Double-transformer serial and parallel structure full-bridge LLC (logical link control) resonant converter

Abstract

The invention discloses a double-transformer serial and parallel structure full-bridge LLC (logical link control) resonant converter, and belongs to the technical field of DC / DC converters. The double-transformer serial and parallel structure full-bridge LLC resonant converter comprises a main circuit and a control module, wherein the main circuit comprises an input direct-current source, a full-bridge switching network, an LLC resonant network, a secondary rectifier filter circuit and a battery pack load which are sequentially connected, and the control module comprises an output voltage sampling circuit, an output current sampling circuit, a feedback adjusting circuit, a control chip and a driving circuit. The full-bridge LLC resonant converter is provided with a double-transformer serial and parallel structure, primary windings of two transformers are serially connected, current flowing through the primary windings is the same, secondary current can be automatically balanced, turns of the primary windings are decreased, current stress of secondary windings and rectifier diodes can be reduced by secondary parallel connection, the size of a magnetic core can be decreased by the double-transformer serial and parallel structure, hot spots can be dispersed, heat management is facilitated, and the full-bridge LLC resonant converter is applicable to places with medium-high power electric vehicle chargers.

Description

technical field [0001] The invention relates to LLC resonant technology and belongs to the technical field of DC / DC converters, in particular to a full-bridge LLC resonant DC / DC converter with a double-transformer series-parallel structure applied to an electric vehicle charger. Background technique [0002] Electric vehicles have the advantages of replacing oil with electricity, environmental protection and high efficiency, and are likely to completely replace fuel-powered vehicles in the future, and have broad development prospects. With the development of electric vehicles, the demand for charging equipment such as on-board chargers and charging piles is also increasing day by day. Electric vehicle chargers generally have a two-stage structure, the front stage is a power factor correction circuit, and the latter stage is an isolated DC / DC converter. The post-stage DC / DC converter of the electric vehicle charger, as the power output stage, is its core component. Traditio...

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Problems solved by technology

In order to adapt to this change, the electric vehicle charger needs to have the characteristics of high output voltage, high power, high power density, small size, and high efficiency. With the increase of the power level of the charger, its main component DC / DC converter The power to be transmitted increases, the size of the isolation transformer increases, and the size of the transformer increases, so that the common magnetic core models on the market cannot meet the design requirements of this medium and high power, and the difficulty of transformer design is increased. aging problem

In addition, the excessive volume of the transformer violates the original design intention of the charger with high power density and small volume

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