| With the power electronics technology matures, the DC-DC converter is increasing in the application areas of human life. The study of the paper is a three-level soft-switch forward-flyback DC-DC converter which is beyond of multi-level DC-DC converter category.This paper briefly introduces the background and meaning of the article and the DC-DC converter development status and direction, describers some common three-level half-bridge soft-switch topology. This paper analyzes the traditional three-level soft-switch DC-DC converter working principle, the advantage and disadvantage. This paper focuses on the analysis of the three-level soft-switch forward-flyback DC-DC converter working principle and working mode. Zero-voltage-switching performance of the lagging-legs at a wide load range condition can be provided because of the soft-switching auxiliary circuit. Switching losses, transformation efficiency and the costs of the converter are greatly improved. Aiming at the demands of the high- power, a novel circuit topology which combines the forward-flyback with the three-level is proposed for wide input voltage range and high transform power. In addition, the advanced magnetic integration technology can be employed to integrate the four windings into a magnetic core, which decreases the volume and quality of the transformer and further improves the power density. Phase-shift control strategy with UC3875 is described in detail in this article, driven by opto-isolator to achieve conversion to get meet the PWM pulse signal to the main circuit. By SIMPLIS simulation software, the paper bases on the UC3875 and sets up the loop control methods modeling and simulation, and analyzes the results in the case of the rated load and 10% rated load in the system, the stability of output voltage and ripple. The waveform of the simulation verified the feasibility and stability of output voltage for three-level soft-switch forward-flyback DC-DC converter system. |
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