Instantaneous-Power-Balance Based Modulation with Natural Power Factor Correction for Single-Stage Bidirectional AC-DC DAB converter

In this article, an instantaneous power-balance-based modulation method with natural power factor correction is proposed for a single-stage bidirectional ac-dc dual active bridge (DAB) converter. The condition for realizing natural power factor at the ac port is derived, and three single-variable modulation methods (namely, phase shift, secondary duty-cycle, and primary duty-cycle) are proposed and discussed subsequently. A 500 W, 110 V/160 V experimental prototype is built to verify the theoretical analysis. It shows that near-unity power factor is naturally realized for bidirectional power transmission under the proposed instantaneous-power-balance-based modulation method without closed-loop control. The highest power factor reaches 0.994 with a minimum total harmonic distortion (THD) of 2.2%. The proposed single-stage bidirectional ac-dc DAB converter adopting the instantaneous-power-balance-based modulation has the advantages of low cost, low control complexity, high reliability, easy implementation, and so on. These advantageous features make the proposed system well suited for vehicle-to-grid systems, energy storage systems, etc.