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Highlander Hybrid and Prius motors

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highlander hybrid mgr prius q211
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106K views 133 replies 18 participants last post by  John_G  
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#1 ·
Hello Everyone!

I am in the process of building an EV using the Highlander Hybrid rear differential(s). The goal will be to use these units for an AWD system.

There has been a previous thread about that here:
http://www.diyelectriccar.com/forums/showthread.php/any-use-highlander-rear-diff-motori-43920.html

I really admire Ryan800's initive in building his Saturn. I'm hoping to get more performance out of these motors by using them to/beyond their maximum capability. If something breaks, that's how we learn stuff. :p

Generally, I'm a person who likes to see physically what I'm dealing with, so attempting to run this thing as a "black box" doesn't work for me.

Here are the basic specs for the unit:
-50kw(68hp) from 4,610-5,120 rpm
-96 lb ft of torque from 0-610 rpm.
-Gear reduction of 6.86/1
-Weight: 94lb

Other than these basic specs, there isn't much information available for the Highlander Hybrid rear differential. However, there is some good information about the Prius. I think there is enough similarity between the second generation Prius traction motor and the HH motor that this information can be shared.

I plan to take apart one of these units as well as share other info I've found on them. If anyone has any questions or would like more details/measurements of stuff, I will be happy to post that as well. :)
 
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#2 · (Edited)
To start out with, here are some exterior pics of the rear differential.
Not too much exiting stuff here.
Top right: Right side. That black thing to the right of the output shaft is a piece of cast-iron. It is static and removable; I suppose it's for vibration :confused: There are two connectors on the upper right side. The one on the left is a 6-pin connector for a resolver. The one on the right is a 3 pin connector for a temperature sensor. (I will go into more detail later)

Top left: Front
Second row, left: Left side of motor
Second row, right: Front of motor
3rd row: Top of motor
4th row: Bottom of motor
 

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#3 · (Edited)
In this set of pics, some easily removed parts and the right side cover are removed.

The first pic shows the 3 phase connector/extension. It's purpose appears to be an adaptor to the Toyota 3 phase wiring harness. The internal pins are the same as what's built into the motor.

The second pic shows the counterweight. It is a fairly roughly machined part that simply threads into the cover plate.

The third pic shows breaking open the right side cover plate. An ATF-like oil is draining out.
 

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#4 ·
Ok, here's the inside of the right cover plate. The sensor mounted to it is a resolver, that appears to have some clocking adjustment.

For those unfamiliar w/ resolvers, they are extremely accurate absolute position sensors. Basically they are rotary transformers, and work by being fed a sine wave, that is picked up by two coils positioned 90 degrees apart from each other. These coils feed back the sine and cosine of the current position. If you look closely at the rotor, you will see an oval shaped piece of metal (between the rotor and bearing) This piece varies the air gap, thus changing the signal at the output coils.

Generally resolvers are found in high accuracy servo applications, like CNC machines. They are very robust and can also function well in an electrically noisy environment. :cool:

My feeling is Toyota chose these for a number of reasons, and replacing them merely because I didn't know how they work would be possible, but both expensive and troublesome. :(

Their signals can be translated to digital quadrature signals as one option. There are IC's made by TI that can do this for about $12. Other than that, I'm going to look into directly using their output in a DIY motor controller.

The other pics show how the sensor ouputs are run through the case. Each connector has plugs on both the inside and outside, with an o-ring seal between it and the case. BTW, one of mine was broken by a ham fisted junkyard removal. :mad: Does anyone know where to get parts like this?
 

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#7 ·
e*clipse,

That looks like the same resolver as in the Prius. Here is a rather old video of me spinning the prius motor using 24volts. I also got it to push a car around at golf cart speeds with 48 volts from 4 lead acid batteries on their last leg.

I am using an eval board from Analog Devices to do the resolver to digital conversion.

My project got put on hold for quite some time but now I am back at it. My goal is to see how much power these Toyota motors can really put out.

I have been doing quite a bit with the Prius inverter as a battery charger and as DC to DC converter to do some battery cycling. I recently got another analog devices eval board to do simultaneous analog conversions that I needed for measuring the phase current outputs for FOC of the motor.

I hope to get the time for working on the motor control again very soon.

