Sunday, October 27, 2013

Update 102713

Lots accomplished this weekend, I've started the wiring!

I'm using 0 gauge wire, which isn't very easy to work with. This should be a little overkill for 100 amps, but maybe I'll increase the system voltage someday. I crimped the big copper lugs by squishing them in a vice with an allen wrench to make an indentation.

Grommets are the unsung heroes of wires going through holes. The distance between the IGBT and the motor needs to be as short as possible to limit inductive spikes from the high-current wiring. It's probably possible to get them even shorter than this, but it's difficult to bend the thick wire.

Shrink wrap and grommets will make anything look professional. Ammo boxes won't, but that's entirely okay. I sanded off the paint between the IGBT, ammo box wall, and aluminum heat sink and bolted it all together with heat sink compound.

With a home for the electronics now built, it's time to put them in! I installed the microcontroller and supporting hardware this weekend. I cut a piece of Plexiglas to slide into the bottom of the ammo box, creating a sturdy and insulated mounting surface for the electronics.

The red PCB on the left is the main microcontroller for the motorcycle. It's a Cypress PSoC 4 Pioneer kit using an ARM Cortex CPU at 48 MHz. Its main purpose is to read throttle position using an ADC and generate the duty cycle output switching the IGBT on and off. It's also driving a LCD display on the handlebars. The red PCB on the right is a relay board that the micro can use to control other stuff on the bike. Toward the back of the box is the IGBT drive and a blank board that will provide 5 volts for the micro.

No worries, the LCD is now securely zip-tied in place. I'd like to get more Plexiglas to mount the display behind, that'll help with waterproofing too. This displays 0 - 255 throttle position for now, but I'd like to add battery voltage, speed, and motor current as well. 

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