A method to extend the low frequency operation of load commutated inverters

Abstract

A novel method for extending the range of thyristor-based load-commutated inverters (LCIs) is proposed. Using conventional single- and three phase LCI topologies, voltage and current waveforms are generated containing a dominant higher-frequency (leading power factor) switching component. A lower-frequency load component is concurrently produced, enabling an LCI to supply lagging power factor and even DC loads. A state-space model is used to apply methods of optimal control in order to improve three-phase LCI operation. Both simulation and experimental results are presented.<>