Thermo-electric Energy Harvesting Powered IoT System Design and Energy Model Analysis

Power consumption of micro-controllers and sensor systems have been greatly reduced in the last decade, new power supply method such as energy harvesting is now an alternative method to power Internet of things (IoT) devices. A few square centimeters sized thermo-electric generators (TEGs) can convert a few degrees Celsius temperature gradients into milli-watts of electric power. This paper presents the design of a TEG energy harvesting powered LoRa IoT device. The power management circuits design, super-capacitor energy storage unit and the IoT low power algorithm are introduced. The system demonstrated the TEG power generation of 0.4-12 mW, IoT device current consumption of 79 mA in data transmission mode, less than 50 μA in sleep mode. With super-capacitor energy storage unit, the IoT device can be powered entirely from thermo-electric energy without batteries. In addition to the system implementation, a comprehensive simulation model is created to optimize the form factor of TEG, selection of the super-capacitor and the operation duty cycles of IoT devices.