Analysis and design of a series connected PWM voltage regulator for single phase AC sources

The authors propose a method to regulate a single-phase AC source by using a series-connected auxiliary voltage source. A voltage source inverter, connected in series with the AC supply through a transformer, is used to compensate the input voltage variations in order to achieve a regulated load voltage. Input power factor improvement can also be obtained, when operating with reactive load, by phase-shifting the compensating voltage with respect to the input voltage. The total kVA rating for the system is a fraction of the load total power, and is determined by the maximum allowable line voltage variation. The use of a series connection together with a high-performance modulation technique results in a fast dynamic response and a small-size filter. A high-quality output is readily achieved. The authors describe the proposed method, implementation principles, design equations, and a design example. Simulated and experimental results confirm the concept and feasibility of the proposed system