Five-level voltage-source inverter for shunt active power filter

A novel single-phase full-bridge inverter without clamping diodes and flying capacitor is presented to achieve five-level PWM operation. The circuit topology of the adopted inverter has fewer power semiconductors compared with the single-phase neutral-point clamped inverter and flying capacitor inverter. There are only six active switches in the proposed inverter. Four power switches with full DC-bus voltage stress and two power switches with half the DC-bus voltage stress are used in this topology. The proposed inverter is operated as an active power filter to eliminate current harmonics and compensate reactive power of the nonlinear load. A hysteresis current control scheme is adopted to draw a sinusoidal line current from the AC source. The five-level PWM technique is used to reduce the voltage stress of the active switches and the harmonic distortion.