Three-phase serial connection DCDC (Direct Current-Direct Current) circuit based on coupling electric reactors

Abstract

The invention provides a three-phase serial connection DCDC (Direct Current-Direct Current) circuit based on coupling electric reactors. The circuit comprises bus capacitors C1 and C2 which are serially connected, and multi-phase IGBT (Insulated Gate Bipolar Transistor) bridge arms, wherein the multi-phase IGBT bridge arms are connected with one end of the bus capacitor C1 and one end of the bus capacitor C2 respectively; meanwhile, the multi-phase IGBT bridge arms are connected in parallel in sequence; and a plurality of groups of coupling electric reactors are arranged and are connected with the multi-phase IGBT bridge arms respectively in a staggered manner. In order to solve a bus balance problem in a staggered working process, the coupling electric reactors are adopted and are used for replacing electric reactors of upper and lower bridge arms, so that a bus can be automatically subjected to voltage sharing; compared with adoption of independent electric reactors, the three-phase serial connection DCDC circuit has the advantages that the quantity of inductors is changed to one from two so that the total volume is reduced and the cost is relatively low; and in a multi-phase staggered working process, the coupling electric reactors can be used for automatically balancing voltage of the bus.

Description

technical field [0001] The invention relates to the field of circuits, in particular to a three-phase series DCDC circuit based on coupling reactance. Background technique [0002] In the case of high voltage, the common half-bridge topology is used, and high withstand voltage switching devices need to be selected, which have high cost, low switching frequency, and high switching loss. To improve these problems, a three-level structure and a series structure can be used. [0003] In DC applications, the three-level structure can adopt the flying capacitor method, but the "capacitive" current stress of the flying span is relatively large, and the wiring layout of the switching devices is not easy, which may lead to high stress. When the series structure is adopted, two sets of independent DC-DCs can be used in series, and the layout is easy, but when multi-phase interleaving works, there is a problem of busbar balance. [0004] When no coupling reactance is used, such as f...

AI Technical Summary

Problems solved by technology

[0005] 1) The actual duty cycle is different (drive delay, IGBT switching speed difference), resulting in a difference in the current time flowing through the positive and negative bus bars;

[0006] 2) The error of the reactance (8%~25%) and the voltage drop of the IGBT are different, so that the current of each reactance is different, and the duty cycle must be adjusted by means of current sharing, and the final result is that the duty cycle of the IGBT is different

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