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DCM Buck-Flyback PFC converter with high power factor

A high power factor, converter technology, applied in the direction of DC power input conversion to DC power output, output power conversion device, high-efficiency power electronic conversion, etc., can solve the problem of large inductor current peak value, converter input current waveform distortion, EMI Problems such as poor differential mode characteristics, to achieve the effect of small input current harmonic content, high input power factor, and small output voltage ripple

Active Publication Date: 2019-09-27
NANJING UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The traditional DCM Buck PFC converter is widely used due to its advantages of high efficiency, low output voltage, low inrush current, low cost, strong short-circuit protection capability, long service life, simple control, small inductance, and no reverse recovery problem of the diode. , is widely used in AC / DC converters, but due to the inherent dead zone of the BuckPFC converter, the input current waveform of the converter is seriously distorted, which reduces the PF value of the converter and increases the The THD value makes it unable to meet the country's requirements for power quality. At the same time, the peak value of the inductor current is large, the EMI differential mode characteristic is poor, the conduction loss of the switch tube is large, and the efficiency cannot be optimized.

Method used

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  • DCM Buck-Flyback PFC converter with high power factor
  • DCM Buck-Flyback PFC converter with high power factor
  • DCM Buck-Flyback PFC converter with high power factor

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Embodiment Construction

[0032] figure 1 It is the main circuit of BuckPFC converter. The following assumptions are made: (1) All devices are ideal; (2) The output voltage ripple is small compared to its DC value; (3) The switching frequency is much higher than the input voltage frequency.

[0033] figure 2 The DCM BuckPFC converter, the inductor current and switch tube current waveforms in one switching cycle are given. When Q b When turned on, D fw cutoff, the inductance L s The voltage across it is v g -V o , its current i Ls Start with zero and start with (v g -V o ) / L s The slope rises linearly, v g to the load and storage capacitor C o powered by. When Q b When shutting down, i Ls by D fw freewheeling, at this time L s The voltage across the two ends is -V o , i Ls with V o / L s The slope of the decline, and i Ls can drop to zero before a new cycle begins.

[0034] Without loss of generality, define the input AC voltage v in The expression is:

[0035] v in =V m sinθ...

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Abstract

The invention provides a DCM Buck-Flyback PFC converter with a high power factor. A design circuit comprises a main power circuit, an output voltage sampling circuit, an output voltage feedback control circuit, a sawtooth wave comparison and switch tube driving circuit, an input voltage comparison circuit and a logic switch circuit. A traditional DCM Buck PFC converter adopts constant duty ratio control, and the input power factor is improved, but the input current has an inherent dead zone, the peak value of the inductive current is large, the EMI poor model property is poor, the conduction loss of a switching tube is large, and the efficiency cannot be optimized.

Description

technical field [0001] The invention relates to an electric energy conversion device, in particular to a high power factor DCM Buck-Flyback PFC converter. Background technique [0002] A power factor correction (Power Factor Correction, PFC) converter can reduce input current harmonics and improve input power factor, and has been widely used. PFC converters are divided into active and passive methods. Compared with passive methods, the active method has the advantages of high input power factor, small size, and low cost. [0003] The traditional DCM Buck PFC converter is widely used due to its advantages of high efficiency, low output voltage, low inrush current, low cost, strong short-circuit protection capability, long service life, simple control, small inductance, and no reverse recovery problem of the diode. , is widely used in AC / DC converters, but due to the inherent dead zone of the BuckPFC converter, the input current waveform of the converter is seriously distorte...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02M1/42H02M3/156H02M1/12H02M1/14
CPCH02M1/12H02M1/14H02M1/4208H02M3/156Y02B70/10
Inventor 张震姚凯邬程健管婵波李凌格陈杰楠马春伟
Owner NANJING UNIV OF SCI & TECH