Optimum energy harvesting for series-connected power sources with uniform voltage distribution

Presented herein are three possible maximum power tracking approaches of harvesting energy from series-connected power sources: (1) commonly drawing the same current without active control for uniform voltage distribution among the output voltages of individual power sources, (2) partially across all individual power sources while being series-connected with uniform voltage distribution (UVD) control of their sourcing voltages, and (3) directly across individual power sources of which their peak-power voltages are independently tracked and controlled using their own independent maximum power tracking (IMPT) controllers. The energy harvesting approach (1) delivers far from optimum power, particularly when these sources are usually not identical. While the IMPT approach (3) enables the ideal peak power to be obtainable, the energy harvesting approach (2) still provides near optimum power with less control complexity that preserves fault-tolerance. This paper presents two power system architectures, each consisting of series-connected power sources and series-input parallel-output (SIPO) converters that are controlled to achieve their uniform input voltages across their respective sources while also tracking the system optimum power point being sufficiently close to the ideal system peak power. Feasible study through computer simulation successfully validates the SIPO power architecture and control concept developed for optimum power transfer.