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The paper presents the development of a GaN DC–DC power converter with a pre-driver module and power device based on a monolithic integrated GaN E/D-mode metal–insulator–semiconductor high electron mobility transistors (MIS-HEMTs) platform. The pre-driver module with direct coupled field effect transistor logic circuit structure has been monolithically integrated with a GaN power transistor on a Si-based AlGaN/GaN commercial epitaxial wafer. The MIS-HEMTs structure adopts an insulated gate dielectric layer to suppress the leakage current and increase gate voltage robustness. The GaN-based floating buck converter employs a 1 mH inductor and a 9 μ F capacitor to achieve 35 V–5 V power conversion. As a result, the pre-driver module is capable of delivering a 10 V driving voltage. GaN monolithic integration of the pre-driver module and power device can reduce the system area in the DC–DC application, which allows for an integrated chip size of 1.8 mm2. [ABSTRACT FROM AUTHOR]

This paper presents a monolithic GaN driver with a deadtime generator (DTG) for half‐bridge DC‐DC buck converters. The proposed GaN integrated circuits (ICs) were fabricated in a 3 µm enhancement‐mode GaN MIS‐HEMTs process. The integrated DTG converter can operate at 250°C with a large gate swing of 10 V, and it exhibits a maximum efficiency of 80% at high temperatures, with VIN= 30 V at 100 kHz. The monolithic GaN DTG driver requires one control signal and generates a deadtime of fewer than 0.13 µs at high temperatures up to 250°C. The proposed DTG converter is compared to an integrated GaN converter without DTG (w/o) under various conditions. At high temperatures, the optimized GaN DTG converter shows better performance than the GaN converter w/o at high load currents, in terms of smaller voltage overshoots and better efficiency as well. This work demonstrates a simple GaN deadtime method for high temperature (HT) GaN power converters. [ABSTRACT FROM AUTHOR]

As one of the promising power interfaces between the energy storage components and the dc link, dual active bridge (DAB) converters have gained extensive researches. Its reliability and healthy operation under one or even multiple unexpected open-circuit faulty conditions have become one of the main design challenges. Conventional fault detection (FD) and fault isolation (FI) methods exhibit obvious limitations in terms of detection speed, number of FD signatures, universality, accuracy, computational burden, and implementation cost due to the added sensors. To fill in this gap, this article presents a robust, fast, accurate, and low-cost FD and FI method for DAB converters, which is applicable under various operational conditions. The proposed method will adopt the differential switch node voltage between the primary and secondary bridge of DAB converters as the universal fault signature for complete FD and FI. The corresponding fault diagnostic circuit is simple, compact, low cost, and easy in implementation. This sensorless fault diagnostic technique can detect the switch open-circuit fault within a quarter of a switching cycle and realize the fault isolation accurately. A DAB prototype with a fault diagnostic circuit was designed, and main experimental results under various faulty conditions were provided to validate the advantages of the proposed method. [ABSTRACT FROM AUTHOR]

The partial power processing (PPP) concept has been extensively employed in many two-port converters to achieve high efficiency and high-power density by modifying one of the original converter ports to be connected in series between input and output. This is attractive but is confined to two-port applications, and how to extend it to multiport applications is not clear. Hence, this article aims to explore a generalized PPP multiport scheme by arranging the connection of the module rather than the converter. For a PPP single-input(output)-N-outputs(inputs) converter, one terminal of all N+1 modules is connected together to construct a radial structure, and another terminal is series/parallel connected with the input/output port. Each module only needs to process partial power caused by the voltage or current difference between input and output. Therefore, the required power rating of components is effectively reduced, contributing to low cost as well as low power loss. In this article, a PPP single-input dual-output converter with active bridge modules is also taken as an example to be introduced in detail, designed and experimented upon, which validates that high efficiency and high-power density can be achieved. [ABSTRACT FROM AUTHOR]

Dual-active-bridge (DAB) converters have been widely recognized as one promising topology for high-frequency-link power conversion applications. However, one critical issue concerning DAB converters is the transient dc-bias current due to the voltage-second imbalance, which may occur frequently in typical dynamic operations of DAB converters such as the start-up, sudden load or output voltage change, and power flow direction change. Due to the high-frequency operation, the dc-bias current of DAB converters will impose more harm to magnetic components because of the limited range of operating flux density and possible magnetic saturation compared with the counterpart low-frequency dc-bias current. Over the past several years, extensive researches have been conducted to address the high-frequency transient dc-bias current of DAB converters under different phase-shift modulation strategies such as single phase shift, extended phase shift, and triple phase shift. In this article, a comparative review of typical dc-bias current mitigation strategies under typical phase-shift strategies for DAB converters is presented. An experimental evaluation of selected strategies under various scenarios is conducted in terms of the settling time, inductor current stress, efficiency, switching number, and implementation complexity. This article ends up with an overview of high-frequency dc-bias mitigation strategies and a discussion for the further optimization. [ABSTRACT FROM AUTHOR]

The dc power transmission system has been obviously attracting more research interests in recent years. In order to satisfy the high-reliability requirement of the dc power transmission system, the power converter should be able to keep uninterrupted operation after multiple unexpected faults. However, high fault-tolerant capability usually leads to the bulky redundant circuit, which increases the cost, volume, and complexity of the power converter. Thus, a fault-tolerant dual active bridge (DAB) converter is proposed to maintain the power transferring ability under multiple unexpected open-circuit faults (OCFs) conditions, which can significantly enhance the reliability of the dc power transmission system. By reconfiguring the central-tapped transformer and two symmetrical auxiliary inductors, the half-bridge conduction branch is built to maintain uninterrupted operation when a single or dual OCF has occurred. The proposed fault-tolerant strategy only requires four extra voltage sensors to detect and locate OCFs for the reconfiguration process. Thus, it significantly improves the system reliability with a low additional cost. Besides, the inductor current, transmission power, and the small-signal models of the proposed fault-tolerant converter have been presented. It proves the proposed fault-tolerant topology can smoothly switch between normal and postfault operation due to the constituency of the inductor current. Finally, the 250-W prototype is designed to verify the advantage of the proposed fault-tolerant DAB converter. [ABSTRACT FROM AUTHOR]