Suspect Vectrix Motor

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Last seen: 1 year 1 month ago
Joined: Saturday, July 7, 2007 - 23:55
Points: 1686
Suspect Vectrix Motor

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 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


Bikemad's picture
Last seen: 1 month 4 weeks ago
Joined: Saturday, December 21, 2013 - 03:03
Points: 213
Re: Suspect Vectrix Motor

Hi Matt,

Could the encoder disc have been faulty when the last two controllers failed? If so, perhaps it could be the result of a timing issue with the firing of the Phase windings.

If the phase wire were being energised too soon (while approaching the magnets instead of already being adjacent to them) it could (I'm guessing) cause excessive load on the switching circuit within the IGBT.

I imagine it would be similar to the sudden shock load exerted on a piston and conrod etc. in a petrol (gasoline) engine recognisable by the pre-ignition knock (or detonation) which is often caused by over advanced ignition timing.

I once read an article on a R/C forum about over advanced BLDC motor running hotter, therefore it would be logical to assume that it must be drawing higher current to cause the extra heat, and switching higher current has got to involve additional load being placed on the switching circuit (i.e. MOSFETS or IGBT)

If the scooter in question has received a Leaf battery upgrade, which has a lot less voltage sag under load (and possibly running on a much higher initial voltage too) then this would also be placing additional current switching loads upon the IGBT.

Over the years, I have killed several eBike controllers after modifying them to produce more power, and I'm pretty sure that the Vectrix controller would also fail eventually if too much load was regularly placed upon it.

Well, that's my theory anyway.


Last seen: 1 year 1 month ago
Joined: Saturday, July 7, 2007 - 23:55
Points: 1686
Re: Suspect Vectrix Motor

the encoder wasn't damaged with the last two motor controllers, though i did require cleaning.

even with a damaged encoder, the current sensors on the MC are used for current limiting, so even if encoder feedback is wrong the hard upper current limit doesn't get exceeded

I cross posted here too:

after more testing, the issue with the MC is actually one of the 15v gate driver power supplies. the IGBT itself is fine

Daily Ride:
2007 Vectrix, modified with 42 x Thundersky 60Ah in July 2010. Done 194'000km

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