マルチレベルDABコンバータの動作点変更時に生じる直流オフセット電流の低減法

抄録

During the operation of a dual active bridge (DAB) converter, reducing the DC offset current, which causes magnetic saturation, is critical when phase shifts change. In other words, reducing the DC offset current is necessary to improve the transient characteristics of the converter. This paper proposes DC offset reduction methods applicable to DAB converters with multilevel inverter topology. The methods developed for reducing the DC offset current are determined based on the phase shift commands for the transient state. The proposed method consists of the following elements: adjustment of the phase between the legs of the active bridges, adjustment of the phase between the active bridges, and voltage polarity at phase adjustment. The effectiveness of the proposed reduction methods has been verified by performing experiments and simulations, from which the peak values of the inductor current moving average in a period of AC voltages have been observed to be lowered to 3.7A and 0.80A, respectively, using the proposed method.