Position Sensorless Control of Surface-Mounted PMLSM with a Novel Starting Method

The paper proposes a novel sensorless permanent magnet linear synchronous motor (PMLSM) feed system. A method of identifying the mover position of a surface-mounted PMLSM and driving a motor smoothly from standstill without any position sensors is presented. When the motor is running, the speed and position of the mover is calculated according to the magnet flux, which is calculated from winding voltage and current. The mover position at standstill is detected based on the saturation effect that d-axis current response changes with the initial position. Once the motor starts up, a three-phase sinusoidal voltage is injected into the motor, then the d-axis current can be calculated after the three-phase currents are measured. Simulation was performed in order to verify the proposed algorithm. It shows that the proposed algorithm can drive a surface-mounted PMLSM smoothly without any vibration or time delay up, and that a sensorless algorithm for mover position over a wide speed range has the characteristic of rapid system response and small tracking error