Heavy duty PWM DC motor controller help

Thread Starter

eggplantparrot

Joined Mar 25, 2015
43
hello, I have salvaged a big 2 HP treadmill motor and have built a disc sander with it, but the treadmill controller stopped working during testing, and now I need a motor controller preferably PWM.
if anyone can help me create a list of components to driver such a big motor it would be greatly appreciated.
the motor is rated for about 105V DC at 18A I have salvaged a bridge rectifier from the treadmill driver and it works in converting AC to DC. I need a simple circuit, variable speed to start the motor at low speed, and can handle at least 15 A since the motor would be started at low speed and slowly turned up, and would never be run at full throttle. I can solder with no problems, but I have no knowledge of specific electronics like PWM chips. a list of parts and a simple diagram would be very helpful.
 

Thread Starter

eggplantparrot

Joined Mar 25, 2015
43
thx for reply. I see that the 555 timer input voltage is 6VDC and the output is also 6VDC, but the voltage I measured from my rectifier is ~100VDC (I don't remember exact number) that means I would have to step it down for the timer right? also the ground on the MOSFET in the diagram is a common ground with the rest of the electronics, but as before, my MOSFET would be receiving ~100VDC and then sending it to motor, I wouldn't be able to ground it with the timer then?
 

MaxHeadRoom

Joined Jul 18, 2013
23,791
The low voltage common and high voltage DC common can be connected.
The low voltage could be sourced from a Wall Wart supply etc.
Max.
 

Thread Starter

eggplantparrot

Joined Mar 25, 2015
43
dam I was hoping to reuse the ones I have, they had heat sinks too, any reason I shouldn't use them? I mean they were from the treadmill controller anyways, rated for way more than I need at 200V and 33A? I mean I will get the ones u suggested but I would prefer to use whatever I already have since it was all free lol
 

Thread Starter

eggplantparrot

Joined Mar 25, 2015
43
oh, you mean like the IRL540 VGS is 5V but on the IRFP250 its 20VGS? im guessing the output on a 555 is the same as the input so if I were to use a 5v wall wart to power the 555 then the output of the 555 would be 5v, and that would be good for the IRL540 and not high enough for IRFP?
 

Thread Starter

eggplantparrot

Joined Mar 25, 2015
43
Wait, so it's ok if I use lower voltage supply for the 555? I have a bunch of 12v charger warts that I can use, what would happen if I use those? Since the IRFP calls for 20V what would happen? To be honest I think I would probably use the one you suggested for simplicity
 

Thread Starter

eggplantparrot

Joined Mar 25, 2015
43
2005-10a-004.gif 2005-10a-004 ver2.gif so if I were to use this circuit and the IRL540 how would I connect everything up? I modified the first pic to what I think I'd hook up, but I feel like im missing some connections, particularly with grounding them.
 

MaxHeadRoom

Joined Jul 18, 2013
23,791
Use whatever suitable separate supply that will work for the motor and a separate one for the 18v and just connect the commons.
The cheap ones you buy on ebay use a single high voltage DC motor supply and a simple zener to supply the 555 circuit.
Max.
 

BillB3857

Joined Feb 28, 2009
2,546
PLEASE - show an isolation transformer before your bridge. Otherwise, you violate the terms of service as well as create a hazardous condition.
 
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