Control Strategy Of SRM For Electric Vehicle Drive System Without Position Sensor

The electric vehicle is an important developing trend of the automobile industry in the 21 st century, and motor control technology is an important key technology of the electric vehicle, which has become one of the research focus. Switched reluctance motor(SRM) is a new type of special motor with simple structure, economical, easy-to-control, strong fault tolerance, etc, which has been gradually applied to civil products, electric vehicles, aerospace and other fields. However, the position sensor detection circuit achieved by traditional hardware makes the SRM volume larger, adds additional mechanical structure, reduces the reliability of motor control and the application range of motor, meanwhile, and increases the cost of the entire system with the use of position sensor. The SRM electric vehicle drive system based on position sensorless has its unique advantages, such as the application of position sensorless can improve the fault tolerance of the electric vehicle. Therefore, this study mainly focuses on the SRM electric vehicle drive system based on position sensorless, and designs the non-linear state observer based on the non-linear features of SRM and the non-linear speed controller based on backstepping.SRM has double salient structure and features of higher-order, strong coupling, strong non-linearity. With the consideration of strong non-linear features of SRM, the SRM nonlinear magnetic chain model is established based on the existing three-phase 6/4 SRM prototype in the MATLAB/Simulink toolbox and the data obtained by finite element analysis software, moreover, the three-phase 12/8 SRM nonlinear model is constructed by adopting the method of look-up table. For position sensorless SRM drive system, taking SRM nonlinear flux-linkage model as a basis, the nonlinear state observer is newly designed according to the state equation of SRM, and the stability of the above-mentioned observer is proved by Lyapunov stability theory. The information of rotor position and speed can be estimated when the stator current and voltage information is detected as the input of the nonlinear state observer, and the high frequency pulse injection method is introduced as the starting scheme for position sensorless. Additionally, the current study designs backstepping speed controller by Lyapunov theory, establishes the whole control system model of position sensorless SRM with the utilization of Simulink toolbox MATLAB software, and conducts the relevant simulations for the above-mentioned reseraches.The simulation results show that the newly-designed nonlinear backstepping controller has good speed-control performance, the nonlinear state observer can accurately estimate the relative position angle of the rotor, and the speed and torque has strong robustness and stability for the uncertain interference. Various hardware and software modules of SRM drive control system are designed based on the existing prototype, the rapid control prototyping experiments for SRM drive control system experimental platform are carried out with the use of RT-LAB simulation platform, and the feasibility of designed control strategy for position sensorless SRM drive system is further validated by the experiment.