Improved Position Sensorless Drive Method for IPMSM Based on Fully Discretized Model and Inductance Identification Utilizing Current Ripple

This article proposes an improved position sensorless drive method for interior permanent magnet synchronous machines (IPMSM) in medium- and high-speed regions, which relies on the fully discretized extended back-electromotive force (EEMF) model and online inductance identification. First, the fully discretized EEMF model is developed for constructing position observers, which overcomes the accuracy deterioration of the conventional Euler-discretized model with the speed increasing. And then, an online inductance identification method for IPMSM, which utilizes the inherent pulsewidth modulation (PWM) current ripple of the voltage source inverter (VSI), is proposed to improve the position estimation accuracy. Compared with the traditional parameter identification method, the proposed method does not require the additional signal injection, therefore, the undesirable torque fluctuation and additional voltage occupancy due to signal injection are avoided. Benefiting from the fully discretized EEMF model and the estimated inductances, the improved rotor position estimation of IPMSM can be achieved. Finally, the proposed method is verified by simulations and experiments.