| Summary: | 碩士 === 清雲科技大學 === 電機工程系所 === 97 === Ever since the initial development in 1970’s, the switching mode power supplies have been widely adopted in various electronic apparatus, such as personal computers, laptop computers, printers, digital cameras , mobile phones, … etc. Switching power supplies become essential for modern human life. From the power supply technical point of view, there are several remarkable progresses in the past decades, such as high-efficiency topologies, high performance power semiconductors, various integrated control circuits, and low-loss magnetics, which make the power supply more efficient and reliable.
However, accompanying with the technologies of high density PCB layout and high-frequency switching, the noise coupling problem between the PCB wirings and the components are getting more and more serious. The so-called “Electromagnetic Interference” (EMI) has always bothered the power supply engineers. In terms of noise generation and noise coupling, many uncertainties exist inside the power supply system. Most engineers can resolve the EMI issues only by try and error method.
In this thesis, an analytic approach to identify the noise amount of an active power factor corrector is proposed, which is great helpful for designing the noise filter. Besides, a common/differential noise separator is adopted to distinguish the noise types, which can be used for efficient filter design. Measurement to identify parasitic parameters of filter components are also included, which illustrates the noise spectrum in different frequency range. Finally a systematic approach is proposed to design a suitable noise filter. Implementation of the noise filter in a 300W hardware is presented to verify the feasibility of the theoretical derivation.
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