Method of controlling operation of synchronous motor and motor control apparatus for the same

摘要

At the time of starting a synchronous motor (40), one method of the present invention assumes that the synchronous motor (40) rotates at a revolving speed of not less than a predetermined level, and detects an electrical angle of a rotor (50) according to a first detection process, which has a practical accuracy when the revolving speed of the rotor (50) is not less than the predetermined level (step S120). In case that the electrical angle has not been detected successfully, the method detects the electrical angle of the rotor (50) according to a second detection process, which has a practical accuracy when the revolving speed of the rotor (50) is less than the predetermined level (step S160). Another method first detects the revolving speed of the rotor (50). The method adopts the first detection process to detect the electrical angle when the observed revolving speed is not less than a predetermined level, and adopts the second detection process when the observed revolving speed is less than the predetermined level. Even when the rotor (50) has already been rotated by an external force or inertia at the time of starting the synchronous motor (40), the method enables accurate detection of the electrical angle.