| Summary: | 碩士 === 國立臺灣科技大學 === 電子工程系 === 103 === The purpose of this thesis is to study and implement a non-linear gain bridgeless buck converter operated in clamped current mode and apply it on power factor correction (PFC). Under light-load, the circuit is operated at discontinuous conduction mode (DCM) to reduce switching losses of the power devices; on the other hand, under heavy-load the circuit is operated at continuous conduction mode (CCM) to lower the peak inductor current and hence the conduction losses. Simulations tools Simplis and Mathcad is utilized to verify the correctness and feasibility of the circuit and calculate the total harmonic distortion (THD). As buck converter structure is used for power factor correction (PFC) function, while input voltage is lower than the output voltage, the input terminal provides no current, and therefore unable to achieve satisfying results in terms of total harmonic distortion (THD) and power factor (PF). As for non-linear converter structure, the input current at both sides are able to follow the input voltage waveform more correctly. This feature contribute a lot to improve the power factor. A 650-W non-linear gain bridgeless buck PFC and a conventional 650-W bridgeless buck PFC are implemented in the laboratory for comparison. The measurement results show that the proposed non-linear converter structure outperforms the conventional one on reduction and is more suitable for high power applications.
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