Instrumentation
From CarrottElectric
Contents |
EVision
Vehicle Speed
The Simovert provides a motor speed output, 5000Hz at 10000rpm. This can be adjusted by a configurable factor f_out_factor. The EVision & the Simovert share a ground, so this output can be directly connected to the EVision's speed input.
The EVision uses pulses per turn and tyre diameter to calculate road speed. We wish to display motor RPM for now, so we scale for 100km/h (27.78m/s) at 10000rpm.
We make our tyre 2.778 metres in circumference or 2.778/Pi=0.8843m in diameter. This tyre does 10 revolutions per second at 100km/h. We set f_out_factor to 3, now the Simovert outputs 500Hz at 10000rpm, we set out EVision to 50 pulses per revolution.
Speedometer/Odometer
The gearbox speedo output interferes with the body, so I need to drive the speedometer and odometer from the Simovert's output. I can either drive the speedo with a motor or replace it with an electronic one.
- Stepper driver http://blog.makezine.com/archive/2011/02/make-it-last-build-series-3-finishing-the-stepper-motor-drivers-for-the-drawbot.html
Wiring
| Purpose | EVision harness | CAT 5 |
| PWR | red | white/blue |
| GND | blue | blue |
| CAN H | orange | orange |
| CAN L | black | white/orange |
| 12v + | brown | |
| 12v - | white/brown | |
| Speed pulse | green | |
| white/green |
CAN Bus
Fuses
The EVision is connected to the pack by 3 wires, these need 50mA fuses. My options seem quite limited here. After quite a lot of searching I found the Bussman FWH-.500A6F which is UL Rated to 500V DC. At US$18 each I'm not so happy. Can be had cheaper at Online Components. (wrong current). Can probably use http://jaycar.co.nz/productView.asp?ID=SZ2014 with a lower voltage pack.
10000 RPM Data Acquisition
Note, this was taken with the shunt incorrectly configured, double all the current readings
grep \\\$IV 10000rpm.csv |cut -d , -f 4- |tr , " " >data.dat gnuplot set terminal png set output "10000rpm-1.png" plot "data.dat" using 1:2 title "voltage", "data.dat" using 1:4 title "charge current", "data.dat" using 1:5 title "discharge current" set output "10000rpm-2.png" plot "data.dat" using 1:6 title "power"
