TRANSFORMER-LESS FIVE-LEVEL DIODE-CLAMPED CONVERTER BASED ACTIVE POWER FILTER WITH AUXILIARY BALANCING CIRCUIT

This paper proposes a approach to filter the harmful harmonics using a five-level diode-clamped converter based shunt active power filter. A multi-level converter provides superior filtering performance however, it suffers from a voltage imbalancement in its DC-link. Therefore, a novel control method for an auxiliary balancing circuit and a pulse-width modulator are also proposed. The mathematical model of the filter is derived through its state-space equations. This model is then be used to design linear controllers. To validate the proposed filter a model was constructed and simulated in Matlab/SimPowerSystems (R). Preliminary results show that the filter can effectively reduces harmonics while keeping its DClink balanced.