Electricity Monitoring System with Interchangeable Piezoelectric Energy Harvesters and Dynamic Power Management Circuitry

Real time electricity monitoring is critical to enable intelligent and customized energy management for users in residential and commercial buildings. Piezoelectric (PZT) energy harvesters (EHs) and sensors have been studied extensively and used for such application. One of the main application requirements is to design a cheap and robust system with flexibility to work with different PZT EHs without adjusting the circuit, enabling low-cost system upgrade or maintenance. This work aims at providing a low-cost and easily-maintainable solution to build wireless sensor network (WSN) for real-time electricity grid monitoring. This paper presents the design and integration of a self-contained, noninvasive system tested with two types of PZT EHs. The system is powered by EH, thus battery-less. The customized interface circuitry is designed to collect and regulate the energy from the EH. The dynamic power management ensures the system to work with two different EHs at a wide range of output power from micro-watt to milli-watt. The unit can achieve a read-transmit duty cycle from <; 1min up to 18min, depending on the characteristics of different EHs and intensity of current passing through the wire being monitored, and is robust against unstable power input.