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Discussion Starter #1
I was recently able to attend a Jaguar event showcasing the I-PACE, and I had a chance to drive it out on the streets. Let me know if you have any questions, but overall, I think it is basically alone in its EV segment at the moment. It really is the only traditional luxury EV on the market right now.

 

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For those of us who are not EEs
http://http://empoweringpumps.com/ac-induction-motors-versus-permanent-magnet-synchronous-motors-fuji/

"Permanent magnet motors tend to be more expensive than AC induction motors and have been known to be more difficult to start up than AC induction motors. However, the advantages of permanent magnet motors include higher efficiencies (as discussed above), smaller sizes (permanent magnet motors can be as much as one third of most AC motor sizes, which makes installation and maintenance much easier), and PMSMs’ ability to maintain full torque at low speeds."
 

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Discussion Starter #3
For those of us who are not EEs
http://http://empoweringpumps.com/ac-induction-motors-versus-permanent-magnet-synchronous-motors-fuji/

"Permanent magnet motors tend to be more expensive than AC induction motors and have been known to be more difficult to start up than AC induction motors. However, the advantages of permanent magnet motors include higher efficiencies (as discussed above), smaller sizes (permanent magnet motors can be as much as one third of most AC motor sizes, which makes installation and maintenance much easier), and PMSMs’ ability to maintain full torque at low speeds."
Thanks for the additional info and reference! :D
 

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It is a good point about PM vs induction for the front motor. Porsche seems to be making the same choice (mistake?) that Jag has. Whereas Tesla is using an induction motor in front - even on the 3 with its SRPM motor in the rear. I guess time will tell which approach is better. Though for the moment, it seems Tesla is making the more experienced choice.
 

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There are pros and cons to each. It depends on what pro you are trying to exploit and which con you are willing to live with.
 

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Discussion Starter #6
It is a good point about PM vs induction for the front motor. Porsche seems to be making the same choice (mistake?) that Jag has. Whereas Tesla is using an induction motor in front - even on the 3 with its SRPM motor in the rear. I guess time will tell which approach is better. Though for the moment, it seems Tesla is making the more experienced choice.
I think the other issue is, very few companies have first-hand experience with induction motors. GM obviously does, with the EV1 and S-10 EV. Tesla does as well because the first Roadster motor was based heavily on the EV1 motor, and they've been focusing on induction motors since.

For GM, it would feel like a step backward (maybe), but they at least have the core competency to make that step. For Jaguar and Porsche, just developing one motor might have been a huge investment in time and research.

Also, it's important to consider that I think you could achieve the same result simply by physically detaching the PMAC from the drive line. GM products have a Neutral, so using two PMAC motors might not be an issue with that configuration. The Jaguar I-PACE, on the other hand, doesn't have a Neutral setting (only Drive/Park/Reverse).

It does have a low regen mode. Perhaps that true freewheeling, but I didn't have enough time with the car to investigate that fully.

There are pros and cons to each. It depends on what pro you are trying to exploit and which con you are willing to live with.
That's definitely true, but the wonderful thing about EVs is, you can literally get the best of both worlds by having one motor type on one axle and the other motor type on the other axle. Perhaps you can do even better than that. The Gen 2 Roadster reportedly has three motors.
 

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Interesting. So let me get this straight, Jag is using two PM motors, which are more efficient, right? And they still get that lousy efficiency? Is that due to weight and aero and mechanical drag?

As for the Tesla Model 3, my understanding is that the PM motor in back is the really efficient one, that's why the LR 2WD model is rated for about 335 miles, even though Tesla advertises 310. Adding the less efficient induction motor in front actually brings down the overall vehicle efficiency, that's why it's rated at 310 miles. Tesla chose to advertise both as 310 miles, but the LR 2wd is about 8% more efficient. I think there's speculation that a change in the future would be to switch out the less efficient front induction motor in the future for a PM one.

It is a good point about PM vs induction for the front motor. Porsche seems to be making the same choice (mistake?) that Jag has. Whereas Tesla is using an induction motor in front - even on the 3 with its SRPM motor in the rear. I guess time will tell which approach is better. Though for the moment, it seems Tesla is making the more experienced choice.
 

