Dual-objective optimization strategy for DAB converter with extended phase shift control
In order to improve the transmission efficiency of the dual active bridge converter,a dual-objective weight optimization strategy for current stress and backflow power based on the new extended phase shift control is proposed.Firstly,the new phase-shift ratio is redefined according to the angle of the high level of the primary-side output voltage and the phase-shift angle between the primary and secondary-side output voltages to simplify the mathematical model of the transmission power,and then three operation modes are classified by the relationship between the phase-shift angles and the corresponding mathematical models of the current stress and the transmission power are derived;Based on it,the mathematical model of the backflow power is deduced and the characterization is carried out;Then,two operating modes covering the full power are selected and the current stress and backflow power weight optimization functions are established,the optimal shift ratio combinations are solved according to the polarity regularization method and the soft-switching characteristics are analyzed;Finally,a simple and fast closed-loop control strategy is designed by combining the optimal shift ratio combinations with the proposed soft-switching conditions.A prototype is built for experimental verification,and the optimization strategy is compared with the traditional one in terms of current stress,backflow power and transmission efficiency.The experimental results show that the dual-objective optimization strategy improves the system efficiency by 20%in low-power mode and 11%in high-power mode compared with the traditional extended phase-shift control,which verifies the feasibility and effectiveness of the design scheme.
dual active bridgenew-extend phase shiftcurrent stressbackflow powerweight optimizationphase-shift ratio
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