Performance evaluations of a position-sensorless IPM motor drive system based on detection of current switching ripples

This paper deals with the effect of inner current control loops on the system performance of a position-sensorless interior permanent magnet (IPM) motor drive system. The position estimation method applied to the motor drive system has been proposed by the authors. Some simulation results show that the inner current loops integrated in the control system make it possible to suppress interference between the q-axis voltage and the d-axis current, thus leading to significant improvements in the stability of position control. Furthermore, this paper discusses a simulation method using the so-called "variable-sampling-time discrete-time system" available in MATLAB/Simulink. The simulation method is intended for the position-sensorless IPM motor drive system including a digital-controlled PWM inverter.