Adaptive back EMF parameter adjustment of simplified vector control for position sensorless permanent magnet synchronous motors

A previously reported simplified vector control for position-sensorless permanent magnet synchronous motors can be affected by errors in setting the motor parameters, because no feedback compensator is used. We examine the effects of errors on the steady-state performance of these motors in this paper. It was found that the current amplitude increases when a parameter error is given and the effect of a back EMF parameter error is especially large. We propose a new back EMF parameter adjustment method based on these results. We determined from our simulation and experimental results that the proposed method can compensate for the current increase caused by the parameter error. A theoretical analysis showed that the proposed method is affected by only the daxis inductance parameter L_d. Therefore, even if there are errors in the other motor parameters, the motor current of the constant load condition is minimized by using the proposed method.