Modeling and design of a neutral point regulator for a three level diode clamped rectifier

This paper proposes a novel neutral point voltage regulator for a three level diode clamped rectifier, which uses a fast space vector modulator in conjunction with a sharing function controller for neutral point regulation. Redundant state choices are controlled via a continuous sharing function, and small signal models are developed for closed loop regulators with this sharing function as the control variable. A significant improvement is seen in the voltage distortion at the neutral point when the regulator is used and this leads to a definitive reduction in the required DC bus capacitance.