Scalable method of proportional active state of charge balancing for managing variations in the state of health of batteries

摘要

A method and system for power management among batteries of varying states of health. Two or more battery packs are switched on and off in square wave pulses to energize a multi-winding transformer, and the output of the transformer is used to power a load. As the state of charge of the battery packs decrease at different rates, the duty cycle of each battery pack's switch pulse is made proportional to its state of charge relative to the other battery packs. The battery pack with the greatest state of charge has the longest on-time and provides the most energy to the transformer, yet all battery packs contribute. A baseline duty cycle is computed by a proportional integral control module, based on voltage measurements at the load. Energy contribution is managed so that state of charge does not diverge even when the battery packs have widely varying states of health.