Flexible multi-level bridgeless power factor correction converter and modulation method

Abstract

The present invention relates to a flexible multi-level bridgeless power factor correction converter and a modulation method. The converter comprises a AC inductor part, an electric power electronic switch network and a DC capacitor part, the anode of a diode D1 is connected with the drain of a switching tube S1, and the source of the switching tube S1 is connected with the drain of a switching tube S2; the anode of a diode D2 is connected with the drain of a switching tube S3, the source of the switching tube S3 is connected with the drain of a switching tube S4, and the source of a switching tube S5 is connected with the source of the switching tube S3; the source of a switching tube S6 is connected with the source of the switching tube S1, the cathode of the diode D1 is connected with the cathode of the diode D2, the source of the switching tube S2 is connected with the source of the switching tube S4, and the drain of the switching tube S5 is connected with the drain of the switching tube S6. The flexible multi-level bridgeless power factor correction converter and the modulation method can reduce the inductor loss and size, enable the on-state loss at a low input voltage to be reduced, are smaller in DC capacitance, have higher power density, and can switch the five-level and seven-level two working states flexibly on the condition of not changing the circuit structure.

Description

technical field [0001] The invention belongs to the technical field of low on-state loss bridgeless power factor correction converters for low input voltage and high output voltage, and specifically relates to a flexible multi-level bridgeless power factor correction converter and a modulation method. Background technique [0002] The input stage of a switching power supply usually adopts an uncontrollable capacitive rectification circuit composed of diodes, but the input current waveform of this circuit contains a large number of low-order harmonic components, and the power factor of the circuit is very low, which causes serious pollution to the power grid. Power factor correction technology, namely PFC (Power Factor Correction), can control the input current waveform of the rectifier circuit to make it as close as possible to a sine wave and improve the power factor of the converter. Among them, the active power factor correction composed of fully controlled power electron...

AI Technical Summary

Problems solved by technology

This circuit is easy to implement and has high reliability, but there are two problems: 1) In one switching cycle, the voltage change at both ends of the inductor is the output voltage, and when the output voltage amplitude is large, the high-frequency switching ripple of the inductor current is large; 2) The on-state loss of the diode rectifier bridge accounts for a large proportion of the total loss of the converter (about 30% to 60%). When the input voltage is low, the on-state loss of the diode rectifier bridge also increases greatly

[0004] In order to solve the above problems, the three-level PFC circuit proposed in Chinese invention patent 201010138311.6 can reduce the volume of the inductor by about 50% under the premise of keeping the switching frequency consistent with the maximum allowable inductor current ripple, but there is still a diode rectifier bridge, so Does not address efficiency drop at low input voltage

The single-inductance three-level bridgeless power factor correction converter proposed in Chinese invention patent 201010039662.1 does not have a diode rectifier bridge, which can improve the efficiency of the converter at low input voltages, but there is a DC capacitor in half a cycle of the power supply voltage. It is in a discharge state, so a capacitor with a large capacity and volume must be used, which is not conducive to improving the power density of the converter

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