CONTROL SYSTEM FOR SYNCHRONOUS ELECTRIC MOTOR

A control system for a synchronous electric motor controls the synchronous motor so that the phase of a current determined based on a magnetic pole position of a moving element of the motor may shift to a phase where maximum torque may be obtained. A magnetic pole position correcting section determines a magnetic pole position correction to be added to a relative magnetic pole position. In connection with a polarity change determining section which determines whether or not a polarity of an acceleration difference changes, a basic correction adjusting section switches computation between an incremental operation of incrementing a basic correction and a decremental operation of decrementing the basic correction by a correction increment/decrement. When the correction increment/decrement becomes a predetermined lower limit value B or less, the basic correction adjusting section stops the computation. The basic correction at that point is determined as a finally-determined magnetic pole position correction.