Good luck
Jeff
 
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#5 ·
One of the difficulties I had with this motor is finding any decent information about it. The real name for the Highlander Hybrid rear motor is either "Q211" or "MGR"

Finally, I stumbled upon some amazing testing done at Oak Ridge National Laboratories. :cool: Here is where they are on the internets...
http://www.osti.gov/bridge/

All the testing was done on various generations of Pruises and Camries.
They did complete tear downs to measure all imaginable details, as well as testing torque, maximum speed, back EMF, gear losses, etc. Also, they did not simply use the Toyota controller - they used another design and double checked that the motors output. All the documents are free, and here are some good documents to check into:

"Evaluation of 2004 Toyota Prius Hybrid Electric Drive System"

"REPORT ON TOYOTA/PRIUS MOTOR TORQUE CAPABILITY, TORQUE PROPERTY, NO-LOAD BACK-EMF, AND MECHANICAL LOSSES – REVISED MAY 2007"

"REPORT ON TOYOTA/PRIUS MOTOR DESIGN AND MANUFACTURING ASSESSMENT"

"EVALUATION OF THE 2007 TOYOTA CAMRY HYBRID SYNERGY DRIVE SYSTEM"

Another really good paper is about the development of the Highlander Hybrid electric motors:

"Development of Traction Drive Motors for the Toyota Hybrid System"
www.e-mobile.ch/pdf/2005/321.pdf

There are many similarities between the motor used in the Q211 and the second generation Prius. Part of my goal in taking apart this motor is to see how closely they match.
 
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#8 ·
Very nice work Jeff! :cool:

I see a lot of opportunity for cheap Pruis transmissions. There are soooo many Priuses out there. Most people won't have a clue what to do with them, so they should stay pretty cheap. I checked on prices for the Prius and Camry (70kW) transmissions, and they range from about $500>$1000.

Did you try to get the motor running open loop?

What year of Prius is it from? Did you get measurements of the rotor?

Have you figured out a way to bypass most of the gearing stuff for a simple single speed drive?

Good luck with that - I'm extremely interested in how it goes. :)
 
#13 ·
I agree that they are cheap and may have some untapped potential.

The video is from a Gen1 prius that I got for free as a reject from a local transmission shop. It may have some defect that I haven't found yet.

To spin the motor I observed the BEMF of the motor in relation to the resolver output on the scope to get a reference point. I then modulated the phase voltages to track the BEMF based on the resolver readings I was getting. No current control at this point.

However the big discovery for me was when I put the motor in a car under a load and had some problems. I was trying to drive the motor like a BLDC motor which worked fine without being under load on the bench. Come to find out the reluctance torque is very significant even at low speeds. By advancing my phase voltage about 30 degrees everything worked much better. This phase shift also matches up with the stall torque graph in one of the ORNL report. Still very crude but it made me research these internal magnet motors a little more.

I am now working with GenII motors and inverters. I am making some progress but it is slow going.

I have some crazy ideas on what I can do with these things. I am far from having a mature controller but the experimenting is a great hobby.

The package I am working towards is a liquid cooled 100kw peak drive train + 20kw battery charger, 12V DC/DC, electric air conditioning compressor for about $1000 by using salvaged Prius components.

Jeff
 
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#9 ·
Here is some info from the ORNL paper "REPORT ON TOYOTA/PRIUS MOTOR DESIGN AND MANUFACTURING ASSESSMENT"

It shows the differences between the first and second generation Prius motors, along with giving some important dimensions.

First, the output curves. Note the increase in power from 33kW to 50kW. Torque increases from 350Nm to 400Nm. This was achieved without increasing the size of the motor. These numbers are tested in the other ORNL papers.

Second, note the 2004 stator and rotor. I'll post a pic soon which shows the MGR stator and rotor.

3rd & 4th pics are the stator and rotor dimensions and weight. I'll verify the rotor dimensions on my MGR soon...

The last pic show the rotor stampings from the 1st & 2nd generation Prius motors. Changing to a V shaped permanent magnet was instrumental in increasing the output power. Technically, these motors are "Interior Permanent Magnet Synchronous Motors." They rely on reluctance (like a switched-reluctance motor) to provide power past the base speed.
 

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#15 ·
Ok, here are some very interesting (and somewhat discouraging :() dimensions. This rotor is significantly smaller than the Prius rotor.

