Best motor for an EV? with no limitations

If there were no limitations in a power suply (a constant suply using no batteries )what would be the "best" type, size, speed, style motor for an Electric vehical? (AC\DC, torque....ect).


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[azzmi]

Hi Gleen,
If there is no limit for electrical power supply, some additional limitations come through. These limitations are,

-Weight of the motor.
-torque-speed characteristics of the motor. (Especially high speeds).
-maintenance needings of the motor.
-Acoustic noise of the motor.
-Vibration.
-Speed control ability of the motor.
Unfortunately there is not a motor type which meets all needs of a high performance EV.

My favorite is brushless DC motor (for easy to control, more torque output with less weight).

or Switched Reluctance Motor can be a robust solution..

And classical squirrel cage induction motor is the cheapest.

Did you ever hear about wheel motors?

Regards

 

[jbartos]

Suggestion:
There appears to be the need for an as:
1. High efficiency
2. Light
3. Reliable
4. Inexpensive
5. Long life cycle
as possible rotary motor (ac or dc whichever will be better) for an electrical vehicle such as car, and possibly linear motor (ac or dc whichever will be better) for a rail electric vehicle. [sig][/sig]

 

I understand that there are other limitiaions or resistances that are associated with any vehicle and that the motor should be designed to suit the weight & size, speed required, power required etc...of the vehicle,
I know there are so many types like
AC/DC
brushless/brushes
wheel
squirel cage
high rpm/low rpm
large/small etc...motors but which ones better??

 

[azzmi]

OK., In my opinion the brushless DC Wheel motor is the best.. (I still think it is not easy to make a strict choice).. [sig]<p>Azmi Demirel<br><a href=mailto:azzmi@elk.itu.edu.tr>azzmi@elk.itu.edu.tr</a><br><a href=

http://triton.elk.itu.edu.tr/~azzmi>Welcome</a><br>I

am handsome but married [/sig]

 

[jbartos]

In many instances/applications:
AC is better than DC for many reasons
Brushless is better than one with brushes because of brush problems
Wheel or rotary is better than linear for the rotary motion and vice versa, the linear is better for the linear motion
Squirrel cage is better than wound rotor type for many reasons
High rpm is better than low rpm unless the low rpm motor eliminates a gear box
Small motor is better than large one for many reasons

[sig][/sig]

 

[azzmi]

Hi
Jbartos,
Why do you think an AC motor is better than a DC one? Can you explain these reasons?
[sig]<p>Azmi Demirel<br><a href=mailto:azzmi@elk.itu.edu.tr>azzmi@elk.itu.edu.tr</a><br><a href=

http://triton.elk.itu.edu.tr/~azzmi>Welcome</a><br>I

am handsome but married [/sig]

 

[jbartos]

1. More readily available power supply
2. More readily available ac motor drives, their controls and protective devices.
3. It is coming with higher and higher efficiencies, e.g. 94 - 95 %
4. Squirrel cage induction motor tends to be very rugged
5. Preferred choice in many residential, commercial and industrial applications
6. 18 phase Chorus Borealis squirrel cage induction motor has very attactive electrical and physical characteristics
7. Induction motors are being built with higher and higher HP, e.g. 25000HP for the ship propulsion. DC motors appear to be unavailable at that size and they would be very expensive
8. Electromagnetic emmissions are lower
9. Less maintenance is needed
10. Tend to run more silent with less airborne and structureborne noise
11. They appear to cost less
12. They are simpler with simpler windings
13. Superconducting induction motor is already running
14. Etc. [sig][/sig]

 

[azzmi]

Thanks for your immediate answer,

1. More readily available power supply

I dont think so.. Don't forget, it is working on an electric car.. I mean If it is not a hybrid car (I mean a petrol engine coupled with an AC generator), probably it has a DC power bus. (for example an accumulator or a solar cell array)..

2. More readily available ac motor drives, their controls and protective devices.

No, maybe 10 years ago but for now, brushless DC and switched reluctance motors and their speed control power electronic devices are highly available.. And I think protection principles are almost same for every kind of motor..(thermal, overcurrent maybe overvoltage & overload)

3. It is coming with higher and higher efficiencies, e.g. 94 - 95 %

This efficiency values are correct, -but I think- in very high power motors. Other motors also (especially brushless DC) can achieve this values.. And additional losses of power electronics systems and of course harmonic losses must be considered to this efficiency estimation..

