How to convert a hybrid

Technical discussion on converting internal combustion to electric
T2
Groupie
Posts: 121
Joined: Sat, 08 May 2010, 04:51
Location: ON,CANADA

How to convert a hybrid

Post by T2 »

-Weber what have you chosen for the base speed of your MX-5
        in mph or km/hr ? Please and thank you.

      Why MPH ? It's an audience thing.
Americans are probably lurking here, and a mostly older demographic.
I wholly agree, SI non gravitational units are much easier to apply.

Plus revs/sec is not colloquial enough vs rpm.    
T2
User avatar
woody
Senior Member
Posts: 1716
Joined: Sat, 21 Jun 2008, 02:03
Real Name: Anthony Wood
Location: Mt Colah

How to convert a hybrid

Post by woody »

coulomb wrote:The units of speed don't matter; you can consider them to equate to miles per hour if you want; we stopped using miles per hour over 40 years ago.

Lies!

Nearly 40 years ago (1974).

But I used them this morning, as I assume did Johnny.

cheers,
Woody
Planned EV: '63 Cortina using AC and LiFePO4 Battery Pack
User avatar
Johny
Senior Member
Posts: 3733
Joined: Mon, 23 Jun 2008, 16:26
Real Name: John Wright
Location: Melbourne
Contact:

How to convert a hybrid

Post by Johny »

In a curious, strangely universe-falling-together way, I read my Humber's MPH Speedo in hexadecimal and due to my excessively assembly language background, do an unconscious conversion to decimal in my head. The conversion from MPH to KPH is within 0.5% of the conversion from the second significant digit (10's) of hexadecimal to decimal.
60MPH = 96.5KPM
0x60 = 96 dec.

It provides no end of ammunition for my other half in affirming that all software engineers are decidedly "odd".

I wonder from time to time whether the Vogue electronic speedo should still be in MPH. Maybe it should be switchable.

It's sad really....

Edit: fickst spalling masteak
Last edited by Johny on Fri, 29 Jun 2012, 11:23, edited 1 time in total.
User avatar
woody
Senior Member
Posts: 1716
Joined: Sat, 21 Jun 2008, 02:03
Real Name: Anthony Wood
Location: Mt Colah

How to convert a hybrid

Post by woody »

That's cool.

I kind of have a look-up table in my head for the NSW speed limits:
km/h = MPH
40 = 25
50 = 30
60 = 37
70 = 43
80 = 50
90 = 56
100 = 62
110 = 68

But the tyres are a bit smaller than factory so it's more like 1.5 now...
Planned EV: '63 Cortina using AC and LiFePO4 Battery Pack
User avatar
woody
Senior Member
Posts: 1716
Joined: Sat, 21 Jun 2008, 02:03
Real Name: Anthony Wood
Location: Mt Colah

How to convert a hybrid

Post by woody »

Back on topic:

yes, the torque is proportional to weight for the same design.

Pancake motors would be able to get more torque/kg.

Higher power through higher speed is better, but the cars come with lower ratios than is suitable for that, unless you keep the gearbox and drive around in 2nd or 1st all the time.

Another thing which is possible with 3 phase motors is connecting in series or parallel and star or delta, which gives you different V/Hz ratios, 1:1, 1.75, 2, or 3.5, kind of like a gearbox. If you were doing a custom winding you could do two (or more) levels of series/parallel, giving you 1:1, 2, or 4 (or 8).

This is quite complex now though, ideally it would be incorporated in the controller, more than 3 pairs of IGBTs, maybe 6 or 12 pairs of smaller ones would be better.
Planned EV: '63 Cortina using AC and LiFePO4 Battery Pack
User avatar
bladecar
Senior Member
Posts: 499
Joined: Tue, 05 Jul 2011, 16:32
Location: Brisbane

How to convert a hybrid

Post by bladecar »

I originally thought that "over 40 years ago" was true because I remember looking at the new $1 coin and $5 note (but really, I think they were $1 and $2 notes at the time, they only went to coins later) on the 14th of February, 1966 and thinking how "monopoly" looking they were. But, speeds, etc, now I'm not sure, since I didn't drive then.

