hello..
I have a plan to make a magnetic leviatation system which can moved by 10 solenoid.
attached file is a circuit of this project.
SO, I used 25V 125A power supply and, J1 and J2 is controlling whole current.
In this circuit, IRF153 explained mosfet transistor, is IRF 1405.
Because,in my drawing circuit program, irf1405 doesn't exist.
In addition, this transistor is controlled by Arduino PWM signal.
And, capacitor is 4700uf.
A and B is controlled part,C and D is solenoid and resistor.
Solenoid is 1.1ohm when I check it's ohm.
R1 is cement resistor that I connected serise,parrallel. So it is 1ohm 500W.
Does my project seems working well?
I'm more carefull cause in past, same project, power supply was exploded
cause of my mistake.(I didn't attach resistor and, it also have 5 solenoid.)
The IRF 1405 MOSFET is not a logic level MOSFET. The Rds is specified at 10V so the MOSFET will not turn on fully with 5V to the gate and will probably get hot.
R1 is cement resistor that I connected serise,parrallel. So it is 1ohm 500W.
What does that mean? One resistor can't be both series and parallel to the solenoid coil. And why is it there?
There should be a reversed biased diode across the solenoid coil to protect the MOSFET from inductive kick from the solenoid.
(In my circuit, capacitor is electrolytic capacitors. It's my mistake..)
I think voltage problem could be solved by transistor for amplifier.
So I could set 10V maybe..
And, R1 mean, one cement resistor has 1ohm and 20W power.
However, 25V*12.5V is 312.5W so it couldn't satisfied.
So I connect 25 cement resistor to make 1ohm 500W resistor.
I got it that I have to attach diode,but, is there another things that I have to changed?
Like, revise the resistor error,using higher resistor ohm or capacitor location?
The resistor is to adjust ohm's law.
Beause, power supply is 25V and 125A and each of parallel circuit,(10) it is 25V 12.5A
But when I use just solenoid, (1.1 ohm) calculate ohm's law, it is 25V/1.1ohm = 25A
However, power supply doesn't do that.
That is the reason,though
I know it is wasteful but I want to test it with power supply which is in my home.
Change solenoid can sole this problem but,
At now, I want to test at this situation.
And I think cap can make smooth the PWM signal.
At now, I think it can be work well when I didn't put capacitor.. So I'm wondering whether to put it in or not.
And I wounder that mosfet transistor is 2
which mean between j1 ,j2 and A,B
At that situation, I think transistor between A and B seems okay but
At J1 and J2, does it cause high voltage and make bad effect itself?
I recognized wrong thing. It reversed..
And R1 resistor is essential?
At my latest project, using irf540, I'm not using R1 resistor but seems like current flouing.I don't know reason though..
The reason for the resistor on the digital output to the gate is that the gate is like a small capacitor. When you turn the gate on it will, momentarily, draw a high current. The resistor limits the current to less than the maximum current that the output pin can supply, protecting the pin. The necessity of the resistor has been debated on this forum before. Many claim that it is not needed, but I like to design on the safe side, so i usually include it.
I don't think that the MOSFET is backward. Source goes to ground like it should, but the pull down resistor should go from the gate to ground.
Thank you to reply my project.Now I can do a test.
Before testing,I have one more question that does capacitor make circuit worse?
At first, I think controlled signal is pulse signal and power is also big.
So I think capacitor will solve this problem but, now on, I think it will work well not using it.
Does it make worse when I add capacitor?
You do not need the resistors to limit the current as long as you can rely on the ability of the FETs to switch.
Because you are driving an inductor, the current will build up slowly while the FET is switched ON, and decay slowly when the FET is switched OFF - because it continues to flow through the diode instead of the transistor. As long as you do not have the FET switch on for more than the right proportion of the time, the current will never exceed the limit you choose.
Note of course, that "build up slowly" is going to be in terms of milliseconds as you will be using a PWM frequency at least in the hundreds of Hertz.
You do not want to add capacitors in the switched circuit as they will briefly draw a very high current when the pulse is applied.
So, it means that when using fet to control current, then it doesn't need resistor.
But, I have some wondering thing that, just looking really short time, then does current exceed power supply's current? does it all right?
And second thing is about capacitor.
How do you think about capacitor location and capacitance?
Does it suitable for my project?
And does it all right to use electrolytic capacitors?
