PMAC vs induction motor for model 3

[SageBrush]

"EPA tests have previously shown that reducing vehicle weight is one of the best ways to improve fuel economy, with a 1-percent improvement per 100 pounds of reduced weight.

That rule of thumb is pre-regen

 

[SageBrush]

My interpretation of dominant wasn't when it becomes the biggest of the factors, but exceeding 50% of power... ie. the majority of where the power goes. If you add up the other 3 that you have, it is about 65 to 70 mph where aerodynamics becomes the majority of the power.

At 68 mph air resistance is 292 N so about 8.9 kW
If we figure a range of about 200 miles to use up the 52 kWh battery at that speed then power is about 17 kW. So yeah, something a bit over 50% or power at that speed goes to overcoming wind.

 

[seattlite2004]

Interesting read: The new Model 3 motor. Its history and what it is likely to be. Long + References. • r/teslamotors

 

[scaesare]

"EPA tests have previously shown that reducing vehicle weight is one of the best ways to improve fuel economy, with a 1-percent improvement per 100 pounds of reduced weight.

Wow... 10,000 pound cars!

 

[Ulmo]

exactly
you can discharge faster than you can charge.
so you can have sub 6 sec acc, but you can't have sub 6 sec dec ( without brakes ),

That's why a small bank of super-capacitors makes sense to me. It would dump road speed to the supercaps, and dump the supercaps back to acceleration. Battery use would be minimized. I would call it a Hybrid. Like a RAM cache, or disk cache, in computers.

 

[Ulmo]

Yay! My current 82 mph limited Focus EV made a list lol

Is that a pure EV? My rental agent let me use an ICE GM Terrain before, and that noisy indecisive transmissioned thing handled well and had a good kick to it if you placed the accelerator all the way to the floor (but the motor would whine and the tac would show high). Now, my rental agent has me in something called a Ford Focus Hybrid (ICE and small EV), and it is gutless, very dangerous, snakes all around the road with no discipline, wants to lose control constantly, and extremely weak. I spend a lot of time blocking other cars while accelerating, and wondering when it's going to go, and deathly afraid it is going to crash. I hate that thing. But it definitely does not max out at 82MPH; once I am able to get it up in speed, it happily keeps whatever I set it to. Yours must truly be an EV?

Ford doesn't get EV's.

 

[22522]

Interesting read: The new Model 3 motor. Its history and what it is likely to be. Long + References. • r/teslamotors

This, and the comments say two things:

1) The front motor will be induction for weight and size reasons.
2) The battery will be NMC for intermittent city charging reasons. (and recycle/reuse reasons)

 

[Ulmo]

Is that a pure EV? My rental agent let me use an ICE GM Terrain before, and that noisy indecisive transmissioned thing handled well and had a good kick to it if you placed the accelerator all the way to the floor (but the motor would whine and the tac would show high). Now, my rental agent has me in something called a Ford Focus Hybrid (ICE and small EV), and it is gutless, very dangerous, snakes all around the road with no discipline, wants to lose control constantly, and extremely weak. I spend a lot of time blocking other cars while accelerating, and wondering when it's going to go, and deathly afraid it is going to crash. I hate that thing. But it definitely does not max out at 82MPH; once I am able to get it up in speed, it happily keeps whatever I set it to. Yours must truly be an EV?

Ford doesn't get EV's.

Did I mention really uncomfortable? It bounces everywhere, for every bump and every wave pattern. The Terrain was smooth as silk on 85 at any speed, and the Focus is bumpy as hell on 85 at any speed. What garbage. Grrr. I'll switch once my week is up. I'm curious how the Model 3 compares.

 

[Ulmo]

This, and the comments say two things:

1) The front motor will be induction for weight and size reasons.
2) The battery will be NMC for intermittent city charging reasons. (and recycle/reuse reasons)

I didn't get that information from there; it said they would use NCA instead of NMC. The IM part is up in air but sounds nice.

 

[Rashomon]

Other way around. You want to use PMAC for acceleration, and IM for highway cruising.

As counter-intuitive as it seems, the most efficient package will be a relatively small PMAC motor in the front, and a big inductive motor in the back. Weight transfer under high acceleration determines the front/rear power ratio. The relatively small PMAC will match or beat the big inductive motor for cruise efficiency and be more efficient at any other higher power level, and you'll have the power of the big motor available for really high acceleration. The advantage of a big inductive is that it can be shut down completely without any magnetic drag. I suspect other automakers will achieve a similar effect by using multiple PMAC motors and clutches.