I no longer think in mph at all, except I always know that 100kmh is nearly 60mph, that 60kph is around 35mph, that 80kph is around 45mph and finally that 40kph is around 25mph (mmm, not sure about 80kph anymore).

So, these days, I occasionally figure out in my head what 314kph might be in mph when watching the moto gp but otherwise, really, it's all metric. (and a good thing too, in case NASA call and want me to calibrate the navigation systems for a Mars landing)
User avatar
coulomb
Site Admin
Posts: 4395
Joined: Thu, 22 Jan 2009, 20:32
Real Name: Mike Van Emmerik
Location: Brisbane
Contact:

How to convert a hybrid

Post by coulomb »

bladecar wrote: I remember looking at the new $1 coin and $5 note (but really, I think they were $1 and $2 notes at the time, they only went to coins later) on the 14th of February, 1966

So you remember Dollar Bill?



I still have a $2 note, and remember the $1 note as well.

Image Image

Edit: Although I was too young to drive when the speed signs were in MPH, I do remember checking Dad's speed against the signs. I seem to recall that they often had the vertical double arrowed line on a separate sign underneath the speed limit sign, if it applied before and after this point (i.e. it wasn't a speed limit change, just advising the present limit).

Edit: After that little blast of nostalgia, perhaps we could get back on to topic.
Last edited by coulomb on Fri, 29 Jun 2012, 18:35, edited 1 time in total.
Nissan Leaf 2012 with new battery May 2019.
5650 W solar, 2xPIP-4048MS inverters, 16 kWh battery.
1.4 kW solar with 1.2 kW Latronics inverter and FIT.
160 W solar, 2.5 kWh 24 V battery for lights.
Patching PIP-4048/5048 inverter-chargers.
User avatar
weber
Site Admin
Posts: 2799
Joined: Fri, 23 Jan 2009, 17:27
Real Name: Dave Keenan
Location: Brisbane
Contact:

How to convert a hybrid

Post by weber »

Johny, reading mph as km/h in hexadecimal is simply a great hack. I so wish I had thought of that. You are my hero. Image
T2 wrote: -Weber what have you chosen for the base speed of your MX-5
        in mph or km/hr ? Please and thank you.

We have a Tritium Wavesculptor 200 with a 2-pole induction motor whose curves you can see here. Those curves are with 330 Vdc and motor current limited to 300 Arms because that's the Wavesculptor's maximum. You'll see that the peak power of 65 kW occurs at about 1800 rpm.

However we designed for, and in future plan to reconfigure for, a battery and inverter DC voltage that is about twice that (under load). So we then expect to obtain a peak power of around 130 kW at 3600 rpm. We have a diff ratio of 3.636:1 and effective wheel circumference is 1.766 m.

Peak power at 3600 rpm therefore corresponds to the following speeds in the various gears:
1st 3.136:1 33 km/h
2nd 1.888:1 56 km/h
3rd 1.330:1 79 km/h
4th 1.000:1 105 km/h
5th 0.814:1 129 km/h

T2, I am in total agreement with you re the desirability of higher frequency motors, and induction motors versus those with permanent magnets. I would have used a 400 Hz induction motor if I could find one at a reasonable price and a suitable configuration (both mechanical and electrical).

I would be happy to use a lower battery voltage in future because I've found that the insulation requirements and the ELV segmentation (pack breakup) requirements become rather onerous at 750 Vdc, although we have solved all the problems and produced what may be the world's safest BMS in the process. But I wouldn't go below about 375 Vdc as the current carrying requirements then become too onerous (at 130 kW or above).

