Implementation of shunt APF based on Diode Clamped and Cascaded H-bridge multilevel inverter

In this paper five level Diode clamped and Cascaded H-bridge multilevel inverter based shunt APF is presented. Traditional two level Shunt APF has disadvantage that its switching frequency is very high causing high switching losses. Also voltage stress on each switch is high equal to grid voltage. Multilevel inverters (MLI) have advantage of they can operate on low switching frequency; so switching losses are low. The dv/dt stress on each device is very low. Also, in high voltage system high rating transformer is required with APF which causes high cost and bulky system. But application of multilevel inverter in active filters effectively reduces harmonics in high voltage system without use of transformer. The reference compensating currents are generated using Instantaneous Reactive Power Theory (P-Q Theory). Sinusoidal pulse width modulation scheme is implemented to generate switching signals. Simulation results shows effectiveness of the multilevel inverters.