A New Analog Controller for Three-Phase Four-Wire Voltage Generation Inverters

This paper introduces a new controller for three-phase four-wire inverters, with the control goal of generating high-quality three-phase output voltages for all sorts of linear/nonlinear and balanced/unbalanced loads. The proposed controller employs a circuit-level decoupling method, and it is implemented by logic circuitry in combination with a control core and a feedback signal processor. Almost all dc-dc control methods can be adapted as the control core, while the feedback signal processor can be implemented by either voltage compensator and/or current compensator. The implementation of the controller is simple and flexible with only logic and analog circuitry needed. Yet, it demonstrated experimentally excellent load handling and source voltage noise rejection ability. The prototype is tested under balanced and unbalanced resistive and nonlinear loads, as well as under extreme load transients. It is also tested with power from a noisy dc input source. In all cases, the prototype demonstrated high-quality output voltages.