Comparison and assessment of current-source-inverter-fed induction motor drive systems with unity power factor

Current-source based rectifier/inverter topologies are used in medium and high power ac drive applications due to their inherent merits over voltage-source based topologies. For current-source based ac drive applications, unity power factor in the utility lines can be achieved through two approaches: one with a PWM current source rectifier (PWM-CSR) and the other using a thyristor rectifier in parallel with an active filter. Despite numerous publications for the two drive systems, the features and advantages between them have not been clearly explained. This paper in detail presents the theoretical analysis and mathematical derivations for the two topologies, from the point of view of converter kVA ratings, switch ratings, input/dc-link reactive component designs, and dc-link current/voltage level requirements. Based on these criteria, the two drive systems are systematically compared.