Optimized Design of Discrete Traction Induction Motor Model at Low-Switching Frequency

By low-switching frequency of power devices, as well as synchronization between control strategies and pulse-width modulation (PWM) pulse update, the control and calculation frequency of the high-power ac traction drive control system of metro vehicle is low, which leads to some problems of instability in a high-speed region and conflict with the control timing of the digital signal processor (DSP) in the conventional discrete traction induction motor model. This paper analyzed the defects of the conventional discrete model at low-switching frequency and proposed an optimized discrete model based on in-depth study of model pole trajectory, which solved the contradiction among stability in high-speed region, the computational load, and the control timing. The proposed model is also applied for the rotor flux observer design of field-oriented control. Simulation and experimental results are given to demonstrate the steady-state and dynamic performance of the proposed model.