Architecture of Low Power Energy Harvester Using Hybrid Input Solar, Peltier Thermo Electric and Vibrational Generation

This project presents the efficient design and development of ambient energy harvesting system based wireless sensor networks (WSN). In this system Super capacitor is used as storage device instead of batteries, which eliminate the complication of replacing the batteries at regular intervals thus developing sustainable and self-powered wireless sensor nodes. This project utilizes photovoltaic cells to sustain energy buffers in the form of super capacitors instead of batteries. Combined with power efficient algorithms, we can increase the lifetime of sensor network nodes using charging mechanisms. In the hybrid architecture, three input sources (PV, thermal and vibration) are combined in parallel to solve the limitation issue of a single source energy harvester and to improve the system performance. Energy will be scavenged from the environment for thermal and vibration sources by converting directly temperature difference and vibrational movement to electrical energy. Vibration produces AC input and will be converted to DC using a rectifier. A converter is used to boost the two sources (thermal and vibration) and DC-DC converter is proposed to step-up these small input sources. Here also proposed a frequency regulation technique to provide constant efficiency at all loads because of the incessant problems of using a Pulse Width Modulation pump with fixed frequency that leads to low efficiency at low load conditions. The team presented a wireless energy harvesting unit in the first instance that uses only a single stage voltage multiplier which they extended to three stages in order to harvest energy much more efficiently with a Low-dropout regulator that cannot boost the rectified voltage. But with a regulated Charge pump they were able to boost the battery voltage up to 3.7 times the input DC Voltage.