Torque estimating system for synchronous electric motor

摘要

A torque estimating system for a synchronous electric motor having a permanent magnet comprises: a superimposing unit (5) configured to superimpose a voltage or current of a frequency different from a frequency of a fundamental wave driving the synchronous electric motor on at least a d-axis of the synchronous electric motor; a magnet temperature estimating unit (14) configured to estimate a temperature of the permanent magnet from the superimposed voltage or current and a current or voltage obtained by the superimposing; and a torque estimating unit (15) configured to estimate a torque of the synchronous electric motor from the estimated temperature of the permanent magnet.