An Energy Feedback LLC Resonant Converter Light Load Voltage Modulation System and Modulation Strategy

Abstract

The invention discloses an energy feedback LLC resonant converter light-load voltage modulation system and modulation strategy. The system includes a power supply, a half-bridge conversion circuit, a resonant network circuit, a high-frequency transformer, a current doubler rectifier circuit and an output load; the strategy Using the structure of the synchronous rectifier tube on the secondary side of the high-frequency transformer, when the system is working at light load, the output capacitor can feed back energy to the power supply side by adjusting the phase shift angle of the power tube on the primary side of the high-frequency transformer and the synchronous rectifier tube on the secondary side , to reduce the light-load output voltage, and at the same time stabilize the output voltage at the rated voltage according to the relationship between the input and output voltages of the system. The invention solves the problem of pumping up the output voltage of the LLC resonant converter under light load through the modulation strategy, stabilizes the output voltage, does not need to increase hardware costs, and does not have problems such as reduced efficiency, limited application range, and large output voltage ripple. There are great prospects for industrial applications.

Description

technical field [0001] The invention relates to the technical field of LLC resonant converters, in particular to an energy-feedback LLC resonant converter light-load voltage modulation system and a modulation strategy. Background technique [0002] As a kind of DC resonant converter, LLC converter is widely used in DC conversion fields such as communication voltage and battery charging because of its advantages such as wide voltage regulation range, high efficiency, and no need for filter inductors on the output side. However, due to the parasitic capacitance of the transformer and power tube and the reason of load interruption, the LLC converter has the problem that the output voltage pump is difficult to adjust under light load, which makes the closed-loop control of the converter become unstable under light load, and the endurance of the power tube The voltage needs to select a larger margin, and the load is damaged because the voltage is higher than the rated value. Thes...

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Problems solved by technology

[0004] The technical problem to be solved by the present invention is to provide an energy feedback LLC resonant converter light-load voltage modulation system and modulation strategy in view of the defects of large loss and large output voltage ripple in the prior art

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