Abstract: The distortion obtained in the Uninterruptible Power Supply (UPS) output due to increasing use of rectifiers in critical loads an effective strategy is needed to control the output of UPS system. Sinusoidal pulse width modulation (SPWM) and space vector pulse width modulation (SVPWM) are the most popular PWM techniques for three phase UPS system. As compared to SPWM, SVPWM is much effective in reducing harmonics and distortions caused by highly non linear loads. In this paper space vector based control strategy is presented for three phase UPS system that are operating under highly nonlinear loads. The proposed controller generates gating signals and guarantees high quality output at the load. SIMULINK is used to design and analyse the controller for three phase ups system

Keywords: UPS, non linear load, Space Vector PWM