Abstract: A power management apparatus 20 comprises: a plurality of energy harvesting input channels 21-24; a first energy storage element connection for connecting to an energy storage element 32; an inductor connection 27; and a switching circuit 28. A controller 30 operates the switching circuit to transfer energy between the energy harvesting input channels 21-24 and the first energy storage element connection 25 by a sequence of energy transfer cycles. Each energy harvesting input channel 21-24 is allocated a plurality of the energy transfer cycles. The controller 30 determines operating parameters for operating the switching circuit 28 which transfer a maximum power from the electrical energy harvesting source connected to the energy harvesting input channel and a maximum power inductor utilisation factor. The controller 30 determines a set of adjusted operating parameters for sharing use of the inductor between the plurality of energy harvesting input channels 21-24.

Abstract: A switching circuit, electrical energy converter, power management unit and energy harvesting system are described. Such apparatus is applicable to energy harvesting applications which involve a variety of transducers, either singly or simultaneously. The transducers may, for example, be photovoltaic, thermoelectric, piezoelectric, or electrodynamic. The described converters operate to convert impedances, voltages and currents. They incorporate inductive energy transfer elements, which are magnetically coupled. Different combinations of these energy transfer elements are used to obtain different conversion ratios, which can be referred to as “gears”. On the input side, having multiple gears enables easier and better matching to a wider variety of energy transducers. On the output side, it enables easier and better accommodation of a wider spread of energy storage voltages and of a wider variety of loads.