Please take these numbers as "comparative" They were measured with my shop calipers, so I wouldn't use these dimensions for anything critical, like bearing fits. I also apologize for the non-SI units.

Rotor laminate OD: 5.825"
Rotor laminate width: 1.8" Width with both endcaps: 2.368"
Bearing OD's: 2.675"
Drive spline OD: 1.375"
Drive spline ID: 1.235"
Drive spline tooth #: 30
Resolver rotor width: 0.156" (made of laminates)

The laminates had 8 flats on the OD, corresponding with 8 notches on the encoder side endcap and 8 flats on the spline side endcap. There are 8 highly magnetic regions in the rotor.
 

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#22 ·
e*clipse said:
Ok, here are some very interesting (and somewhat discouraging :() dimensions. This rotor is significantly smaller than the Prius rotor.

Please take these numbers as "comparative" They were measured with my shop calipers, so I wouldn't use these dimensions for anything critical, like bearing fits. I also apologize for the non-SI units.

Rotor laminate OD: 5.825"
Rotor laminate width: 1.8" Width with both endcaps: 2.368"
Bearing OD's: 2.675"
Drive spline OD: 1.375"
Drive spline ID: 1.235"
Drive spline tooth #: 30
Resolver rotor width: 0.156" (made of laminates)

The laminates had 8 flats on the OD, corresponding with 8 notches on the encoder side endcap and 8 flats on the spline side endcap. There are 8 highly magnetic regions in the rotor.
Click to expand...
That's encouraging for someone like me.... :) Thanks for posting the numbers.
 
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#16 ·
Well, THAT throws a big monkey-wrench into the whole "it's the same as a Prius motor" theory. :mad:

Just to make sure I wasn't too insane, I verified the specs (right off a Toyota Highlander spec sheet )

Motor Generator Rear (MGR)
-Function
Drives rear wheels, regeneration during braking
- Type
Permanent magnet motor
- Max. Voltage
AC 650V
- Max. Output
68 hp (50 kw) @ 4,610 – 5,120 rpm
- Max. Torque
96 lb.-ft. @ 0-610 rpm
Click to expand...
I guess it sort of works out if you plug these #'s into the classic Horsepower sanity check equation, IF the rpm is high enough.

HP = Torque (ft-lb) * n (rpm) / 5252
Torque = 68 hp *5252 / 4610 rpm = 77 ft-lb
rpm = 68 hp * 5252 / 96 ft-lb = 3720

However, 96 ft-lb * 610 rpm/ 5252 = 11 hp.

Something's not right here. Could they have included the gear reduction?

Any suggestions from any BLDC motor experts out there?? :confused:
 
#18 ·
I'm not an expert on BLDC motors but I found some references that show a peak torque at a lower RPM and then a lower rated torque at the highest RPM where power is greatest.
http://motion.control.com/thread/1276775704
http://www.linengineering.com/line/contents/stepmotors/pdf/BrushlessDC_Basics.pdf
http://en.wikipedia.org/wiki/Talk:Brushless_DC_electric_motor
http://www.appliancemagazine.com/editorial.php?article=551
http://what-when-how.com/electric-m...tablish-speed-torque-curve—no-load-load-and-peak-torque-values-electric-motors/

It seems unusual for the peak torque to be at such low RPM, but the rated torque (77 lb-ft) is only a bit less than the peak torque (96 lb-ft). It may be related to the higher power losses at higher RPM (and higher voltage), where heating and high frequency core losses may reduce the safe level of continuous torque.
 
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#20 · (Edited)
Thanks for all the tips, Jeff! It really helps to hear from someone who's been there. :)
Thanks also PSTechPaul - those last two links combined w/ the ORNL papers should lead somewhere...:)

Right now I'm trying to resolve what seem to be some really big motor output issues. Something in their specs just refuses to make sense. I can make things work by fudging numbers (like the base speed of the motor.)

Let's assume this motor has a torque-speed and power-speed relationship similar to the ones I posted for the 2004 Prius. Obviously, with the rotor being a completely different diameter and length, this curve will be different, but follow a similar pattern.

