Research on Synchronous Rectification Driver Technology of High-Frequency DC-DC Resonant Converter Based on GaN Devices

Jiqing Dong,Xingkui Mao,Yiming Zhang,Youtu Lin,Zuyuan Li

doi:10.1109/access.2021.3131563

Jiqing Dong, Xingkui Mao + Show 3 more

Open Access

https://doi.org/10.1109/access.2021.3131563

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Abstract

With the increase of switching frequency to tens of MHz, the synchronous rectification faces many new challenges, among which a significant one is the design of the driver circuit for the synchronous rectification with wide bandgap gallium nitride (GaN) devices. According to the self-resonant driving theory, this paper proposes an in-phase feedback synchronous rectification driver circuit (SRDC) based on GaN devices and the driver chip. In this SRDC, the nonlinear parasitic capacitors are replaced with external capacitors, and the synchronous driving signal is in-phase with the excitation source. The new scheme can provide precise driving timing, stable driving amplitude and flexible phase-shifting characteristics for the synchronous rectification of a high-frequency DC-DC resonant converter (HFDRC) based on GaN devices. In this paper, a detailed parameter design method is introduced by analyzing the characteristics of the feedback network. The feasibility and effectiveness of the proposed SRDC are verified on a 20 MHz prototype with 18 V input and 5 V / 2 A output.

Highlights

Increasing switching frequency of converters can significantly reduce the volume and weight of passive components, increase the power density and the dynamic response [1]-[4]
OPERATING PRINCIPLE OF PROPOSED synchronous rectification driver circuit (SRDC) Aiming at the problem that the design flexibility of the feedback network in the traditional SRDC is limited by the parasitic parameters of QSR, this paper proposes an in-phase feedback SRDC with external capacitors
Due to the shortcomings of oversensitive parameter adjustment and unstable feedback network, the traditional SRDC is not suitable for synchronous rectification based on gallium nitride (GaN) devices at tens of MHz

Summary

INTRODUCTION

Increasing switching frequency of converters can significantly reduce the volume and weight of passive components, increase the power density and the dynamic response [1]-[4]. If the gate source or drain source of QSR was paralleled with capacitors to obtain a stable driving signal, the working state of QSR would be affected This self-resonant SRDC greatly limits the stability of the driving signal and the freedom in the feedback network design. This paper proposes an in-phase feedback synchronous rectification driver circuit (SRDC) with external capacitors for GaN devices. The SRDC keeps the excitation source signal and the synchronous driving signal, vS, in-phase, which greatly improves the flexibility of the feedback network design to adjust the amplitude-frequency characteristics of vS. It consists of a driver chip LMG1020 and a feedback network that is composed of external capacitors CS1 and CS2, inductor LS, resistor RS, and DC bias source Vbias, where no additional comparator is required. VS will always be lower than VL, making QSR straight on

FEEDBACK NETWORK OF PROPOSED SRDC

LS CS1

EXPERIMENTS

CONCLUSION