Inductive current zero-cross detection circuit of CRM mode PFC (Power Factor Correction)

Abstract

The invention discloses an inductive current zero-cross detection circuit of a CRM mode PFC. The inductive current zero-cross detection circuit comprises a signal processing circuit. The input rectifying circuit of the PFC is connected with the two ends of the MOS tube through a direct current bus, and the inductor is connected in the direct current bus in series; the input end of the output rectification circuit is connected with the two ends of the MOS tube, and the output end of the output rectification circuit is the DC output end. The first input end of the signal processing circuit is connected with the output voltage of the input rectifying circuit, the second input end is connected with the output voltage of the direct-current output end, and the output end is connected with the in-phase input end of the comparator; the voltage division circuit is connected with the voltage of the D pole of the MOS tube relative to the S pole, the output end of the voltage division circuit is connected with the inverted input end of the comparator, and the output end of the comparator is connected with the input end of the MOS tube driving circuit. According to the invention, the PFC inductive current return-to-zero point and the lowest point of the voltage of the D pole to the S pole of the MOS tube can be accurately found, so that the opening of the MOS tube is controlled, and the effect of reducing the opening loss is achieved.

Description

technical field [0001] The invention relates to an inductor current zero-cross detection circuit, in particular to an inductor current zero-cross detection circuit of a CRM mode PFC. Background technique [0002] With the development of power electronic technology, the application of high-power converters is becoming more and more extensive, and the requirements for the power density and efficiency of the converters are also getting higher and higher. In order to improve the working efficiency of the converter, MOS tube soft switching technology is usually used. like figure 1 As shown, the common practice of the CRM mode BOOST PFC with bridge to achieve soft switching is to add an auxiliary winding to the inductor L to detect the change of the inductor voltage and determine that the current of the inductor L returns to zero, thereby controlling the time to turn on the MOS tube. . exist figure 2 in, i L is the PFC inductor current, and Vgs is the MOS transistor drive vo...

AI Technical Summary

Problems solved by technology

This method is simple and effective, and is widely used in actual products, but the disadvantage is that it is impossible to accurately find V DS The voltage crosses zero point or valley, so the switching loss increases and the efficiency becomes low

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