A kind of control method of series resonant converter

Abstract

The invention discloses a control method of a series resonant converter. The method obtains a feedback signal by collecting an analog output signal of the series resonant converter, and changes the operating frequency of the series resonant converter according to the feedback signal; and when the series resonant converter When the load is light-loaded or no-loaded, it adopts a hybrid control mode combining frequency modulation width modulation and fixed width frequency modulation. Ring control to switch. The present invention adopts the mixed control mode when the load is light-loaded or no-loaded and realizes the switching between the mixed control mode and the frequency modulation control mode through the hysteresis control, thereby solving the problem of the voltage of the series resonant converter under the low-voltage light-loaded or no-loaded state. The problem of instability effectively expands the output range, and at the same time solves the problem that the output voltage gain is not monotonous and the loop is difficult to control when the duty cycle is adjusted.

Description

technical field [0001] The invention relates to a resonant power conversion technology, in particular to a control method for a series resonant converter. Background technique [0002] With the development of power conversion technology, high efficiency and high power density has become an important development trend. The resonant converter has been widely used and paid attention to in the application of switching power supply technology due to its advantages of soft switching, high efficiency, high operating frequency and small size. As one of the simple circuit topologies, the series resonant converter can not only meet the high frequency requirements, but also achieve high conversion efficiency, and has been widely adopted in the industry. [0003] Take the LLC (abbreviation of Lr, Lm, Cr, which respectively represent the resonant inductance, excitation inductance and resonant capacitor in the resonant parameters) series resonant converter as an example. The voltage on ...

AI Technical Summary

Problems solved by technology

[0021] The object of the present invention is to provide a control method for a series resonant converter, which solves the problem of voltage instability of the series resonant converter under low-voltage light load or no-load conditions, effectively expands the output range, and solves the problem of Due to the problem that the output voltage gain is not monotonous when adjusting the duty cycle, the loop is difficult to control

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