Coulomb, I think your main remaining source of disagreement with T2 comes because you are assuming an idealised PM or IPM motor that goes to constant power when you run out of volts per hertz, whereas T2 has always been talking about real induction motors. What does your model tell you if the torque falls off as say 1/f^1.2 ?
One of the fathers of MeXy the electric MX-5, along with Coulomb and Newton (Jeff Owen).
User avatar
PlanB
Senior Member
Posts: 465
Joined: Sat, 16 Jan 2010, 15:24
Real Name: Kris McLean
Location: Freemans reach
Contact:

How to convert a hybrid

Post by PlanB »

350Nm from that ABB Dave, that's 110Nm more than TJs Sew. So that's 350 x 3.636 = 1273Nm at the wheels in 4th gear? I wish I had a better handle on the whole motor specs scene. I still can't fathom why that Lexus transaxle at 900Nm post gearing turned out to be such a dog on hill starts for young Ryan.
I found a 400Hz motor/controller combo in my incessant web trawling a few weeks back, I've read this thread 3 times & I still don't get what the sweetspot with these is or why induction is better than PM for that matter. I may have to come up to Brisbane for a Pizza & a quick indoctrination. Is there a time & a place where I could button hole you, Mike & TJ all at the same time?
User avatar
weber
Site Admin
Posts: 2799
Joined: Fri, 23 Jan 2009, 17:27
Real Name: Dave Keenan
Location: Brisbane
Contact:

How to convert a hybrid

Post by weber »

PlanB wrote: 350Nm from that ABB Dave, that's 110Nm more than TJs Sew. So that's 350 x 3.636 = 1273Nm at the wheels in 4th gear? I wish I had a better handle on the whole motor specs scene. I still can't fathom why that Lexus transaxle at 900Nm post gearing turned out to be such a dog on hill starts for young Ryan.
The MX-5 wouldn't do hill starts too well in 4th gear either. I agree with your calculations. And if you want the actual force in newtons you can divide by the wheel radius of 0.28 m.
I found a 400Hz motor/controller combo in my incessant web trawling a few weeks back,
It would be good if you could find it again and post the link.
I've read this thread 3 times & I still don't get what the sweetspot with these is or why induction is better than PM for that matter.
I'm hoping Coulomb will address the case where power droops above base speed. And I'd be happy if anyone would answer my questions about what we're trying to optimise here, and under what conditions. What are _you_ trying to achieve, Kris?

There are obviously good reasons to use PM and IPM motors since major car manufacturers are using them. I favour induction motors because they are simpler and safer. Permanent magnets tend to require elements that are far less abundant than iron, aluminium and copper, and you can't turn them off, so if the inverter fails you can get uncontrolled regenerative braking or excessive voltage, and you need special equipment to take PM motors apart, and overtemperature can cause permanent loss of magnetism.

But I have to admit that ultimately I have an emotional attachment to induction motors. It's a kind of minimalist aesthetic, or an Occam's razor kind of thing.
I may have to come up to Brisbane for a Pizza & a quick indoctrination. Is there a time & a place where I could button hole you, Mike & TJ all at the same time?

You'll always find Mike and I at my place at Bardon on Fridays. TJ and you would be quite welcome. Tritium is about 30 minutes drive from my place.
One of the fathers of MeXy the electric MX-5, along with Coulomb and Newton (Jeff Owen).
User avatar
PlanB
Senior Member
Posts: 465
Joined: Sat, 16 Jan 2010, 15:24
Real Name: Kris McLean
Location: Freemans reach
Contact:

How to convert a hybrid

Post by PlanB »

Those 400Hz links on my other PC, will post when back in Sydney on Thursday. I guess I want to build an EV where I don't have to change gears that isn't a slug, to borrow a phrase it's a minimalist aesthetic. I'm starting to despair a bit I must admit though.
User avatar
PlanB
Senior Member
Posts: 465
Joined: Sat, 16 Jan 2010, 15:24
Real Name: Kris McLean
Location: Freemans reach
Contact:

How to convert a hybrid

Post by PlanB »

I don't understand why you couldn't do hill starts in 4th Dave?
F needed to accelerate 1200kg to 100km/h (27.8m/s) in 10s F = ma = 3336N
F needed to overcome rolling friction, driveline losses, aerodynamic drag say 10% = 334N
F needed to overcome say a 4 degree slope = 0.07 x 1200 x 9.8 = 823N
Total force needed = 3336 + 334 + 823 = 4493N
Force available = 1273Nm/0.28m = 4546N
User avatar
bladecar
Senior Member
Posts: 499
Joined: Tue, 05 Jul 2011, 16:32
Location: Brisbane

How to convert a hybrid

Post by bladecar »

Not to go on about a Blade car, but it seems to me that they have a pretty good setup.

