Tinytroller Trolls Straight RazEr

Thursday, November 24th, 2011 @ 0:22 | Motor Controllers, Project Build Reports, Straight RazEr

Last time, Tinytroller was trolling Straight RazEr already, but it still had the occasional strange phase latchup issue. Well, I swapped Arduino Nanos, and it turns out the other one just has a damaged pin or has mild Turet’s or something.

So now it works great. With the current sensor bandwidth increased to the 800 Hz it should be at, the throttle nonlinearity dubbed “turbo lag” has been eliminated, at least for this drivetrain. Time for video!

While you can’t really observe a speed controller working (it’s in the same vein as watching epoxy set and batteries charge), the difference between current limits is clearly obvious using a standstill-launched Straight RazEr. In the video, the hardware current limit (the point at which the sensors peg on either voltage rail) was made to be 60 amps, and tests were performed at 10, 20, 40, and 60 amps. Motor phase amps were controlled to be around those values at all times, and I set the throttle mechanical zero position to induce a little bit of drag braking so I wouldn’t splat too hard on the far wall.

40 and 60 amps looked very similar, mostly because I had to begin braking almost immediately to avoid planting into the wall. I’d really need a larger hallway for a more conclusive test. When everything is properly working, it seems like 60 amps is no problem for this board. There were no observed noise effects or aberrant resetting instances. The current sensors can only be bridged so many times with low-ohm precision resistors, and I think at currents higher than this the traces might begin to blow up again.

The only thing I can do now is wait for the new board and see if it’s still as good.

On a side note, RazEr rEVolution and Straight RazEr are almost equal in a drag race, with Straight RazEr taking a slight lead. This I did not know until I had 2 working scooters, and it also comforts me to know that RREV’s hub motor is brütally oversized. I never measured the output of RREV’s chopped Jasontroller, but ballparking it by equivalent torques (for roughly equivalent accelerations) it has to be in the neighborhood of 50 or 60 amps peak.

 

 

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