| In AC/DC and DC/AC power converters, the power flow from the dc port is constant, while it is time- varying from the ac port. A conventional way to deal with the difference is to employ an electrolytic capacitor to smooth the dc port and support energy storage. However, the electrolytic capacitor, which is large in volume, short in life, and poor in the performance, limits the lifetime and application situations of the devices severely. Therefore more and more applications need to avoid using electrolytic capacitors with the development of energy-saving lighting and renewable energy generation technology.This paper has classified and summarized the present methods of removing electrolytic capacitor, studied the theory of employing a smaller capacitor by fluctuating power decoupling, and derived the ratio of the decoupling capacitor and storage capacitor in the traditional scheme. What’s more, taking the bidirectional Buck/Boost converter as an example, the process of absorbing ripple power and removing electrolytic capacitor is analyzed. O n this basis, a new control strategy based on the feed- forward of DC bus voltage fluctuation is proposed, which greatly reduced the output capacitance value o f the PFC circuit. Instead of an electrolytic capacitor, a thin film capacitor can be used, which will improve the system’s life greatly. In order to decrease the component voltage stress, a buck circuit structure is introduced to the power decoupling system, which also has realized the purpose of removing the electrolytic capacitor. As a result, t he cost of the circuit is reduced, and the reliability of the system is improved.In order to validate the feasibility of the proposed control strategy and the power decoupling scheme, a prototype of PFC power without electrolytic capacitor is designed, which is proved effective in both the boost circuit and the buck circuit. The experimental results verify the correctness of theoretical study and simulation. |
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