Abstract
The initial rotor position estimation is a serious problem affecting sensorless drives of permanent magnet synchronous motors. This paper presents an estimation method of initial rotor position for interior permanent magnet synchronous motors. The principle of the estimation is based on the nonlinear magnetization characteristics of the stator core caused by the magnet of the rotor. The estimation is performed using the variation of the current response caused by the magnetic saturation when the voltage vector is applied to the motor. This method can be performed without motor parameters and any additional hardware. 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. It is found that the average of the estimation error is ยฑ1.34 electrical degrees, and the estimation is completed within 15.2 ms in the test motor. ยฉ 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 156(4): 69โ76, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20062