Hot-rodding the Toyota MGR

[Cobb]

My bad e*clipse. Seems you are way ahead of the guys on the insight forum. Yeah I heard something the new prius 3 or v uses 650 volts as its more efficient even if its generated from a voltage doubler using the same prius battery the other cars use. I just dont see that many golf cart controllers rated for that amount, but then again this seems more advance and why those who pushed on with current 100 volt ev technology passed it on as with that low of voltage performance would of been on par with a kids power wheels toy or the motorized scooters for disabled people at walmart.

[e*clipse]

No, really I owe the apology.
I'm just a technical person, and I know my replies get a bit, um rough. I ***really*** love the open discussion over at the 3phase motor controller thread, and I ***really*** think that has a lot to do with Paul's open attitude.
So, I'm trying to learn this and I hope folks will give this discussion the input it deserves, in spite of me.

I'm sure we can learn from each other, and I'll check out what they're doing. For some reason I missed that thread - I have a 1st gen Insight (which I will NEVER get rid of), and I really enjoy seeing what folks are doing over @ InsightCentral.

-E*clipse

[freebeard]

Thanks for posting the pics, it makes the wait for mine to show up more bearable.

The gearset. Freebeard's suggestions for polishing and hardening the gears would be a good help.

For the record:
Isotropic Superfinishing

• www.remchem.com/‎
• Isotropic superfinishing - Google Search
• In-house REM Superfinishing process by Weddle Industries | Weddle Industries | High Performance Driveline Components for Race Vehicles | Off-Road Transaxles, Clutches, Gears

Cryogenic Tempering/Hardening

• en.wikipedia.org/wiki/Cryogenic_hardening‎
• cryogenic tempering - Google Search
• High Performance Brake Pads and Brake Rotors - Frozen Rotors

Another one, Heat Rejection Coatings

• Why Coat Radiators, Intercoolers, Oil Coolers And Casings?

I believe the shade tree mechanic method for a locked diff was to spark up the arc welder and weld the spiders to the ring gear.

[e*clipse]

Thank you for the links. Do you know if anyone does group discounts? I'd send mine up your way if that's the case.

I've seen the shade-tree method, I can probably weld well enough to make a reasonably robust set-up. I was just hoping for a more elegant solution. It's probably better to spend the money on more critical parts of the project, especially since no one will see my welds on that part anyway...

Oh yeah - regarding mounting the motor on the VW. . . that Scoobie motor is tranny forward, motor back, correct? If so, the critical space would be where the Scoobie tranny is. Otherwise, it looks the the MGR was made for the job! Is that the place that is 11" between the frame rails?

The Toyota mounting method is to bolt the MGR to a bar that has rubber cushions on it. I will probably go with the extra (front & rear) mounting bar, but I'm debating whether to use isolators or not. I'm a bit odd about that stuff - I don't mind feeling the engine. My diesel uses those hard motor mounts intended for sporty cars. I doubt the vibration from an electric motor would bug me.

Originally Posted by freebeard

Thanks for posting the pics, it makes the wait for mine to show up more bearable.

I believe the shade tree mechanic method for a locked diff was to spark up the arc welder and weld the spiders to the ring gear.

[freebeard]

I've only ever had a set of brake parts done. But any science lab with a vat of liquid nitrogen and clock has the setup.

As for Isotropic Superfinishing, that's not rocket science either (jk: it probably is). Eastwood company sells a desktop unit that polishes rusty nuts and bolts. I'm sure the whole story is on Youtube.

that Scoobie motor is tranny forward, motor back, correct? If so, the critical space would be where the Scoobie tranny is. Otherwise, it looks the the MGR was made for the job!

You do better at descriptions, and you're starting to see the beauty of the whole thing. The VW transaxle doesn't weigh much more than 100lb. So I have the weight of the motor, a full tank of gas and the shift rod/lever to play with. For planning—how many pounds per kilowatt-hour?

Everything to the right with the cylinder bores is engine case. The rear trans mount is a plate bolted across the ends of the 'tuning fork'. The front mount is at the bottom of the center tunnel. I get to use the stock rubber mounts, or their polyuethane race-car red replacements. So I think I'm good on that.

Peak power's in the middle of the rpm band. The Lexus/Highlander probably has 28" tires. So maybe I can build an undervolted (288v) version with 26" tires as proof of concept; and then double the battery pack and go to 30" tires to put it out on The Salt.

Edit: I'm going to hold off on that pre-build thread, since the drivetrain should be available tomorrow. I should decide whether to go with the original thread in Aerodynamics, or start a new one here or in Ecomodder Central.

