Development of Hybrid Energy Harvester for Low Power Devices in IoT Application

Abstract

In combining multiple energy harvesters from different sources, there is a problem caused due to varying direct current (d.c.) which reduces coupling efficiency and total working of the system. Thus, in this research a hydridizing system is designed in which the blocking oscillator is used as an energy combiner to improve on the coupling efficiency and enhance the system's working operation. The hybrid harvester comprises of a blocking oscillator, radio-frequency (R.F) harvester and piezoelectric harvester. The blocking oscillator is made up of four inductors all wounded on a single toroid with three transistors as switches for the input. R.F. harvester was designed using copper coil as antenna to receive the necessary power needed. Piezo-electric harvester was designed using piezo elements arranged in parallel to each other on a board. Solar panel with dimension 238 by 140 by 17mm was used for solar energy harvester. The result of the system was that it was able to power a sensor of 3V and charge a 10V super-capacitor even at a low level of 0.3V. it attained 90% efficiency. In conclusion a hybrid energy harvester with an improved combining system was successfully developed which achieved better performance at maximum working condition and was still able to give a manageable performance at low working condition.