POWER CONVERSION DEVICE AND CONTROL METHOD FOR PERMANENT MAGNET SYNCHRONOUS MOTOR

摘要

A problem exists in the prior art wherein when operation of a permanent magnet synchronous motor is stopped, current and voltage become zero and information cannot be obtained, thereby causing magnetic pole position information that has been estimated up until that point to be lost and resulting in the magnetic pole position information being estimated each time that the permanent magnet synchronous motor is restarted. Provided is a power conversion device that performs variable speed control of a synchronous motor in which a permanent magnet is used, that is provided with a power conversion unit that converts direct current into alternating current, and wherein: a current detection circuit that detects current that flows through the synchronous motor, an estimation means that estimates the magnetic pole positions of the synchronous motor when starting the synchronous motor, and a memory that stores magnetic pole position estimation data that indicates the magnetic pole positions at the time the synchronous motor is stopped are provided; and said power conversion device is configured so as to comprise a selection means that selects either magnetic pole position estimation data that is stored in the memory or magnetic pole position estimation data that is obtained by the estimation means and a control unit that uses the magnetic pole position estimation data that is selected by the selection means to drive the synchronous motor.