Patent ID: 8164305

Claim:
A battery management system for managing a battery pack including a plurality of battery cells, comprising: a magnetic device comprising a plurality of windings wiring around a magnetic core; a plurality of switches, each switch coupled between a battery cell and a winding; and a detecting and controlling unit operable for detecting parameters of said battery cells, and for turning on a first switch, which is coupled between a first battery cell and a first winding, and a second switch, which is coupled between a second battery cell and a second winding, alternately to balance said first battery cell and said second battery cell via said magnetic device if a first parameter of said first battery cell is greater than a second parameter of said second battery cell, wherein the detecting and controlling unit further performs the steps of: selecting a battery cell B 1H whose parameter has a maximal value and a battery cell B 1L whose parameter has a minimal value from said plurality of battery cells; determining whether a terminal, which is coupled to a polarity mark of a corresponding winding, of said battery cell B 1H has different polarity from a terminal, which is coupled to a polarity mark of a corresponding winding, of said battery cell B 1L ; if said terminal of said battery cell B 1H has different polarity from said terminal of said batter cell B 1L turning on respective switches coupled to said battery cells B 1H and B 1L alternately to balance said battery cell B 1H and said battery cell B 1L ; and if said terminal of said battery cell B 1H has the same polarity as said terminal of said batter cell B 1L selectins a batter cell B 2H whose parameter has a maximal value and a battery cell B 2L whose parameter has a minimal value from a set of said battery cells whose terminals, which are coupled to polarity marks of corresponding windings, have different polarity from said terminal of said batter cell B 1H turning on respective switches coupled to said battery cells B 1H and B 2L alternately to balance said battery cell B 1H and said batter cell B 2L and turning on respective switches coupled to said battery cells B 2H and B 1L alternately to balance said battery cell B 2H and said battery cell B 1L .