Switched-capacitor power sensing in low-power energy harvesting systems

A method for power sensing in low-power energy harvesting systems is presented. The technique utilises a small sense capacitor between the converter output and the main storage capacitor. The storage capacitor is disconnected from the converter for a short period of time and the change of sense capacitor voltage is measured. This change is proportional to the average output current of the converter for the period of the measurement, thus the relative output power can be determined using only voltage measurements. The method has been experimentally validated in a low-power energy harvesting system that employs a microcontroller-based control implementation.