That's a serious amount of current. More than most logic-level MOSFETs, which usually top out about 90A. You are going to need some dedicated MOSFET driver circuitry.
PWM is still the best way to go. analogWrite() will be quite sufficient for control.
"Transform in voltage"? Try asking the question again, a different way.
Ok, thanks. But the 100amp is the stall current and I found that the driver only need to support the continuous current which is usually around 25% of the stall current. So I would need a driver for about 30amp.
I would need a H bridge, I think to put the controller before the bridge and after some relay to make the bridge.
Or can I use some mosFET to make the bridge and control the speed a the same time?
And for the "Transform in voltage" was if it's possible to make the voltage vary depending of a pwm signal, but I will stay with pwm controller, not voltage one.
If the driver could handle 100A do you think they would not advertise it? Even the 80A peak is probably wishful thinking.
However, what batteries are you going to use for this? It's going to be very difficult to get 100A from a battery. Imagine if your power wires are excellent and they have a resistance of 0.02Ω - what is the voltage drop with 100A? It will be 2V. Does the motor draw 100A when it only gets 10V? Probably not.
I expect that that driver would work so long as you don't have a most excellent 100A power supply. It's certainly good enough for testing and getting started until you eventually blow it up and need to move on to something bigger.
Standard 12V car battery can easily provide >500A if you short it... Large lead-acid
or LiPo batteries will readily pop MOSFETs if you don't provide fast overcurrent
detection and protection circuitry.
You can just rate the MOSFETs for the full stall current - though this can be rather
overkill, and then not worry.
A better approach is find a ready-made MOSFET H-bridge which is rated to handle
100A peak (20A continuous would be fine though). Try always to get a motor controller
with over-current protection, you shouldn't normally be anywhere near stall current
levels, but neither do you want your controller to blow its MOSFETs if theres a fault
or software glitch...
Note that this motor is a poor performer compared to many, the no-load current is large
and you'd do much better with a brushless motor. I can guess that's why the project
failed... A bike with that motor would be extremely hard to ride with a flat battery.
Ok thanks for you reply, I found this mosfet (link datasheet) and I have a problem with it.
When I apply 5 volt to the gate, should it supposed to be fully open because of the threshold voltage is min 2v max 4v? I was testing it on a led with my arduino and the led wasn't able to bright to it's max, the voltage was something like 2,75v after the mosfet and it supposed to be 4,5v or 5v.
I my supposed to apply more voltage to the gate to open it more?
And yes I'm using a medium sized lead battery, which can provide a lot of amp, but my system only peak at 100amp, I think that the current will probably be around 25 or 30 with load. My mosfet is good to 50amp continuous current.
Hi,
You need to look at Fig 3 of the MOSFET datasheet.
It tells you how much current you will conduct for a given Gate to Source Voltage.
You need what is call a Logic Level MOSFET, it is designed for 5V logic circuits.
TomGeorge:
Hi,
You need to look at Fig 3 of the MOSFET datasheet.
It tells you how much current you will conduct for a given Gate to Source Voltage.
You need what is call a Logic Level MOSFET, it is designed for 5V logic circuits.
If you want to operate the motor in both directions, you might consider an H-bridge like below. The h-bridge chips probably have thermal shutdowns if high currents cause it to start to overheat.
Beurnii:
No I would use the logic level mosfet for openning the bigger mosfet which can handle my amp.
But should I use a logic level mosfet or a simple transistor? (it will be appeared buy an Arduino (pwm, 5v)).
You can't drive a high power MOSFET from a single MOSFET, it needs high gate currents in
both directions, you need two MOSFETs to drive a gate. All of this is there in easy to use
form inside a MOSFET driver chip, look at the IRS2001 or FAN7380 or FAN7388 or HIP4081
for examples.
MarkT:
You can't drive a high power MOSFET from a single MOSFET, it needs high gate currents in
both directions, you need two MOSFETs to drive a gate. All of this is there in easy to use
form inside a MOSFET driver chip, look at the IRS2001 or FAN7380 or FAN7388 or HIP4081
for examples.
I dont understand why I would need to drive each powerfull mosef by 2 mosfet.
MarkT, I would really like to discuss with you on facebook or something like that, you seems to know how is this stuff working and I need help. Message me if you want to/can help me.
I've heard that MOSFETs can be paralled to some extent. Why not get a couple of logic level MOSFETs like below and wire them like in the bottom link except with more parallel MOSFETs. If your motor is actually drawing 100 amps, other parts of the circuit or the battery are probably overheating too.
Beurnii:
I dont understand why I would need to drive each powerfull mosef by 2 mosfet.
Because the gate capacitance is huge and lots of current is needed to get rapid (ie efficient)
switching. At high power this is often the limiting factor. Typical MOSFET drivers can
source/sink currents of 100mA upto 9A.... Pull-up or pull-down resistors don't hack it at all.
While a MOSFET is switching a significant fraction of the load power is dissipated inside
the device - with PWM this happens at twice the PWM frequency.
MarkT, I would really like to discuss with you on facebook or something like that, you seems to know how is this stuff working and I need help. Message me if you want to/can help me.
Please,
Bernard
I do not engage in private messaging here, since the forum exists for everyone.
Here is an image of my current circuit. (no H-bridge for now, i'm testing some stuff. And sorry, I made it on paint).
I don't understand why is the emitter pin of my transistor emitting 5v to the ground only. With 12v, the mosfet is supposed to be open enough to let flow 100+ amp (3rd graph in datasheet), but with 5v, it's only 20/30 amp, which is not enough.
And do I have to put a resistor on the green line? I have a few 10k that I could used.
Here the datasheet of the transistor:BC337-25
Here the datasheet of the mosfet:IRFZ44N
I fried my arduino, so it's only outputing 5v flat, but if it would work, i would use the pin 9 and pwm.
And why, if I put the motor after the mosfet (- of motor to ground, + to mosfet source, and the drain of mosfet to 12v battery), it will only received something like 9v when the mosfet have a 12v at the gate and only 3v when it's 5v at the gate? I really dont un understand, but I was planning to counter this problem with simple relay for the H-brige.
Thanks you everybody, I trying to learn and I really like electronics even if i'm bad at it.
I would appreciate any answer of any kind, thanks a lot.
I don't see anything in IRFZ44N that shows performance with Vgs = 4.5 to 5V, which I think is what you are asking:
With 12v, the mosfet is supposed to be open enough to let flow 100+ amp (3rd graph in datasheet), but with 5v, it's only 20/30 amp, which is not enough.
I can't open whatever you attached. Normally there would be 1K pullup resistor from the gate to 12V supply, and the N-channel resistor would connect the gate to Gnd to turn it off, and let the gate get pulled high to turn it on (acting as an inverter to the Arduino output).
There would be a 220, 270 ohm resistor between the arduino pin and the NPN base to limit current flow from the arduino pin to ~20mA.
CrossRoads:
I don't see anything in IRFZ44N that shows performance with Vgs = 4.5 to 5V, which I think is what you are asking
When the gate have a 12v, the motor still get a nice 12v and accelerated really quickly, but when the gate is at 5v, the motor is at 12v, but it doesn't accelerated as fast as the other one. I guess that it does not have enough amps.
