A Position Error Correction Method for Sensorless Control of Dual Three-Phase Permanent Magnet Synchronous Machines

In this paper, an online rotor position error correction method is proposed to eliminate the impact of parameter mismatch in sensorless control of dual three-phase (DTP) permanent magnet synchronous machines (PMSMs). The position error production mechanism is firstly derived, i.e., the error changes with the trend of current variation when there is a parameter mismatch. Based on this mechanism, by injecting sinusoidal current signals into both sets of three-phase windings, the presence of parameter mismatch and its level can be revealed through the corresponding sinusoidal responses from the estimated speed of sensorless observers. Since the amplitudes of rotor position error responses decrease as the parameter mismatch level reduces, with the help of the least mean square (LMS) algorithm, the parameters can be adaptively adjusted to the actual values, and the position error can be thus corrected. Moreover, through a simple technique and with the extra freedom of DTP machines, the detrimental effects because of current signal injection can be eliminated. The proposed method has been validated through simulation and experimental results.