 

[SageBrush]

As counter-intuitive as it seems, the most efficient package will be a relatively small PMAC motor in the front, and a big inductive motor in the back. Weight transfer under high acceleration determines the front/rear power ratio. The relatively small PMAC will match or beat the big inductive motor for cruise efficiency and be more efficient at any other higher power level, and you'll have the power of the big motor available for really high acceleration. The advantage of a big inductive is that it can be shut down completely without any magnetic drag. I suspect other automakers will achieve a similar effect by using multiple PMAC motors and clutches.

Add me to the list of those confused by this subject.

Are you saying that a PMAC is torque limited (or at least not competitive with IM) without gears ?

 

[Young]

Add me to the list of those confused by this subject.

Are you saying that a PMAC is torque limited (or at least not competitive with IM) without gears ?

For PMAC motor, larger torque means stronger magnet, and this increases magnetic loss when the rotor spins. To reduce loss, you do not want the PMAC motor too powerful.

 

[techmaven]

For PMAC motor, larger torque means stronger magnet, and this increases magnetic loss when the rotor spins. To reduce loss, you do not want the PMAC motor too powerful.

Yup.. in the non-performance dual drive models, the PMAC rear + induction front makes a lot of sense. For performance models, induction all around.

 

[Young]

As counter-intuitive as it seems, the most efficient package will be a relatively small PMAC motor in the front, and a big inductive motor in the back. Weight transfer under high acceleration determines the front/rear power ratio. The relatively small PMAC will match or beat the big inductive motor for cruise efficiency and be more efficient at any other higher power level, and you'll have the power of the big motor available for really high acceleration. The advantage of a big inductive is that it can be shut down completely without any magnetic drag. I suspect other automakers will achieve a similar effect by using multiple PMAC motors and clutches.

I agree that this will be the most efficient configuration. When you apply large torque, you want it to rear wheels, not to the front wheels.

 

[JRP3]

Yup.. in the non-performance dual drive models, the PMAC rear + induction front makes a lot of sense.

Don't you mean the opposite? Smaller PMAC front larger ACIM rear?

 

[techmaven]

Don't you mean the opposite? Smaller PMAC front larger ACIM rear?

Nope.. on non-performance models, the Model 3 PMAC is fine in the rear... then add an ACIM for the front for more efficient highway cruising. For performance vehicles, big power output ACIM in the rear plus the same small ACIM front. You wouldn’t want a much bigger PMAC than the Model 3 motor.

 

[techmaven]

I agree that this will be the most efficient configuration. When you apply large torque, you want it to rear wheels, not to the front wheels.

The issue is that ACIM is far less efficient during low rpm, high torque situations. And you don’t need all that big of a motor for non-performance vehicles. If you want very high performance, and retain better efficiency at high speeds without a gearbox, then definitely stick to ACIM all around. Other automakers might try PMAC with gearboxes for performance models... should be interesting to see what Porsche does with the Mission-E.

 

[JRP3]

Worth noting that the Rimac ConceptOne uses PMAC motors.

 

[techmaven]

Worth noting that the Rimac ConceptOne uses PMAC motors.

Sure.. but with 4 separate motors and the rear ones have two speed dual clutch gearboxes. Apparently rpm’s are limited to 12,000, as opposed to 17,000 or so in the Model S. Also, the 217 miles or so of range on a 90 kWh pack means it isn’t particularly efficient.

 

[az erik]

Is that a pure EV? My rental agent let me use an ICE GM Terrain before, and that noisy indecisive transmissioned thing handled well and had a good kick to it if you placed the accelerator all the way to the floor (but the motor would whine and the tac would show high). Now, my rental agent has me in something called a Ford Focus Hybrid (ICE and small EV), and it is gutless, very dangerous, snakes all around the road with no discipline, wants to lose control constantly, and extremely weak. I spend a lot of time blocking other cars while accelerating, and wondering when it's going to go, and deathly afraid it is going to crash. I hate that thing. But it definitely does not max out at 82MPH; once I am able to get it up in speed, it happily keeps whatever I set it to. Yours must truly be an EV?

Ford doesn't get EV's.

Pure EV. It's speed limited at 85, but the speedo is off by 2.5 mph from the factory, it reads high. So your speedo hits 85 and the car just doesn't go any faster. Most likely to protect all the things. This is my second Focus EV. Great car for the $9k used purchase in AZ. I leased the first as a POC and it did well enough I bought one, not in black this time lol. This is as fast from 15-65 as my IS350 was. Merging to the HOV lane has yet to bother me, and it's only a 143 hp motor witha 28kw battery (new one is a touch more at 33.5 and D.C. Charging) gets 118/96 mpe. My hold over til my 3's come