Hello Everyone,

I'm working on a BMS, the gate driver I use is only 1 channel to control the charge and discharge mosfet.
As we know, the BMS must also control the precharge circuit.
The problem is that I am limited to only use 1 channel gate driver.

thus, is there any other method to handle the precharge capacitor without using the precharge circuit (limiting precharge current with resistor)?

 

Without a schematic its impossible to comment.

 

Here is the diagram, my question is, is it possible to precharge the load capacitor without using the red circuit and red parts?
I mean is there any other method to precharge the load capacitor?

 

It depends on scale and the voltage levels of your system.
But if the voltage levels are small, you technically don't need the pre-charge current limiting resistor and the additional MOSFET. Use the main MOSFET to control the current initially by operating it in its linear/ saturation region. Be carefull and make sure the MOSFET is not crossing the SOA boundaries.
There are specialized mosfets that are made for this kind of application, They are called Linear Mosfets :
From Infineon
From littelfuse

You also have controllers that do this Job for you:
LTM9100



I have used the above mentioned controller with good results.

 

our system has 84V maximum voltage.
I want to make sure because it's new for me.
to control the current initially by operating it in its linear/ saturation region means I should gradually provide voltage Vgs above the threshold, right?

 

Precharge can work if there is no load (or very light load) across capacitor. You need to ensure this state by turning the load off.

Regarding precharging using mosfet in linear region:
A 5m6 at 84V is a big amount of energy (20 Joule or W.s) so you have to charge slowly. Check SOA of mosfet and be aware of secondary mosfet breakdown (high voltage across mosfet + even medium current is enough to destroy mosfet).

 

our system has 84V maximum voltage.
I want to make sure because it's new for me.
to control the current initially by operating it in its linear/ saturation region means I should gradually provide voltage Vgs above the threshold, right?

Yes, You would essentially need a closed loop system which monitors the current through the MOSFET and makes sure it does not go beyond a certain threshold.
You can either do this via a microcontroller or just use ready made controllers which achieve the same with a few additional components.

our system has 84V maximum voltage.
I want to make sure because it's new for me.

If this is new to you , I suggest you get a evaluation board to try this out mimicking your existing system.
What is your system capacitance and what MOSFET are you using?

 

Yes, You would essentially need a closed loop system which monitors the current through the MOSFET and makes sure it does not go beyond a certain threshold.
You can either do this via a microcontroller or just use ready made controllers which achieve the same with a few additional components.


If this is new to you , I suggest you get a evaluation board to try this out mimicking your existing system.
What is your system capacitance and what MOSFET are you using?

Total capacitance 5600uF
Mosfet Part Number : IPB027N10N5

Do you have any suggestions on which manufacturer provides EVB/EVM that matches our requirements?