Software based RDC Using Pulse Excitation

Abstract: Resolvers are angular position transducers used to measure the absolute angle. These are mounted on the motor shaft to measure the shaft’s absolute angular position. This paper discusses the design of software based Resolver to Digital Converter (RDC) using pulse excitation and is implemented in MATLAB® SIMULINK®. In the proposed simulation model, inverse tangent algorithm is proposed to measure the motor shaft angle. The resolver rotor is excited with a pulse signal and the resolver two output signals are proportional to sine and cosine of the motor shaft angle. These modulated output signals are sampled by two Analog to Digital Converters (ADCs), with a sampling frequency equal to that of excitation frequency. The angle is measured by applying inverse tangent algorithm to the samples values of sine and cosine signals. The proposed software based RDC model is successfully implemented and the performance of the model is validated through various rotor speeds.

Keywords: Resolver, Resolver to Digital Converter, Inverse tangent, Pulse excitation, lookup table, CORDIC.