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Discussion Starter #8
Interesting. So let me get this straight, Jag is using two PM motors, which are more efficient, right? And they still get that lousy efficiency? Is that due to weight and aero and mechanical drag?
The problem is (as I understand it), the I-PACE cannot power down one of the PMAC motors while driving. Essentially, you have two motors and motor controllers running at the same time, effectively doubling your losses. At its most efficient, you're looking at close to a 10% loss between each motor and controller. So instead of being 10% to 15% more efficient than the Tesla Model X, it's about 5% to 10% less efficient.

As for the Tesla Model 3, my understanding is that the PM motor in back is the really efficient one, that's why the LR 2WD model is rated for about 335 miles, even though Tesla advertises 310. Adding the less efficient induction motor in front actually brings down the overall vehicle efficiency, that's why it's rated at 310 miles. Tesla chose to advertise both as 310 miles, but the LR 2wd is about 8% more efficient. I think there's speculation that a change in the future would be to switch out the less efficient front induction motor in the future for a PM one.
The "rated 335 miles" was a bit of a myth perpetuated by Tesla people. The tests are based on the automaker's claimed numbers about things like aerodynamic drag (which aren't actually tested on the dyno during EPA testing cycles). However, if you have an over inflated efficiency number, you run the risk that the EPA tests your vehicle themselves and finds that you were overly optimistic. The fact that Tesla corrected down most likely means that the aerodynamics of the Model 3 aren't quite a good as they advertised, but who really cares? Cd is just a number anyway.

The fact that most Model 3 owners get right around 300 miles in real world driving should show that whatever Tesla was correcting for, it brought the Model 3's EPA efficiency and range more in line with what it should be.
 

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On the dual motor S and X, the two induction motors are geared differently. So the car switches between the two as needed and most efficient via “torque sleep”. On the 3 they can only torque sleep the front motor. The Jag would have to run both motors all the time.
 

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As an aside, the CT6 PHEV uses an induction motor for MG-A. Perhaps someone with full access to the SAE paper could comment on why they did it. But this does seem to be an area where GM is evolving their thoughts. The Gen 1 Volt used a PM MG-A with rare earth magnets, whereas in Gen 2 MG-A uses ferrite magnets.
 

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As an aside, the CT6 PHEV uses an induction motor for MG-A. Perhaps someone with full access to the SAE paper could comment on why they did it. But this does seem to be an area where GM is evolving their thoughts. The Gen 1 Volt used a PM MG-A with rare earth magnets, whereas in Gen 2 MG-A uses ferrite magnets.
I have the full SAE paper on the CT6 motor designs — 2016-01-1220.

Basically, the major decider was cost reduction (and likely the lower cost volatility risk due to potential price swings in the rare earth metals of the magnets). They wave their hands about other tradeoffs and how an induction motor is well suited for the typical duty profile of that motor but they seem to hint that cost is the overriding factor.

For what it’s worth, the older generation Two-Mode hybrid RWD transmissions used in their SUVs and pickups between 2008-2013 used induction designs for both motors. I think the same is true for the transit bus variant of the Two-Mode hybrid.

To some degree this may also be a function of “whatcha got”. They may have used a pair of the same induction motors in those older Two-Mode transmissions because that was simpler than designing distinctly separate motors. The same could apply to Jaguar which found it cheaper and less risky to just use a pair of the same motors rather than use two quite different motors — especially in their first EV. Same again for Tesla when they used a pair of very similar induction motors on their older car designs.
 

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Discussion Starter #12
I have the full SAE paper on the CT6 motor designs — 2016-01-1220.

Basically, the major decider was cost reduction (and likely the lower cost volatility risk due to potential price swings in the rare earth metals of the magnets). They wave their hands about other tradeoffs and how an induction motor is well suited for the typical duty profile of that motor but they seem to hint that cost is the overriding factor.

For what it’s worth, the older generation Two-Mode hybrid RWD transmissions used in their SUVs and pickups between 2008-2013 used induction designs for both motors. I think the same is true for the transit bus variant of the Two-Mode hybrid.
Are you referring to the Remy motors (like what they used in the hybrid Suburban)?

https://gm-volt.com/2011/05/02/remy-ev-motor-reduces-dependence-on-foreign-rare-earth-supplies/

To some degree this may also be a function of “whatcha got”. They may have used a pair of the same induction motors in those older Two-Mode transmissions because that was simpler than designing distinctly separate motors. The same could apply to Jaguar which found it cheaper and less risky to just use a pair of the same motors rather than use two quite different motors — especially in their first EV. Same again for Tesla when they used a pair of very similar induction motors on their older car designs.
Yes, I think you are right about Jaguar. I'm wondering, though, if they actually lack a true neutral mode. While having a clutch mechanism to connect the motor to the wheels creates an additional point of failure, it seems like it could solve the issue without needing a second motor design.
 

