Elimination of the Output Voltage Imbalance in Half-Bridge Boost Power Factor Correctors

• Main Authors: Chin-Tse Ho, 何金澤
• Other Authors: Yu-Kang Lo
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/99358853933443680023

博士 === 國立臺灣科技大學 === 電子工程系 === 95 === The subject of this dissertation is mainly related to the cause and compensation strategies of the output voltage imbalance on the half-bridge (HB) boost-type power factor corrector (PFC). At first, this dissertation introduce the definition of the power factor, and the input equivalent circuit of the PFC. This dissertation also illustrate the operating principles of six boost-type PFC circuits and the various power factor compensation schemes. Next, the voltage imbalance of a two-switch HB PFC circuit is analyzed by using the averaged circuit model. A DC component is injected in the input current to eliminate the output voltage imbalance. Also, the averaged circuit model is used to analyze the power factor for imbalanced dual loads. Furthermore, a four-switch half-bridge PFC circuit is proposed to eliminate the voltage imbalance by controlling the switches in accordance with the output voltage variation. No DC component is required to be added in the source current to compensate the output voltage imbalance. The modified averaged circuit model is analyzed to derive the boundary of the level of a single load and the ratio of the levels of dual loads. Prototype circuits are built and tested in the laboratory to verify the theoretical analysis. The conclusions of this dissertation are given by 1.Two-switch HB PFC circuit：The levels of these DC components agree with the difference between the dual loads. The load mismatch actually influences the output voltage imbalance and the input power factor, and a low-pass filter to eliminate the AC component of the voltage difference can be added to help raise the power factor. 2.Four-switch HB PFC circuit：For the single load, the compensation effect of output voltage imbalance can be achieve. However, for the dual loads, there indeed exists a limited range for the ratio of the dual loads to eliminate the output voltage imbalance. To increase this legitimate range, either the conversion efficiency is reduced or the voltage gain is raised.