Wide input range three-level LLC resonant converter and level switching control method

Abstract

The invention discloses a wide input range three-level LLC resonant converter and a level switching control method, and belongs to the technical field of electric power electronic transformation. The inverter is mainly formed by electrically connecting an input direct current voltage source Vin, bus dividing capacitors Cin1 and Cin2, two-way switch tubes S1 and S2, full-bridge switch tubes Q1, Q2, Q3 and Q4, resonant capacitors Cr1 and Cr2, a resonant inductor Lr, a magnetic inductor Lm, a transformer T, rectifier diodes D1 and D2, an output filter capacitor Co and a load Ro. When the inverter works in a three-level mode, the switch tubes S1 and S2 are closed, the switch tubes Q1 and Q3 are simultaneously turned on / off, the switch tubes Q2 and Q4 are simultaneously turned on / off, the switch tubes Q2 and Q4 are complementary to the switch tubes Q1 and Q3, and a duty ratio is fixed as 0.5. When the inverter works in a two-level mode, the switch tubes S1 and S2 are disconnected, the switch tube Q1 and the switch tube Q4 are closed, the switch tube Q2 and the switch tube Q3 are turned on in a complementary way, and the duty ratio is fixed as 0.5. The wide input range three-level LLC resonant converter has the advantages of wide input voltage range, simple circuit topological structure, simple driving control and the like.

Description

technical field [0001] The invention relates to a power electronic conversion technology, in particular to a three-level LLC resonant converter with a wide input range. Background technique [0002] With the increasingly serious problems of environmental pollution and energy shortage, people pay more and more attention to renewable energy. The forms of renewable energy power generation mainly include photovoltaic power generation, wind power generation, hydropower generation and fuel cell power supply, all of which have the characteristics of wide output voltage range. Therefore, in order to efficiently utilize renewable energy and reduce energy waste, a DC / DC converter capable of operating in a wide input voltage range is required. [0003] At present, the traditional three-level LLC resonant converter has the following advantages. For example, the voltage of the switching tube is half of the input voltage, and ZVS can be realized in the full load range. to restore the pr...

AI Technical Summary

Problems solved by technology

The three-level LLC resonant converter has thus attracted much attention, but it is still not suitable for wide input range applications

In addition, the driving signal of the traditional three-level circuit topology is more complicated, and the control is not easy to realize

In order to increase the input voltage range, some scholars have proposed circuit topologies that can work in both three-level mode and two-level mode. Larger quantity increases cost

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