PWM voltage and current control of four-leg VSI

In the paper, two control methods of a four-leg three-phase invertor for UPS and active filter applications are discussed. The inverter output voltage is represented as a three-dimensional space vector. Two PWM schemes are investigated: open loop sinusoidal PWM; and feedback multilevel hysteresis PWM current control. Some simulated figures and experimental oscillograms illustrating the properties of the both presented PWM methods are given.