Design and Construction of Multipurpose Voltage Source Converter

A Multipurpose Voltage Source Converter (MVSC) has been constructed and tested. The converter can perform five different functions at different operation requirements. It can serve as a step –down dc chopper, full-bridge dc chopper, half- bridge single-phase inverter, full-bridge single-phase inverter, and as a three-phase inverter.A three-phase voltage source inverter topology is used, but with different control techniques, depending on the application required. Considerable effort is also dedicated to the design analysis of different converter topologies with particular attention to the criteria governing the choice of converter topology, the prediction of performance, the criteria of selecting power semiconductor devices and the determination of devices rating and other associated components. A closed loop operation is introduced with a PL controller for a step-down dc chopper operation to maintain constant the speed and the constant torque of a dc motor. For inverters operation, the rms values of the output voltage are controlled such that they vary proportional with the frequency. The results show that different converter topologies can be derived from a three-phase voltage source inverter topology by introducing different control strategies for different converter applications.