HARMONICS REDUCTION IN FRONT END RECTIFER OF UNINTERRUPTIBLE POWER SUPPLIES WITH ACTIVE CURRENT INJECTION

Harmonics are the by-products of modern electronics devices so it is necessary to mitigate the harmonics and offer techniques to mitigation of harmonics. It is greatly hampered by a three phase rectifier used as a front-end ac-to-dc converter in many systems. High power factor is achieved by injecting high-frequency currents into the three-phase rectifier. This study presents the high power factor operation of the converter with reduced total harmonic distortion up to 47.06%. The power quality up gradation is due to high-frequency current injection, at the input of the front-end rectifier. Sinusoidal PWM technique is used for controlling the output voltage. DSP is used for generating the desired gate pulses. The converter has high efficiency, low EMI emissions, high power packing density and suitable for UPS system.