Watching the video, it uses 2nd in general. You can go from 0 to probably 120kph in that gear and is very usable.   1st is for more go from start. The other gears put the motor at a more suitable rev range. So, really, it's a gearless system if you're too lazy to bother, sort-of Image
antiscab
Senior Member
Posts: 2704
Joined: Mon, 26 Nov 2007, 05:39
Real Name: Matthew Lacey
Location: Perth, WA

How to convert a hybrid

Post by antiscab »

the blade uses the original hyundai gearbox

it wasn't really designed to be driven in 2nd the whole time, so service life will be somewhat reduced, but you would have to drive it nearly 100'000km to find out

Matt
Matt
2017 Renault zoe - 25'000km
2007 vectrix - 156'000km
1998 prius - needs Batt
1999 Prius - needs batt
2000 prius - has 200 x headway 38120 cells
User avatar
woody
Senior Member
Posts: 1716
Joined: Sat, 21 Jun 2008, 02:03
Real Name: Anthony Wood
Location: Mt Colah

How to convert a hybrid

Post by woody »

PlanB wrote: I don't understand why you couldn't do hill starts in 4th Dave?
F needed to accelerate 1200kg to 100km/h (27.8m/s) in 10s F = ma = 3336N
F needed to overcome rolling friction, driveline losses, aerodynamic drag say 10% = 334N
F needed to overcome say a 4 degree slope = 0.07 x 1200 x 9.8 = 823N
Total force needed = 3336 + 334 + 823 = 4493N
Force available = 1273Nm/0.28m = 4546N
4 degrees isn't that steep. Steepest near me is Rothwell Rd, Warrawee, 11.6% = 6.6 degrees.

Force to lift 1200kg car up 11.6% slope = 11.6 * 1200 * 9.8 = 1364N
330Nm motor at the rear wheels through 4.3:1 95% diff and 185/60R14 tyres = 3000N - so still some leeway there.

In car parks the ramps can be 1 in 6 or 17%.
So 17% * 1200 * 9.8 = 2000N. Which means 2/3 of the torque has gone to lifting the car, 1/3 for acceleration.

Or another way, you need at least 220Nm in a direct drive MX5 to navigate a car park ...
Planned EV: '63 Cortina using AC and LiFePO4 Battery Pack
User avatar
PlanB
Senior Member
Posts: 465
Joined: Sat, 16 Jan 2010, 15:24
Real Name: Kris McLean
Location: Freemans reach
Contact:

How to convert a hybrid

Post by PlanB »

Last edited by PlanB on Thu, 05 Jul 2012, 13:21, edited 1 time in total.
Tritium_James
Senior Member
Posts: 683
Joined: Wed, 04 Mar 2009, 17:15
Real Name: James Kennedy
Contact:

How to convert a hybrid

Post by Tritium_James »

That looks identical to the original AC Propulsion motors.
User avatar
coulomb
Site Admin
Posts: 4395
Joined: Thu, 22 Jan 2009, 20:32
Real Name: Mike Van Emmerik
Location: Brisbane
Contact:

How to convert a hybrid

Post by coulomb »

I've been considering input from various sources, and I've come to the conclusion that I'm wrong, and T2 is right. Perhaps I could summarise the situation.

T2 is considering how much to "overclock" an induction motor for direct drive applications. Although there is also the possibility of using a Prius transaxle as a transaxle (rather than the actual motor, as is usually the assumption if converting a Prius). For now, let's just consider direct drive for simplicity.

