Five-degree-of-freedom modulation method of dual-active bridge type DC-DC converter

Abstract

The invention discloses a five-degree-of-freedom modulation method for a dual-active bridge DC-DC converter, the modulation method is used for a DAB converter, and the modulation method comprises the following steps: S1, determining the working mode of the DAB converter based on the conduction sequence and time length of switches in the DAB converter; and S3, with the minimum inductance current peak-to-peak value as an optimization target, solving the minimum peak value current in each working mode under the KKT condition, then obtaining a global current peak-to-peak value minimum strategy through comparison, wherein it is worthy that the inductance current peak-to-peak value expression is simple and can be regarded as another form of root-mean-square current, and the optimization complexity can be greatly simplified. The DAB converter has a smaller inductive current effective value, almost all switching tubes can realize soft switching, and the conduction loss and the turn-on loss of the DAB converter can be reduced to the greatest extent; in addition, the method also keeps the simplicity of control, and is easier to implement.

Description

Technical field [0001] The present invention relates to the field of power electronics control, and is specifically a five degree of freedom modulation method for a dual active bridge DC-DC converter. Background technique [0002] In recent years, with the rapid development of distributed power and energy storage systems, the demand for bidirectional isolation converters (IBDC) is getting bigger and large; double-active full bridge bidirectional DC / DC (DAB) converter is simple due to structural symmetry Advantageous power density, high efficiency, modularization, etc. The core topology in the bidirectional isolation converter is widely used in power electronics transformers, electric vehicles, battery energy storage and network systems, etc. [0003] The traditional DAB converter modulation method is the phase shift modulation (PSM), which controls the direction and size of the transmission power by adjusting the transducer protocol full bridge (external transpare angle); altho...

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Problems solved by technology

[0003] The traditional DAB converter modulation method is phase shift modulation (PSM), which controls the direction and magnitude of the transmission power by adjusting the phase shift angle (external phase shift angle) between the primary and secondary full bridges of the converter; although the PSM method is simple, But when the input and output do not match, the zero-voltage switching (ZVS) operation will be lost, thereby increasing the switching loss; in addition, a large amount of reactive power increases the RMS value of the inductor current, resulting in a higher conduction loss; therefore , its conversion efficiency decreases, especially at light load

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