Position-sensorless method for three-phase electric excitation doubly-salient motor based on terminal voltage filtering

The invention discloses a position-sensorless method for a three-phase electric excitation doubly-salient motor based on terminal voltage filtering. A terminal voltage can reflect the change law of acounter electromotive force according to the characteristic that the zero crossing point of the falling edge of a three-phase counter electromotive force fundamental wave and a commutation point of the doubly-salient motor are coincided. Through the detection and filtering of a three-phase terminal voltage of the three-phase electric excitation doubly-salient motor, the fundamental wave of the terminal voltage is obtained. The impact caused by a DC component in the terminal voltage is eliminated through coordinate conversion, and the phase compensation is performed, thereby enabling the zero crossing point of the falling edge of the fundamental wave of the voltage to coincide with the counter electromotive force, i.e., coinciding with the commutation point. In order to accurately extract the fundamental wave in th