| 摘要 |
PROBLEM TO BE SOLVED: To provide a torque estimation system of a synchronous motor which can estimate torque precisely in a wide operation range to a high rotation speed from a low rotation speed of an electric motor, without using a torque sensor.SOLUTION: Voltage or electric current of frequency different from that of a fundamental wave which drives a synchronous motor 2 is superposed on at least d-axis of the synchronous motor 2. Temperature Tm of a permanent magnet is estimated from the superposed voltage or electric current and the voltage or electric current obtained by superposition. Torque of the synchronous motor 2 is estimated from the estimated temperature Tm of the permanent magnet. |
