Impact on ZVS Operation by Splitting Inductance to Both Sides of Transformer for 1-MHz GaN Based DAB Converter

Abstract

Zero-voltage-switching (ZVS) of dual active bridge (DAB) converter and its range extension have been studied intensively. However, this paper proves that the external inductance location, i.e. placing on which side of the transformer, does affect the ZVS operation due to transformers' parasitic capacitances, in particular at a high switching frequency of higher than 1 MHz. Thus, this paper, for the first time, gives the mathematical model of the resonant transition during the dead time and thereby analyzes partial hard switching under different modulation schemes with consideration of transformer's parasitic capacitances. From the analysis of ZVS operation, the solution of splitting the interfacing inductance and placing them on both sides of the transformer is proposed and its associated methodology of selecting these inductances is introduced. It extends the ZVS for all the switching devices, therefore, enhance the efficiency or move losses away from the critical semiconductor devices. Finally, the theoretical analysis is verified by the experimental results from a 1 MHz Gallium Nitride (GaN) based DAB converter prototype.

Advancements in energy efficientGaNpower devices and power modules for electric vehicle applications: a review

“…The converter topologies such as LLC resonant, dual active bridge (DAB) and phase shift full bridge (PSFB) are widely used in EV applications. [96][97][98] However, there are several critical issues while designing these converters. The DAB converter can achieve the wide output voltage range and inherent reactive current generation.…”

Artificial Intelligence Assisted Parametric Design by Splitting Inductance in Dual Active Bridge Converter

“…Throughout theoretical analysis and simulations in [2], it is revealed that the existence of Cp1 and Cp2 leads to a nonsinusoidal switching-node voltage Vac1. The increase of the high-voltage side external inductance Le1 forms a quasisinusoidal Vac1 which further reduces the minimum dead time to achieve ZVS.…”

“…When selecting the dead time Td to be 6 ns, Le1 should be between 2 µH and 18.4 µH while Le2 is within 100 nH and 1.125 µH to ensure the ZVS. The detailed calculation process can be found in [2].…”

“…INTRODUCTION ubstantial research has been performed for dual active bridge (DAB) converters since it was proposed in [1]. Through decades of development, the DAB converter is widely employed in various industrial applications such as electric vehicles, fuel cell power conversion, renewable energy storage system, etc [2] [3]. With the desire for higher efficiency and higher power density power converters, the operating frequency is usually increased to megahertz (MHz) range [4].…”

“…However, under high operating frequency, the transformer's parasitic capacitances become non-negligible, which can cause the current resonance and the narrowing of the ZVS region [6]. To mitigate the current resonance, the approach of distributing the external inductance on both sides of the transformer is introduced and analyzed in [2]. With the consideration of more parasitics, the converter model becomes more complicated and makes it harder to derive a precise analytical model.…”