Dumb question

[Stephan Linn]

I thought I understood how controllers and brushless motors worked UNTIL I got a Glion Dolly scooter into my shop and it seems like it needs a controller replaced. The display turns on and then off again when the button is released. I did all the usual things and replaced the throttle/display and brake using (genuine expensive Glion parts ). The problem persists and I want to try another controller, but Glion dont have any. So I start looking around and I notice the Glion controller dont have any motor hall sensor wires. My question is how can the motor work without hall sensors. I have also noticed controllers on the aftermarket with only two "motor wires" - Doesn't a brushless motor need three phase wires?

 

[eee291]

Only two wires would mean brushed DC, but I can't really find anything online. Could you take a few pics?

 

[amberwolf]

Controllers and motors with only three thick phase wires and no sensor wires at all are called Sensorless. The typical ones don't operate as well from a stop under load as sensored systems do, but using FOC controllers it is possible to write controller software that does a good enough job (see Lebowski's posts about that, and others here on ES and elsewhere).

Controllers and motors with three thick phase wires and other thin wires that are not hall sensor wires may use other types of position sensors than the common UVW three-hall types, there are a number of different kinds.

Controllers with only two motor wires are for brushed motors, which don't have multiple phases operated by the controller, their phases are operated by a mechanical commutator built into the motor.

 

[amberwolf]

Regarding the problem with the scooter itself:

Displays *usually* turn the system on and off by taking battery positive from the controller that they always run off of (even when the system is "off" they use some standby power, unless you physically turn off or disconnect the battery). This goes to a tiny transistor switch inside the display which is turned on or off when you use the display's power button. This feeds battery voltage back tot he controller's LPVS that makes it's 5v/etc that the brain and stuff runs off of, so the controller itself doens't take any significant standby current when off.

If turning on the display via power button does turn on the display and leave it on, but the system doesn't operate, then it's usually the display at fault, or a connection between display and controller.

If turning on the display vai the power button turns the display on but it turns right back off it usually means the battery cant' supply enough power to run it, either the battery is too empty (too low a voltage) or has a problem so that even the power-on load is too much for it so it turns itself off at it's internal BMS, or the system has a problem such as blown FETs in the controlelr or shorted motor wires or windings (overheated), etc. that creates such a high load on the battery that it shuts off to protect itself.

 

[Stephan Linn]

Regarding the problem with the scooter itself:

Displays *usually* turn the system on and off by taking battery positive from the controller that they always run off of (even when the system is "off" they use some standby power, unless you physically turn off or disconnect the battery). This goes to a tiny transistor switch inside the display which is turned on or off when you use the display's power button. This feeds battery voltage back tot he controller's LPVS that makes it's 5v/etc that the brain and stuff runs off of, so the controller itself doens't take any significant standby current when off.

If turning on the display via power button does turn on the display and leave it on, but the system doesn't operate, then it's usually the display at fault, or a connection between display and controller.

If turning on the display vai the power button turns the display on but it turns right back off it usually means the battery cant' supply enough power to run it, either the battery is too empty (too low a voltage) or has a problem so that even the power-on load is too much for it so it turns itself off at it's internal BMS, or the system has a problem such as blown FETs in the controlelr or shorted motor wires or windings (overheated), etc. that creates such a high load on the battery that it shuts off to protect itself.

Wow, thanks for all the useful information. I did load-test the battery and it is ok. I also looked at the motor phase lines using one of those gadgets with flashing leds - they flashed. I tried turning the system on with the phase lines disconnected - no change. Last but not least, I looked inside the controller - no burned FETs.
I did forget one tiny bit of information the guy told me - that the problem had happened once before. He tried turning it on and he rode it. The next time he tried to turn it on - no cigar.

Now it's in my shop in pieces. While interesting from an intellectual POV, I cant realistically charge this guy for the time I'm spending.

 

[AussieRider]

Does the scooter have a fuse? I had a glass fuse go high resistance on me. Flowed enough current to charge the controller caps so it seemed to turn on for a bit then blank. Took a while to work it out, hope I can save yous some time. Changed the little bugger to a blade type fuse.
Never trusted glass fuses again.

AussieRider

 

[Stephan Linn]

Does the scooter have a fuse? I had a glass fuse go high resistance on me. Flowed enough current to charge the controller caps so it seemed to turn on for a bit then blank. Took a while to work it out, hope I can save yous some time. Changed the little bugger to a blade type fuse.
Never trusted glass fuses again.

AussieRider

Yes, I another detail I forgot to mention. It has two non-glass fuses ( power(30A- seems high?) and charger(5A) ) - both OK.
Gracias