4. Squirrel cage induction motor tends to be very rugged

Absolutely I agree.. But other two type of motors has a solid rotor too.. Especially switched reluctance motor..(as you know it has only laminated iron in its rotor -no even aluminium bars-)

5. Preferred choice in many residential, commercial and industrial applications

That is not a academical approach And also, EV is a new research area.. You cannot put it into an ordinary commercial or industrial category

6. 18 phase Chorus Borealis squirrel cage induction motor has very attactive electrical and physical characteristics

I have nothing to say for this..

7. Induction motors are being built with higher and higher HP, e.g. 25000HP for the ship propulsion. DC motors appear to be unavailable at that size and they would be very expensive

What type of electric car uses this huge motor?

8. Electromagnetic emmissions are lower

If you are using a power electronic variable speed drive system with your asynchronous motor., Because of harmonics.. Electromagnetic emissions are awful.. -like the other motors-

9. Less maintenance is needed

True, I agree. But it is not the most important thing on an EV.. Besides other motors (Brushless DC & SRM) also need low maintenance.

10. Tend to run more silent with less airborne and structureborne noise

Again in a car, there are many and more powerful noise sources like tires, wind, road bumps and for some people so loud music

11. They appear to cost less

If you add the Power electronics syst. They become the same cost level.

12. They are simpler with simpler windings

Absolutely, you are wrong. Especially SRM -I believe- has one of the simplest winding of all motors..

13. Superconducting induction motor is already running

I wish to know operating temperature of the superconductor..
14. Etc.

?
[sig]<p>Azmi Demirel<br><a href=mailto:azzmi@elk.itu.edu.tr>azzmi@elk.itu.edu.tr</a><br><a href=

http://www.elk.itu.edu.tr/~azzmi>Welcome

to my homepage</a><br>........................[/sig]

 

[jbartos]

I presented the AC vs DC generic comparisons since the question was posed quite generally.
Remarks:
1. Please, see the initial posting. I would not reduce the electric vehicle to pasenger cars only, although it will encompass a large number of passenger cars.
2. Items 1 and 7 seem to be simplifying the electric vehicle to a car.
3. Item 8. There are variety of priciples of ac motor drives. Many of them are supposed to meet various EMI Industry Standards.
4. Please, spell out less known abbreviations.
5. The Switch Reluctance Motor (SRM) is relatively new and it is just comming to AC and DC motor comparisons and assessments.
6. The temperature of superconducting materials is increasing. Some day, large electric vehicles, e.g. ships, may have many superconducting items.
7. Item 12. Have you ever considered rewinding costs of traditional dc and ac motors with commutators and have receipts ready for comparisons?
[sig][/sig]

 

[azzmi]

Hi JBartos,

I think your references are a little bit out of date, because a DC motor only means to you as a brush type DC motor. Also, Switched Reluctance Motor is one of the oldest motor which is used on earth. (Maybe I'm wrong, in former British navy, to align big cannons to the target)

Since 1980 it is heavily researched and used in different applications area..

If you insist on to compare brush type DC and squirrel cage induction motor (IM), you are right, IM is better.. But I think, to limit the comparision by this two types of motors narrows our perspective.. If the IM was the best, there is no need to new motors and their power electronics topologies.

As I pointed before, SRM still has the simplest winding technology. So let's forget commutators..

I think the superconducting material is not for using only in asynchronous motors.. It will be a total revolution in electrical and relevant engineerings.

I don't agree with you about a speed controlled (by mean of an inverter) asynchronous motor is the best about EMI. All systems (I mean other motor types) which are used in industry, must meet the same EMI standards..

OK., My friend, I think this conversation will be continued.

Thank you for sharing your opinion with me (and of course with others).

Azmi Demirel
azzmi@elk.itu.edu.tr

http://www.elk.itu.edu.tr/~azzmi

Welcome to my homepage ...

