This paper develops a 200 W two-stage rail grade dc-dc module based on gallium-nitride devices. It converts a wide input voltage (64-160 V) to a constant output voltage (24 V). Different devices and topologies are evaluated for the target application, based on which a two-stage configuration is proposed. The first stage is a two-phase regulated buck converter working under critical mode (>400 kHz), which is followed by an unregulated 48-V/24-V LLC converter (2 MHz) for 3000-V dc isolation. The voltage regulation is discussed for the buck converter when the inductors are negatively coupled, and then the zero voltage switching (ZVS) extension is explored. However, due to the limitation of the digital controller, a tradeoff is made between the dynamic response and the footprint. The compromise solution is to use a small and slow microcontroller for high frequency control (including voltage regulation, critical mode operation, phase interleaving) and various demands (including soft start-up, external communication, and various protections). Finally, all the required functions are verified in a standalone quarter-brick prototype module. It can achieve 95.1% peak efficiency and 130 W/in3 power density.

中文翻译：

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用于铁路应用的基于 GaN 的 DC__C 模块：设计考虑和高频数字控制


本文开发了一种基于氮化镓器件的 200 W 两级导轨级 DC-DC 模块。它将宽输入电压 (64-160 V) 转换为恒定输出电压 (24 V)。针对目标应用评估不同的器件和拓扑，并在此基础上提出两级配置。第一级是在临界模式 (>400 kHz) 下工作的两相稳压降压转换器，后面是一个用于 3000V 直流隔离的非稳压 48V/24V LLC 转换器 (2 MHz)。讨论了电感器负耦合时降压转换器的电压调节，然后探讨了零电压开关 (ZVS) 扩展。然而，由于数字控制器的限制，需要在动态响应和占地面积之间进行权衡。折衷的解决方案是使用小而慢的微控制器来实现高频控制（包括电压调节、临界模式操作、相位交错）和各种需求（包括软启动、外部通信和各种保护）。最后，所有必需的功能都在独立的四分之一砖原型模块中得到验证。它可以实现95.1%的峰值效率和130 W/in3的功率密度。