US 12,483,043 B2
Bi-directional active battery cell balancer and method for bi-directional cell balancing
Zhigang Liang, Fremont, CA (US); Jia Wei, Cary, NC (US); John H. Carpenter, Jr., Malabar, FL (US); and Masaya Emi, Tokyo (JP)
Assigned to Renesas Electronics America Inc., Milpitas, CA (US)
Filed by Renesas Electronics America Inc., Milpitas, CA (US)
Filed on Jan. 13, 2021, as Appl. No. 17/147,967.
Prior Publication US 2022/0224124 A1, Jul. 14, 2022
Int. Cl. H02J 7/00 (2006.01)
CPC H02J 7/0014 (2013.01) 18 Claims
OG exemplary drawing
 
1. A device comprising:
a controller; and
a circuit coupled to a first battery cell and a second battery cell connected in series arrangement, the circuit comprises:
a first switching element, wherein a terminal of the first switching element is connected to a terminal of the first battery cell;
a second switching element;
a third switching element;
a fourth switching element, wherein the first, second, third, and fourth switching elements are connected in series arrangement, and a terminal of the fourth switching element is connected to a terminal of the second battery cell;
a capacitor, wherein a first terminal of the capacitor is connected to a first node located between the first and second switching elements, and a second terminal of the capacitor is connected to a second node located between the third and fourth switching elements;
an inductor, wherein a first terminal of the inductor is connected to a third node located between the second and third switching elements, and a second terminal of the inductor is connected to a fourth node between the first and second battery cells; and
the controller being configured to:
detect, from the inductor, an inductor current flowing through the inductor;
compare the detected inductor current from the inductor with a programmable current limit stored in a local memory of the controller;
determine a charging status of the capacitor based on a result of the comparison between the detected inductor current from the inductor and the programmable current limit, wherein:
the detected inductor current from the inductor being greater than the programmable current limit indicates that the charging status of the capacitor is being charged; and
the detected inductor current from the inductor being less than the programmable current limit indicates that the charging status of the capacitor is being discharged;
determine that voltage levels of the first and second battery cells are unbalanced;
in response to the determination that the voltage levels of the first and second battery cells are unbalanced, generate a plurality of driver signals based on the charging status of the capacitor; and
use the plurality of driver signals to selectively drive the first, second, third, and fourth switching elements to perform battery cell balancing between the first and second battery cells, wherein the battery cell balancing between the first and second battery cells comprises:
in response to the charging status indicating that the capacitor is charged, generate the plurality of driver signals to discharge the capacitor to charge one of the first and second battery cells that has a lower voltage level;
in response to the charging status indicating that the capacitor is not charged:
generate the plurality of driver signals to charge the capacitor using one of the first and second battery cells that has a higher voltage level; and
in response to the charging status indicating that the capacitor is charged, discharge the capacitor to charge one of the first and second battery cells that has the lower voltage level,
wherein a balancing speed of the battery cell balancing between the first and second battery cells is dependent on the programmable current limit stored in the local memory of the controller.