Hot-rodding the Toyota MGR
 

Some years ago I discovered the Toyota MGR, and thought "This has amazing potential for an electric vehicle drive."

The Toyota MGR is an integrated motor, gearbox, and differential that was originally designed for the rear drive of the Toyota Highlander Hybrid.

The sister-company Lexus, also made a version, the RX400h that was equipped with this rear differential.

The vehicles were available from 2006 to 2010, and the drives were also called "Q211" by Toyota, and can also be found by looking for "rear differential" and "rear differential carrier."

Ok, why bother?

1) They are a compact, powerful unit. They are rated at 50kW. (68hp)
2) Everything's included: Motor, gearbox, differential
3) All this weighs approximately 100lbs
4) It's possible to find used ones for less than $400, because no one knows what to do with them. :rolleyes:

I'm starting this thread to provide as much information as I've been able to find on these motors. My intent is to actually get MORE than the rated power out of them, hense the "hot-rodding" name for the thread.

I purchased 3 of them and took one apart.

Here are some quickee specs from Toyota:
Type: Air/oil cooled permanent magnet
Power: 68hp (50kW) @ 4,600 - 5120 rpm
Torque: 96ft-lb (130 N-M) @ 0-610 rpm ( Don't know if that's motor or MGR data)
Max RPM: 10,500 rpm
Gear ratio: 6.860:1

Here are some pics to show what we're dealing with.

Gearbox side:
http://i1369.photobucket.com/albums/...ps128182f9.jpg

Front:
http://i1369.photobucket.com/albums/...ps8203597f.jpg

Resolver side:
http://i1369.photobucket.com/albums/...psbc9bbc38.jpg

Back:
http://i1369.photobucket.com/albums/...ps3fc972a5.jpg

Bottom:
http://i1369.photobucket.com/albums/...ps17de78ee.jpg

Top:
http://i1369.photobucket.com/albums/...pscf8bb38e.jpg

If this is what I think it is there was a discussion of using it on the insight forum not too long ago.

The problem was it uses 650 volts vs the 288 volts that the prius uses and in order to get that voltage you need a lot of damn batteries or some type of voltage doubler or tripler.

What exactly are you considering to do? An all-electric conversion or some sort of hybrid setup?


Some hybrid trucks and buses have been fitted with a 650-volt setup nowadays, not impossible to source parts from.

Theres a few guys on the insight forum who would love to talk to you. :thumbup:

Im guessing you can stack a few prius packs for the voltage, then you need a regulator or speed controller of some sort that isnt a basic carbon pile. Lastly use a few stacked mean well led power supplys to charge the prius packs and keep them in balance.

I've got to get one of those. How do you attach it to the car? Are there only a few car types that would work for connecting it? Also, I forgot. Is the resolver signal only functioning while the 3 phases are getting their sine waves? Or was it eniugh just to manually rotate the shaft? And is there 3 lines that are sin(theta), cos(theta), and a neutral line that serves as the theta axis? So there is no 4th line that is the power supply for the resolver?

Yes, I'm familiar with the voltage they require.

If one uses NiMh cells; yes - it will require a LOT, because the voltage is less than half that of the Lithium cells I am using.

The controller is going to be orders of magnitude better than "a carbon pile" and it's being developed right here. http://ecomodder.com/forum/showthrea...ler-10839.html To make full use of this motor's capability requires knowledge of it's advanced magnetic structure. If one takes advantage of the amazing design Toyota did, then it's possible to make use of the reluctance torque to help fight the back-emf that starts to dominate at high rpm.

If I remember correctly, there was also a thread on DIYEV about using this motor. The conversion was a Saturn, and I think (I could be wrong here) he used a Prius sub-300V battery pack and a standard BLDC motor controller. To be perfectly honest, the author of that thread wasn't happy with the results. I definitely DO NOT want to diss on the author of that thread. He was doing ground-breaking work and was very innovative. :) If I could point out two reasons for his dissappointment 1) the vehicle was a bit heavy for a 50kW power source. 2) I doubt he got anywhere near 50kW, simply because the power source was supplying only half of what the motor was designed for.

While it **may** be possible to rewind this motor for lower voltages, I am not going that route. There are a number of extremely well-executed tests on these motors indicating the necessity of the high voltage. In addition, there is some excellent information from Toyota about this as well.

