A universal topology based on buck-boost converter with optimal resistive impedance tracking for energy harvesters in battery powered applications

This paper presents a universal topology based on buck-boost converter for energy harvesters used in battery powered applications. This topology can operate with both dc and ac harvesters and provides optimal resistive impedance tracking feature to allow for maximizing harvested energy. The ac-dc conversion is done in a single stage without utilizing a bridge rectifier at the input, unlike the conventional topologies for energy harvesting. That results in reducing voltage drop and power losses enabling the topology to be used with relatively low-voltage harvesters without increasing system complexity related to using synchronous bridge rectifiers. Also, bias supply scheme and gate drives needed with this topology are discussed and shown in this paper. Experimental results show the capability of the topology to operate with 50 Hz, 1.2V electromagnetic harvester with 6–7Ω optimal resistive impedance and provide perfect matching as desired at different battery voltage levels changing from 3.7V to 12V. The topology, with off-shelf discrete components, achieves efficiencies between 70–80% depending on cells' voltages which is comparable to the state of the art approaches that run at the same conditions, can work only with dc harvesters and do not provide impedance matching.