Variable Dead-Time Based Novel Soft-Start Method for Dual Active Bridge Converters

Electrical engineers Sachith Wijesooriya and Sandun S. Kuruppu have published a paper detailing a breakthrough in power converter startup safety. Their novel "Variable Dead-Time Based Soft-Start Method" specifically targets Dual Active Bridge (DAB) converters, which are crucial components in modern power systems for applications like electric vehicle charging and renewable energy integration. The core innovation lies in dynamically adjusting the dead time—the brief period where both switches are off—during startup, gradually reducing it from nearly a full switching cycle down to the hardware's minimum limit. This controlled approach allows the secondary-side voltage to build smoothly, unlike conventional methods that often cause abrupt surges.

Simulation and experimental validation on a substantial 15 kW hardware platform confirm the method's effectiveness. Traditional startup techniques were shown to produce severe voltage overshoot and high inrush currents, which can damage components and reduce system lifespan. In contrast, the proposed method achieves a gradual voltage rise with well-regulated current profiles, effectively suppressing these dangerous transients. The technique's simplicity and hardware-friendly design mean it can be easily implemented on standard microcontrollers without complex additional circuitry, making it a versatile and practical solution for enhancing the reliability and safety of nth-order DAB architectures in real-world applications.