Design, simulation and realization of the filter for high power NPC inverter

The paper presents a three-level pulse-width modulation (PWM) technique for AC/DC/AC converter with high voltage (line to line voltage is up to 6000 volts) and high power (up to 2500 kilowatts) for the pump of the power plant. In the inverter, a capacitor voltage compensator is adopted to balance the neutral point voltage for maintaining good quality voltage waveforms on the output of the inverter. A common-mode voltage reactor (CMVR), a three-phase LC-filter and the neutral-point-clamped (NPC) technique are employed in order to eliminate the bad impact of the common-mode voltage (CMV), to reduce the harmonic contents of the inverter output voltages. In the inverter side, the integrated gate commutated thyristor (IGCT) has been adopted as the output switches in this equipment. Computer simulation results based on MATLAB environment are given to confirm the proposed methods which are suitable for designing the high voltage and high power inverter applied to induction motor drive.