Help pls, Applying PWM to load while controlling current

Thread Starter

farzad latifeh

Joined Oct 3, 2017
59
Hey there
I have an electrolysis cell to produce brown's gas from water, in the process gas barrier decreases efficiency of cell while it may consume huge amounts of current too.
So, I need to apply PWM pulses to increase electrode efficiencies and control current consumption in one circuit.


I have this current limiter example
IFD2634_F2-big.gif


And this simple PWM generator
pulse-generator.gif


But I have no clue how to couple them in one circuit for load full control, I mean can I just use one FET in series with load that PWM circuit controls it? Is that so simple though? Or I should do some modifications to reach the target!
If anyone here can help me, I'll be really appreciated.
 

ronsimpson

Joined Oct 7, 2019
341
Here is a circuit that might work. The IC is for driving LEDs. (replace the LED with your cell) In this case it takes a supply near 12V and makes 1A for the LED.
It includes a current monitor much like what you used in your first post. The PWM is inside the IC also.
1575133341256.png
I have not used the part in your application. When driving LEDs it works with a output voltage from 0V to almost Vin while holding the current at 1A. (current is adjustable)
There are many other parts like this. The idea is to use a "LED buck PWM driver" because they are built for constant current and high efficiency.
 

Thread Starter

farzad latifeh

Joined Oct 3, 2017
59
Here is a circuit that might work. The IC is for driving LEDs. (replace the LED with your cell) In this case it takes a supply near 12V and makes 1A for the LED.
It includes a current monitor much like what you used in your first post. The PWM is inside the IC also.
View attachment 193475
I have not used the part in your application. When driving LEDs it works with a output voltage from 0V to almost Vin while holding the current at 1A. (current is adjustable)
There are many other parts like this. The idea is to use a "LED buck PWM driver" because they are built for constant current and high efficiency.
It's useless if it's only 1 amp
 

ronsimpson

Joined Oct 7, 2019
341
Here is a little IC that can do 4A. Yes I know it is "useless".
Question: must the cell connect to ground?
It is hard if the cell must be on ground like in post #3. It is much better for me if the cell is not be on ground. This circuit has the cell sitting where the three LED are. It will be 0.1V above ground. RS is the current sensing resistor.
1575176892134.png
I have another design that can easy do 10A but one end of the cell will connect to +12V. Is that ok?

What voltage do you expect across the cell?
 

Thread Starter

farzad latifeh

Joined Oct 3, 2017
59
I have another design that can easy do 10A but one end of the cell will connect to +12V. Is that ok?

What voltage do you expect across the cell?
If with switch it goes on and off yes sure it's OK
Cell is 12 Volts, because of that current limiter with low voltage drop I used
 

Thread Starter

farzad latifeh

Joined Oct 3, 2017
59
Here is a little IC that can do 4A. Yes I know it is "useless".
Question: must the cell connect to ground?
It is hard if the cell must be on ground like in post #3. It is much better for me if the cell is not be on ground. This circuit has the cell sitting where the three LED are. It will be 0.1V above ground. RS is the current sensing resistor.
View attachment 193507
I have another design that can easy do 10A but one end of the cell will connect to +12V. Is that ok?

What voltage do you expect across the cell?
Actually using LED drivers are interesting but not effordabal for me, if you can use my sample circuits and answer it that would be really great
Anyway thanks for your kind support
 
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