Generalized Torque Performance of Two-Phase Induction Motors Controlled by Triac---An Approximate Analysis

Abstract

In the present work, an analysis concerning the torque performance of a two-phase induction motor is carried out. The analysis is based on the first-harmonic approximation of distorted by triac voltage waveforms and concerns the case where the motor is driven by two quadrature voltages one of which is controlled by a triac. As an extension to the above analysis, the unusual case in which the motor is driven by two in-phase voltages with the triac acting on one-phase winding, is also considered. For this case of motor driving, it is pointed out that a torque is developed in motor due to voltage phase shifting caused by triac nonlinear action. This could be perhaps of value for specially designed motors which would provide the ability of using triacs instead of capacitors for quadrature voltage production and torque generation.