This is my first Post here, because i didn't stumble upon any other solution during my research. For a university project i need to control a dc motor i got out of an electric driller. (HRS 550S 6828F DC 18V). I want to control it using an arduino nano with an FQP 27P06 MOSFET. I'm Powering everything with 17V and 1,75Amps. I will try to draw a datasheet and attach it to the post.
So after a few days of trying out different components, i got it to work: Kind of...
I've uploaded the "fade" sketch to my arduino, and the motor gains and loses momentum, just as the sketch tells it to. However, i can't stop my motor entirely, even when i tell the Mosfet "analogWrite (9, 255, because it's a p-channel one.)
I hope that someone of you has experienced this problem aswell, and/or has a solution to it, because i'm really desperate, since not even my friends with expericence in electronics could help me.
The thing is: It worked before with smaller 5V Motors and LED's.
Now i put everything the way you suggested it still works with smaller motors, but not with the big 18V DC Motor, and i don't really get why it should make a difference, when i use a bigger motor...
That motor is rated at 8A for max efficiency point, 62A stall current. Its completely outside
the capability of a 70 milliohm MOSFET or 1.75A power supply.
These cordless drill motors handle hundreds of watts of power, they are nothing like a
tiny toy motor.
I would recommend getting an n-channel MOSFET with about 2 milliohms of on-resistance,
using low-side switching. The power supply needs to be much bigger or it will just max-out
immediately.
MarkT:
That motor is rated at 8A for max efficiency point, 62A stall current. Its completely outside
the capability of a 70 milliohm MOSFET or 1.75A power supply.
These cordless drill motors handle hundreds of watts of power, they are nothing like a
tiny toy motor.
I would recommend getting an n-channel MOSFET with about 2 milliohms of on-resistance,
using low-side switching. The power supply needs to be much bigger or it will just max-out
immediately.
Ok, yeah, you're totally right. In the Aliexpress description it said over 2 Amps, which i have mistaken for exactly 2 Amps.
Not with an Arduino output to control it. The Rds(on) is specified at 10V so an Arduino 5V output will not turn it on fully, You need to find a logic lovel (Rds(on) specified at 5V or less) MOSFET that will handle the stall current of the motor (with some overhead).
You might be able to combine parts you already have
If you went back to controlling the FQP 27P06 MOSFET off the PWM pin 9, but instead of the load being the motor, have it switch a voltage divided source ( down to the 10v needed from the 17v source) to your RDS which then switches the full power to the motor.
Rememeber to link the arduino + 27P06 + RDS grounds together.