The Highlander Hybrid has a "governer limited" top speed of 114 mph, according to Car&Driver:
http://www.caranddriver.com/reviews/2011-toyota-highlander-hybrid-road-test-review

With stock P245/65 R17 (Base) tires, the tire circumference would be 93 inches, and would make 681.5 revolutions/mile. Thus, the rear axle would be spinning @ 1294.9 rpm. With a gear ratio of 6.86:1, the motor would be spinning @ 8882.7 rpm. It would probably be safe to say the rotor is balanced to spin at 10,000 rpm, although a gernading rotor would make a very exiting stop. :p

IF the 50kW specification is correct, the peak horsepower (assuming a curve similar to the 2004 Prius) occurs right around or slightly after it's base speed. Further assuming the 96 ft-lb torque specification is corrrect, then the corresponding rotor speed would be:
rpm = HP*5252/Torque = 68hp * 5252 / 96ft-lb = 3720 rpm

This is nearly double the Prius' base speed, but corresponds roughly with the base speed spec of 610 RPM if the 6.86:1 gearing is included. Perhaps they were referring to the AXLE speed? :confused:

So, given that the rotor can physically handle high rpm, is it reasonable to think the base speed is 3720 rpm?

Because the diameter is smaller, would the back EMF generated be smaller than the Prius? Otherwise, the voltage is going to be much higher than 650V. In fact according to the ORNL test, at 6000 rpm, the Prius back EMF was 850V peak.

I'm still trying to wrap my head around the fact that this significantly smaller rotor could put out the same power. I've seen it frequently in examples like geared starter motors, but this situation has some serious back-EMF limits. I mean, I really don't want to have a 1000V battery pack! :eek:

Would any motor experts out there have any advice for practical limits that can be put on these rough analyses?:confused:
 
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#23 ·
Arlo:
That's encouraging for someone like me.... :)
Click to expand...
And it should be for me as well! :D I was just stuck with the thought that it should be physically similar to a Prius. Lighter is almost always better.

Bottom line: The dimensions and my rough analysis agree.

I simply needed to read & understand the link I posted previously:
"Development of Traction Drive Motors for the Toyota Hybrid System"

That paper details how Toyota thought it would be better to make the motor lighter, and details how they did it. Granted, they are talking about the MG2, not the MGR. However, there are enough details in the MGR that match to say the MGR is a smaller version of the MG2 from the Highlander, not the Prius.

Some specific changes:
1) design the rotor to be able to physically handle 12000 rpm. :cool:
To do this, the "bridges" that surounded the magnets were optimized.
2) Don't change the maximum DC bus voltage of 650V.
To do this, the motor relies more on reluctance torque and field weakening
3) increase the proportion of reluctance torque to magnet torque.
To do this, the magnet shape and rotor OD were optimized.
4) improve the efficiency, particularly in the frequently used area of the speed-torque map.

The graphs below are from the MG2, and match the Toyota Highlander spec sheet. I think it would be reasonable to scale them for the MGR.
 

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#24 ·
e,
The smaller rotor you have resembles the smaller motor in the Prius called MG1. I don't have any dimensional measurements. MG1 spins about twice as fast as MG2 for the same voltage so yes the bemf is half for the same rpm.

I am hooking MG1 and MG2 mechanically together so they will spin at the same speed. This way MG1 will still be able to provide torque at higher speeds when MG2 is out of voltage headroom. Hopefully this combo will make for a better all electric drive.

A single motor with the proper characteristics would be more simple but this is what I have to work with for now.

j
 
#25 ·
I've been subscribed and limping along through the technical discussion. I've been searching for a more open source set of "internals" to develop a motor for my e-bike, Scrape. This sounds and looks tantalizingly like what I am after - 12K being the "jump-in" tipping point for me. I doubt that I'll be able to contribute much on the electronic side of things, other than a lot of pesky questions, but if this works and you guys don't mind me riding your coattails I would be willing to openly share what I do physically.

When I find the right "guts", my plan is to develop my own CAD/CNC case. Scrape's specific case will be a bit intense and expensive to machine, but if there are people interested in adapting this motor to other applications (than using the Prius or Highlander cases) I would be able to easily simplify the design to suit the need. A person would be able to download the files and have the case cut, or prototyped and cast, locally or through an online vendor.

The "IFs" are whether this motor will work for me, and if there is enough interest in this for it to benefit the community? In the meantime, a couple questions:

  1. This is the MGR motor you're disassembling and measuring e*clipse, correct?
  2. What is the O.D. of the stator?
Fascinating, fun, thread! ;)
 
#26 ·
Todd I've been following this also wondering about rehousing these motors. I'd certainly be interested. Remember 12krpm would require gearing down. I'd think using the two motors and planetary gear set as a variable ratio transmission would be great for a bike though very big and heavy. Otherwise only one motor MG1 with a reduction gearing to drive a bike.