 

[jbartos]

You are welcome. The following is to ad to the above motor broader posting.
References:
1. PDF document pbra058.pdf &quot;Digital Signal Processing Solutions for the Switched Reluctance Motor,&quot; Texas Instruments Europe, 1997

http://www.ti.com/sc/docs/psheets/abstract/apps/bpra058.htm

2. PDF Document spra420a.pdf &quot;Switched Reluctance Motor Control - Basic Operation and Example Using the TMS320F240,&quot; Texas Instrument Application Report SPR420A, February 2000

http://www.ti.com/sc/docs/psheets/abstract/apps/spra420a.htm

3. Switched Reluctance Drives, Ltd. site

http://www.srdrives.co.uk

It appears from some of the above postings that some motors do not have any shortcomings/drawbacks; especially the Switched Reluctance Motors (SMRs). The switched reluctance motor is classified as a salient synchronous switched reluctance motor, Reference 1, Figure 3. As any salient motor, the SMR has the same disadvantages as other salient pole machines over the cylindrical rotor motors. The salient motors tends to be more voluminous, heavier, and with more complicated mathematical descriptions, Reference 1 and Reference 2. The SRM winding is simple; however, the controllers are fairly complex/complicated since their mathematical model is more complicated in comparison to induction motors. Presently, SRM are applied in selected applications because they appear to be advantageous in smaller sizes and in applications where the motor volume and weights are less important, Reference 3. How come that, if these SRMs are so good and have been around for so long, they are not very widespread in applications? Maybe they are not so good overall for everything and universal for many applications. Also, they need the modern switching power electronics complexity. Incidently, I am not advocating commutator machines anywhere in my postings. Next, for example, zero (soft) switched ac motor drives have a vary small EMI, and may be used for Induction Motors. [sig][/sig]

 

[vayuste]

Hi Everybody:

I´m writing from Venezuela (that´s the cause of my bad english). I´m looking for information in two especifical matters: superconductors and rechargeable batteries. More than that, I need to know about the use of Vanadium in this applications and the level of conssumptions of this items in the international market.
Can anybody give some information?

Thanks a lot... [sig][/sig]

 

[jbartos]

Suggestion:
Vanadium, V, 23, is more likely to belong to the Material Science and Mechanical Engineering that are part of this Forum.
Vanadium is not a major element in rechargeable batteries. There might just be negligible traces of vanadium present.
Superconductors do not use vanadium as a major element. There might just be negligible traces of vanadium present.
Vanadium is more known to be part of vanadium steel used for tools, screwdrivers, knives, etc. [sig][/sig]

 

[SRMwizard]

To come back to the initial topic: motor technologies and especially Switched Reluctance Motors, the main reason why SRMs are not very widespread in applications is the high number of patents protecting different designs and innovations.

http://www.motorsoft.net/brivit.htm

is the biggest database gathering most publications, articles...on SRMs. Basically if you look at the number a patent publications, you will find that 4083 have already been published and this number keeps increasing.
As it has already been said, the main advantage of the SRMs is the simplicity of their mechanical structure as they have neither permanent magnets nor windings on the rotor. The rotor is only a piece of iron and the motor windings are only located on the stator.
It had been mentionned that salient motors tend to be more voluminous, heavier, and with more complicated mathematical descriptions, this is true, but the torque they can produce can be from 2 to 10 times higher that an induction motor of the same physical size.

I think it is obvious to notice that I completly support SRMs in this forum. The fact is I only discovered this technology when I moved to UK. I used to work a lot with induction motors, but, in my mind, SRMs have a much better potential in industrial applications.

I would be interested to know if some of you have ever worked with SRMs and what is their opinion.

Thanks very much.

 

[jbartos]

Suggestion to the SRMwizard (Electrical) Nov 22, 2000:
The statement that &quot;the (SRM) torque they can produce can be from 2 to 10 times higher that an induction motor of the same physical size&quot; might be provided traceable to some reference.

 

[SRMwizard]

Well sorry for not explaining correctly the result I mentionned. So the &quot;2 to 10 times higher torque&quot; comes from my personnal experience in SRM research.
However, what I would like to raise is that this result is not a general one: I am not trying to say that SRM are always better than induction motors, this is not true, I used to work with induction machines before and I think they are much more flexible. The point is for apllications such as pumps, fans, where the dynamic response is not as important as in other industrial applications SRM can provide a fantastic solution.
I would like to add that the SRM I worked with are prototypes developed by research students in UK and are all below 2KW. The structures we tested are unfortunatly protected by patents and all their benefits can not be found in other SRMs.
The problem with SRM remains the same: Huge potential but too many patents to be able to come to mass production.

I hope this will clarify the situation

 

[Guest]

I am looking for a very low RPM gearmotor. It has to be about 1 rotation every four hours. Does anyone know where to get them. A fractional H.P. is ok it doesn't need a lot of power.