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2017-Chevrolet-BoltEV-022.jpg
Interesting discussion. I just love the simplicity of this drive unit. The one in my Bolt.
 

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The problem is (as I understand it), the I-PACE cannot power down one of the PMAC motors while driving. Essentially, you have two motors and motor controllers running at the same time, effectively doubling your losses.


The "rated 335 miles" was a bit of a myth perpetuated by Tesla people. T

The fact that most Model 3 owners get right around 300 miles in real world driving should show that whatever Tesla was correcting for, it brought the Model 3's EPA efficiency and range more in line with what it should be.
First I would hope that Jaguar efficiency is just a software update away. That is not a large vehicle and a 95khw battery should have delivered a lot more miles.

As far as the 335 is a myth, at 70 or under I can easily beat the estimates. The TM3 is rated at 310 miles on a 75kwh battery which means I would need to average 241 wh/mi. On my trip to Ohio and back that I posted elsewhere the only time I did worse than that was when I was doing 75+ in the rain. My 1700 mile trip was completed with 232wh/mi. My drive up was 221 wh/mi keeping speeds below 73 and mild temperatures.

So 335 is not a myth. Before I bought the TM3 I looked into the Bolt but the charging network held me back, that trip to Ohio and back was not possible using any route planner. Seems what people think of a long trip in a Bolt is not even close to what people in a Tesla will do. Plus my numbers were at speeds averaging over 70. So I am a believer in the range was under reported.

Now don't think I am totally sold on the TM3, I do like the car a lot but Tesla has its share of boneheaded decisions.
 

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The problem is (as I understand it), the I-PACE cannot power down one of the PMAC motors while driving. Essentially, you have two motors and motor controllers running at the same time, effectively doubling your losses. At its most efficient, you're looking at close to a 10% loss between each motor and controller. So instead of being 10% to 15% more efficient than the Tesla Model X, it's about 5% to 10% less efficient.
Interesting, so can a software patch, fix this motor idling issue, so that efficiency improves in the future? I would think this is a pretty big deal if they could fix it.

The "rated 335 miles" was a bit of a myth perpetuated by Tesla people. The tests are based on the automaker's claimed numbers about things like aerodynamic drag (which aren't actually tested on the dyno during EPA testing cycles). However, if you have an over inflated efficiency number, you run the risk that the EPA tests your vehicle themselves and finds that you were overly optimistic. The fact that Tesla corrected down most likely means that the aerodynamics of the Model 3 aren't quite a good as they advertised, but who really cares? Cd is just a number anyway.

The fact that most Model 3 owners get right around 300 miles in real world driving should show that whatever Tesla was correcting for, it brought the Model 3's EPA efficiency and range more in line with what it should be.
Like Shiveyta, I don't think the 335 miles is a myth. There's been plenty of testing, dyno and real world that indicates it's not a unicorn.
 

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Discussion Starter #16
First I would hope that Jaguar efficiency is just a software update away. That is not a large vehicle and a 95khw battery should have delivered a lot more miles.
Interesting, so can a software patch, fix this motor idling issue, so that efficiency improves in the future? I would think this is a pretty big deal if they could fix it.
I don't think it is that simple, but hopefully it is. The charge rate does sound like it is a simple reflash, though. Also, it's a 90 kWh battery, not 95 kWh, and it appears that not all of it is usable.

As far as the 335 is a myth, at 70 or under I can easily beat the estimates. The TM3 is rated at 310 miles on a 75kwh battery which means I would need to average 241 wh/mi. On my trip to Ohio and back that I posted elsewhere the only time I did worse than that was when I was doing 75+ in the rain. My 1700 mile trip was completed with 232wh/mi. My drive up was 221 wh/mi keeping speeds below 73 and mild temperatures.

So 335 is not a myth. Before I bought the TM3 I looked into the Bolt but the charging network held me back, that trip to Ohio and back was not possible using any route planner. Seems what people think of a long trip in a Bolt is not even close to what people in a Tesla will do. Plus my numbers were at speeds averaging over 70. So I am a believer in the range was under reported.

