The dual-active-bridge (DAB) converters inherit favorite features including zero-voltage switching (ZVS) capability, wide voltage range, and natural bidirectional power flow. Facing different applications and high market requirements, conventional DAB topologies with various modulations are gradually inadequate, so topological modifications are emerged in the literature to deal with these situations. Based on their characteristics of these modified DAB topologies, in this article, we provide a comprehensive review and classification, and the methodology to modify DAB topologies is proposed. First, basic cells including input/output types, active bridges, transformers, and auxiliary high-frequency networks are introduced. Next, by combining these cells flexibly, modified DAB converters are derived, and they are classified in terms of structural characteristics and discussed in detail. Finally, the characteristics, merits, and demerits of the modified DAB converters are concluded. Evolvement history, future trends, and the derivation of new topologies are also analyzed. This article aims to present a clear picture of the general law and framework of the modified DAB topologies and give the inspiration to derive new DAB topologies to address specific requirements.

Dual active bridge (DAB) converters are widely studied for applications requiring isolation, bidirectional power flow and high efficiency. To solve the problem of limited zero voltage switching (ZVS) range and achieve seamless transition for extended-phase-shift (EPS) control, the magnetizing current is utilized and an optimized control law is proposed in this article. With the injection of magnetizing current, the two ZVS regions under EPS control will be creatively intersected with a large region, instead of disconnected or just intersected at a particular point as in previous studies. The ZVS model considering switch junction capacitors, ZVS region analysis with magnetizing current injection and power transfer characteristics are analyzed. Based on these analyses, the optimized EPS control is proposed to achieve full load range ZVS, low root-mean-square current and maximum transmission power capability. A 250 kHz, 500 W GaN-based DAB prototype is built to verify the effectiveness of the proposed solution.

The active power-decoupling (APD) method is an effective solution to handle the inherent double-line frequency ripple power in single-phase power systems. It removes the bulky passive devices and facilitates the improvement of the system power density and even the reliability. This article provides a comprehensive review of the prior-art and state-of-the-art control strategies in APD. They are categorized into four groups according to the basic control ideas of “power balance,” “harmonic suppression,” “volt-second balance/charge balance,” and “virtual impedance.” And the specific control strategies under each control idea are discussed and compared. The pros and cons of each control idea are also presented . Finally, this article draws a sketch of the global trends in APD control.

This paper proposes a voltage match (VM) control for hybrid-bridge-based dual active bridge (DAB) converter in wide voltage conversion gain applications. With the addition of an auxiliary half-bridge circuit, the topology becomes an integration of a half-bridge and a full-bridge DAB converter. Unlike other pulse width modulation generation method for DAB converters, this converter utilizes four-level voltage at one port of the transformer to obtain matched voltage waveforms within the range of twice the minimum conversion gain. Wide conversion gain, decoupling of the two power control variables and wide zero-voltage switching (ZVS) ranges can be achieved with the proposed VM control. Full load ranges of ZVS for the six main power switches can be achieved and the two auxiliary switches can also operate in a wide ZVS range. In addition, the power control is done only using two control variables and its implementation is very simple, only needing a divider and a conventional voltage regulator. These characteristics and benefits of the proposed control are verified by experimental results from a 1-kw converter prototype.

Dual-active-bridge (DAB) converter is an attractive topology to be used as a dc transformer (DCT) in the dc power distribution system. Because the voltage gain for dc transformer is relatively fixed, single-phase-shift (SPS) control is popularly adopted for the DAB converter to achieve simple power control. Aiming at increasing the light load efficiency of high-frequency DAB converter under SPS control, this letter proposes a concept to achieve full load range zero-voltage-switching (ZVS) with minimum rms current in certain voltage variation range. In the proposed method, the added magnetizing inductance creates the possibility to achieve ZVS for all power switches. The voltage gain of the converter is specially controlled by turns ratio, which is no longer the conventional unity voltage gain condition. The key parameters optimization, including the turns ratio, magnetizing inductance, and leakage inductance of the transformer, is introduced based on ZVS and current stress analysis. A 250 kHz, 400/48 V, 1000 W GaN-based DAB prototype is built, which shows performance improvements at light load.

It is a challenge for dual-active-bridge (DAB) converters to take a good balance between full-load-range zero-voltage switching (ZVS) and control complexity with a wide voltage range. Dual-phase-shift (DPS) control can extend the ZVS range greatly compared with single-phase-shift (SPS) control, and it has fewer control variables with reduced operation modes compared with triple-phase-shift (TPS) control. However, with conventional DPS control, at least a pair of switches will be operated under hard switching within a large power range, which severely reduces the efficiency, especially at the high switching frequency. To solve this problem, based on the Lagrange multiplier method (LMM), an optimized DPS control utilizing magnetizing current is proposed. In this article, the magnetizing inductance is designed to create the possibility of full-load-range ZVS achievement for all power switches. Based on ZVS analysis considering switch junction capacitors and power characteristics analysis, a power control law premised on full-load-range ZVS achievement is proposed to achieve low current stress. Finally, the effectiveness of the proposed solution is verified by experimental results obtained with a 500-W, 250-kHz gallium–nitride (GaN)-based prototype.