Position Estimation for Sinusoidal Doubly Salient Electromagnetic Machine Considering Crosscoupling Effect

Aiming at the defects of traditional highfrequency (HF) voltage injection method, such as relying on the saliency of rotor, complex demodulation processes, and estimation accuracy susceptible to cross-coupling effect, a method for estimating the rotor position of sinusoidal doubly salient electromagnetic machine (SDSEM) by injecting HF voltage into its excitation windings with angle compensation for cross-coupling effect is proposed. Firstly, a mathematical model of SDSEM considering cross-coupling effect is established. Then, based on the mutual inductance characteristic between excitation windings and armature windings of SDSEM, the HF voltage signal is injected into excitation windings and the rotor position is estimated by the HF resulting current of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$d$</tex>-axis and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$q$</tex>-axis. Next, the influence of cross-coupling effect on the accuracy of the proposed position estimation method with HF voltage injection is analyzed. The cross-coupling angle caused by this effect is calculated by using online method, and the angle compensation is carried out during sensorless control. Finally, simulation results show that the proposed method effectively reduces the DC bias error of position estimation under various speeds and load conditions, enhancing position estimation accuracy and demonstrating good steady-state and dynamic following performance.