Low-power low-voltage AC-DC converters for electromagnetic energy harvesting with efficient indirect feedback scheme

In this study, two single-stage AC-DC converters for low-voltage electromagnetic energy harvesting are presented. The converters are designed to boost very low AC voltage (hundreds of millivolts) to a high DC voltage (3.3 V DC). The successful operation of such systems depends on proper development of control and driver circuits. The converters also need to be designed in proper accordance with the associated microgenerator. Detailed discussion on the design and selection of critical components of the converter is also presented. Low-power driver circuits are used to enable a self-sustaining system. Unlike DC-DC converters, direct AC-DC converters generally do not have a common ground. Such a structure makes implementation of feedback and control difficult. A novel indirect feedback strategy is proposed to solve this problem. The idea is to obtain the output voltage information referenced to the system ground. The feedback circuit is very simple to implement and consumes very low power. An auxiliary supply has also been designed to provide power to the gate drivers. It is shown that the indirect feedback strategy also works for load variations. Both simulation and experimental results with a suitable microgenerator are presented to verify the self-sustainable efficient operation of the harvesting systems.