In the spring of 2001 or thereabouts, I was bored on a train ride going to a convention, and my thoughts wandered toward trying to fathom the reasons that many electric vehicles of the time were using AC induction drive motors. There *had* to be something better, something more controllable at low speeds and better suited for efficient regenerative braking -- perhaps a design similar to the Hall-effect switched DC motors found in computer fans, but with either a slip-ring fed rotor field winding or permanent magnets, and smarter control. I figured the semiconductors and some switching smarts could mount right inside the housing, and it would thus be possible to build a very smooth, efficient and reliable plug-and-go traction motor whose only connections would be main power and a PWM input lead. With enough poles, losing one power transistor wouldn't be a showstopper -- the remainder could simply continue powering the motor to limp home, just with a bit of torque blip every time the bad phase came around.

As the train's own diesel series-hybrid system pulled it onward through the NJ pine barrens, I doodled out a sketch of a six-pole rotor spinning in a seven-pole stator, and a set of MOSFETS to pulse-width-modulate varying currents into the stator windings as the rotor turned and activated position sensors. But I couldn't come up with the right way to switch windings at first. To finally determine the switching order, I made a paper cutout of the rotor so I could spin it relative to the stator and figure out which coil[s] had to be on next and in which polarity, and drew out all the winding waveforms in time. The result was basically a stepper controller gone horribly wrong, but from that emerged a surprisingly simple pattern. It was all a very silly way to pass the time, but took me one more step toward an interest in modern motor control.

I never really managed to figure out how to change directions, or how to fiddle the switching vs. rotor position to recapture energy by regenerative braking. I sort of lost interest/time at that point -- too many other projects to deal with first. Something in the back of my brain told me that the EV/hybrid people would eventually come around to using more sensibly-controllable motor types, but it would take a few more years because they were still out there losing away with off-the-shelf parts and controllers -- cheap and available, maybe, but not really designed for the purpose. In fact, by then the revolution had already started, but I wasn't aware of it yet.

  Times sure can change, can't they.

---

I now own a Prius, after thinking for years that they were too small, too weird/complex, too this, too that. In around February 2005 the concept of replacing a somewhat unsatisfactory generic wagon with *some* sort of hybrid began grabbing a larger chunk of my attention. I started poking around on the net for info on what might be available, and soon discovered the many Prius and other hybrid discussion groups. I spent almost a month just finding and reading information, particularly the more technical sort, and along with that my overall view on several aspects of vehicle ownership and usage began to change.

To help me escape from the brief delusion that the hybrid Highlander would meet my needs, I did extensive testing of the Prius and got to go spin one around in snowy parking lots for a while. The result? I bought it, under the full realization that not only would this be transportation, it was about to become a long-term project. By the time I took delivery, many ideas for modifications were already in the pipeline. And after another month or two, I had become a total mileage geek.

This is an ongoing chronicle of that process, detailing the many hacks, theoretical discussions, reverse-engineering, ivory-tower guesswork, and entertaining events that have come since then and will continue to happen. It's not just transportation, it's a rolling lab! It's the first time in many years that I've actually had any enthusiasm about a *car*, which for me is saying quite a bit. This is my learning experience, which seems like something useful to share with those who have similar interests. All of my mods are fully documented along the way, in the hope that they will be useful to others.

Through this I have become that very person I kept looking around for at the local alternative-transportation festivals -- the one who could help answer those questions about hybrid drivetrains, motor control, long-term reliability issues, energy conversion and efficiency curves ... Now I can teach other people about it, and help encourage acceptance of more efficient vehicles and consumption-aware lifestyles.

Use this index to start. The sections are presented in REVERSE chronological order, so that occasional revisits will show the newest stuff first. If you want to read it from the beginning as it happened, start from the bottom at file 000 and work back up. Enjoy!

_H* 050522

[A tarball of these files *may* be available as allfiles.tgz -- no guarantees]