Research on initial rotor position estimation for SPMSM

This paper proposes two schemes for magnetic polarity detection in initial rotor position estimation for surface-mounted permanent-magnet synchronous machines (SPMSM). A high-frequency sinusoidal voltage is injected into the estimated d-axis which brings about the saturation of magnetic field. The impact of saturation on the current response is investigated. The positive peak current in d-axis is a bit larger than the negative one due to the impact. Meanwhile, the current response in d-axis includes a positive dc component. As a result, the magnetic polarity can be detected either by the sign of the dc component or by the relationship between the positive peak current and the negative one in the estimated d-axis. Theoretical analysis is verified by the simulations and experiments.