Electric Vehicles

[SV650rules]

Originally Posted by Ruffy

Erm, I'm not sure that's correct. I admit it's been a long time since I've been involved in such detail but I'm sure I recall that AC induction motors have much lower torque at startup that at peak (typically about 1/3rd to 1/2?)

If higher torque is required to deal with a high inertia load this is generally dealt with by electronic starters or drive controllers that vary the frequency of supply to control the start & ramp up to 'steady state' speed.

Yup, but electric vehicle induction motors are fed from inverters that can vary the timing, voltage and current to get max running torque ( or even higher ) at startup. Single phase induction motors ( capacitor start and capacitor run ) are really bad on starting torque due to small phase displacement.

[Luckypants]

Originally Posted by DarrenSV650S

I've never understood why anyone thinks max torque at 0rpm is a good thing. That's the last place I'd want it. That's when you are most likely to break traction.

You've then got the disappointment of producing less and less power as you rev.

I think it makes more sense to have enough power down low for normal riding, then when you need it you thrash it to get the most power

I'm not following the detailed talk of varying phases / timing / voltage etc. however I did find this article from Volkswagen about their ID.3 motor which states max torque is produced across a wide range of speeds and to produce max power it must spin at high speeds. Max speed is achieved at 16000 rpm motor speed. So no sign of power falling off as you rev by the look of it. This is what is being done for real.

https://www.volkswagenag.com/en/news...-gearbox.html#

[Ruffy]

Originally Posted by SV650rules

Yup, but electric vehicle induction motors are fed from inverters that can vary the timing, voltage and current to get max running torque ( or even higher ) at startup. Single phase induction motors ( capacitor start and capacitor run ) are really bad on starting torque due to small phase displacement.

I can be too pedantic at times. You originally said "induction motors have ..." If you'd said "induction motor drive systems can have ..." ...

For the benefit of the completely clueless or dodgy internet 'researchers', I hope you can tolerate my fussiness quirks!

[garynortheast]

Don't worry Ruffy, I have had no idea what any of you have been saying for quite some time. You could all be speaking some obscure Klingon dialect!

[Seeker]

Originally Posted by garynortheast

Don't worry Ruffy, I have had no idea what any of you have been saying for quite some time. You could all be speaking some obscure Klingon dialect!

...but you did identify my wildflowers

[Ruffy]

Originally Posted by garynortheast

Don't worry Ruffy, I have had no idea what any of you have been saying for quite some time. You could all be speaking some obscure Klingon dialect!

[Ruffy]

Originally Posted by DarrenSV650S

I've never understood why anyone thinks max torque at 0rpm is a good thing. That's the last place I'd want it. That's when you are most likely to break traction.

You've then got the disappointment of producing less and less power as you rev.

I think it makes more sense to have enough power down low for normal riding, then when you need it you thrash it to get the most power

Originally Posted by Luckypants

Max torque is available at zero RPM, doesn't mean you have to use it. It means you don't have to rev like crazy and slip the clutch to get going on a hill, just smooth torque to get going.

Not sure what you mean by producing less and less power as you rev? An electric motor produces pretty much a flat torque curve, so its producing the same torque at 6000rpm as at 1rpm. With power being a function of torque and rotational speed, as you rev power increases. With an electric motor, you have power everywhere. Or is it me misunderstanding something?

Originally Posted by Luckypants

I'm not following the detailed talk of varying phases / timing / voltage etc. however I did find this article from Volkswagen about their ID.3 motor which states max torque is produced across a wide range of speeds and to produce max power it must spin at high speeds. Max speed is achieved at 16000 rpm motor speed. So no sign of power falling off as you rev by the look of it. This is what is being done for real.

https://www.volkswagenag.com/en/news...-gearbox.html#

I'm with LP. "Power" is often a misnomer. When you twist the throttle more (i.e. thrash it) you are really calling for 'more torque'.

Torque is the force that you feel when accelerating. Power bands are really about the spread and change of torque over the rev range.

Yes, with electric motor/drives, you can generally have a much wider spread of useable torque than most ICEs. And same torque at higher revs should equal more power by definition - physics innit!

[DarrenSV650S]

I was talking about electric motorcycles. Maybe that explains the misunderstanding

I don't really need or want tyre shredding torque when pulling away. In fact demand for torque is probably highest at high speed as wind drag increases

[svenrico]

Originally Posted by garynortheast

Don't worry Ruffy, I have had no idea what any of you have been saying for quite some time. You could all be speaking some obscure Klingon dialect!

I suspect you aren't alone !

[Bibio]

Originally Posted by DarrenSV650S

thats the thing with leccy motors you can program the drive electronics to make them behave how you like depending on the physical capabilities of the motor. one of the great things about leccy motors is it will always be in the right gear as it has none and you can have masses of engine braking aided with regular brakes to give eye popping stopping power.

i'll never be able to afford one but i will be going for a test ride on one (if i can get on it).