Closed Form Solution for Minimum Conduction Loss Modulation of DAB Converters

摘要

An optimal modulation scheme that enables minimum conduction and copper losses is presented for a bidirectional dual active bridge (DAB) dc–dc converter. The considered converter system is employed for an automotive application and comprises of a high voltage (HV) port with port voltage $V_1$, $240,{rm V}le V_1le 450,{rm V}$, and a low voltage (LV) port with port voltage $V_2$, $11,{rm V}le V_2le 16,{rm V}$; the rated output power is $2 , {rm kW}$. The closed-form expressions for the optimal control parameters are derived and implementation details are presented in order to facilitate the direct application to a given DAB converter. The paper further details the properties of the presented modulation scheme with respect to switching losses. Experimental results confirm a considerable increase of the converter efficiency achieved with the proposed optimal modulation scheme, compared to the efficiency obtained with conventional phase shift modulation. The efficiency increase is most distinct at $V_1=450,{rm V}$ and $V_2=11,{rm V}$ with an increase from 78.6% to 90.6% at $1 , {rm kW}$ output power and from 85.9% to 90.7% at rated output power as compared to conventional phase shift modulation.