Patent ID: 11927642
Assignee: O2MICRO INC.
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC G  H  Y | IPC G  H

Claim 7:
8. An open cell detection system in a battery management system, wherein said battery management system comprises a plurality of monitoring resistors corresponding to a plurality of cells, a plurality of capacitors, a plurality of balance switches and a plurality of balance resistors; wherein a first cell in said plurality of cells corresponds to a first monitoring resistor, a second monitoring resistor, a first capacitor, a first balance switch and a first balance resistor; wherein said open cell detection system comprises:
a control unit; and
a measure unit, coupled to said control unit;
wherein said open cell detection system is configured to execute a method comprising:
(a) generating a first control signal with said control unit, to turn on said first balance switch for a first time period;
(b) generating a second control signal with said control unit, to turn off said first balance switch for a second time period wherein said second time period follows said first time period;
(c) measuring a voltage value on said first capacitor at the end of said second time period, with said measure unit;
(d) if said voltage value on said first capacitor is less than an open cell threshold, then determining with said control unit that said first cell has an open cell failure;
(e) for each cell of said plurality of cells, repeating steps (a)-(d); and
(f) if at least one cell of said plurality of cells has an open cell failure, then determining, with said control unit, that said battery management system has an open cell failure,

wherein said method further comprises:
if there is not an over-temperature situation, then further determining, with said control unit, whether said plurality of cells are being charged;
if said plurality of cells are not being charged, then further determining, with said control unit, whether there is an under-voltage situation;
if there is said under-voltage situation, then further determining, with said control unit, whether it is a first time said under-voltage situation has occurred; and
if it is not the first time, then clearing, with said control unit, an open cell detection timer again.