Heh, heh, Let's look into the maths of that.So this solenoid draws 75 A at 12 V. To "regulate" it to half power means that it has 6 V applied and 6 V across the controlling FETs. OK, we now have the FETs dissipating 6 by 37.5 - I calculate that at two hundred and twenty-five watts!That is basically going to require quite a few FETs and a maybe a water cooled heat-sinking system with a large fan-cooled radiator somewhere. OK, they sell those for gaming machines, don't they? Maybe not so bad.With PWM as discussed so far we have three FETs and perhaps a six by eight inch conventional heatsink.
If you don't mind maybe you have a short explanation how ESCs (Electronic Speed Controllers, used in RC hobby planes, boats, etc.) handle that issue without huge cooling elements.
What type of MOSFETs would these be? Would they each need to withstand the full load of 75A? Searching around on amazon the highest-power MOSFETs I can find peak at 35A.
The circuit still would include a high power diode in parallel with the inductor such as below, correct?
lastly where would the shunt resistor plug in to such a circuit if the diode is already in place?
Also, I forgot to mention that within the circuit there is a shunt used for a multimeter in order to measure power flow of the circuit. The shunt can be found here: https://www.amazon.com/gp/product/B013PKYILS/ref=oh_aui_search_detailpage?ie=UTF8&psc=1It is 100A 75mV.So I am seeing a few optionsA) Parallel Diode//IND with use of three expensive relays (Does this imply splitting source wire to three strands and wiring each strand to relay?)B) Parallel Diode//IND with use of Tri-MOSFETs and an enormous cooling system (Same deal as above)C) Parallel Diode//IND with use of ESCWhich is the best option, though?
"None of us are going to duplicate your system so we can determine which is the best option"I'm just asking what would logically make the most sense in practical design. You don't have to duplicate anything to answer that.Three dedicated Relays, Three Mosfets, or Electronic Speed Controller makes the most sense?
The core material will magnetize and demagnetize relatively quickly, say 0.5s-1s.
I decided the MOSFET plan was most suitable based on project requirements.Looking on Mouser I am finding N-Channel FETs which are rated for 100A. Would this not be a simpler way to resolve the problem than wiring several lower-rated FETs in parallel or is there something I am missing
They also claim power dissipation of 100W or so, is this a manageable amount considering there is a case fan in the device and average heat sinks on the circuitry or am I way underestimating it?
Lastly, shot in the dark here, but could you just regulate the current to say 1 amp or less at shut-off time with some sort of current regulator and open the circuit a matter of ms after to prevent large kickback compared to opening the circuit at full amperage? It would seem this would eliminate the need for most kickback protection and FETs in parallel.
to avoid the return of current in the electromagnet, you could smoothly reduce the voltage in the same as aids to the use of diodes, for this could use PWM and gradually reduce the pulse width, but should not connect the pin directly to MOSFETS and electromagnets, you must connect a low pass filter between the MOSFETS and the electromagnet to obtain a smooth voltage reduction on the electromagnet. it would not be a good idea to connect the low pass between the Arduino and the MOSFETS as it would dissipate too much heat.