Patent ID: 6876170

Claim:
A controller for controlling a synchronous motor having a movable member and a stationary member, one of said movable member and stationary member being provided with magnetic poles and the other thereof provided with excitation coils, said controller comprising: a motor control section for drivingly controlling the synchronous motor and detecting position of the magnetic poles relative to the excitation coils by exciting the excitation coils at a predetermined excitation phase using a sensor for detecting position or velocity of the movable member; and a numerical control section for performing numerical control by issuing commands to said motor control section, wherein said numerical control section outputs a start command to start detection of the position of the magnetic poles to said motor control section, said motor control section starts detection of the position of the magnetic poles in response to the start command and informs said numerical control section of a state of the detection of the position of the magnetic poles, and said numerical control section determines a normal completion or an abnormality of the detection based on the state of the detection informed by said motor control section.