Design of sensorless controlled IPMSM with concentrated winding for EV drive at low speed

The sensorless control based on the high frequency voltage signal injection method is typically used for detecting the rotor position of an interior permanent magnet synchronous motor (IPMSM). This technique is essential at zero and low speed operating region, where back electromotive force is extremely low. The sensorless-oriented machines require the same minimum value positions of the d-axis self-inductances, regardless of the rotor position. It means that the zero-crossing points of the dq-axis mutual-inductances varied with the rotor position should be constant as well. This paper introduces the design procedure of a saliency-based sensorless controlled concentrated winding IPMSM for vehicle traction, fulfilling the requirements mentioned above. The evaluating process of the sensorless drive feasibility by using finite element analysis (FEA) is proposed, with taking account of cross-coupling effect and saturation. Utilizing the evaluating method, some geometry design parameters are examined to figure out which ones have a positive effect on detecting the rotor position. Based on the influences of the parameters on the dr i ve feasibility, the design conditions for the sensorless drive concentrated winding IPMSM are determined. Finally, the proposed model applied with the geometry design conditions and the FEA results are shown. It is found that accuracy of the rotor position estimation is improved by means of the proper geometry design of the machines.