference adaptive system speed identification method, first and second order sliding mode observer is used to estimate the motor rotor speed, and the speed accuracy is considered in many conditions.Simulation analysis has been done for the two methods based on model reference adaptive speed identification scheme. The simulation results show that the bad road and motor variable parameter in the operating vehicle degrade the identification result even system instability can be caused and the system response is very slow.Solving these problems, a method based on sliding mode observer is designed to identify rotor speed. According to simulation results, this method has a strong robustness, fast dynamic response, but the character of vibrating for variable structure control and parameter change cause the identification accuracy is not high. To solve these problems, a second order sliding mode observer is proposed, this method uses supertwisting algorithm to make the system continuous control which deduce the vibrating of the system and it can estimate rotor resistance which increases the identification accuracy.Finally the experiment platform is designed based on TMS320F2812. The experiment validates the feasibility and problem of second order sliding mode observer speed identification method.