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The article classifies, describes and critically compares different modeling techniques and control methods for dual active bridge (DAB) dc-dc converters and provides explicit guidance about DAB controller design to practicing engineers and researchers. Firstly, available modeling methods for DAB including reduced order model, generalized average model and discrete-time model are classified and quantitatively compared using simulation results. Based on this comparison, recommendations for suitable DAB modeling method are given. Then we comprehensively review the available control methods including feedback-only control, linearization control, feedforward plus feedback, disturbance-observer-based control, feedforward current control, model predictive current control, sliding mode control and moving discretized control set model predictive control. Frequency responses of the closed-loop control-to-output and output impedance are selected as the metrics of the ability in voltage tracking and the load disturbance rejection performance. The frequency response plots of closed-loop control-to-output transfer function and output impedance of each control method are theoretically derived or swept using simulation software PLECS and MATLAB. Based on these plots, remarks on each control method are drawn. Some practical control issues for DAB including dead time effect, phase drift and dc magnetic flux bias are also reviewed. This paper is accompanied by PLECS simulation files of the reviewed control methods.

In many DC/DC converters applications, classical proportional-integral control is often considered. However, when complex converters structures, such as Dual Active Bridge converters, are considered, several challenges may be faced in the control design. In fact, achieving an accurate Dual Active Bridge model may be complex, considering that the small signal model of the circuit varies according with its operating mode. Moreover, Dual Active Bridge converters usually requires a robust control design, due to their high input/output voltage ratio and power level. In order to address these issues, a Moving Discretized Control Set - Model Predictive Control is introduced. The proposed control can achieve faster dynamics and stable operation throughout the power and terminal voltage ranges, considering global control parameters. It also presents a fixed switching frequency with low computational burden, due to the use of only two prediction horizons. Experiments on a 20kHz 1kW Dual-Active-Bridge converter are carried out to verify the effectiveness of the proposed control technique.

An Active-Bridge-Active-Clamp (ABAC) topology with its associated switching patterns and modulation techniques is introduced in this paper. The topology has been designed to comply with stringent power quality requirements in a More Electric Aircraft (MEA) application. The dual transformer secondary structure of the ABAC allows the definition of a particular phase shift based switching pattern. The proposed switching pattern ensures not only the output current switching harmonics elimination but also even power sharing between the secondary half bridges. Consequently, passives on the low voltage side of the converter are minimized and transformer DC bias is eliminated. All these features can be achieved independently from the operating point of the converter. In this paper, the basic operation of the ABAC converter is firstly introduced. Theoretical analysis of switching harmonics elimination and power sharing is then carried out in the development of the proposed switching patterns. The theoretical claims are validated by both simulation and experimental results on a 10kW 270V/28V ABAC converter.

A Phase-Shift-Modulation (PSM) technique is proposed for an Active-Bridge-Active-Clamp (ABAC) topology. This topology is aimed for high power more-electric-aircraft applications. The proposed PSM has a complete switching harmonics cancellation on the low voltage terminal, independently of the operating conditions by effectively interleaving inductor currents. This results in a DC current at the low voltage terminal without any AC components, thus minimizing the passive filtering requirements. Additionally, when terminal voltages vary from their nominal values, the maximum power transfer capability of the ABAC converter can be greatly improved by using the proposed PSM. In this paper, the limitations of the conventional modulation technique for the ABAC converter are introduced and analysed. Then, a PSM scheme is proposed, which can provide high quality power on the low voltage terminal whilst maintaining high power transfer capability and efficiency in a wide operating range. The theoretical claims are validated by both simulation and experimental results on a 10kW 270V/28V ABAC converter.

High performance power conversion equipment is currently gaining an increasing interest for aircraft applications. In particular, isolated bidirectional DC/DC converters are often proposed for modern HVDC aircraft distribution systems. For such reason an evaluation of several isolated DC/DC converter topology is carried out considering the proposed application, interfacing a 270V DC network with a 28V DC network. A trade off evaluation has been carried out for three different topologies and an experimental prototype has been manufactured for the selected conversion architecture. Simulation and experimental results are provided in order to validate the trade off and the design of the proposed converter.