[jdsanderson]

Announcing the one month birthday of SHAZAM! my electric truck.

One month ago with much effort and few fla batteries he hopped of of the ramps and tasted pavement as an ev. Made the first few laps around the neighborhood, and carried his first k9 and human passengers.

After a month of very boring stuff like code revisions and more fla batteries we a achieving faster speeds smoother regen braking and bigger hills.

Progress can be viewed at "evmaker.tumblr.com"

Please don't laugh too hard, everything is made by my own hand. Of course
SHAZAM! is a work in progress and will have soon proper racks for the fla, or at least a cover that looks like a tool box.

Once I have perfected my drive architecture and code I intend to open source it and provide the biggest baddest hex inverting duino motor shield ever. In DYI, in kits, and in assembled and tested assy.

 

[jdsanderson]

The bat wires are #2. The software adapts the frequency and voltage going to the motor to keep current under 110 amps. This keeps the motor form having excessive rotor slip and produces the most torque without overloading the motor. The wires do not seem to ever get hot however battery #2 and #4 are several years old and have some internal resistance due to sulfate and get rather warm.

 

[jdsanderson]

It would be very very bad in a dc rig, To use such small wire Supplying both the armature and stator at a high acceleration load. That is why SHAZAM is such an odd little beast,
because he uses a slightly modified industrial 3 phase AC motor. The software allows me to dose the motor with the correct amount of voltage through pulse width modulation and adjust the frequency on the fly, Adjusting the frequency of the ac under acceleration would be like repositioning The brushes in a dc rig on the fly. This allows me to keep the motor in traction with it's self as close to unity as I can reasonably keep it. In other words if the amp draw is to high I retard the timing slightly which increases torque and lowers the amp draw. Every time I increase the drive frequency it advances the timing until the vehicle speed catches up. The accelerator pot advances timing and the feed back loop allows or denies the advance or retards if the motor is loosing ground against a big hill or other load based on amp draw.

 

[jdsanderson]

Ultimately SHAZAM will have 24 batteries and run 285 ~ 300 volts. This will give me applyed voltage of around ~208 at 30% pwm duty cycle.
Shazam should be able to cruse along about 50 or so amps with an actual 3 phase motor amps arround 28 ~ 32. Regen braking seems to generate about 2/3 that depending on how it is set up that is a work in progres. Right now with only 9 batteries it takes the whole 110 amps to maintain 50 ~55 on flat ground. This is possible by runing the motor on an extreemly modifyed sine wave resulting in applyed power of 70 volts at 90% duty cycle.

This is pay day weekend and tomorow we will pick up a couple more batteries. The 2.0 code is almost redy for testing. This code should have better throttle responce, faster top end speed, and regen that is baised on the g force generated form the friction brakes and the presure transducer in the hydraulic line.