[thingstodo]

Originally Posted by freebeard

Insofar as the manuals, I'm curious about whether it's solid or rubber mounted in the chassis and best practises for crimping cable ends or whatever Toyota knows about working safely with those voltage levels. The biggest bite I ever took was 800v, but that was from a TV set, not a power plant.

At the day job, our controllers put out 575 VAC (DC bus trips at 1000 VDC, 815 nominal). So for the AC side (DC only exists inside the controller) I would pass along these suggestions:
- use fine stranded cables
- strip only as much insulation as the lug takes
- crimp lugs onto the cables with a hydraulic crimper
- bolt the lugs properly
- torque the bolts during installation with a torque wrench
- re-torque/check every 6 months to 12 months (if not taped)
- separate the phase connections in the motor junction box
- tape the connections individually after testing
- use armored cable clamps (if using armored cable)
- terminate the ground cable at both ends

I hear from a couple of our consultants that new installations are having good results from individually shielded (per phase) 3 phase cables, where each shield is connected to ground at the controller only. I have no experience with this setup. It is said to minimize noise in adjacent electronics.

[MPaulHolmes]

OK I think I need one more go at how the resolver works. Let's take the perspective that it is a black box. I have a controller with +5v, ground, and 3 A/D inputs available. The resolver needs a periodic waveform from the controller for it to operate (instead of a +5v power supply)? If I supplied a 10KHz 50% duty square wave, would that suffice for "powering" the resolver? I'm thinking it would be a good idea to first get the controller working with a PMSM motor. While the rotor flux angle is the only difference between PMSM and ACIM, it's a significant step with a number of uncertainties. If I knew the code was good in the PMSM case, I could then focus exclusively on the ACIM rotor flux angle without all the uncertainty of other stuff. There really wouldn't be much to change. For testing, I could deal with 2 sine waves that were 90deg out of phase for computing the angle using the A/D. I would just need those 2 sine waves coming in.

[e*clipse]

First, I'd like to thank Thingtodo for the excellent description of how to properly connect wires in high-power applications. I'm just not sure of where to get a hydraulic crimper and what the taping procedure is about.

I'm a bit more familiar with some of the EV parameters; I've made a silly detailed spreadsheet of the E*clipse, including aerodynamic stuff, weight removed and where it was, added weight and where it will go, tire diameter, gearing, different motor options, battery pack options, etc etc.

Throwing a couple of numbers into that spreadsheet -
We'll use the 6.86:1 ratio of the MGR, and consider no weight or aerodynamic issues.
26" tires will allow a top speed of 115 mph, based only on the motor rpm limitation. However, reality is aerodynamic drag, friction, etc are working against hp that decreases from mid rpm > max rpm. The car will be power limited long before 115mph.
Personally, I don't see any use for increasing the tire diameter unless you find a way to dramatically reduce the aerodynamic drag or dramatically increase the power from the motor.

The speed freak in me is the one advocating multiple motors for my project.

Regarding battery weight, and here's a place I've spent ridiculous time searcing for some sort of "optimum"... The lbs/kwh number will directly relate to decisions here.
Consider lithium cells rated at high discharge values. The motorcycle racers and a few top-end electric racecar builders understand this. There are a lot of different pack options because each of the cell listed below have different voltage specs.
Here are some possibilities:
Enerdel 15Ah pouch cells rated at 15C discharge.
NEB 20Ah hybrid super-capacitor rated at 25C discharge
CALB 40Ah cells rated at 12C (torture tested on EV TV)
A123 20Ah pouch cells rated at 30C discharge
Nissan Leaf 23Ah (I think) cells rated at 8C discharge (This is cell, not module data)

If anyone has any more options, I'd love to hear about them.

- E*clipse

Many of the cells listed above are pretty much unobtanium. Either the cost is ridiculous, or the only way to get them is sponsorship or taking your chances dealing with China. I've decided to go with the Leaf cells because I've found a reasonable source for them and they're pretty close to my performance requirements.

Originally Posted by freebeard

You do better at descriptions, and you're starting to see the beauty of the whole thing. The VW transaxle doesn't weigh much more than 100lb. So I have the weight of the motor, a full tank of gas and the shift rod/lever to play with. For planning—how many pounds per kilowatt-hour?

Peak power's in the middle of the rpm band. The Lexus/Highlander probably has 28" tires. So maybe I can build an undervolted (288v) version with 26" tires as proof of concept; and then double the battery pack and go to 30" tires to put it out on The Salt.

Edit: I'm going to hold off on that pre-build thread, since the drivetrain should be available tomorrow. I should decide whether to go with the original thread in Aerodynamics, or start a new one here or in Ecomodder Central.

