An Active Power Decoupling Method for Single Phase DC/AC DAB Converters

Abstract

The existence of the double grid frequency (100 Hz) ripple current in dc/ac dual active bridge (DAB) power converters can degrade their performance and as such these ripples need to be compensated. An active power decoupling method is proposed in this paper to attenuate the 100-Hz current ripple in single phase dc/ac DAB converters. Compared to other current ripple reduction methods for which additional switches are used, the proposed method does not require any additional switching components thus decreasing the system cost. In the proposed method, the existing switching devices of the primary side full bridge converter and an LLC circuit integrated to form a 100-Hz ripple current reduction circuit, which is controlled by regulating the duty cycle of the primary full bridge converter switching legs. The mathematical analysis and the circuit parameter design methods are proposed. In addition, a current sharing method is proposed to keep the currents of the inductors in the LLC circuit are balanced against any possible circuit parameter deviations. The effectiveness of the developed method is evaluated through the simulation and experimental tests.

Operation Characteristics of Discontinuous Current Mode for a Dual-Active-Bridge AC-DC Converter with an Active Energy Buffer

“…Generally, a small-capacity film capacitor is used as and an energy storage element, and absorbing the power pulsation is achieved by controlling its voltage. So far, circuit topologies with the auxiliary circuit at single-phase AC power supply side (10) (11) , DC link section (12) , high-frequency link section (13) (14) , and DC output side (15)- (17) have been proposed. However, these schemes have a problem with the size of the auxiliary circuit for voltage control of the added small capacitor.…”