Universal phase shift control method for transient DC bias of dual-active-bridge direct-current converter

Abstract

The invention discloses a universal phase shift control method for transient DC bias of a dual-active-bridge DC converter, and the method focuses on the analysis from the perspective of triple phase shift because single phase shift and dual phase shift can be regarded as the special conditions of triple phase shift. The method comprises the steps that in the steady state period, the output sides of a primary side full bridge and a secondary side full bridge in the dual-active-bridge DC converter are named as VAB and VCD respectively; the primary side inner phase shift duty ratio is D1, the primary side and secondary side outer phase shift duty ratio is D2, and the secondary side inner phase shift duty ratio is D3. Supposing that the phase shift duty ratio suddenly changes from D1, D2 and D3 in the steady state to D1'', D2'' and D3'' in the next steady state and the converter is in a transient state, the on-off time of a switching tube in the first switching period after the duty ratiois suddenly changed is adjusted to meet a certain relation, and after the second switching period after the duty ratio is suddenly changed, the phase shift duty ratio is stabilized to be D1 '', D2''and D3 '', so that the transient DC bias of the converter can be eliminated. According to the invention, the current impact in the transient state can be reduced, and the dynamic response is accelerated.

Description

technical field [0001] The invention belongs to the technical field of power electronics and relates to a dual active bridge DC converter, in particular to a general phase-shift control method for transient DC bias of a dual active bridge DC converter and its application. Background technique [0002] The dual active bridge DC converter has the advantages of simple topology, bidirectional flow of energy, and easy realization of soft switching. It has good application prospects in energy storage systems, electric vehicle charging piles and other occasions. However, due to sudden changes in the phase-shift duty cycle and differences in device parameters, transient bias currents will appear in the high-frequency transformer and inductor of the dual active bridge DC converter. Transient bias currents cause increased current stress, increased losses, and reduced converter efficiency. If the bias current exists for a long time, it may also cause the magnetic components to saturat...

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Problems solved by technology

[0006] Chinese patent "Application No.: CN201410678003.0 "A Transient Phase Shift Control Method for Dual-Active Full-Bridge DC Converter"" aims at single phase shift control, and proposes the first period after the phase shift duty ratio mutation Inside, adjust the turn-on and turn-off time of the switch tube to eliminate the transient bias. This method has a faster response speed, but this implementation method is only applicable to the phase-shift duty cycle of the primary and secondary sides, which is a single phase-shift modulation strategy. However, the transient DC bias suppression capability cannot be achieved in the double-phase-shift or triple-phase-shift modulation strategies

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