Improvement of Power Conversion Efficiency of DC-DC Boost Converter Using Passive Snubber Circuit

Abstract

This thesis presents a method of improving the power conversion efficiency of a dc-dc boost converter. The proposed method uses a passive snubber circuit, which consists of two inductors, a capacitor, and a diode, to reduce switching loss. The proposed passive snubber circuit provides ZCS turn-on for the boost switch, and reduces reverse-recovery-current of the diodes. To verify the effectiveness of the proposed boost converter, the prototype circuit was built and tested on the various size edge-lit light-emitting-diode (LED) backlight units (BLUs), high power condition, and high voltage condition. In the LED BLUs experiment, the power-conversion efficiency for an input voltage of 24 V was measured as 96%, 95.1%, and 93.7 % for the 42-, 47-, and 55-in edge-lit LED BLUs, respectively

these values were 2.3%, 2.2% and 2% higher than those of the conventional boost converters in the corresponding BLUs. In addition, the proposed boost converter ensured reliable operation and high-power efficiency under the ± 10% variation of input voltage, ± 20% variation of the passive snubber component values, and dimming operation. In the high power experiment, the proposed boost converter for an output voltage of 160 V had better power efficiency than the conventional one by 1.7−4.7 % over the entire output power range (75 ~ 1000 W). In the high voltage experiment, the power conversion efficiency of the proposed boost converter with an output voltage of 400 V was higher than 92 % at the duty ratio < 0.6, and 4 ~ 7 % higher than that of the conventional one over the entire duty ratio range (0.35 ~ 0.675).