Hey guys, I am working on a fuel pump controller for a drag car. The fuel pump is a spur gear pump with a 24v DC brushed electric motor. The pump should draw a continuous amperage of about 60 amps at 24v. The pump will only need to run for about 20 seconds at a time, and most of that time would be at like 50% duty or less. It will have at least a minute or so of cooldown between turning on again. The pump will be powdered by its own pair of small lead acid batteries and I want to be able to ramp in the power to the pump with PWM ramping from like 30% duty to 100% controlled by the arduino. The arduino will be powered off the car's 12v electrical system.
Looking into options for mosfets with good packaging I came up with an IXFN200N10P but I am not knowledgeable enough to understand the data sheet and I'm not certain how to wire it since the controller and load are on different power sources.
This is what I was thinking for a circuit. Any advice on this or alternate suggestions?
Know thar fully charged lead battories provides more then 12 volt. Check controller absolute maximum Vin voltage.
The schematics look okey in principle. Reservation for the MOSFET. Brushed DC motors usually draw 5 - 10 times the current during the start.
Not to me. The gate only gets 4.3volt from the emitter follower.
And what is that diode in the gate line doing there.
Fets like that need a proper gate drive chip. If you don't have the experience in power electronics, then it might better to try to find a ready made SSR for that motor.
Leo..
I would love to use a ready made SSR if I could find one that will run that high of amperage at a decent frequency. If you know of one I would love to know.
I don't know what I am doing and that is why I am here asking for help. What kind of gate drive chip would you recommend?
I have seen the TC4420 mentioned a few times on this forum.
It seems that layout and capacitor choice is very important with these currents.
Good luck.
Leo..
Suggestion1: you must apply fast recovery diode between +,- terminal of dc_motor with proper polarity.
When mosfet is 10A~60A switching High spike voltage are applyed to mosfet device.
(because dc_motor has high coil turns so high spike voltage generate)
Suggestion2: as possible as a low value capacitor(with low ESR) apply between dc_motor terminal.(because of dc_motor brushing , High spike voltage make Nana controller maloperation.
Suggestion3: If switching frequency of mosfet is high, Fast recovery diode apply to mosfet terminal(D-S)
(because body diode of mosfet is slow recovery time)
Good Luck !
It would be helpful to suggest an appropriate controller to use. Otherwise I have to throw your well meaning advice on the garbage heap of advice that doesn’t get me closer to a solution.
The body diode of a fet, and an external diode across that body diode has no function.
It has in an H-bridge, but not with a single fet.
There should of course be a diode across the motor.
Leo..
@someguy2800
Designing a high current switching circuit is not a trivial task and won't be something you could do on a breadboard.
There are MOSFETs that could work but all the ones I know of are SMD. So, unless you have already designed similar high current switching PCBs, I would pay someone to do it for you.
