Optimum System Design of a Three-Phase Rectifier-Inverter Type of Frequency Changer

Steadily decreasing prices and improved performance of semiconductor devices have raised expectations towards the development and large-scale application of motor-mounted static converters. In view of this, the design of a rectifier-inverter type of frequency changer which requires very small reactive components is considered. Accordingly, rectifier and inverter PWM schemes which generate the minimum possible harmonic distortion are first discussed. By using a suitable analysis method, ``optimum'' design data are obtained for every major system component. Resulting reactive component values are shown to be considerably smaller than the ones required by typical rectifier-inverter structures. Predicted key results are verified by computer simulation.