Design of an Energy Harvesting Interface Circuit Consecutively Powering Two Loads

Abstract

ABSTRACT This paper presents an energy harvesting interface circuit for a single ambient energy source that consecutively delivers power supply to two loads including one light load and one heavy load. The proposed circuit consists of a step-up converter, a temporary storage element (e.g. supercapacitor), two charge control circuits for the loads, and two power transistors. The converter receives low-voltage from the output of the energy source to charge the supercapacitor at the output of the converter to high voltage levels. The supercapacitor delivers energy to the light load through corresponding control circuit. Due to the light load, the generated energy by the energy source is greater than the required power by the load. This results in accumulating the surplus energy into the supercapacitor. Once the supercapacitor stores sufficient energy, the energy direction from the supercapacitor is shifted from the light load to the heavy load. Once the supercapacitor discharges to a voltage level where the heavy load stops to receive power supply, the energy direction will be toward to the light load again. The same powering pattern will be repeated over the time. As a result, these loads operate in burst mode. The proposed circuit, constructed with off-the-shelf components, regulates outputs to nearly 3.9 V, starts the operation from an input voltage as low as 0.1 V and achieves a peak efficiency of 73.29%. The proposed circuit provides the highest output power of 124.14 mW which is greater than prior IC work supports. Apart from the highest output power, the proposed circuit meets the goal of self-sustainability since there is no need of extra power source (e.g., battery) other than the ambient energy source.