Optimal Simultaneous PWM Control for Three- Phase Dual-Active-Bridge Converters to Minimize Current Stress in the Whole Load Range
Jiahao Sun, Lin Qiu, Xing Liu, Jian Zhang, Jien Ma, Youtong Fang
Abstract
In order to reduce the current stress and improve the efficiency of three-phase dual-active-bridge (3p-DAB) converters in the whole load range, in this article, a simplified derivation based on a segmented analytical method is proposed to obtain an optimal simultaneous pulsewidth-modulation (PWM) control scheme. First, the average transferred power and the current stress of the 3p-DAB at different modes can be calculated based on the segmented analytical method. Second, in the light of the expressions of current stress and average transferred power of the 3p-DAB, the current stress minimization problem can be transferred into inequality constraints’ issues for different modes. The optimization process is derived step by step and the closed-form analytic expression of the optimal control strategy is presented. Then, a simple table of the global optimal control scheme that minimizes the current stress under buck or boost operating scenarios can be obtained. Furthermore, a closed-loop control structure is designed to implement the optimal simultaneous PWM control in practice. Finally, experimental comparison with existing modulation schemes has been implemented on a laboratory prototype to verify the theoretical analysis and the outstanding performance of the proposed strategy.