Studies on a sensorless initial rotor position estimating method for hybrid stepping motors

A new sensorless initial rotor position estimating method for hybrid stepping motors is proposed. The proposed method is based on the relationships between the maximum electromotive forces (emf) induced in the nonexcited windings with respect to the rotor position when a winding is excited by DC voltage source. An accurate estimation for the initial rotor position can be achieved with the proposed method, enabling the motor to control precisely.