A hybrid bridge-arm type isolated bidirectional DC converter and its control method

Abstract

The invention provides a mixed bridge-type isolated bidirectional DC converter and a control method therefor. The converter comprises a first bridge arm, a second bridge arm, a third bridge arm, a fourth bridge arm, a high-frequency isolation transformer T, a capacitor C1, and a capacitor C2. The first bridge arm consists of two switching tubes S1 and S2, and the second bridge arm consists of two switching tubes S3 and S4. The third bridge arm consists of two switching tubes S5 and S6, and the fourth bridge arm consists of two switching tubes S7 and S8. The switching tubes S2, S4, S7 and S8 are SiC-MOSFET switching tubes. According to the invention, the converter enables the novel SiC-MOSFETs with smaller switching loss to be combined with a current mainstream semiconductor technology, enables the switching loss to be centralized on the SiC-MOSFETs through control, enables an isolated bidirectional DC converter to have the advantages of two types of switching devices, and improves the system efficiency and switching frequency.

Description

technical field [0001] The present invention relates to the technical field of electrical automation equipment, in particular to a hybrid bridge-arm type isolated bidirectional DC converter with integrated IGBT and SIC-MOSFET applied to a DC microgrid and a control method thereof. Background technique [0002] The isolated bidirectional DC converter is one of the key components in the DC microgrid. Its status is similar to that of the transformer in the AC grid. It can realize the bidirectional transmission of DC energy, voltage level conversion and fault isolation. One of the more mature isolated bidirectional DC converters uses a dual phase-shift bridge topology, which has a simple structure and control. Under medium and high frequency operation, the volume of the isolation transformer can be greatly reduced and the efficiency is higher. [0003] The traditional dual phase-shift bridge topology uses Si-IGBT as the switching device, and the control method adopts phase-shift...

AI Technical Summary

Problems solved by technology

Under this control method, eight switching losses will be generated in one switching cycle. The switching loss of IGBT is basically on the order of tens of mJ / time. The direct multiplication of this value and the switching frequency is the switching loss. Therefore, with the system frequency increase, the loss will be very considerable, which is not conducive to the further improvement of system efficiency

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