An optimum voltage sensing technique for a single phase ups system

In this paper the "optimum" load voltage sensing technique for a single phase uninterruptible power supply (UPS) system utilizing the sine pulse width modulation (SPWM) technique is obtained. For this purpose an analysis method is developed. The system is first analyzed under open loop conditions and the analysis is verified on an 1 kVA experimental unit. Predicted and experimental results show that the open loop system requires a voltage regulation loop in order to meet typical UPS specifications. The closed loop system is analyzed with various load voltage sensing techniques and the "optimum" sensing technique is selected. This technique is employed in the voltage regulation loop of the 1 kVA experimental unit. Results obtained from this unit verify the closed loop analysis method. Finally design considerations concerning the voltage regulation loop are discussed.