Here is a paper written by Munehiro Kamiya: "Development of Traction Drive Motors for the Toyota Hybrid System"
http://e-mobile.ch/pdf/2005/321.pdf
The paper details the power and efficiency advantages for increasing the voltage to 650V.

In addition, there are a mind-bending number of tests done by Oak Ridge National Labs on the various Toyota Hybrid systems. This is a perfect example of our government labs going all out with amazing results. For example:

REPORT ON TOYOTA/PRIUS MOTOR TORQUE
CAPABILITY, TORQUE PROPERTY, NO-LOAD BACK-EMF,
AND MECHANICAL LOSSES – REVISED MAY 2007
SciTech Connect: Report on Toyota/Prius Motor Torque Capability, Torque Property, No-Load Back EMF, and Mechanical Losses, Revised May 2007

EVALUATION OF THE 2010 TOYOTA PRIUS
HYBRID SYNERGY DRIVE SYSTEM
http://info.ornl.gov/sites/publicati...s/Pub26762.pdf

Reading a few of these publications leads one to the conclusion that Toyota might have a pretty good idea of what they are doing. :p While dropping the voltage significantly may reduce the amount of cells required, there are some very complelling reasons to use those scary-high voltages.

While I call this thread "hot-rodding" the MGR, I do NOT consider dropping the supply voltage significantly a method for improving the performance. It would be a bit like dropping the boost pressure on a turbocharged car and calling that a performance improvement. :rolleyes:

Ok, to answer some questions about what I'M going to be doing with this.
1) They (yes, more than 1) are going to be the primary power source for an EV.
2) I am using a high voltage lithium pack to supply the power. The modules are from a Nissan Leaf, and so far I have a pack with over 400V. Boosting the pack to the full 600+V will require another 24 modules, which is not ridiculously expensive or heavy.

- E*clipse

Hi Paul!

Would you like to borrow one for testing?
Seriously, I think these are great little units, and I think the possibility of using Prius motors could open up with HUGE possibilities for the EV folks. :)

The MGR is bolted to the car with 4 bolts, two front, two rear. The threads and spacing makes no sense to me, I'll just give some dimensions later. Each output shaft has four bolts to connect it to a CVT. Again, I'll give some dimensions later.

The various versions of Toyota hybrids all use this type of resolver. The resolver's output is completely independent of the stator's signal. The resolver connector has 6 pins, 2 for the input signal, 2 for each pair of output signals.

Basically, a high frequency sinusoidal signal is injected into the resolver. I've messed with a bunch of different frequencies and waveforms. You can get away with a very NON-sinusoidal waveform if you're sloppy. :D The resolver's rotor is a semi-circular stack of disks that spin with the rotor. For this sytem, there are two lobes, but other resolvers may have four lobes. A device that looks a lot like the stator, just a lot smaller is used to inject and pick up the signals that are reflected back by the resolver's rotor. In essense, the resolver forms an envelope around the base signal, this envelope varies sinusoidally as the rotor rotates. There are two output signals, positioned 90 degrees apart. By comparing the magnitude and sign of the two signals, it is possible to figure out the rotational position of the rotor shaft.

Let me know if this helped or confused - I'd be happy to try again. :)

E*clipse

I have seen several of these at the scrap yard, some in pieces had no idea what they were until now.

Any chance you could find them again?

They tend to go on E*bay for about $300 > $600. You should be able to talk the scrap yard out of them for less.

Seems the power harness and connectors would be pretty good to have...

I'm going to see if my local scrapyard has any next week.

I previously posted that I took one of these apart. Unfortunately, I didn't photograph the process, but suffice to say it was pretty easy and didn't require any special tools.

Basically, there are three major parts to the assembly; assembled horizontally. The oil is sealed inside with some silicone sealant, no special gaskets or huge o-rings.

Before taking it apart, I'm going to show the electrical connectors. First are the position and temperature sensors. The 6-pin connector is for the resolver, the 3 pin connector is for the temperature sensor. According to Toyota, if the ECU determines the temperature is too high, it will shut down the MGR until it fall back into the proper range.

http://i1369.photobucket.com/albums/...ps3cd5692a.jpg

This connector is the main 3-phase power connector. Note that this part is some sort of extension to the main connector.
http://i1369.photobucket.com/albums/...ps533661a2.jpg

Locating these plugs (both data and main power) could be a real PIA, especially if it turns out Toyota is the only source.

