Design of a Low Power Hybrid Energy Harvester System Using Radio Frequency, Thermal and Vibration Inputs for Mobile Phone

Nowadays, mobile phones become effective devices for various daily tasks. However, their batteries need to be charged in order to perform the heavy multimedia and applications tasks that run on them. This research presents a design of Low Power Hybrid Energy Harvester (LP HEH) system used for self-charging of mobile phones. In this HEH design, three input sources (thermal, vibration and radio frequency) are combined to improve the system performance and overcome the limitation issue of a single source energy harvester. The inputs are set to 0.02V DC, 0.5V AC with the 2 kHz and −20dBm with 915MHz for Thermal, Vibration and RF sources respectively. LP HEH circuits are designed and simulated using PSPICE software. Rectifier is used to convert the AC voltage produced by vibration source to DC voltage. To step-up the small voltage harvested by thermal and vibration sources, boost converter is used. Meanwhile, the frequency of RF waves is quite high, so the voltage multiplier is used to rectify and step up the input voltage. LC resonant circuit is used to amplify low RF ambient input passively before using voltage multiplier. The proposed design of LP HEH is able to achieve output of 4.2V which is sufficient for charging mobile phone.