T2's claim was that one should overclock the induction motor agressively, keeping the staring torque out to about 60 km/h or more (let's say that's 50% of the motor's working speed range). I claimed that this is bad, because you don't get full power till 50% speed; you're better off getting full power at say 33% speed, and getting "almost constant" power above that. I showed that IF you keep the power of the motor constant, and if you assume perfectly constant power above base speed, putting the base speed lower is better.

However, my assumption that changing the base speed keeps the motor power constant is not correct. As has been pointed out, it is the torque that remains relatively constant; the peak power actually increases as you overclock more and more. So T2 is right; pushing the base speed higher is beneficial, as you are getting the same torque out to higher speeds, thus getting more power above base speed of the motor with the lower base speed. (In my example, both motors would output the same torque up to 33% speed, but between 33% and 50% the motor with the higher base speed keeps outputting the same torque, but the motor with the 33% base speed is outputting constant power, and torque reducing at 1/f.)

So why not push the base speed lower and lower? Well, of course you would need a higher and higher power controller; same voltage but more and more current would be required. Indeed, as the base speed is pushed higher by a factor of n, the current required by the controller (and hence its kVA rating) has to increase by more than a factor of n. This is partly due to the way that the direct and quadrature currents sum; when the quadrature current is doubled, and the direct current remains the same, the vector sum of the direct and quadrature currents (which is the current the controller has to supply) more than doubles. You can see this effect with our motor:

Image

100 A gives 130 Nm, but 300 A gives around 355 Nm, less than the 390 Nm you might expect from merely scaling the torque linearly with current. It's not a huge effect (355/390 = 91%), but it means that you need more current from the controller even at low speed and power, so you get a little less power from the same kVA controller when you push the base speed higher.

Of course, you could say that this is just one of the costs to be paid for more power from the motor.

So T2, thanks for persevering with me, I finally get it.

It still seems to me that there should be a way to push the base speed lower for a given motor size and controller rating, without affecting peak torque or power too badly, but I can't see it at present.

[ Edit: "scaling the current" -> "scaling the torque linearly with current" ]
Last edited by coulomb on Mon, 09 Jul 2012, 07:14, edited 1 time in total.
Nissan Leaf 2012 with new battery May 2019.
5650 W solar, 2xPIP-4048MS inverters, 16 kWh battery.
1.4 kW solar with 1.2 kW Latronics inverter and FIT.
160 W solar, 2.5 kWh 24 V battery for lights.
Patching PIP-4048/5048 inverter-chargers.
User avatar
PlanB
Senior Member
Posts: 465
Joined: Sat, 16 Jan 2010, 15:24
Real Name: Kris McLean
Location: Freemans reach
Contact:

How to convert a hybrid

Post by PlanB »

Tritium_James wrote: That looks identical to the original AC Propulsion motors.
That's probably because it is TJ, the controller they're offering with it is a gen2 AC-150, gosh I like that reductive charging idea.
Mike, stop posting graphs showing 350Nm+ for your ABB, you're making me jealous.
User avatar
weber
Site Admin
Posts: 2799
Joined: Fri, 23 Jan 2009, 17:27
Real Name: Dave Keenan
Location: Brisbane
Contact:

How to convert a hybrid

Post by weber »

Good post, Coulomb.

PlanB, if you want a high torque 132-frame motor for direct drive, you should look at the 4-pole lower-voltage version of ours that Woody got.

What are the specs on that thing, Woody?
One of the fathers of MeXy the electric MX-5, along with Coulomb and Newton (Jeff Owen).
User avatar
woody
Senior Member
Posts: 1716
Joined: Sat, 21 Jun 2008, 02:03
Real Name: Anthony Wood
Location: Mt Colah

How to convert a hybrid

Post by woody »

weber wrote: Good post, Coulomb.

PlanB, if you want a high torque 132-frame motor for direct drive, you should look at the 4-pole lower-voltage version of ours that Woody got.

What are the specs on that thing, Woody?