Here are some of the guts. I'm breaking the posts up to make discussion easier. :)

I'll start with the stator. It's part of the middle section of the assembly.
http://i1369.photobucket.com/albums/...ps2a1c14cc.jpg

Here's a closup of the stator slots and windings. There are 48 slots. The stator OD is 235mm, and the ID is 150mm. The slot width is 45mm.
http://i1369.photobucket.com/albums/...ps88960951.jpg

Here's a closup showing some of the winding details. The winding wire diameter (including varnish) is 0.030", close to AWG #21. There are three wire groups/phase; I think there are 12 wires/phase.
http://i1369.photobucket.com/albums/...ps52ca762c.jpg

That pile of motors is long gone.
I am pretty sure they were opened up and the copper already harvested out.

Next, is the right side of the assembly, which I call the "resolver" side.

Here is the resolver itself, and the inside of the resolver side.
http://i1369.photobucket.com/albums/...psf015289d.jpg

You may have noticed a space for a ball bearing in the previous photos of the stator. Note there is also space for a ball bearing centered in the resolver. The motor's rotor actually runs on ball bearings nestled within the rotor itself. A spline on the rotor transfers torque to the first driveshaft. Here is a shot of the rotor fitting on it's bearing space on the resolver side.
http://i1369.photobucket.com/albums/...ps8c6d173d.jpg

Here is a closup of the rotor, looking at the resolver side. Note the semicircular resolver rotor just behind the bearing.
http://i1369.photobucket.com/albums/...ps7089d90d.jpg

An side view of the rotor. The resolver (between the bearing and main laminations) is only a few laminations thick.
http://i1369.photobucket.com/albums/...psada763b7.jpg

The gearbox side of the rotor. The bearing is nestled in the laminations; also note the output spline.
http://i1369.photobucket.com/albums/...psdf739233.jpg

The rotor OD is 5.825" (148mm) Also note how you can only see laminations. The magnets for this rotor are buried in a "v" form. Details about the reasons for this are in the papers I posted earlier.

I like the title. Bill Fisher's book How to Hot Rod Volkswagen Engines has been a classic for years.

My thought was at $400 I'd get two and use the best one. In the event I went with the $650 Lexus part. I rationalize it by saying maybe the yard knows it's worth more than others. We'll see—it should be delivered by Monday.

I've measured the vehicle and I have 11" between the frame rails. It might be tight getting the axle centerline to the original location. I may have to rotate the unit 5-10° up in front and the vertical clearance looks tight. The plan is to make a 1/8" steel plate carrier that will lie below the MGR, adapt it's mounting tabs and fit to the stock VW rubber transaxle mounts.

For benefit of those not in the AC controller thread, my hope is to use the Toyota gearset as a raw material for additional hardening and machining, and put it in an understressed installation to see if I can get by without an external oil pump.

Toyota must have training materials for their mechanics. Those mechanics must go someplace for a beer after work. Hmmmm.....

Edit: Will it be possible to drive one of Paul's controllers from 120v or 240v mains power, at a bench dynamometer?

Ya, but you would need a rectifier. The capacitor filter is already there. A big fat 600v 1000uf ring cap.

Glad to see you're rolling with this! :)

The differential is off-center on the drive. I was just planning on using different length half-shafts. Actually, even though the differential is off center those driveshafts that connect to the differential are different lengths, so the CVT joints themselves could be centered. How do you plan to position the drive vertically? Is the drive between the rails at the centerline of the axle?

Oh yeah - you do plan to mount oriented so the motor is in front of the differential? That way the built-in lubrication will work. In that case, if you wanted to add an external pump and oil cooler, it would be helpful but not critical. It could also be pretty easy using the drain and a fill port that is located next to the breather.

I have a couple mechanic's training manuals from "Toyota University" if you would like. They're mostly for the entire vehicle, with not tooooo much info on the MGR. I'll see if I can find the original link, otherwise I'd be happy to e-mail them to you. :)

**edit** found one of them:
http://facultyfiles.deanza.edu/gems/...torOutline.pdf

This might be a good time to put out a request for a factory service manual for either the Highlander Hybrid or the Lexus. So far I've had no luck, but I've found the manuals to be invaluable for my Toyota Pickup.

