Combined type DC-DC (direct current) converter

Abstract

A combined type DC-DC (direct current) converter is composed of two DC power supplies (1) connected in series and two completely symmetrical boosted modules (2 and 3). The combined type DC-DC converter is used for converting lower voltage of a renewable DC source such as a photovoltaic /fuel cell and the like to higher voltage for outputting. Compared with the existing boosted converter, the combined type DC-DC converter provided by the invention has a larger boosted transformation ratio under the condition of the same duty cycle, the voltage current stress of a switching tube is low, ripple of input current is low and ripple of output voltage is low; meanwhile, the combined type DC-DC converter has the outstanding advantages of simple structure and convenience in control and the like, and is very applicable to the grid-connected system of renewable energy sources such as photovoltaic /fuel cells and the like in the future, thus the combined type DC-DC converter has better applicationand promotion prospects.

Description

technical field [0001] The invention relates to a combined DC-DC converter and a control method thereof, belonging to the technical field of power electronics. technical background [0002] In recent years, due to the gradual shortage of global primary energy, soaring oil prices, and people's emphasis on environmental protection, countries around the world have been actively developing and utilizing renewable energy and clean energy. Among them, solar photovoltaic cells and fuel cells are connected to the grid. received widespread attention. Due to the influence of the environment, temperature and other factors, the output voltage of these renewable energy sources usually fluctuates greatly, and the voltage level of the monomer is low, so the current solar photovoltaic cell or fuel cell grid-connected power generation device generally adopts a two-stage structure . In order to boost the voltage of the photovoltaic or fuel cell array to the DC bus voltage required by the gr...

AI Technical Summary

Problems solved by technology

In order to boost the voltage of the photovoltaic or fuel cell array to the DC bus voltage required by the grid-connected inverter, the photovoltaic or fuel cell array is usually connected in series, and then boosted by a BOOST or two-phase interleaved parallel BOOST circuit. The boost ratio of the converter is equal. When the input voltage is low, in order to achieve a higher output voltage, the switch on-duty ratio will be close to 1, which will reduce the efficiency of the converter on the one hand, and at the same time the switching frequen...

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