Permanent magnet generator q-axis inductance adaptation using high-frequency signal injection

The model-based rotor position estimation methods for permanent magnet generators (PMGs) are susceptible to machine parameter variations, especially inductances which are operating point dependent. This paper presents a PMG apparent q-axis inductance adaptation method which is used with the PLL-based rotor position estimation methods to improve their accuracy. These methods exhibit position estimation error if the used q-axis inductance value is incorrect. The proposed method extracts the position estimation error by using high-frequency signal injection technique and improves the accuracy of the estimated rotor position by determining the correct value of the q-axis inductance. Upon obtaining correct q-axis inductance value, current references are adjusted to provide accurate torque reference tracking. Experimental verification of the proposed method was done on a 375 kW PMG. The experimental results show the effectiveness of the proposed method.