Analysis and Simplified Control of the Matrix Converter under Unbalanced Input Conditions

Voltage unbalance is a power quality problem of significant concern at the electricity distribution level. An excessive level of voltage unbalance can have serious impact on mains connected induction motors. The level of the current unbalance that is present is several times that of the level of the voltage unbalance. Such unbalance in the line currents can lead to excessive losses in the stator and the rotor, which may cause protection systems to operate, causing loss of power production. Although induction motors are designed to tolerate a small level of unbalance, they have to be derated. If the unbalance is excessive and if operated at the nameplate rated capacity without derating, the useful life of such induction motors is reduced. However, there are utility system level mitigation techniques and plant level mitigation techniques that can reduce the voltage unbalance and its effects.