A zero-current sampling method of a bridgeless PFC circuit and its circuit

Abstract

The invention discloses a zero-current detection method of a bridgeless PFC circuit and its circuit. The invention uses a detection winding coupled to the inductance of a bridgeless PFC circuit to generate an induced voltage, and then sets the winding and resistance to generate two midpoints. Take one midpoint as the ZCD trigger signal detection point, and take the other midpoint as the reference ground of the ZCD trigger signal detection point. The voltage between the ZCD trigger signal detection point and the reference ground is the ZCD trigger signal required for zero current detection: inductance When demagnetizing, control the ZCD trigger signal detection point and another midpoint through the switching device without current passing through, so that the switched-on switching device and its corresponding resistance are in a floating state; when inductive excitation, control the ZCD trigger signal detection through the switching device The voltage value of the point and the other midpoint are equal. The method or circuit of the invention can realize the zero current detection of the inductance of the bridgeless PFC circuit, and then complete the control of the bridgeless PFC circuit, and the circuit structure of the invention is simple, the cost is low, and the signal processing is simple.

Description

technical field [0001] The invention relates to the field of bridgeless PFC circuits, and more specifically, to a zero-current detection method and a circuit thereof. Background technique [0002] Active power factor correction (APFC, ActivePowerFactorCorrection) is widely used in communication power supplies, and the AC input current needs to be sampled in the control of APFC. At present, the bridgeless PFC circuit structure reduces the rectifier bridge, so that the system loss is significantly reduced and the efficiency is significantly improved, so it has received widespread attention. However, in a bridgeless PFC circuit, especially in a totem pole bridgeless PFC circuit, it is difficult to directly detect the zero current of the inductor. Currently, there is no relatively simple, convenient and effective solution for sampling the zero current of the bridgeless PFC circuit. [0003] To solve this difficulty, many researchers have invented patents such as the following: ...

AI Technical Summary

Problems solved by technology

[0010] Publication No. US9899909B2 discloses a totem pole bridgeless power factor correction (PFC) soft switch control device and method, such as Figure 2a , Figure 2b , Figure 2c As shown (respectively derived from the patent attached Figure 4 , attached Figure 7 , Accompanying drawing 8), it can be seen intuitively from the accompanying drawings that the patent solution requires at least three logic gate devices and a comparator, the hardware circuit is complex, there are many electronic components, and the cost will be relatively high

[0011] As analyzed above, the zero-current detection circuit in the current bridgeless PFC circuit still has certain defects.

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