A novel position sensor elimination technique for the interior permanent-magnet synchronous motor drive

An approach to the position sensor elimination of an interior permanent magnet (IPM) synchronous motor drive is proposed. The phase inductance of an IPM synchronous motor varies appreciably as a function of the rotor position. This feature is utilized to get an estimate of the rotor position. Analytical equations are developed for the calculation of the phase inductance of an IPM motor driven by a current-controlled PWM power converter with a hysteresis controller. The calculated phase inductance is used to estimate the position of the rotor. To obtain an unambiguous relation between the phase inductance and the rotor position, the phase inductance of phases a, b, and c is calculated during different segments of each electrical cycle. A direct approach to inductance calculation is proposed. Simulation results show the effectiveness of the controller. The position error is very small for speed control applications. A current regulator using constant-frequency switching is analyzed in order to avoid the random switching of the hysteresis current controller.>