Loss Equalization and Current Harmonic Suppression in Unbalanced Three-phase Inverter using Pulse-voltage-injection Two-phase PWM Featuring Variable Switching Pause Period

Three-phase inverters undergo degradation owing to imbalances in the losses among their components. We have been working to mitigate such imbalances by switching patterns. To this end, we herein propose a variable switching pause period two-phase pulse width modulation (PWM)-based scheme to equalize switching device losses in unbalanced three-phase inverters, thereby enhancing their lifespan. However, usage of two-phase PWM schemes in three-phase inverters may give rise to current harmonics. To overcome this issue, we integrate a pulse-voltage-injection two-phase PWM scheme featuring a variable switching pause period. The experimental results demonstrate that the proposed PWM scheme simultaneously equalizes the switching device losses and reduces the output current harmonics of an unbalanced three-phase inverter operating with an inductive load and induction motor.