Patent ID: 9136705
Filing Date: 2015-09-15
Classification: H02J,Y02T

Abstract:
1. A power management system for delivering electrical power from two or more battery packs to a load, said power management system comprising: sensors for measuring a state of charge in each of the two or more battery packs; a switch positioned in a positive lead of each of the two or more battery packs, where each of the switches provides a switched power signal from one of the battery packs; a diode in series with each of the switches in the positive leads of the battery packs; a transformer responsive to the switched power signals from the two or more battery packs, said transformer receiving on primary windings the switched power signals from positive terminals of the battery packs, where each of the battery packs provides current to the transformer during each switch cycle, and where each of the switched power signals operates on a different duty cycle with different on-times and off-times, said transformer converting the switched power signals to an output voltage and an output current to power a load; and a controller responsive to state of charge signals from the sensors and configured to control the switched power signals from the two or more battery packs so that the output voltage at the load is maintained at a designated target value and the state of charge in each of the two or more battery packs is balanced, where the controller computes a duty cycle for each of the switched power signals as a baseline duty cycle multiplied by a ratio of the state of charge for each of the battery packs to a highest state of charge for all of the battery packs, and where the baseline duty cycle is a ratio of on-time to total cycle time, wherein the controller uses a proportional-integral algorithm to compute the baseline duty cycle.