Soft starting control method of dual-active bridge DC converter applied to intelligent power distribution network

Abstract

The invention discloses a soft starting control method of a dual-active bridge DC converter applied to an intelligent power distribution network. According to the soft starting control method, a primary-side full bridge is unlocked, a secondary-side full bridge and closed-loop control of an external shift phase angle are shunted, the primary-side full bridge employs chopping control, a switch tubeQ3 and a switch tube Q4 are complementarily conducted at a duty ratio of 50%, the switch tube Q3 and the switch tube Q4 employs variable-duty ratio control, and the period of each switch is increasedat a certain step; when a secondary-side voltage is raised enough to drive the switch tubes and the duty ratios of a switch tube Q1 and a switch tube Q2 both are increased to 0.99, the secondary-sidefull bridge and the closed-loop control of the external shift phase angle are unlocked; and when an output voltage reaches a rated value, a load is switched, the output voltage is stable, and the starting process is completed. By the soft starting control method, the current overshoot of the dual-active bridge DC converter during the starting process is effectively prevented, the positive and negative symmetry of the current is ensured, the current-resistant requirement of the switch tubes is reduced, the cost is reduced, a magnetic biasing phenomenon of a transformer is prevented, and the capacity, the volume and the cost of the transformer are reduced.

Description

technical field [0001] The invention relates to a start-up control method of a dual-active-bridge DC converter, in particular to a soft-start control method for a dual-active-bridge DC converter applied to an intelligent distribution network. Background technique [0002] With the rapid development of smart distribution network and new energy and the continuous increase of DC load, requirements are put forward for the flexible control, reliability and multi-port access of AC and DC of distribution network. Due to the advantages of small size, high power density, low cost, symmetrical structure, soft switching, electrical isolation and bidirectional flow of power, the dual active bridge DC converter (DAB) is widely used in new applications. Energy generation systems, electric vehicles, energy storage systems, DC distribution networks, and power electronic transformers, etc. At present, many scholars have studied the soft switching technology and phase shift control of dual a...

AI Technical Summary

Problems solved by technology

However, since the duty cycle of the primary full-bridge output voltage is the same in each switching cycle, and the duty cycle of the primary full-bridge output voltage is inconsistent between different switching cycles, the excitation and demagnetization of the transformer between different switching cycles are unbalanced. , will still produce a certain magnetic bias, affecting the stable operation of the converter

And when the converter is started in stages, at the initial stage of start-up, the full bridge of the secondary side of the converter is in a locked state, and the external phase angle cannot be applied, so this method is also not applicable

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