Universal sensorless vector control applicable to line-start permanent magnet synchronous motors with damper winding

This paper proposes an improved Universal Sensorless Vector (USV) control which can drive not only induction motor and damperless Permanent Magnet Synchronous Motor (PMSM) but also Line-Start PMSM with damper winding (LS-PMSM) by a unified control algorithm without a position/speed sensor. The reason why the step-out problem occurs when the conventional USV control is employed to operate the LS-PMSM is investigated and clarified. As a result, it is found that, by only adding a low pass filter to the load angle calculator to suppress the high-frequency vibration of the estimated load angle, the step-out problem is completely removed and the USV control becomes applicable to the LS-PMSM. The validity of the proposed method is demonstrated with experimental results on a 0.5-kW, 4-pole, 1500-r/min LS-PMSM.