Analysis of self-oscillating switched-mode circuit for low-voltage energy harvesting

The operation of a self-oscillating switched-mode circuit topology for low-voltage thermal energy harvesting is analysed and experimental efficiency results are presented. Circuit self-start-up function as well as high-efficiency power transfer are obtained by using only one transformer without additional inductors. It is shown that even without using a maximum power point tracking (MPPT) tracking circuit, it is possible to achieve efficiencies up to 65% over a relatively broad input voltage range which can be optimised by properly varying the transformer turns ratio n.