Realization of Signal-Injection Sensorless Control of SMPMSM by Modification of Current Trajectory

Abstract

In this paper, the feasibility of signal injection sensorless control (SISC) in surface mounted permanent-magnet synchronous motors (SMPMSMs) is discussed. At first, dynamic inductances of a target SMPMSM according to rotor position and dq-axes currents are measured from an experimental test. Based on the measured inductances, current response induced by the injected voltage is calculated. The induced current signal in every operable dq-axes current point is analyzed with an index variable. An optimal current trajectory for the SISC is proposed after the analysis. By adopting optimal trajectory control (OTC) instead of maximum torque per ampere (MTPA) control, the performance of the conventional SISC of the SMPMSM can be conspicuously improved at the cost of slightly increased copper loss. The proposed method is verified with experimental results.