fan cooled 10kW BLDC motor

[Raedy07]

hello,
i have a fan cooled 10kW BLDC motor, 48V. it's almost new, I ran it just for a few minutes to test. today I installed it permanently (to drive an air compressor), but after less than a minute something burnt. it can't have been overloaded, as a 5kW motor had been doing the job for 2 years. as I recently increased the number of solar panels, I wanted to upgrade to 10kW-motor  to get full compressor output  (needs 6.5kW).

in 2 shaft positions it's much harder to turn it over (by hand), as if rotor is touching somewhere. compared to d 5kW, it was always MUCH harder to turn over. I will open & check myself - are there any blow-ups available for this motor?  disassembly instructions even?

thanks for any input,

Radek

[Bikemad]

Hi Radek andto the forum.

Unfortunately there are no exploded diagrams to help with disassembly of the motor, but if it's almost new, I presume it is still under warranty, so perhaps you should contact the seller before you attempt to dismantle it.

Was there actually a burning smell coming from the motor?

What controller are you using and does it show any error codes? (i.e. flashing LED.)

In 2 shaft positions it's much harder to turn it over (by hand), as if rotor is touching somewhere. compared to d 5kW, it was always MUCH harder to turn over.

It shouldn't have two noticeable tight spots (unless it is still connected to a 2 cylinder compressor.)

I would expect it to be twice as stiff to turn compared to the 5kW motor as it basically contains the magnets and stators of two 5kW motors combined into a single unit.

Alan
 

[Raedy07]

thanx Alan,
i have found d problem: I opened d motor and found a loose washer in there !!!!   well not exactly loose, as it was stuck to a magnet, but definitely it shouldn't have been there. so it brought everything to a halt      must've fallen in there on d assembly-line......
anyway, 'only' 1 of d 2coils was burnt; I took it out, in d meantime (until replacement arrives) i'm just using it with 1  (=5kW).  some mags were slightly scratched, but I detected no anomalies when testing them with d hall-sensor.
not many moving parts but assembly is a bit tricky due to d strong mags.  and it's not noticably harder to turn over -without d washer- maybe because number of mags is identical?
cheers,
Radek

[Bikemad]

Hi Radek and thanks for the update.

Make sure that the Motor blockage protection and Motor overtemperature protection is enabled in the controller settings, as I would have expected these settings to have prevented the stator coils from being overheated.

And it's not noticeably harder to turn over -without d washer- maybe because number of mags is identical?

The rotor on the 10kW motor should have 16 magnets (8 on each side of the rotor disc) whereas the 5kW motor only has 8 magnets mounted on just one side of the rotor disc:



Perhaps the magnets and stator coils positioned on either side of the rotor disc are staggered by 7.5° to reduce the residual magnetic drag and smooth out the electromagnetic pulses. 
Although, this would mean that the coil timing on one stator would be out by 7.5° (either advanced or retarded) when a single controller using the single set of Hall sensors on the other stator was used. 

Alan