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Electric motors for cars

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Ian Parkin28/11/2020 12:49:19
885 forum posts
215 photos

What sort of motors are used for retro fitting into cars?

i was watching a programme about a company converting a variety of classic cars into electric powered

the motors they were fitting were so small

i’m used in the day job to motors that i can lift being up to 5kw or so

but a 25 kw motor is fork lift territory

so what sort of a motor generates 65kw that you can almost fit into your pocket?

then the end plate is B plate and has 4 m8 bolts to hold it on

by the look of the motors they are 3 phase


this is a link to a motor


anyone any experience with them?

Edited By Ian Parkin on 28/11/2020 12:50:31

JasonB28/11/2020 14:00:58
19602 forum posts
2150 photos
1 articles

You must have big pockets Ian, that motor is 9" diameter and 13" long and weighs in at 38.5Kg

96V x 650A = 63KW

Edited By JasonB on 28/11/2020 14:29:15

not done it yet28/11/2020 14:16:59
5428 forum posts
20 photos

50kW only? The description with that motor says A/C induction. The cost looks like a fairly complete package for home installation?

I would expect it to be down-rated from 50kW due to the 96V controller and, presumably, a few volts less from the battery (less than 96V at full charge?) as the motor presumably would only output rated power at maximum voltage?

Many simply use fork truck motors - have a look at Rich Rebuilds on the toob as he is currently converting a BMW Mini to electric. There are plenty of other videos around, but that one has an attractive ‘side-kick’ involved at times.🙂

Lower powered motors are sufficient for steady motoring, but not particularly startling (see some Morris Minor/VW beetle conversion videos?). Run through the vehicle’s transmission does give the opportunity to select a more appropriate gear ratio, depending on the circumstances🙂 .

Robert Atkinson 228/11/2020 14:26:05
886 forum posts
17 photos

The modern motors are what most on here would consider "brushless DC" with sensors. So a rare earth magnet rotor and polyphase (most are 3 phase) stator. They run at high freguency (less magnetic material and fewer field coil turns needed) and fairy high speed.

Using an old type brushed DC "forklift" motor is a very poor choice as they are so heavy (weight is a bonus in a fork lift) quite apart from the poor electrical efficency.

A lot of the classic conveters are droppin the systems from a used early Nissan Leaf into them.

Robert G8RPI.


Edited By Robert Atkinson 2 on 28/11/2020 14:46:55

Andrew Johnston28/11/2020 14:45:46
5841 forum posts
662 photos

Back in the 1990s when I was working full time on designing the power electronics for electric vehicles we started with simple induction motors (up to 100kW) and full vector control, ie, a VFD. One thing an electric vehicle needs is full torque at zero speed which makes the controller a bit more upmarket than VFDs intended for machine tools. We then modified the software to deal with trapezoidal motors aka brushless DC. We then did another tweak for permanent magnet motors, similar to BLDC motors. We used off the shelf commercial motors, which were large. Now motors are much better tuned to the application. Like IC engines electric motors in cars rarely run at full power for any significant period of time, so the motors can be small compared to full rated motors. We used a single motor per vehicle, apart from buses where we needed two motors gearbox coupled to get the power. These days each wheel tends to have it's own motor which can be smaller and dispenses with the need for gearboxes and differentials.

We did a project with Oxford University with a weird kind of induction motor that had 10 poles and 12 windings, or the other way round, can't remember which. I never did get to the bottom of understanding how it worked.

I think modern vehicles use a mix of induction and BLDC. If anything the battery management system is more important. One thing we discovered early on is that one needs to monitor each cell and use a charge balancing algorithm. Otherwise the batteries get out of kilter and one ends up overcharging or over-discharging individual batteries.

Electric gliders mostly use BLDC for self-sustainers but the only self-launching glider we have at our site uses an induction motor (I think).



Edited By Andrew Johnston on 28/11/2020 14:47:14

Robert Atkinson 228/11/2020 15:18:37
886 forum posts
17 photos

Nice bit of background from Andrew.
One other advantage of the Brushless DC is that they re good generators so they recover energy on decelleration and downhill. You get braking with a induction motor but they are not good generators.
A lot of the motors are liquid ooled as well

My Outlander PHEV has a complex system with the IC enging driving a generator and the front wheels through a CVT plus a motor on both front and rear axles. So it will do pure electric FWD, pure electric 4WD, engine driving generator to battery to FWD or 4WD electric, engine driving CVT for FWD(no electric), Engine to genenerator and CVT for FWD / 4WD.

When the IC engine is running the control system tries to keep it at it's optimum load point. If this produces more power than needed for propulsion the extra charges the battery. This, using the eletric to assist acceleration and the CVT mean the IC engine is fairly simple and optmised for efficency at a set load point rather than wide torque and power bands for driveability.

Robert G8RPI.

Niels Abildgaard28/11/2020 15:35:52
369 forum posts
150 photos

some state of art electric motors from Slovenia.

Link opens a PDF document



Edited By Niels Abildgaard on 28/11/2020 15:36:49

pgk pgk28/11/2020 15:49:21
2035 forum posts
290 photos
About 7 mins in for the motor itself

Howard Lewis28/11/2020 17:24:33
4177 forum posts
3 photos

Saw a picture, only the other day of a company that converts original Minis from petrol ,power to electric drive.

It looked to be a fairly small package.

No mention of where the battery pack goes, or of the power available.

For only £7,000!

The waiting list may well be fairly short!

Hope that it wasn't like an attempt to power a Hillman Imp with Hydrogen. The cylinder took half the back seat and the passenger seat!


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