- E*clipse

I like this idea - I was planning on something like this - a three-phase rectifier for that rev 0.1 controller. I've found BIG diodes in the SOT-227 format. They're available as a pair in both parallel or apposing orientation.

My only problem is some sort of pre-charge circuit. That big fat ring capacitor has virtually no impedance, and some of those diodes (if you get Silicon Carbide) have virtually none. That's all well and good when the capacitor is at operating voltage. However, I'd hate to see what happens if the capacitor was a 0V. :eek:

Perhaps some precharge circuit using a much smaller rectifier, a lot of resistance, and a sensor that can turn on a contactor for the big rectifier when the voltage is right? Or am I missing something important? :confused:

E*clipse

Peer pressure. :)

Here's a handy picture of a Subaru transaxle on VW pan. It's about 19" between the front and rear transaxle mounts.

http://ecomodder.com/forum/member-fr...592-951771.jpg

I'd like the simplest possible install, MGR forward, axle centerline as close to stock as possible, optional external cooler, etc. With the thought of a limited production run of adapter cradles; because if this works, nobody will do VW conversions the old way again. As long as supplies hold out.

OTOH, it's going into a Baja'd Beetle. So if I need to move the axle centerline up and/or to the rear or modify the sheet metal, then 'oh, well'. If the unit won't drop between the rails, it might rotate up in the front. I had thought the diff was centered and the motor hung off to the right, but it looks roughly symmetrical.

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. :eek:

Alrighty then - more guts, more glory! :D

Here is the gearbox side of the system; this is where I figured some improvement could be added.

Here is the gearbox side of the center (stator, etc) section. Not really much to see here, except note that there are pockets for bearings on every shaft, and that there is very little extra room.

Also, there is a potential for an oil fill or cooling oil port directly above the output shaft. You can see the plug bolt in the "top" view next to the breither port (above the power connector in this view) The next views that show the other side of the gearbox will show the oil flow better.
http://i1369.photobucket.com/albums/...ps136725da.jpg

Here is a shot of the gearbox side of the MGR, with the geartrain loosely fit in. In this shot the "oil pump" made by the differential's main gear and the gearbox is visible. Oil is deposited into the containers above the geartrain. While this system is very reliable, there are two problems. 1) You cannot run this motor for any extended time in reverse. It will not get any oil. 2) Oil is used for both lubrication and distributing the heat load. The case and the fins on the case are the only method for getting rid of heat. While this might work ok for standard gearboxes, in this case there is a significant additional load - the motor! To ensure the system reliability, Toyota built into the control a thermal limit measured by sensors in the stator. By doing a better job of cooling the oil, it will be possible to cool the stator more effectively, and thus push the motor harder. :cool:

The gear on the right is the output of the motor, with a splined connection to the rotor. Both the motor rotor and this shaft each have a set of ball bearings on the shaft ends. I think it is made this way so balancing the rotor for 10,500rpm is easier.
http://i1369.photobucket.com/albums/...ps57b64607.jpg

This is the gearbox side without the gears in place. Note the oil passages and specifically the one for the motor. There is a special passage made to deliver oil through the center of the hollow shaft.
http://i1369.photobucket.com/albums/...ps53927ea8.jpg

The outside of that part. The bearing pockets and oil passages are all easily visible. They didn't spare a bit of metal in making this part! Also note that there is an oil port right where oil is put into the motor's hollow shaft. It may help to add cooled oil directly here.
http://i1369.photobucket.com/albums/...psbf52ffa5.jpg

The gearset. Freebeard's suggestions for polishing and hardening the gears would be a good help. Also, My EVIL plan is to use one of these motors for every wheel. I will need to lock the differentials to do this. Does anyone have ideas for a company that makes custom spools or something like that?
http://i1369.photobucket.com/albums/...ps6bbd9885.jpg

My bad e*clipse. Seems you are way ahead of the guys on the insight forum. :thumbup: 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. :turtle:

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. :o

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

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

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.

:)
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...:p

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? :confused:

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.

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.

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.

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.

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.

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. :confused:

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. :cool:

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.

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.

