Question : How to design a cell balancing circuit using Bi-Directional converters.

[Chiranka K]

Hello guys,
Im trying to design a cell balacing circuit using bi-directional converters, this should make the SOC's of my cells same, incase there is an imbalance.

 

[boBK7IQ]

This would be an "active" battery balancer rather than the usual passive balancer.

Have you tried Googling for this ?

What you can look into might be a synchronous buck converter running at 50% duty cycle. A cell on one port and another on the other port.
Then leap-frog more of these for more cells.

boB

 

[BradtheRad]

The above post brings to mind a topology I simulated:
One inductor serving a double duty buck converter role. I've depicted clock pulses as a simplification though they can come through a half-bridge (or a 555 IC if current demand is low). Volt level must be adjusted low enough so that no battery can overcharge.

Low battery asks for current. Full battery requests no current. The scope trace depicts batteries in different states of charge. For example battery voltage might range between 3.7 and 4.2 V.