High-Bandwidth Control of Unfolding-based AC-DC Converters

Benefit

High-bandwidth control is vital for preserving grid-side power factor correction and enhancing output power regulation but achieving it can be challenging to implement without affecting the stability of the converter. LC resonance adversely affects closed-loop control, reducing the phase margin and rendering the closed-loop system unstable. Conventionally, large passive damping networks are employed to address this issue, but they substantially raise system cost and reduce power density — problems that worsen at higher power levels. 

To eliminate reliance on bulky passive damping networks, this work introduces a software-implementable control method to actively damp LC resonance and enable high-bandwidth control. Simulation studies and hardware tests show that the proposed controller can increase achievable bandwidth by an order of magnitude compared to the undamped case. The approach is aimed at improving the stability and dynamic performance of T‑type bridge dc–dc converters in unfolding-based ac–dc systems, particularly for power factor correction and output power regulation, while avoiding the size, cost, and power‑density drawbacks of conventional physical damping networks. 

This technology unlocks wider adoption of efficient unfolding-based converters by eliminating bulky passive damping networks, while simultaneously boosting control bandwidth. By enabling software-configurable active damping and allowing adaptation of permissible LC resonance for different applications, it delivers higher power density, lower system cost, and improved dynamic performance. 

Market Application

This innovation targets the power conversion equipment market. As governments, businesses, and consumers accelerate adoption of electrification and green technologies, demand for uninterrupted power solutions is growing, increasing the need for advanced rectifiers and converter systems. By improving performance while reducing size and cost, this technology can help power-conversion manufacturers meet rising market demand and support broader electrification efforts.