From memory (I'm on holiday)

ABB 132-007 HXE 18.5kW 4 pole foot and face 92kg
122Nm nominal torque at 1460rpm
Breakdown Ratio of 3.0 => 366Nm peak torque
12 wire factory winding, allowing nominal connections for:
400V (Star Series) 8V/Hz
230V (Delta Series) 4.6 V/Hz
200V (Star Parallel) 4V/Hz
115V (Delta Parallel) 2.3 V/Hz

The 12 wire winding was very special order, I had ABB on the ropes after what I originally ordered (132316) had the wrong specs in the catalogue and was no longer suitable.

Took about a year from order to delivery :-(
Planned EV: '63 Cortina using AC and LiFePO4 Battery Pack
User avatar
PlanB
Senior Member
Posts: 465
Joined: Sat, 16 Jan 2010, 15:24
Real Name: Kris McLean
Location: Freemans reach
Contact:

How to convert a hybrid

Post by PlanB »

So that 366Nm is at the 300A max of the wavesculptor Woody? A year is a long wait, what did the beast cost?
User avatar
woody
Senior Member
Posts: 1716
Joined: Sat, 21 Jun 2008, 02:03
Real Name: Anthony Wood
Location: Mt Colah

How to convert a hybrid

Post by woody »

366Nm is what the motor is rated to do DOL (Direct OnLine) I.e. Plugged into the wall 3 phase 415 50Hz.
It should do that with enough current from any controller.
It should do more with more V/Hz and enough current. (danfoss call this Torque boost)
It takes about 4xNominal current to get 3xtorque at breakdown according to the ABB formulas.
This depends on which wiring you use:
75A star series
130A delta series
150A star parallel
260A delta parallel

It cost me $1200, although I was quoted $1000 which was a volume price apparently. The one off price should have been $2K.
Planned EV: '63 Cortina using AC and LiFePO4 Battery Pack
User avatar
weber
Site Admin
Posts: 2799
Joined: Fri, 23 Jan 2009, 17:27
Real Name: Dave Keenan
Location: Brisbane
Contact:

How to convert a hybrid

Post by weber »

PlanB wrote: 400Hz MotorController combo $15k
http://400hertz.net/Products/ME-400-200 ... 00-416.htm
OK. That's the same motor I found bac ... 508#p10508

Woody, If we were to settle on a single ABB motor that would be of use to the greatest number of AC EV converters (gearbox and direct-to-diff, WaveSculptor 260 Vrms and industrial VFD 415 Vrms), so that it might be ordered in larger quantity to get the price down, then yours would seem to be the ideal model.

This would be for folks who are willing to pay more and put up with more weight for slightly more power than the otherwise excellent SEW motor from Tritium.

My only question is whether anyone would ever want to, and be able to, use the 400 V star configuration. And if not, then the 230 V delta is fairly close to the 200 V star and so we could probably do without it too, and get it down to a 6 wire motor with 200 V star and 115 V delta, which might get the price down a little more.

I'd love to hear others' thoughts on this.

Woody, is there any way we could get your motor up to Brisbane to go on Tritium's dyno?

For that matter, it would be good to see the SEW motor in star on Tritium's dyno.

Dunno how we got here from "How to convert a hybrid". Image

[Edit: Replies to this thread please:
viewtopic.php?title=rx400h-transaxle&p= ... 435#p37969]
Last edited by weber on Thu, 12 Jul 2012, 12:37, edited 1 time in total.
One of the fathers of MeXy the electric MX-5, along with Coulomb and Newton (Jeff Owen).
User avatar
woody
Senior Member
Posts: 1716
Joined: Sat, 21 Jun 2008, 02:03
Real Name: Anthony Wood
Location: Mt Colah

How to convert a hybrid

Post by woody »

I'd be quite happy to send it up and TJ to hook it up and see what it will do, as long as he doesn't disconnect the wave sculptor before he sends it back.
Planned EV: '63 Cortina using AC and LiFePO4 Battery Pack
Post Reply