| Summary: | 碩士 === 國立臺北科技大學 === 電機工程系 === 107 === This thesis focuses on the design and implementation of a power supply with soft switching. The front stage of the implemented power supply is a soft switching SEPIC power factor corrector (PFC) which has the advantages of reducing current ripple, achieving step-up and step-down and positive output. In addition, the implemented power supply can be combined with a resonant circuit to reduce switching losses and improve conversion efficiency. The post stage in the developed power supply is a half-bridge LLC resonant converter of which the power switch can achieve zero voltage switching (ZVS) by resonance. The synchronous rectification (SR) is designed on the secondary side of the used transformer to reduce conduction loss and effectively enhance the overall efficiency of the system.
In this thesis, the microcontroller TMS320F28035 produced by Texas Instruments is used to realize the average current control method of the power factor corrector to make the source current follow the voltage. The frequency modulation method is performed to control power component switching frequency of the half-bridge LLC resonant converter and supply stable output voltage.
The system specifications of this thesis are source voltage AC110V~220V/60Hz, output voltage DC24V and maximum output power 300W. The experimental results of the actual circuit verify that the efficiency of the power factor corrector is up to 95.4%, the efficiency of the half-bridge LLC resonant converter is up to 95.2%, the total efficiency of the two-stage series is up to 90.6% and the power factor is up to 0.99.
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