48V 40 Amp Brushed Motor Controller

ronv

Joined Nov 12, 2008
3,770
Yes, we are looking for mistakes. If you look at the schematic you can see UP-3 should be tied to +12 with a wire, so It should measure the same as UO-3. So somehow it is getting the higher voltage - maybe under the board or if some other pin is tied to +48 and the part is shorted it could feed back. When you remove the part measure all the voltages on that IC. None of them should be over 12 volts.
 

ronv

Joined Nov 12, 2008
3,770
Something like that would work. It just needs to hold the high current stuff, which would be the stuff to the right of the 2 small transistors in the schematic.
How's the trouble shooting going?
 

Thread Starter

ncccengineering

Joined Nov 20, 2013
31
The trouble shooting is going. We have only found some small stuff and we are waiting for the sense resistor to come in. Hopefully, before this week is done our motor controller will be functional.

Do you have any idea why our U5 isn't controlling the LEDs?
 

Thread Starter

ncccengineering

Joined Nov 20, 2013
31
We have now gotten all the new parts in, and rebuilt the new "high Current" section. We are going to test it tomorrow with just the LEDs and take some readings. Hopefully, we will find that everything is fixed!!!!!!
 

Thread Starter

ncccengineering

Joined Nov 20, 2013
31
UPDATE!!!!!
We turned on the motor controller today and we instantly got 52.7 Volts on the LEDs. When we tested the chips we got 12.2 V. We turned it off and heat sinked it before we tried with the motor and U4. When we turned it on there was a large amount of sparks and we melted the corner of the FET and the Diode. We also melted a resistor to the Sense resistor. So we obviously did something horribly wrong trying to heat sink those parts. So our next plan of action is to trade out the melted parts and try again without the motor and heat sink and take some more readings again.
 

Thread Starter

ncccengineering

Joined Nov 20, 2013
31
We once again have that mysterious high voltage going to the lm339 chips. which is causing nothing else to work properly. We are still going keep investigating this odd voltage anomaly.
 

jrz126

Joined Sep 17, 2008
7
Disclaimer: There was quite a bit of variance in these Voltages, while testing the LEDs flickered brighter and dimmer. We tried to measure when the LEDs were brighter (9.8V from inductor), but that may not be true 100% of the time.

UP-3 31.5 V
UO-3 12V
UP-14 31.5
UP-7 21; 28
UP-1 10;30
UO-8 10
UP-9 10.4
UO-7 25
UO-6 0
FET 10.1

Any suggestions on breadboards that can handle the current?
You are using perf. board for your prototyping. You need to solder the components in place. Otherwise you will have intermittent connections everywhere. That may explain why you were getting flickering LEDs.
 

Thread Starter

ncccengineering

Joined Nov 20, 2013
31
We tested today. Here are the readings we took.
UP-3 13.0V
UO-3 13.0V
UP-14 12.7
UP-7 7.9; 7.0
UP-1 10.8; 11.0
FET gate 51.6V

The pot still doesn't have any effect on the motor, but the motor does run. We just don't seem to control the power at all. Any more suggestions
 
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