Novel single-phase five-level voltage-source inverter for the shunt active power filter

To achieve five-level pulse width modulation (PWM) operation, a single-phase voltage-source inverter is proposed. A shunt active power filter based on the proposed inverter is implemented to achieve harmonics elimination, reactive power compensation and dc-link voltage regulation. Whereas eight power switches are used in the conventional five-level inverter, only six power switches are needed in the proposed inverter. The proposed voltage-source inverter achieves five-level PWM operation without clamping diodes and flying capacitors. The proposed inverter functions as a controllable current source to supply the necessary active power for compensating for inverter losses, to suppress the current harmonics and to compensate for the reactive power drawn by the non-linear loads. The current commands are tracked using the hysteresis current controller. Simulation and experiments based on a laboratory prototype are carried out to verify the effectiveness of the proposed topology and its control scheme.