Position Estimation for Sinusoidal Doubly Salient Electromagnetic Machine by Injecting High-Frequency Current Signal into Excitation Winding

The conventional position estimation methods use high-frequency (HF) signal injection into the armature winding at zero- and low-speed. However, when applied to sinusoidal doubly salient electromagnetic machine (SDSEM), these methods rely on the saliency of the rotor and suffer from complex demodulation processes and poor position detection accuracy. Therefore, a position estimation method for SDSEM by injecting an HF current signal into the excitation winding is proposed. Firstly, a mathematical model considering the cross-coupling effect is established. Then, based on the mutual inductance characteristic between the excitation winding and armature winding of SDSEM, the pulsating HF current signal is injected into the excitation winding. Subsequently, the rotor position is estimated by the HF voltage response signals of the d-axis and q-axis. Finally, simulation results show that the system stability of the proposed method is unaffected by variations in impedance parameters and the proposed method exhibits high estimation accuracy in both steady-state and dynamic response.