suspect Vectrix Motor

[antiscab]

Hi All

I have a vectrix that seems to eat motor controllers (internal IGBT failures)

It's back with me as it's not going again

encoder disc was damaged, so that has been replaced

however, I don't have an easy way to test the motor

The bike behaves as though it's down a phase (most likely a dead MC again, though I won't know for sure until I remove it)
this is the 3rd motor controller to have failed in this bike in around a year.

I'm wondering how I would test for shorted turns inside the motor, as being my only theory as to what could cause early IGBT failure

I haven't meggered the motor (I don't think I have access to that equipment anyway)
resistance between phases is lower than my DMM can measure accurately

I wish I had taken note which phase has failed on the last two motor controllers, to see if it's the same one each time

I'm tempted to replace both the motor and motor controller, but I don't really have anything more than a hunch to back up the decision to replace the motor as well

Matt

[antiscab]

to add to the confusion:
I ran the motor no load at 110kmh (wheel off the ground) whilst measuring AC voltage between phases.
phase 1 - 2 = 76vac
phase 2 - 3 = 18vac
phase 1 - 3 = 18vac

But then I did the same test on a known good bike:
phase 1 - 2 = 15vac
phase 2 - 3 = 15vac
phase 1 - 3 = 76vac

which suggests to me that at no load bouncing off the rev limiter, the motor controller drops a phase, which means the measurements don't tell me anything useful

I may have to get hold of a portable DSO, or even just a 3-phase volt meter do check what's going on while actually riding

[jonescg]

Were you able to add some load? Like an upturned wheelbarrow wheel?

[antiscab]

I will have to give that a try

I was thinking of using the rear brake, but I didn't have enough hands.
I will have to give it a go though

The surprising part for me was how much lower the no load back emf was compared to the battery voltage, when supposedly at maximum speed.

[coulomb]

The surprising part for me was how much lower the no load back emf was compared to the battery voltage, when supposedly at maximum speed.

I wonder if it's using a lot of field weakening to get a wide constant power region. But the difference between phases is very surprising to me too.

I assume it's a permanent magnet motor?

[antiscab]

The surprising part for me was how much lower the no load back emf was compared to the battery voltage, when supposedly at maximum speed.

I wonder if it's using a lot of field weakening to get a wide constant power region. But the difference between phases is very surprising to me too.

I assume it's a permanent magnet motor?

yes perm magnet motor, and yes the MC uses field weakening.
when riding, max DC bus current draw peaks at 220A (which is awfully close to the IGBT 6-pack max 300A) at 70kmh, above which it enters a constant power region.
I always assumed this was where field weakening started.

I'm now wondering whether it is the transition from field strengthening to field weakening, and the permanent magnets aren't that strong (maybe to improve efficiency at part load)

On another note, I have done some more testing today.
testing body diodes on the IGBT 6-pack showed all upper and lower to be 0.35v drop, with reverse polarity checking out as above what my DMM can measure.
So that suggests the IGBT's themselves are likely okay.

I did a separate test, measuring AC voltage between phases, and between individual phase terminals and batt +/- whilst motor was not connected, but MC powered up and motor spinning (by foot action).
I measured a varying AC voltage in all scenarios, except between phase 1 and batt - terminal. That stayed resolutely at 0v (well hovering around 0.2vac, but that's a 0 point issue with my DMM I think)

That tells me the low side IGBT on phase 1 isn't conducting.
now to test the gate driver signal (after I look up the IGBT spec sheet to work out which terminal is supposed to be triggered)

EDIT: no vac between batt - and phase 1 terminal would suggest high side IGBT (between + and phase 1 terminal) to not be conducting.
EDIT2: I would also have to check the 15V gate drive power supply, as the high sides each have their own
EDIT3: IGBT module in question: https://www.digchip.com/datasheets/part ... 60-pdf.php

[wovenrovings]

I you want me to measure stuff I have a vectrix and a spare motor and igbt board. As long as its simple as I only have a DMM and in the early stages of learning all this stuff.
And my vectrix is working fine.

[antiscab]

more testing:
phase 1 high side powersupply is dead. (0v)
phase 2 and 3 high side are 15v and 16v

I can't imagine a scenario in which a motor issue could cause a gate drive powersupply to fail, but not the IGBT it's driving.
Maybe the MC failures are co-incidental

[antiscab]

I you want me to measure stuff I have a vectrix and a spare motor and igbt board. As long as its simple as I only have a DMM and in the early stages of learning all this stuff.
And my vectrix is working fine.

That's okay, I have around 4 vectrix at my house, in various states of assembly.
I am tempted to externally spin up my spare motor to measure the open circuit back emf at high speed (to satisfy my curiosity)

[antiscab]

update:

I fitted a different (2nd hand) motor controller
All seems well, however, intermittently the motor stutters on take off.
It seems to be only when the MC heatsink is low enough temperature for the fan to turn off, and only at full throttle.

At lower heatsink temperature, the MC raises the phase current limit to maximum.
My thinking is the I2T increases by enough that the internal IGBT temp protection kicks in and drives all gates to off.
Not enough thermal mass on the gates, and not enough heat transfer between gates and heatsink.
Time between cut out and cut back in is around 0.5 seconds

[Azzuro]

Hi Matt,

Thx again for the fw sources, shared recently, making progress. If you look filter out the code sections in the MCR1004.asm referring to "IGBT" it would show how the MC is handling different scenarios. In case a failure is determined PGN FECA (05) byte 3 bits are also set (ref. ****In FaultCause Register ) :

PhaseCur Fault - Bit0
BusCur Fault - Bit1
MotorTemp Fault - Bit2
CapTemp Fault - Bit3
LowBusVolt Fault - Bit4
IGBT Fault - Bit5
Thrtl Fault - Bit6
HeatsinkTemp Fault - Bit7

Due to the rare nature of these problems it is hard to say if these faults would also initiate the 'Wrench' telltale immediately but I would assume.

/ Azzuro

[evcruiser]

Maybe too late but ...
you can put a constant current DC [or current limiting DC supply] over your motor phases and measure with a volt meter to then calculate low motor phase resistances with accuracy.
It does sound like a motor issue.
How did you go anyhow?!?

[antiscab]

Motor turned out to be fine, I just happened to have two consecutive dud motor controllers. The first mc had a cracked solder join where the igbt module connects to the board.

The second mc igbt was worn out. The Vectrix now has a brand new mc, and all is well again.

That Vectrix is actually for sale now (it's up on gumtree)

[evcruiser]

Oh that's great to hear. Persistence pays off.
Its comforting to know parts are available for the Vectrix. I reckon they're a great bike.
Last time i looked the company was in turmoil but that seems to have settled.

I had a buyer the other day tell me to get better pictures for my ad.
It still [obviously] sold to them though.