Modeling and design of a novel voltage control system for three phase fixed frequency static power supplies

Pulse width modulated voltage source inverters (PWM VSI) for uninterruptible power supply (UPS), parallel redundant system applications require fast acting inverter output current and voltage control. This paper describes a multivariable state feedback control technique for the design of the voltage regulator for a three-phase current controlled PWM VSI. The control method provides a fast response and robust control (insensitive to plant parameter variations) of the load voltage in the presence of load/line disturbances. The voltage regulator is operated in the rotating d-q frame in synchronism with the fundamental frequency. The state space model of the plant of the voltage regulator is developed in the d-q frame. The description and analysis of the voltage control method is presented. A simple procedure to design the voltage regulator has been outlined and digital simulations are carried out which demonstrate the excellent dynamic performance of the voltage control system