Double-Buck inverter improvement modulation method based on auxiliary power supply

Abstract

The invention discloses a double-Buck inverter improvement modulation method based on an auxiliary power supply. The method comprises the following steps of S1, designing a scheme: adopting two groupsof Buck circuits and adopting a time-sharing control mode; S2, adding the auxiliary power supply and an auxiliary switch, wherein S5 and S6 are auxiliary switches which are alternately conducted in positive and negative half periods, and Ub is the auxiliary power supply; S3, carrying out sine output calculation; and S4, carrying out working mode analysis, and dividing into a power frequency positive half period and a power frequency negative half period. By using the improvement modulation method of the invention, conduction losses of a switch tube can be effectively reduced, and a voltage stress and a current stress of the switch tube are obviously decreased; an inductive current fundamental wave, a ripple wave and an inductive voltage are all improved, and copper losses and iron lossesof a magnetic element are reduced; an electrolytic capacitor adopts the electrolytic capacitor with lower cost so that circuit cost and a volume can be effectively reduced; and in a modulation mode, differential output is performed through a group of Buck converters and the auxiliary power supply, accuracy is improved, and errors are reduced.

Description

technical field [0001] The invention belongs to the technical field of photovoltaic inverters, and more specifically relates to an improved modulation method for dual Buck inverters based on auxiliary power supplies. Background technique [0002] With the depletion of fossil energy and the aggravation of environmental pollution, distributed power generation, as an important form of future energy, has attracted more and more attention from scholars at home and abroad. Non-isolated photovoltaic inverters with small size and low cost have become a research hotspot. H-bridge inverters are widely used because of their simple structure, flexible control, and high voltage utilization. However, it has the problem of straight-through of the power tube of the bridge arm, and the dead time needs to be set, which affects the quality of the output voltage waveform and increases the difficulty of later filter design. Since SlobodanCuk and R.W.Erickson proposed the new Cuk combined inver...

AI Technical Summary

Problems solved by technology

With this modulation method, the power switches of the two Buck circuits are always in a high-frequency state throughout the entire cycle, and the device loss and voltage and current stress are large, making it difficult to improve efficiency

[0004] Aiming at the defects that the existing Buck circuit inverter technology is always in a high-frequency state throughout the entire cycle, and the device loss and voltage and current stress are large, and the efficiency is difficult to improve, we propose a dual-Buck inverter based on an auxiliary power supply Modulation method and device for improved device

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