Fast Initial Position Estimation of IPMSMs Using Comb Filters

This paper proposes a method for the fast initial position estimation of IPMSMs (interior permanent magnet synchronous motors) which is based on intentional pulse voltage injection and comb filters. Generally, the rotor position can be estimated by detecting the high-frequency current caused by the injected high-frequency voltage because its response includes inductance information due to saliency. In general, the sinusoidal current, sinusoidal voltage, and pulse voltage are utilized for saliency excitation. Methods based on the sinusoidal current and voltage, however, would require a shorter control period for precise signal injection so that methods based on pulse voltage injection would be desirable. The methods based on pulse voltage injection generally utilize the amplitude or differential value of the high-frequency current. These algorithms to calculate the saliency with its amplitude or differential value, however, appear to be complicated and unsuitable to improve the response of the position estimation. In particular, algorithms for calculating the amplitude values require some low-pass filters (LPFs) with a low cut-off frequency for the amplitude calculation, which degrades the response of the initial position estimation. In order to overcome this problem, this paper proposes a new algorithm using comb filters that can rapidly calculate the amplitude values of the high-frequency current and improve the initial position estimation performance.