Research on Electromagnetic Transient Model and Control Strategy of Dual Active Bridge Considering Transformer Core Nonlinearity

Abstract

Dual active bridge (DAB) converters have been widely used in distributed power systems and energy storage equipment. Due to the difference in the characteristics of power electronic devices, sudden changes in load, and changes in power flow, the volt-second balance of the phase-shifted inductor is broken. The sudden change of the phase-shift angle will cause a DC component in the inductor current, which will increase the current stress of the power electronic device. Meanwhile, as the frequency of the switching device increases, the working frequency of the transformer in the DAB also increases, the DC resistance in the high-frequency transformer is small, and the DC component will saturate the transformer when it flows through the transformer. It is necessary to study the suppression measures for the DC component, the parameters of the transformer will change with the degree of saturation, so the accurate modeling of the transformer is necessary for the study of the control strategy. Firstly, obtain the leakage inductance, excitation inductance, resistance and other parameters of the transformer, build a dual active bridge test platform, then obtain the electrical characteristics of the transformer port under the conditions of sudden load changes and power flow changes. Finally Build a model and simulate.