The harmonic effects in an induction motor fed from a cycloconverter

A 12-pulse cycloconverter is used to investigate experimentally the performance of an induction motor drive system. The cycloconverter has the facility for continuous control of both the frequency and magnitude of the output voltage to keep a constant flux in the induction motors. The nonsinusoidal output voltage of the cycloconverter is analysed and the extra losses produced by harmonic currents in the stator and rotor are then evaluated using an equivalent circuit model. The magnetic saturation of the leakage and mutual inductances of the induction motor were neglected. However, the influence of the skin effect of the deep bar rotors was taken into consideration. The harmonics do not contribute any significant torque and the effect of the presence of harmonics is a slight increase in the motor copper losses. A loss factor representing the harmonic rotor copper losses is evaluated without and with the skin effect