Where should I set GND?

[iamkim]

I am currently producing an active cell balancing model using the Resonant Switched Capacitor method. However, I am writing this because I have a question. I first grounded GND to the - part of the battery series, but if the odd MOSFET is closed during balancing, the source part of the MOSFET does not seem to be connected to GND. Should I connect GND to another part?
I am upload 2CEll and 3CEll Circuit. Thankyou for your interest. Have a good day!!

 

[KlausST]

Hi,

The schematics show no GND at all... nor can I see where you intend GND to be.

Indeed the schematic is so incomplete .. thus it´s hard to give a good answer.
Controlling the MOSFETs you need some MOSFET drivers. How do they work, what input levels, what are they referenced to?

Basically MOSFETS are controlled by V_GS. The voltage between gate and source.
Thus: for each MOSFET you need the GATE voltage referenced to it´s SOURCE voltage. .. no matter which node you define as GND.

Klaus

 

[iamkim]

Hi, Thankyou for your apply. I use TC4420 as Gate driver. and I just wonder Where should I put GND.

 

[KlausST]

Hi,

as already said: The GATE must be driven with respect to SOURCE.

In case of TC4420: It´s OUTPUT is referenced to it´s GND. Thus:
TC4420_OUTPUT --> MOSFET_GATE
TC4420_GND --> MOSFET_SOURCE

wich makes the supply for each individual TC4420 rather difficult. And for sure the PWM_signal translation, too...

There is a good reason why there are dedicated HIGH_SIDE_MOSFET_DRIVERs

Klaus

PS:
Did you read some cell balancing application notes .. to see how they do it?
No need to re-invent the wheel. No need to make the same mistakes others already made.

--- Updated Jun 4, 2024 ---

At the Microchip (TC4420) internet site you find a lot of informations / Applicatin Notes on how to drive MOSFETs.
Other manufacturer provide more informations.