Inductive current zero-crossing detection method of bridgeless power factor correction circuit

Abstract

The invention discloses an inductive current zero-crossing detection method for a bridgeless power factor correction circuit, and the circuit comprises an AC power supply, a first bridge arm, a secondbridge arm, a switch module group capable of enabling a current to flow in two directions, an inductor, an auxiliary winding, and a signal processing circuit. The detection method comprises: enablingthe auxiliary winding to generate a sensing voltage; the signal processing circuit generates an inductive current zero-crossing detection signal by using the sensing voltage; and when the inductive current zero-crossing point detection signal is a falling edge, the switch module capable of realizing bidirectional current flowing is conducted. According to the invention, an inductive current zero-crossing point detection signal is obtained by detecting the rectified voltage of the inductive current auxiliary winding, therefore, the H-PFC works in a critical conduction mode without detecting the positive and negative half cycles of the power frequency of the inductive current and the input voltage, and an inductive current zero-crossing detection signal irrelevant to the AC input voltage and the output load is obtained, so that the action of the switch module is accurate, the conduction loss is reduced, and the efficiency is improved.

Description

technical field [0001] The invention relates to the field of AC / DC conversion, in particular to an inductor current zero-crossing detection method capable of realizing a critical continuous current mode (Critical Continuous Current Mode) of a bridgeless power factor correction circuit (Bridgeless Power Factor Correction Circuit-PFC). Background technique [0002] Traditional boost (Boost) PFC circuits are divided into bridge PFC and bridgeless PFC. In the bridged PFC, the rectifier bridge loss is serious, and the bridgeless PFC omits the rectifier bridge structure compared with the bridged PFC, which reduces the on-state loss of a diode, so the bridgeless PFC is more conducive to improving the conversion efficiency of the entire switching power supply. H-Power Factor Corrector (H-PFC) is a bridgeless PFC topology suitable for medium and high power (such as figure 1 ). exist figure 1 , the bridgeless PFC accepts an input voltage of V in , generating an output voltage V o...

AI Technical Summary

Problems solved by technology

This control method needs to detect the input voltage V in The positive and negative half cycles of the input voltage, but near the zero-crossing moment of the input voltage, the input voltage amplitude is very small, and the signal sampled by the input voltage is easily disturbed by noise, so that the switch S 1 with S 2 Therefore, in order to avoid this situation, a certain size of dead time is often set when the input voltage power frequency is changed. The existence of this dead time will lead to a decrease in power factor

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