A Wireless Energy and Thermoelectric Energy Harvesting System for Low Power Passive Sensor Network

In this paper, a combined solution using underground temperature difference energy and wireless energy to provide power for wireless transmission is proposed. A thermoelectric power generation system is in series with wireless energy transmission system to charge a 4.2V lithium battery. The whole system uses the temperature difference between the ground and the surface to produce power and a 915MHz circularly polarized antenna is used as the receiving source. At a distance of 1.5m from the RF source which has a transmitting power of 20dBm, the real-time voltage obtained from a triple voltage conversion circuit is 1.38V, which is adequate for subsequent circuit boosting. Experiments show that after a day of testing, the thermoelectric system can provide 463.126J energy for charging under good weather conditions. The entire power management circuit uses passive components to save power. The measured results demonstrate that the combined power supply system is feasible for wireless sensor network applications.