Interleaved totem-pole bridgeless PFC phase control method

Abstract

The invention discloses an interleaved totem-pole bridgeless PFC phase control method. The method comprises the steps of controlling switching-on of master-slave phase switching tubes in interleaved parallel connection through an inductive current zero-crossing detection signal; setting the period value of the PWM module, wherein the period value of the PWM module is higher than the lowest switching frequency of the switching tube; capturing a PWN count value when a main phase in a main phase and a slave phase triggers an inductive current zero-crossing detection signal through a DSP processor, and recording the PWN count value as a first count value; capturing a PWN count value when the slave phase in the master-slave phase triggers the inductive current zero-crossing detection signal through the DSP, and recording the PWN count value as a second count value; and adjusting the conduction time of the switching tubes on the master and slave phases through the first count value and the second count value. According to the invention, two-phase or multi-phase interleaved master and slave phases are all subjected to frequency conversion control, each phase realizes zero-current switching, and phase control enables system input current ripples to be greatly reduced, thereby improving the efficiency of the whole machine.

Description

technical field [0001] The invention relates to the field of power factor correction, in particular to an interleaved parallel totem pole bridgeless PFC phase control method. Background technique [0002] In order to improve the power factor and reduce the harmonic content of the input current, the power factor correction (Power FactorCorrection, PFC) circuit is widely used in power electronic equipment. The traditional PFC interleaved parallel technology is to parallel the input and output of two or more PFC circuits with the same structure. The working signal frequency of each PFC unit is the same, and the phase angles of the switch tubes are staggered from each other by a fixed angle, such as two phases staggered by 180 degrees. , so that the input current ripple is partially or completely offset, greatly reducing the input current ripple. Traditional power factor correction circuits generally adopt fixed-frequency PWM control, and make the circuit work in a continuous c...

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Problems solved by technology

However, in the case of staggered parallel frequency conversion work, the realization of 180-degree interleaving is relatively complicated compared to fixed frequency work. The reason is that the switching frequency at different times in a mains power frequency cycle is actually different, and because of the differences in the components of the circuit itself, The current zero-crossing moment of the interleaved parallel power devices is not exactly the same. If only the main phase is controlled, the PWM of the slave phase has a fixed interval and a fixed angle phase relationship, instead of the zero-crossing detection of the inductor current of the slave phase (ZeroCurrent Detection, ZCD) signal triggers the control, so the moment when the slave phase switch is turned on may not be zero-voltage turn-on or valley-bottom turn-on, and lower switching losses cannot be guaranteed

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