openinverter forum

The new Nissan Ariya and a numbe rof other EVs are moving away from permanent magnet motors.

Here's a brief article from chargedevs.com

https://chargedevs.com/features/a-close ... rs-in-evs/

The elimination of the stupid field weakening would indeed be a big advantage. I reckon the auxiliary PWM output could serve as the field current regulator

Hasn’t the Renault Zoe been using this style of motor?

Ev8 wrote: ↑Sun Aug 21, 2022 5:53 pm Hasn’t the Renault Zoe been using this style of motor?

Yes, powered rotor and wye-wired stator, it's a really interesting motor but not too useful for DIY-Projects.

Does that mean it has slip rings with carbon brushes for the rotor?

johnspark wrote: ↑Sat Jan 21, 2023 9:22 am Does that mean it has slip rings with carbon brushes for the rotor?

Those are called collectors as a company in Slovenia designed them - Kolektor. They are in their logo.
I think they are working on some strange design of multi phase multi pole motors - like 5 phase 15 pole motor or something with slip ring excited rotor. Can you imagine how such inverter would look.
I was talking with one of them and he said those motors like high revs most but vibrate under low speed. They are trying to solve that with lots of poles. But for that they need higher frequency to form pwm... some 800hz motor base fq that means 18khz pwm minimum. SiC chips are a must!

johnspark wrote: ↑Sat Jan 21, 2023 9:22 am Does that mean it has slip rings with carbon brushes for the rotor?

Yes, the Zoe motor has a pair of sliprings.

I found an image of the Zoe motor on the Speak EV forum. There have been problems with the brushes, notably with carbon dust causing current leakage to the frame. The early Zoe at least, used the motor as part of an AC rapid charger (up to the 43kW limit of the type 2 connector with 3 phases) and the leakage prevented charging.

Search "Zoe Caméléon charger"

Well that is very interesting arber333. I have seen a few papers on 5 phase motors for sometime.
Not only is the inverter more complicated, but fault finding will be too.

For a 3 phase motor that we are used to, faults can be catalogued into any combination of: positive, negative and zero sequence faults. Positive sequence means: a then b then c phases rotate past a point, negative sequence means: c, then b then a rotate past a point. zero sequence means: a, b and c vectors are all in the same direction and rotate past a point at the same time.

For a 5 phase motor, faults can be catalogued into: positive, negative, zero and two others. Positive sequence means: a, then b, then c, then d, then e phases rotate past a point. Negative sequence means: e, then d, then c, then b, then a phases rotate past a point. But there are two extra systems of symmetrical vectors: a, then c, then e, then b then d rotate past a point; and also, a, then d, then b,then e and then c rotate past a point.
(Thank you Edith Clarke from 1943).

In other words, I am stating in a very complicated way that 5 phase motors are very complicated, and can have potential very complicated problems.

I suppose with clever chips and more clever software all these things can be ironed out. Agreed with SiC chips.

Thank you SciroccoEV. Good photo of the rings . One set of problems that can happen with induction motors is unwanted current flowing through the bearings causing havoc to the hard coating on the ball bearings, to solve that, if this problem can occur they insulate bearings at both ends of the motor. Here we have the potential for carbon dust to earth one of the bearings.(if I remember rightly, this can occur if there is a bit of zero sequence current flowing).
I guess as always, it comes done to good engineering of the whole package...


I personally don't like DC motors because of carbon rings, and here we have carbon rings in an AC motor. At least these ones don't get to be filed down overtime by a commutator.

johnspark wrote: ↑Sun Jan 22, 2023 4:47 am One set of problems that can happen with induction motors is unwanted current flowing through the bearings causing havoc to the hard coating on the ball bearings, to solve that, if this problem can occur they insulate bearings at both ends of the motor.

You only need to insulate one bearing to prevent the rotor and stator forming a single turn shorted winding. Many of the references to this problem hark back to the early variable frequency drives with a 16 step waveform and low PWM frequency resulting in lots of harmonic content.

Most of the 'experts' on the machne tool forums will insist you need to buy an inverter grade motor to convert your lathe, mill etc. to run from single phase AC with a variable frequency drive. You'll destroy your old motor with a VFD!. My unpopular opinion was to 'use up' the motor you already had and for example the 1963 motor on my Harrison L5 has been happily running on a cheap Chinese VFD for over 15 years.

Yes makes complete sense, use what you have got (If it works don't fix it). Anyway, these 'old' things were made by tradesmen who were taught properly, perhaps the insulation used was better than what the books said to use... . So it is wonderful your Harrison L5 is humming along

Yes well that is true about only insulating one bearing, they just have to be careful with what the shaft is connected to. Do they insulate the end that has no output shaft?