[Cobb]

Maybe this will help?

You can drive the IMA rotor using the original ima controller with a square wave generator, ie a 3 phase rc car speed controller that also works on the same principle. Of course you need to have the ima rotor position sensors connected, but the main guts can handle up to 600 volts, 600 amps, the other parts use between 12 and 24 volts.

I got some misleading info that I could use a square wave generator to work the ima controller to make the ima system do what you want, but they it got too complicated too fast for me to manage.

[e*clipse]

Ok, I guess I don't understand it well enough

It's not really a matter of "powering" the black box, it's more a matter of putting in a waveform, altering the original waveform a bit, then measuring that waveform... If you have a nice clean waveform to start with, then measuring the output is easier. I've tried square waves, and they produce enough noise at the corners to mess up the output signal. It is possible to create a sine wave by filtering a 50% square wave, thus it's not necessary to use microprocessor resources to create the input signal.

Here's another go at a resolver description, with some (hopefully) helpful links.

Think of a resolver as a rotating transformer of a sort. There are some decent pictures that will help my discriptions on page 27 of this link. (Unfortunately, I can't figure out how to steal a picture from a *.pdf)
http://facultyfiles.deanza.edu/gems/...torOutline.pdf

Look at slide 62 of the link to help with this description.
The stator is made of 3 sets of coils, arranged so that they are rotated 90 degrees from each other. Say the input coil is at 0 degrees, at the top. Rotated 90 degrees from that would be the "detection coil S" or sine coil. Rotated another 90 degrees from that would be "detection coil C" or the cosine coil. With this arrangement, there is no need for brushes to get the signal onto the rotating part.

The transformer part is really the flat laminations that are lobed or semi-circular. Their job is to reflect the magnetic signal generated by the input coil. Imagine for a moment that they are simply round. Ok, now the input coil gets a fairly high frequency (say 10kHz) signal. It's important that the input signal is fairly high frequency so that the output signal can be high resolution, as I will attempt to show later. Now, if the transformer laminations that are on the motor shaft were simply round, both of the output coils would get the same output signal. Specifically, we're talking about the AMPLITUDE of the output signals, because the frequency would also be replicated. If the transformer laminations are lobed, then the amplitude of the signal recieved by the detection coils would vary in proportion to the distance between the laminations and the coils.

Thus, there will be a sinusoidally varying amplitude of the input signal seen by the detection coils as the motor shaft rotates. Since they are 90 degrees apart, the different amplitudes will be 90 degrees apart, like a sine and cosine wave.

Now here part of the trickiness, and this is shown by slide 63 on page 27 of that link.
Notice how the input signal is a fairly high frequency sinusoidal signal. Below that pic is another pick of a signal composed of a high frequency sinusoidal signal varying in amplitude sinusoidally. Now, all we REALLY care about is the peak amplitude of each of the high frequency signal's peaks. Imagine we put a dot at each of those points. Later, we come along and draw a curve based on all those dots. (I think this is called an "envelope filter." Anyway, we need to generate two envelopes, one for the sine and one for the cosine. Then we compare the amplitudes of the envelopes to calculate the position. Also, you can see that if we used a lower frequency input signal, the dots would be spread apart more and the envelope created by the dots would loose resolution. This may not be a problem at low speeds, but when the motor is spinning at 10,000 rpm, this resolution would be important.

***whew***

I've gotten pretty close to producing the waveforms needed to use the resolver. I'm just stuck in one of my "gee - it could be REALLY simple if we didn't bother with a specific angle thoughts." In other words, when you look at the calculations for field oriented control, you don't really need all 360 degrees, only part of it.

Or we could say screw it - we've got the computing power, just calculate the *** angle!

Or we could just use one of those resolver>digital translators to keep the project moving.

- E*clipse

Originally Posted by MPaulHolmes

OK I think I need one more go at how the resolver works. Let's take the perspective that it is a black box. I have a controller with +5v, ground, and 3 A/D inputs available. The resolver needs a periodic waveform from the controller for it to operate (instead of a +5v power supply)? If I supplied a 10KHz 50% duty square wave, would that suffice for "powering" the black box? I'm thinking it would be a good idea to first get the controller working with a PMSM motor. While the rotor flux angle is the only differentce between the 2 controllers, it's a significant step with a number of uncertainties. If I knew the code was good in the PMSM case, I could then focus exclusively on the ACIM rotor flux angle without all the uncertainty of other stuff. There really wouldn't be much to change. For testing, I could deal with 2 sine waves that were 90deg out of phase for computing the angle using the A/D. I would just need those 2 sine waves coming in.