A circuit and switching power supply for optimizing switching power supply pf value and thdi

Abstract

The invention relates to a circuit for optimizing the PF value and THDI of a switching power supply and the switching power supply, and the circuit comprises: a PFC boost circuit which receives a rectification filtering signal, and generates a PFC voltage signal and a zero-crossing signal according to the rectification filtering signal; a detection circuit connected with the PFC boost circuit andused for receiving the zero-crossing signal and carrying out detection process on the zero-crossing signal so as to output a correction compensation signal; a composite compensation circuit connectedwith the detection circuit and used for superposing the correction compensation signal and a compensation signal generated by a PFC control circuit so as to output a superposed signal; and the PFC control circuit. The PFC control circuit is connected with the PFC boost circuit and the composite compensation circuit, and is used for receiving a PFC voltage signal, the zero-crossing signal and the superposed signal, and outputting a driving signal used for adjusting the PF value of the switching power supply and the THDI according to the PFC voltage signal, the zero-crossing signal and the superposed signal. The circuit can effectively optimize the PF value and THDI of the switching power supply, is suitable for different switching power supply products, is wide in application range, and ishigh in practicality.

Description

technical field [0001] The invention relates to the technical field of switching power supplies, more specifically, to a circuit for optimizing the PF value and THDI of the switching power supply and the switching power supply. Background technique [0002] Switching power supply has the advantages of high conversion efficiency and small size. More and more electronic products use switching power supply as power supply device. In order to reduce the pollution to the power grid, maximize the use of power grid energy, and reduce reactive power loss, the industry standard The higher the value, the higher the requirements for power factor (PF value) and current harmonics (THDI). [0003] The switching power supply power factor correction circuit roughly goes through the following stages of development: [0004] 1. No power factor correction line switching power supply, the grid voltage is directly rectified and then supplied to the switching power conversion circuit. Due to the...

AI Technical Summary

Problems solved by technology

[0009] Some of the existing PFC control chips have THDI optimization function. The principle is to increase the drive turn-on time when the AC zero crosses inside the chip, so as to increase the input current when the AC zero crosses, and compensate the current platform when the zero crosses, so as to improve THDI characteristics. , but because the internal compensation parameters of the chip are fixed, and the capacitance of the external input terminal of each switching power supply product is not uniform, and the input voltage range is not uniform, the effect of this compensation method is limited, and the ideal effect cannot be achieved.

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