Modulation Strategies for a New SCR-Based Induction Motor Drive System with a Wide Speed Range

new SCR-based naturally commutated induction motor drive that provides high torque over a wide speed range is presented. Topology is similar to that of certain naturally commutated current source inverters, but modulation techniques and system performance are very different. Two novel switching algorithms are proposed to cover the low-speed and high-speed regimes. Torque ripple is negligible in the low-speed region. With these two switching techniques, commutation is reliable and operation within peak device voltage stress limits is guaranteed. For induction machine loads, this drive has the torquespeed capability typical of a cycloconverter (but with far fewer devices), plus a field weakening range that the cycloconverter does not have. Simulation and experimental results are presented.