LLC resonance type three-port DC-DC converter and control method thereof

Abstract

The invention discloses an LLC resonance type three-port DC-DC converter and a control method thereof. The converter is composed of a primary side circuit, a secondary side circuit, a transformer and LLC resonant network. The primary side circuit is composed of a full-bridge unit integrating two paths of two-way buck-boost circuits connected in parallel in a staggered mode. The secondary side circuit is composed of a rectifier circuit. The transformer and LLC resonant network is composed of a high-frequency transformer, a resonant inductor Lr, an excitation inductor Lm and a resonant capacitor Cr. By adjusting the duty ratios and frequencies of power switch tubes of the primary side circuit, two-way energy transmission and output one-way energy transmission between two ports of the primary side can be effectively controlled at the same time. According to the converter and the method, a non-isolation type two-way buck-boost converter is integrated with an isolation type full-bridge LLC resonant converter, so that multiplexing of the primary side switch tubes is achieved, the number of the switch tubes is reduced, cost is reduced, and power density and reliability are improved. The converter is suitable for renewable energy source power generation, hybrid electric vehicles, fuel cell vehicles, hybrid energy storage systems and other systems.

Description

Technical field [0001] The invention relates to the field of power electronic converters in systems such as renewable energy power generation, hybrid electric vehicles, fuel cell vehicles, etc., in particular to an LLC resonance type three-port DC-DC converter and a control method thereof. Background technique [0002] The depletion of the earth's resources and people's widespread attention to environmental issues make renewable energy power generation systems more and more important. At present, photovoltaic power generation and wind power generation are the two most widely used forms of renewable energy power generation, but due to the influence of natural conditions, their power supply has the shortcomings of instability and discontinuity. For this reason, it is generally necessary to combine a variety of renewable energy sources with other energy sources and energy storage devices to form a renewable energy joint power supply system, and use the complementarity between them t...

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Problems solved by technology

However, when the converter works under light load, it is difficult for the converter to realize ZVS soft switching, which is not conducive to the high-efficiency operation of the converter.

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