A Novel method for online correction of amplitude and phase imbalances in sinusoidal encoders signals

Abstract

Resolvers and other sinusoidal transducers are angular position and speed sensors that produce supposedly perfect sine and cosine signals in which the angular position is encoded. Suitable converters are normally used to determine the encoded position from the transducer signals. Frequently, the signals present defects, particularly displaying phase and amplitude imbalances. Such defects have detrimental effects on the angle measurement precision. An online method for correcting the transducers signals is presented in this work. This allows elimination of unbalance errors and enable the converters to work properly. The proposed method is based on using three different data points to carry out the correction. Each data point consists of a pair of values of the transducer signals without the need for knowledge of the actual angle itself. A simple algorithm, that may be implemented on a simple microcontroller or processor, performs automatic correction based on the proposed technique. The paper presents details of the theory, algorithm, and simulation results which demonstrate the effectiveness of the proposed method.