Robust Initial Rotor Position Estimation for SPMSM Based on High Frequency Pulsating Voltage Injection

摘要

This paper investigates robust initial rotor position estimation for surface-mounted permanent magnet synchronous motor (SPMSM) based on high-frequency (HF) pulsating voltage injection method. HF carrier voltage is injected in the estimated d-axis, and rotor position is demodulated by forcing the amplitude of the q-axis carrier current to be zero. The magnet polarity is determined based on the second-order harmonic of the d-axis carrier current, but its reliability can be affected by decreasing the corresponding carrier current signal to noise ratio (SNR), due to position estimation error, PWM phase delay, and HF Resistance Effects. Explicit expressions of the HF currents carrying magnet polarity information have been derived based on the d-axis magnetic saturation model, considering the effects of the PWM phase delay and HF stator resistance. By employing the phase shift information of the first-order d-axis carrier current, a phase compensation strategy is designed to maximize the SNR of the carrier signals for magnet polarity detection. The validity of the proposed method has been verified through simulation and experimental tests implemented on an in-wheel motor.