Sorry for the thread hijack.

Jeff, how easily can the motor be Rd moved from a transmission for this purpose? Could we use the gears to create a reduction drive also and 'recycle' the parts? Thanks
 
#33 ·
Everything comes apart very easily. I have considered some configurations that only use the smaller MG1. It appears rather doable to remove MG2 stator and rotor and cut away all the casing for it while still keeping MG1 and reduction gearing intact for a light weight application. You will need to plug some openings to keep the transmission fluid in but it is not under any pressure. ( at least for the Gen 1 Prius, before 2004). I haven't take the Gen II transaxle apart yet but I expect very much the same thing.

You could also just use MG1 stand alone cut away all the casing for reduction gearing and for MG2. MG1 has a splined open center rotor which looks ideal for installing a shaft and sprocket. I am thinking they will mount nicely on an outboard boat motor.

Lot's of cool Frankenstein possibilities if you ask me.
 
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#27 ·
jddcircuit:
The smaller rotor you have resembles the smaller motor in the Prius called MG1. I don't have any dimensional measurements. MG1 spins about twice as fast as MG2 for the same voltage so yes the bemf is half for the same rpm.
Click to expand...
Yes, it does... I was just noticing that as I re-read one of the ORNL papers this morning. I wonder how much power that generator can kick out. That wasn't addressed in those ORNL tests. The other thing I'd like to find out is what the wiring scheme for the stator is. That would help a lot for figuring out the maximum current for this (MGR) motor.

Major - would you have any suggestions, short of disassembling the stator, for figuring out the stator wiring scheme?

Welcome tylerwatts & toddhotrods! :) No, you're not hijacking this thread as far as I'm concerned. In fact, I had a similar evil plan....I am considering making a 2 motor case for a 100kw module.

To answer Tylerwatts first point - the drive has a 6.86:1 reduction built in.

To answer toddshotrods' questions:
1) Yes, it is a MGR
2) What accuracy would you like? Is "big ruler" type accuracy ok? Right now I can say the OD has 3 evenly spaced tabs for mounting bolts.

It seems to me that building a case is very do-able. On the other hand, making gears is difficult and all that R&D Toyota put into those motors would be nearly impossible - might as well put their work to good use! :D

One of the goals of this disassembly is to figure out if putting the motor in another case is feasable. I'll definitely post more picks along the way and try to obtain any dimensions folks are interested in. :)

So far I've learned a couple things:
1) parts are all precision slip fit into the case. Fortunately I haven't run into any press or shrink fits. I've read the stator fits the case in a similar manner. Right now, I don't want to remove it.
2) (I'll post picks showing this) The case has an intricate oil circulation scheme built in. It uses the differential drive gear for a pump. Also, the motor's stator relies on this circulation/oil flinging to cool the windings. So, it would be very bad to run this thing backwards. Additionally, this oil circulation will need to be replicated in any different case, so there are some opportunities/challenges involved with that.
 
#28 ·
e*clipse said:
...Welcome tylerwatts & toddhotrods! :) No, you're not hijacking this thread as far as I'm concerned. In fact, I had a similar evil plan...
Click to expand...
Thanks and awesome! :)




e*clipse said:
...To answer toddshotrods' questions:...
2) What accuracy would you like? Is "big ruler" type accuracy ok?...
Click to expand...
"Big ruler" is fine at this point - I just want to see if the size is in the ballpark of what I can stuff in my bike. If it looks good, I will eventually get a diff, and disassemble it to get super accurate measurements.




e*clipse said:
......the OD has 3 evenly spaced tabs for mounting bolts.

