An efficient estimation method of sensorless initial rotor position for surface PM synchronous motor

The purpose of this work is the development of an estimation method of initial rotor position for surface permanent magnet (PM) synchronous motor without a position sensor. The principle of the estimation is based on the variation of the current response caused by the magnetic saturation of the stator core when the voltage vector is applied to the motor. The initial rotor position is identified by observing the maximum d-axis current caused by the magnetic saturation. This method can be performed without motor parameters and the additional hardware. A decision method of the optimal voltage vector applied to the motor is also proposed to accurately implement the estimation. Experimental results show that the initial rotor position can be estimated without rotating the rotor by using the optimal voltage vector.