The need for use of cycloconverters is in controlling a.c motors at low speed drive especially in high power application. The MATLAB-SIMULINK model for three pulse, six pulse and twelve pulse three phase to three phase cycloconverter has been constructed. The control strategy of supplying the firing pulses is based on the cosine wave crossing method. The SIMULINK model for the control circuits to perform the procedure of this strategy has been constructed. A control circuit for each thyristor to control its firing pulses has been constructed separately to prevent any complexity in the control circuit. An R-L load was used. In additional a three phase induction motor has been connected to test the reliability of the system in controling the output frequency and then the motor speed. The present study includes circulating current and semi-circulating current modes of operation with study of measuring and correction of output power factor of the cycloconverter and output voltage waveform harmonics.
Keywords:Three-phase to Three-phase, Cycloconvereter, Modeling and Simulation, MATLAB-SIMULINK model