Neutral Point Voltage Fluctuation Suppression Control for Auxiliary Resonant Commutated Pole Inverter

Abstract

An auxiliary resonant commutated pole (ARCP) inverter can achieve not only so-called soft switching but also PWM control. The fluctuation of the neutral point voltage, however, causes commutation failure of the inverter.
It was found by analytical and experimental results that flux vector following control for switching pattern generation gives larger value of the voltage fluctuation than sin-triangular wave comparison method. Then a new control scheme to maintain the neutral point voltage at a half of dc link voltage was proposed. The method utilizes the redundancy of zero voltage vector of the voltage source inverter. For the ARCP 3 phase inverter (AC output 200V, 4.5kVA) built and tested, the value of capacitors to keep the neutral point voltage with the control can be decreased to about 1/60 of that when no control is applied.