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

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

The tips are not mine. Our electricians contributed them. I will thank them.
I had asked for their tips for my own education some time ago ;)

On e*bay, search "hydraulic cable crimper" and you should get a range of items .. from Chinese made crimpers that have dies that you change out manually (like the one I have) around 6 tons of pressure .. up through the more automatic crimpers that are name brand and use a rotating wheel to choose dies, in the 8 - 12 tons of pressure .. and finally to the crimpers that look like a cordless drill, choose your crimp size automagically, and power the crimp with a trigger ($$$)

Taping. The higher voltage tape (5000V and higher) is a specialty tape that is supposed to prevent corona (not the beer!) from forming around sharp edges of the lugs and bolts. The corona causes some sort of problem if it is not mitigated with tape.

For 1000V and under, electrical tape is used to prevent the connectors on the motor leads from touching each other and from touching the junction box or anything else. I end up using a bit of tape the first time, then pull it off to check the connections about a week later. After that check, bury the connections in a ball of tape.

CALB has a higher rated cell that is physically smaller and lighter. CAM72 is what they are called, I think. Price premium - just under $2 per a-h. But they take up less room and weigh less than the CA series. EVTV testing has gone up to 15C .. or was it 20C? Unless you are going to short circuit the batteries and weld with them, I don't think there is much difference?:D I guess the dragsters would notice the difference.

The web site for CALB lists a 25 a-h version but I have not seen one for sale so far.

Another link from EVTV

EVTV Motor Verks Store: 1 CALB CAM72FI LiFePo4 Cell, Lithium Battery Cells, CAM72FI

There is also a CAM80 which has a different form factor.

I found my way here from the Aerodynamics subforum. And this time next week I hope to be on The Salt for the 36hp Challenge. So I bring a perspective of self-imposing limitations, for the challenge. The record for a stock bodied 36hp Beetle is about 90mph, a belly-tank Lakester—about 129mph. So 68hp (as a base) is comfortable for me.

I'll start with a simple EV conversion; ultimately, with a 2nd MGR, I'd like to run a reverse tricycle belly-tank in the 130mph Club—probably the only class that would accept such a curious beast.

Here it is, dragging a fourth wheel to try to fit in better.

http://ecomodder.com/forum/member-fr...belly-tank.png

awesome, I have been watching these motors for a BMW rear wheel drive conversion, would leave tons of space under the hood for controller/computer/bms/batteries, good value compared to alternatives i have been looking at

Wholey ****e! That is REALLY cool! :cool:

I didn't know such a class existed - what an awesome idea!

Alrighty then; I stand very corrected - with a vehicle like THAT to wrap around the power plant. My numbers were merely for standard vehicles with standard frontal areas and standard Cd's.

With an open mind like that, there's a world of possibility. I'd love to keep in touch and see how the challenge went. :)

- E*clipse

I'm not too familiar with BMW back ends, but in general, these motors are not much larger than a standard rear differential. For my 1G Eclipse, I will be able to fit two motors in the back end (I've already removed the rear differential.) The motors will have to face backwards, necessitating some oil system mods.

You may want to consider the vehicle balance, and how you can creatively get it closer to 50:50. Most front motor cars are seriously weight biased toward the front. It's likely if you put the entire battery pack in the front, it will only get worse.

For example, on my Eclipse, the rear differential and driveshaft weighed 100lbs, exactly what one MGR weighs! :p Now, if I go with two MGR's in the rear, I've moved some of the weight biase toward the rear, but the battery is a pretty huge chunk. On the other hand, It might be possible to split the pack so that along with the additional electric motor weight in the back you could achieve a very nicely balanced car.

With a mind that open you never know what going to fall out. Here's the same design in a motor home size:

http://ecomodder.com/forum/member-fr...-w-caption.jpg

This could be built with 3 MGR, with welded spider gears, the wheel bolted/sprocketed to one output shaft and a emergency/parking disk brake on the other.

Oh, we will be talking again. :)

/my MGR still hasn't been delivered, but the shop's on notice I'll need the big orange cables/connector.

Great! I live for these sorts of competitions. :)

Also, I can show you some stuff I did for the super-milage vehicle competition. At the time, I had access to a wind tunnel and all the CNC time I wanted...

What do you plan to do for the power connector?

- E*clipse

Here's a post from another thread, but I think it will be happy here.

It's a cutaway of the MGR, and a great way to help make sense of all the pics I've posted.

[IMG]http://i1369.photobucket.com/albums/...ps7fd97d67.jpg[/IMG]

Why both in the back end? Put one for fwd in the front and rwd one in the back with the gears. Even weight close to direct drive awd or partial 4wd /2wd and shut off one or the other to conserve power