Self-voltage-sharing hybrid LLC direct-current converter

Abstract

The invention relates to a self-voltage-sharing hybrid LLC direct-current converter, and the converter comprises n input capacitors C1 to Cn, which are sequentially connected in series from the top tothe bottom, wherein a positive wiring terminal ui1 and a negative wiring terminal ui2 are respectively led out from the positive electrode and the negative electrode of the input capacitor Ci; n-1 resonant switched capacitor units RSCU1 to RSCU<n-1> which are connected with the input capacitors; n-2 rectification units REC1 to REC<n-2> which are connected with the resonant switched capacitor units; wherein the n-2 rectification units REC1 to REC<n-2> correspond to the output ports Uo1 to Uo (n-2); and n-2 series resonance branches are also arranged between the rectification units and the resonance switch capacitor units, and comprise a resonance inductor Lkr and a resonance capacitor Ckr which are connected in series. According to the invention, a structure modular design is adopted, theexpansion is easy, the control is simple, and the voltage self-balancing of the input DC capacitor can be realized without an additional voltage-sharing control strategy; a transformer is additionallyarranged, so that electrical isolation between the input side and the output side is realized; and the LLC link assists in realizing soft switching.

Description

technical field [0001] The invention relates to a multi-level resonant DC converter, specifically a self-equalizing hybrid LLC DC converter. Background technique [0002] High-speed trains run fast, stable and comfortable, energy-saving and environmentally friendly, and have received widespread attention in recent years. Electric traction drive systems are a key part of high-speed trains. With the development trend of high-speed, lightweight and heavy-duty railways, the traction power of the electric traction drive system has increased, and the volume and weight of power frequency traction transformers have further increased. In order to meet the development trend of high-speed railways, the non-power frequency traction transformer technology was proposed, combining multi-level cascaded pulse rectifier converters with DC converters to realize the small and lightweight design of electric traction transmission systems, which is the future of electric traction transmission. Th...

AI Technical Summary

Problems solved by technology

[0004] When the turn-off time of the diagonal switch tubes is inconsistent, the voltage of the input capacitor of the diode-clamped multilevel circuit will shift; the flying-capacitor-clamped multilevel converter replaces the clamping diode with a flying capacitor, but In high-voltage and high-power circuits, capacitors are large in size and high in cost; when the hybrid clamp multilevel converter has a large number of levels, the number of capacitors and diodes required is large, and the voltage balance of each capacitor is difficult to achieve. In practical applications, there are relatively large limitations

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