Mitigation of Total Harmonic Distortion in the Output Voltage of Thyristor Voltage Controller for Single-Phase Asynchronous Motors - A Case Study

Thyristor Voltage Controller is one of the well-known techniques used in controlling stator voltage supply of asynchronous motors. However, this technique of controlling motor generates some amount of harmonics in the voltage waveform of the supply. Research has shown that, the presence of harmonics in voltage waveform negatively affects the operation of the motor. This paper analyzes the effect of firing angle and total harmonic distortion (THD) of the thyristor voltage controller on the input power, rotor speed and main winding current of a single-phase asynchronous motor using the FFT toolbox available in MATLAB/Simulink software. The designed system was designed with and without LC filter. The results of the simulation showed a reduction in the THD level and increase in the time taken by the rotor speed and the main winding current to reach steady state.