It seems to me that building a case is very do-able. On the other hand, making gears is difficult and all that R&D Toyota put into those motors would be nearly impossible - might as well put their work to good use! :D

One of the goals of this disassembly is to figure out if putting the motor in another case is feasable. I'll definitely post more picks along the way and try to obtain any dimensions folks are interested in. :)

So far I've learned a couple things:
1) parts are all precision slip fit into the case. Fortunately I haven't run into any press or shrink fits. I've read the stator fits the case in a similar manner. Right now, I don't want to remove it.
2) (I'll post picks showing this) The case has an intricate oil circulation scheme built in. It uses the differential drive gear for a pump. Also, the motor's stator relies on this circulation/oil flinging to cool the windings. So, it would be very bad to run this thing backwards. Additionally, this oil circulation will need to be replicated in any different case, so there are some opportunities/challenges involved with that.
Click to expand...
I noticed the tabs and figured those were for mounting the stator. I can usually reverse engineer things if I get my hands on them, so if and when I get one I should be able to get all that stuff translated into CAD - from there it's usually just a matter of how a person wants/can afford to realize it...

I'm not planning on any internal gear reduction. That will be by conventional chain and sprocket in my case. I just wanted a motor with 10K rpm potential to make trying to kill myself a more feasible proposition! :D


Thanks, looking forward to exploring this with you guys! ;)
 
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#29 ·
Highlander Hybrid gearbox

Here's the gearbox side of the MGR.

The pic of the gearbox is upside-down, sorry about that. In this view the differential spins clockwise when going forward. Oil is pulled up around the outside then deflected to the other half of the gearbox when it reaches the top. From there, it is deposited into multiple "holding tanks" (those lumps that seemed to have no purpose when viewing the MGR from the outside.)

These holding tanks have small holes near their bottoms to meter oil flow out to bearings, cooling the stator, etc.

The third shot is the differential; it also has interesting lubrication channels.
 

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#31 · (Edited)
Here's some stator info that might help determine what this bugger can really do.

There are 48 slots in the stator.
The wires are grouped into 8 groups around the stator (see pic)
The phase connections are split into 3 wires each, color coded red, green and white.
To my best ability to count, there are 12 winding wires connect at each phase connection. (see pic)

The winding wires measure 0.030" in diameter with insulation.
I believe the motors are connected in a wye pattern. The phase to phase resistance (measured w/ a Fluke dmm) is 0.3 Ohms.

To figure out the max current, I checked out these sources:
http://www.powerstream.com/Wire_Size.htm
www.smma.org/pdf/conferences/2010/F10 Current Density.pdf
https://www.highpowermedia.com/blog/3296/electric-motors-cooling-concepts


The easiest was powerstream's suggestion of 9A/wire this would limit motor current to 12*9A = 108A.
The other sources were much more comprehensive and suggested current densities between 7000A/in^2 to 15,000A/in^2, depending on cooling method, duty cycle, etc. This would result in maximum currents ranging from 51A to 110A.

Am I in the right ballpark w/ this?
 

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#32 ·
I think your calculations of about 100 amps sounds right for this motor but with the temp sensor and with the right cooling you might be able to safely get more for a while.

My hope is the larger motor in the Prius (MG2) can handle 200 amps and the smaller MG1 can handle 100 amps. That way I may approach 150kw with a 500 volt pack.

However I did read that at these currents the motor heats up very quickly in someones thesis paper that I can't locate at the moment.
 
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#36 ·
jddcircuit: ORNL tested the 2nd gen Prius motor @ 250A for their locked rotor test. I think they found it could do more, but limited it because the testing they were doing required relatively long ( > 10 sec ) measurements.

I do plan to implement some sort of oil cooling system for this. It will basically consist of a circulating pump and small radiator; I may be able to simply tap the oil drain/fill holes for this. The main issue will be to ensure the motor always has enough oil, even if the circulating pump quits.

Major: Thank you very much for the help. I'm going to need to digest this for a while... ;) BTW, what sort of accuracy is necessary for the resistance measurement?

I plan to get a set back EMF measurement. I do have a scope, and I *think* I can drive it at a fixed speed, maybe with my mill.

I don't exactly have ORNL type facilities here :rolleyes:, so I'd like to get enough info to determine how to get the most from this motor. If this can be done w/o dynos and load cells, I'd love to hear about it.

few2many: To be perfectly honest, I don't know if its star or delta. :eek: I assumed it was delta from the diagrams on the ORNL tests with the Prius motor.

noob 3phase motor question: what is the advantage of wye (or star) vs delta? Can it be changed w/0 taking the stator apart? I'm fairly sure I don't want to take it apart, as I figure Toyota knew what they were doing when they chose made it. Considering the subtleties they investigated when developing it, basic wiring should have been covered long ago.
 
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