Closed-Loop Detection System for a MEMS Resonant Voltage Sensor Based on Phase-Sensitive Detection

Voltage measurement is a fundamental requirement for the intelligence and digitalization of modern power grids. Benefiting from their low power consumption and miniaturized design, Micro-Electro-Mechanical System (MEMS) voltage sensors can achieve voltage detection via non-intrusive electric-field measurement, while a high-performance closed-loop detection system is essential to ensure measurement accuracy. This article presents a closed-loop detection system based on phase-sensitive detection (PSD). The sensor electrodes are reconfigured to form a differential detection structure, effectively suppressing common-mode interference and parasitic coupling. A dual closed-loop circuit integrating a phase-locked loop (PLL) and automatic gain control (AGC) are implemented to stabilize the reference signal and enhance the accuracy of PSD. Furthermore, a low-power design strategy is adopted to reduce overall power consumption. Experimental results show that the proposed system achieved a linearity (R²) of 0.9989, a minimum relative deviation of 0.01%, and a total power consumption of 57.6 mW. These results indicate that the proposed system provides an effective balance among precision, stability, and power efficiency, offering reliable technical support for the engineering applications of MEMS voltage sensors in smart grids.