A Low-cost Miniature DC/AC-compatible Switched-Rogowski Current Sensor

The power grid is undergoing a significant transformation as an increasing number of distributed energy resources (DERs), often a combination of DC and AC resources, are integrated into the grid. As essential blocks in metering and control systems for the integration of DERs, low-cost sensors with small form factor, easy installation, and AC/DC measuring capability are needed. This paper presents a low-cost, miniature sensor for DC/AC current measurement using incorporated switching elements with wide range and bandwidth. Compared to traditional solutions such as shunt resistor combined with isolation amplifiers, the proposed design retains a lower cost and overcomes the challenges posted by amplifier offset - a critical issue in high-current sensing applications. Its operating principles, frequency response, system design, and architectural variations are presented. Design considerations are discussed, along with design variations for series element, shunt element, or inherent switched-current sensing scenarios. A hardware prototype is built to validate the proposed operation, and the experimental results are presented. A miniaturized full sensor system implementation with 1-kV and 1-kA rating, a size of 35 mm x 57 mm, and local data processing and communication capability is also constructed.