Reliable interruption of high fault currents in compact DC systems remains a key technical challenge, especially for next-generation power electronics and mobility applications. This study aims to develop a robust interruption strategy by coordinating a current-limiting fuse and a pyrofuse through active sensor-based control. Especially, by estimating the current-limiting fuse resistance in real time from voltage and current measurements, the system accurately identifies the completion of current-limiting and operates the pyrofuse at the optimal moment. Experimental validation confirms that a 750V DC fault can be interrupted within 3.4ms using compact, low-cost hardware. The proposed method offers a reliable control method for DC fault protection in powerful, space-constrained applications.

Compact and cost-effective DC circuit breakers are becoming increasingly crucial as the prevalence of household solar panels and electric vehicles for a sustainable society. For this demand, a current-limiting fuse, which can limit current flow, and a pyrofuse, which physically interrupts circuits by detonating gunpowder, have been focused on as practical and compact components. This paper presents an active control of a pyrofuse in a compact circuit breaker consisting of a current-limiting fuse and a pyrofuse in series connection. The system interrupts fault currents by first limiting the current through the current-limiting fuse and then activating the pyrofuse to interrupt the circuit. The pyrofuse is activated based on a real-time estimation of the current-limiting fuse, developed in our previous research, which detects the end of the current-limiting by utilizing a real-time current data. This system safely interrupts fault currents that each component alone is unable to handle. The effectiveness of this breaker has been validated through experiments, with the interruption of a fault current of 1.7 kV and 10 kA occurring within 8.3ms.

Hybrid DC circuit breakers have become a critical choice for ensuring safety in modern DC transmission and distribution systems. In this paper, we validate a current path control strategy in the fuse-semiconductor hybrid circuit breaker. This strategy utilizes an RC circuit model to describe the arcing current of the fuse and applies the Recursive Least Squares (RLS) algorithm to minimize the difference between the modeled current and the observed current data in real-time. By presenting the fuse’s current-limiting state in real-time, this method effectively prevents re-arcing and potential fuse explosions. Our approach addresses the limitations of the predetermined current threshold method, enabling a more accurate current model in complex situations. The proposed strategy was experimentally validated under extreme conditions of 1.7 kV and 10 kA fault currents, demonstrating its robustness and reliability.

A method to generate wind based on electrohy-drodynamics (EHD) using corona discharge has been applied to various thrust-producing devices. However, the relationship between electrode structure and wind-induced thrust is still unclear, and electrode design guidelines have not yet been established. Therefore, this paper aims to formulate the relationship between the thrust and electrodes' configuration by taking continuous data from experiments. Experiments were conducted to investigate the change in thrust when the gap between electrodes was varied continuously, and when changing the shape of electrodes, after a preliminary experiment on the relationship between voltage polarity and thrust. Experiments revealed that thrust increased as the gap decreased at the same voltage, thrust began to be generated at a lower voltage when the emitter electrode was needles than when it was a wire. From these experimental results, it was demonstrated that the thrust was expressed as a linear equation of voltage, that there is an inverse proportion-like relationship between the gap and thrust, and that the corona discharge inception voltage became lower when needles were used as the emitter electrode, where the voltage applied, instead of a wire. These findings and considerations will greatly help to establish guidelines for designing devices using this method, which generates thrust without any moving parts.

A corona discharge is a kind of self-sustaining discharge that is generated by applying high voltage to asymmetric electrodes. The thrust by the corona discharge is expected as a new actuator since it has no moving parts, is quiet, and is robust. However, the relationship between the applied voltage and the thrust is highly nonlinear, which means that this problem must be solved by control. Furthermore, a control system that compensates for disturbances such as wind and modeling errors is also required. Therefore, this paper proposes a control system with a voltage range limitation that takes into account the characteristics of corona discharges and the disturbance observer to improve disturbance suppression characteristics. Two experiments were conducted to confirm the effectiveness of the proposed method. The first experiment shows that the proposed method improves the response speed by 70.0% in step response. The second experiment indicates that the proposed method enhances the response speed by 60.0% in disturbance response and suppresses angle change by 42.3%. Through experiments, it is confirmed that the proposed method succeeded in attitude control on the centimeter order and improved control performance.