Compensation of Amplitude Imbalance and Imperfect Quadrature in Resolver Signals for PMSM Drives

This paper proposes a compensation algorithm for reducing the position errors that are due to two nonideal output signals of a resolver in the vector control of a permanent magnet synchronous motor. Practically, a resolver generates periodic position errors because of the amplitude imbalance and imperfect quadrature between the two output signals of the resolver. As a result, the dq-axis currents of the synchronous reference frame have ripple components that are twice the stator fundamental frequency. In this paper, the effects of the position errors are analyzed on the basis of the synchronous dq-axis current equations, including the position errors. The d-axis current is directly used as the input signal of the proposed compensator to estimate the position errors by using a simple integral operation according to the rotor position, because the d-axis current is typically constant or zero. The proposed algorithm additionally considers the bandwidth effect of the closed current control loop to estimate the exact error signals according to the variation of the rotor speed. Therefore, the proposed algorithm does not need any additional hardware and much computation time. Furthermore, this algorithm can be applied to both the steady and transient states. The experimental results verify the effectiveness of the proposed algorithm.