Isolated type circuit-voltage zero-crossing detecting circuit

Abstract

The invention discloses an isolated type circuit-voltage zero-crossing detecting circuit and belongs to the technical field of electrics. The isolated type circuit-voltage zero-crossing detecting circuit comprises a capacitor charging circuit, a discharging loop / return circuit, a photoisolator and a capturing circuit of a digital signal processor, wherein an input end of the capacitor charging circuit is respectively connected to a phase A and a phase B of a three-phase voltage on a network side; an output end of the capacitor charging circuit is connected to a capacitor discharging loop / return circuit; and the discharging loop / return circuit is used for outputting zero-crossing information of a circuit voltage through the photoisolator and is connected to the input end of the capturing circuit of the digital signal processor, thereby obtaining accurate zero-crossing information. With a simple circuit structure, the isolated type circuit-voltage zero-crossing detecting circuit is used for realizing the zero-crossing detection, is successfully applied, is excellent in effect and is easily realized.

Description

technical field [0001] The invention relates to an AC line voltage zero-crossing detection circuit of a system power factor correction control circuit, in particular to an isolated line voltage zero-crossing detection circuit. Background technique [0002] With the development of power electronics technology, eliminating the harmonics introduced into the power grid, reducing system reactive power, achieving electromagnetic compatibility, and improving the efficiency and quality of energy conversion have attracted more and more attention. In order to improve the power factor and reduce system harmonics and reactive power, it is necessary to ensure that the input current and input voltage on the grid side of the system are in the same phase. Therefore, a voltage zero-crossing detection circuit is needed to obtain the voltage phase, and then control the current phase to meet the current and voltage requirements. Phase requirements. [0003] The current voltage zero-crossing de...

AI Technical Summary

Problems solved by technology

[0003] The current voltage zero-crossing detection circuit is mainly composed of a Hall sensor, a voltage comparator composed of an operational amplifier, and a photoelectric isolator. Most of them have the problems of high circuit cost and difficult control of dynamic parameters.

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