Design and Implementation of a Non-Contact Power Meter Using TMR Sensing and Capacitive Coupling

Monitoring and regulating power consumption are imperative for enhancing the efficiency and reliability of modern electrical infrastructures, including smart grids, renewable energy systems, and electric vehicles. However, conventional power meters necessitate direct galvanic contact with energized conductors, posing significant integration and safety challenges. This paper proposes a novel non-contact power meter that leverages a tunneling magnetoresistance (TMR) current sensor integrated with a non-intrusive voltage sensor based on spatial capacitive coupling. Notably, the voltage sensor output is ingeniously utilized to provide the bias power for the TMR current sensor, facilitating a direct proportional relationship between the aggregate output and the line power. A dedicated hardware prototype was developed to evaluate the linearity and phase performance under controlled installation conditions. Experimental results demonstrate that within a measurement range of 0–2500 W at 50 Hz, the sensor achieves high-accuracy performance with a full-scale error of less than 0.7% FS and a sensitivity of 0.44 mV/W. The proposed solution provides a robust and efficient alternative for non-contact power monitoring in residential and industrial grid applications.