Adjustable transformer ratio-based wide-input LLC resonant converter and regulation and control method

Abstract

The invention provides an adjustable transformer ratio-based wide-input LLC resonant converter and a regulation and control method. The adjustable transformer ratio-based wide-input LLC resonant converter comprises an inversion module, a resonance module, a transformer and a rectification module, wherein after an input voltage passes through the inversion module and the resonance module in sequence, the input voltage is subjected to voltage reduction through the transformer; then a stable direct current voltage is output through the rectification module, and taps are arranged on the secondary side of the transformer and are used for adjusting the transformer ratio according to the magnitude of the input voltage. By adoption of the LLC resonant converter designed in the invention, a relatively small switching frequency variation range can be maintained, and can be basically stabilized between 0.8fr and fr (which is illustrated in the specification); and meanwhile, the stable output voltage can be guaranteed in a relatively wide input voltage range, so that the efficiency and the stability of the LLC resonant converter are improved.

Description

Technical field [0001] The invention relates to the field of electrical engineering, in particular to a wide-input LLC resonant converter based on an adjustable transformer ratio and a control method. Background technique [0002] LLC resonant converter has the advantages of high efficiency and high power density, and is widely used in DC-DC converter applications. The LLC resonant converter can achieve zero voltage turn-on (ZVS) of the primary side switch (ZVS) and zero current turn-off (ZCS) of the secondary side switch within the entire operating range. Its parasitic components include the junction capacitance of semiconductor devices and the leakage of transformers. Both inductance and magnetizing inductance can be used to achieve ZVS, which makes LLC resonant converters have high operating efficiency. The loss caused by the most important lossy magnetic element of LLC resonant converter, LLC resonant converter usually uses variable frequency modulation (VF) technology, that...

AI Technical Summary

Problems solved by technology

[0003] However, when the input voltage changes in a large range, it is necessary to adjust the switching frequency to deviate from the resonance point, which will lead to a decrease in the performance and efficiency of the LLC resonant converter, and will cause the gain sensitivity of the converter, resulting in system instability

However, the current hybrid control introduces symmetrical PWM modulation or asymmetrical PWM modulation that reduces the duty cycle, which will lead to a reduction in efficiency or require a filter inductor on the output side, which is not conducive to the improvement of the efficiency and stability of the LLC filter.

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