Bidirectional CLLLC resonant converter with variable capacitor and control method

Abstract

The invention discloses a bidirectional CLLLC resonant converter with a variable capacitor and a control method. The bidirectional CLLLC resonant converter comprises a primary side full bridge, a secondary side full bridge and a CLLLC resonant cavity. The CLLLC resonant cavity comprises a transformer T, a primary side resonant tank, a secondary side resonant tank and a direct current bias applyingcircuit; the primary side resonant tank is provided with a primary side resonant capacitor C1 and a primary side resonant capacitor C2 which are connected in series; the secondary side resonant tankis provided with a secondary side resonant capacitor C3 and a secondary side resonant capacitor C4 which are connected in series, and the direct-current bias applying circuit is connected to the two ends of the primary side resonant capacitor C1 and / or the secondary side resonant capacitor C3 and used for applying direct-current bias to the C1 and / or the C3. When the primary side resonant frequency and the secondary side resonant frequency are not matched or deviate from the working frequency, the duty ratio of an auxiliary switch in the direct-current bias applying circuit is adjusted and thus the resonant capacitance value of the primary side resonant tank and / or the secondary side resonant tank is changed, so that the primary side resonant frequency and the secondary side resonant frequency are matched or returned to the working frequency.

Description

technical field [0001] The invention relates to the technical field of power electronic converters, in particular to a variable capacitance bidirectional CLLLC resonant converter and a control method. Background technique [0002] In order to realize the connection between DC microgrid and DC distribution network or between DC distribution networks of different voltage levels, high-power DC converters are widely used to realize the transmission and conversion of DC power. Because traditional power transformers are difficult to achieve DC conversion, DC power distribution systems often need to rely on power electronic converters to achieve power transmission. The isolated bidirectional dc-dc converter (IBDC) is an important power electronic converter. With its advantages of galvanic isolation, bidirectional power transmission, symmetry and modularization, it can realize DC microgrid voltage And the flexible control of power has received extensive attention. Among them, the ...

AI Technical Summary

Problems solved by technology

However, due to errors in parameters such as power switching devices, capacitors, and transformer leakage inductance, and they will change with actual power and temperature, the resonant frequency will deviate from the set switching frequency, and the performance of the converter will decrease

In addition, within the converter operating frequency range, the converter's operating frequency may vary according to different requirements and conditions, causing the resonant frequency to deviate from the operating frequency, which will also reduce the converter's transmission power and efficiency, and cannot maintain a stable unit voltage gain

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