Now don't think I am totally sold on the TM3, I do like the car a lot but Tesla has its share of boneheaded decisions.
Like Shiveyta, I don't think the 335 miles is a myth. There's been plenty of testing, dyno and real world that indicates it's not a unicorn.
It's not a myth in that it is not achievable. I can easily exceed 300 miles in my Bolt EV, but that doesn't mean that it is fair to state that the Bolt EV's EPA range is 300 miles. Quite a few Model 3 owners struggle to exceed 310 miles in normal driving, which makes the revised EPA figure of 310 miles appropriate.
 

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Interesting, so can a software patch, fix this motor idling issue, so that efficiency improves in the future? I would think this is a pretty big deal if they could fix it...
There are fundamental differences in the motor types that likely can't be compensated for. But time will tell if there are still improvements which can be made. It is going to be fun to see how it plays out over the next few years. Stuff like this is one reason why over-the-air software updates are becoming increasingly desirable.
 

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It's not a myth in that it is not achievable. I can easily exceed 300 miles in my Bolt EV, but that doesn't mean that it is fair to state that the Bolt EV's EPA range is 300 miles. Quite a few Model 3 owners struggle to exceed 310 miles in normal driving, which makes the revised EPA figure of 310 miles appropriate.
LOL - its very clear your fixated and as such I see no reason to for further discussions with you. so have a nice day.

Though I will leave you with this, I can do my 300+ at 70+ and I can go 600+ miles in a day easily on a trip in any direction I choose from my home in a TM3. I could not and still cannot according to a well known EV planner site using a Bolt
 

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Discussion Starter #19
LOL - its very clear your fixated and as such I see no reason to for further discussions with you. so have a nice day.

Though I will leave you with this, I can do my 300+ at 70+ and I can go 600+ miles in a day easily on a trip in any direction I choose from my home in a TM3. I could not and still cannot according to a well known EV planner site using a Bolt
I'm sorry. You clearly have some sensitivity issues, but it's just a car.

My point is, especially with electric vehicles, it is very, very easy to exceed EPA numbers. I can go 220+ miles at 70+ mph in my Bolt EV and drive 600 miles in three different directions in a day. But that's not really relevant to the discussion. Now, if you said you can do 335 miles at 70+ mph (you more than likely can't, based on all of the feedback I've gathered from Model 3 owners), then you'd have a point about Tesla's understating the EPA range.

Based on what I've seen, the most recent EPA test cycles put the combined EPA numbers very close to the efficiency that a driver can expect doing sustained 65-70 mph on the freeway. That's good for prospective owners in general, as it gives us a very good sense of what our actual real-world mileage will be. The fact that Tesla needed to correct the results simply means that they needed to adjust for something in their calculations in order to put the results inline with EPA standards.
 

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LOL - its very clear your fixated and as such I see no reason to for further discussions with you. so have a nice day.

Though I will leave you with this, I can do my 300+ at 70+ and I can go 600+ miles in a day easily on a trip in any direction I choose from my home in a TM3. I could not and still cannot according to a well known EV planner site using a Bolt
My opinion — you’re both right...

Yes, the RWD Model 3 EPA estimate of 310 is artificially suppressed. The individual test cycles used to create the final estimate are higher for the RWD car yet it is given the same 310 as the AWD version which scores lower on the individual test cycles. Calculated normally, the RWD estimate would have been 335. That’s not a myth.

Seems what people think of a long trip in a Bolt is not even close to what people in a Tesla will do.
It mostly depends on charging infrastructure. It seems the Bolt was not a good option for you now but it’s fine for some others who have adequate charging coverage for long distance destinations they want to drive to. Nationwide highway charging coverage for the Bolt will be dramatically better next year as the first wave of Electrify America DC charging locations are installed. Some newer cars like the I-PACE and e-tron won’t really be in many customer hands until the EA network is up and running.

I recently wrote about my summer vacation drive from California to Edmonton, Alberta and how I had fun today driving ~400-500 miles a day for that 1,600 mile one-way distance but also how it will be easier next year.

https://electricrevs.com/2018/10/12/bolt-ev-road-trip-san-francisco-to-edmonton/

Progress on EA buildout:

https://electricrevs.com/2018/10/23...website-adds-dozens-of-new-sites-coming-soon/
 
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