Motor Speed Controller
Saturday, September 10, 2011
Motor Speed Controller
A friend of mine gave me an old broken Curtis motor controller. I spent about $70 in parts and a couple hours replacing a dozen burnt out MOSFETs and power diodes. Sadly when I powered it on, it was still not operational. Oh well, it was worth the gamble. I forked over the money to buy a bran new one.
I proved out a concept that I read about on line where you modify a standard ATX computer power supply to take in 120 volts direct current and it will put out 12 volts DC. This will come in handy for powering all the 12 volt systems on the truck, (headlights, horn, radio, signals, relays, etc) without needing an extra 12 volt battery and additional charger.
I found a nice metal box at NPS for $8 to hold all the electrical parts. I drilled some holes, primed it, painted it white and mounted things up. Here it is being assembled in the mad science lab in my basement.
Here is the white box of parts that makes an electric truck tick. The big yellow thing that looks like a bomb is actually a capacitor array that I am using in a circuit for an experimental quick charger.
Trying It All Out:
On Friday Sept 2nd, 2011, I took the truck out for its maiden voyage. Initially, it drove great. I got it up to 40 mph in 2nd gear.
You can watch the video here.
There were a few bugs that I still needed to work out.
- The welded motor mounts broke and had to be redesigned and rebuilt.
- The motor speed controller needs a larger heat-sink. It overheated after 10 miles.
- The clutch still doesn't work well, although it isn't needed in an EV.
- The controller is a little sluggish at take off. I need to adjust it so I get more power while accelerating.
The next day, I came up with a better motor mount design where a metal strap supports the motor. You can see a day-time 2nd run here.
For more info on my electric truck, click here.
My electric truck can go up to 40mph in 2nd gear and up to 70mph in 3rd gear. It's range is still limited by the battery pack to about 40 miles. Before I can use it as a commuter truck, I need to break in the motor and the pack. I hope to have a 70 mile range by the time I finish tweaking everything.
To date, I have driven the truck over 120 miles.
That's pretty cool considering all my electricity is generated by the power of the sun. In effect, this makes the truck solar powered.