Development of three-phase controlled converter for induction motor stator voltage controlled drive using computer

This project discusses the development of a simple computer controlled variable three-phase variable supply system for induction motor stator voltage controlled drive. Variable output three-phase voltage supply is generated by the controller using phase-controlled method. The firing scheme for the three pairs of thyristors in inverse-parallel configuration is controlled by the software written in Quick-Basic Language. The control circuit detects the zero-crossing of each line voltage and waveform and upon receiving voltage signal from digital-to-analog converter (DAC), and generates the controlled gating pulses for the triggering hardware circuit. The thyristors used are back to back pairs and the conduction angles of all the thyristors are the same and vary accordingly with the serial command signal from the computer.