A control method for intermittent mode of two-stage converter

Abstract

The invention discloses a control method for an intermittent mode of a two-stage converter. When the Buck-Boost LLC two-stage converter works in the intermittent mode, at the beginning of each intermittent mode period, a microcontroller configures a timer to trigger a one-shoe mode once and controls the timer to generate a set of four-pre-regulated pulse width signals; four switch tubes S1-S4 of the converter are controlled after isolation drive, thereby enabling the S1 driving signal to be "low", the S2 driving signal to be "high", the S3 driving signal to be "high", and the S4 driving signalto be "low"; and therefore, a front-stage inductance current is pre-regulated to a preset negative value from zero. After four pre-regulated pulse widths, the microcontroller configures the timer towork in a multi-periodic mode. Through the added four pre-regulated pulse widths, the front-stage inductance current rapidly enters a stable state, and the zero voltage switch-on of the front-stage switch tube is guaranteed, so that the efficiency of the converter in the intermittent mode is improved.

Description

technical field [0001] The invention relates to a Buck-Boost LLC converter, in particular to a control method for an intermittent mode of a Buck-Boost LLC two-stage converter. Background technique [0002] The LLC resonant converter can realize zero-voltage turn-on of the switch tube and zero-current turn-off of the synchronous rectifier tube in the full load range, thereby reducing switching loss and improving efficiency. However, the LLC resonant converter adopts frequency conversion control. When the gain range is wide, the switching frequency range is also wide, which is not conducive to the design of magnetic components and electromagnetic interference. However, the Buck-Boost LLC two-stage converter adopts cascaded Buck-Boost and LLC of the same level. The latter stage LLC works at the resonant frequency point, and the gain is adjusted by adjusting the front stage Buck-Boost, which can ensure the In the case that the tube realizes zero voltage turn-on, it still has a ...

AI Technical Summary

Problems solved by technology

[0004] However, the above-mentioned intermittent working mode still has some deficiencies

For example, when the ON signal is generated, the current of the front-stage inductor is zero, and the waveform of the front-stage inductor current needs multiple cycles to reach a steady state. That is to say, in these cycles, the upper and lower tubes of the front bridge arm cannot guarantee Implementation of zero-voltage turn-on, which compromises efficiency at light loads

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