Fundamental-frequency components in single-phase motors with SCR Voltage Controllers

This paper describes how to extract the fundamental-frequency components from the voltage and current waveforms in a split-phase induction motors that is fed through a static voltage controller. These components are derived not from conducting a fast Fourier transform, but rather from few phase angles that are easily provided by zero-crossing and peak detectors. It is shown that knowledge of these components is useful when attempting to optimize load efficiency, and when assessing the power loss due to harmonic distortion. The analysis in this paper is partially validated by laboratory tests on a 1/3 hp split-phase motor.