Geared hub motor, no hall sensors, starting from standstill

[agrumpinthedust]

Hello,

I have what I hope are a few relatively simple questions.

I've read that if a BLDC hub motor doesn't have hall sensors that it will need kick-starting to both get it moving and to set the direction of rotation. Is that correct?

I've heard of hall-less controllers that can sense on the phase lines and use that information in place of hall sensors Are those controllers capable of starting a hall-less motor from stopped, or does this sensing only help while the motor is already spinning?

I'm considering geared BLDC hub motors (similar to http://www.uumotor.com/store/124-2014-new-6-inch-hub-motor-geared-with-no-hall-sensors-250w.html) but I'm having trouble finding a supplier that builds both hall sensors and gears into their motors. If I have the above type of motor with gears but without hall sensors, can I get this motor started from standstill with the right controller, or are the hall sensors absolutely required?

Advice appreciated and hopefully your answers will help future readers too.

Thanks!

 

[motomech]

Hello,

I have what I hope are a few relatively simple questions.

I've read that if a BLDC hub motor doesn't have hall sensors that it will need kick-starting to both get it moving and to set the direction of rotation. Is that correct?

I've heard of hall-less controllers that can sense on the phase lines and use that information in place of hall sensors Are those controllers capable of starting a hall-less motor from stopped, or does this sensing only help while the motor is already spinning?

I'm considering geared BLDC hub motors (similar to http://www.uumotor.com/store/124-2014-new-6-inch-hub-motor-geared-with-no-hall-sensors-250w.html) but I'm having trouble finding a supplier that builds both hall sensors and gears into their motors. If I have the above type of motor with gears but without hall sensors, can I get this motor started from standstill with the right controller, or are the hall sensors absolutely required?

Advice appreciated and hopefully your answers will help future readers too.

Thanks!

I have what I hope are a few relatively simple questions

Haha, nothing is ever simple with this EV stuff.
It's funny you should ask this now. I just came in from playing around with running a sm. geared bicycle hub motor sensorless.
A "Cute Q100H motor with a 350W Elifebike controller.
And,
I have been running a MXUS geared with an Infineon controller sensorless for years.
Here is some general observations that I think will apply to the motor you linked.
First-motors. Motors with a high comutation speed don't like to run sensorless. The controller can't keep up and loses "sync" with the motor, resulting in a "studdering" from zero start-up or quick application of full throttle.
The Q100 has a pole count of 16 with compound gears, which makes it a very high speed motor and I got the results listed above. Rideable, but not fun.
My Mxus has a pole count of 8 and a single set of gears, moderate speed motor, and 95% of the time, one wouldn't know it's sensorless. Only when pointing up a hill at a dead stop will it studder.
That link doesn't supply the pole count info. but I think it would be 8, witha single set of gears.
Controllers-I have tried a number of controllers and the genaric $30 to $40 one work ok, but I have found that the more expensive Infineon controllers work better when used sensorless.
They are avalible from Ebike CA or Lynn for $100 to $125.
Grin(Ebike ca) has a 15 Amp unit that they only list with a kit, but if you asked them, they would sell you one.
Lynn custom programs his controllers and the nice thing about that, is you can tell him what battery you will be using and he can program a Low Voltage Cutoff(LVC) to protect your battery.
The downside is, you have to wait a couple of weeks to get it.
Bottom line-If you go with an Infineon, I think you could expect sensorless performance on par with my MXUS/Infineon combo.

 

[agrumpinthedust]

Thanks for the info, mototech. I have more research to do based on your suggestions.

Can you comment on my original questions? I'm particularly interested in starting off from a standstill with sensorless motors.

Thanks

 

[amberwolf]

I have what I hope are a few relatively simple questions.

They are indeed simple questions.

The answers, on the other hand....

I've read that if a BLDC hub motor doesn't have hall sensors that it will need kick-starting to both get it moving and to set the direction of rotation. Is that correct?

Depends on the controller and how it does whatever it does.

Older "dumb" sensorless controllers did need that sometimes.

Nwere ones are smarter, and can probably all work from a stop. But I wouldn't make aguarantee o f that.

but I'm having trouble finding a supplier that builds both hall sensors and gears into their motors.

The older Fusin geared motors had halls. Could be used sensorless or sensored, but the controllers that came with them were sensored.

The newer ones (like on my Delta Tripper) have just one as a speed sensor, but not hte usual 3 as position sensors. The controllers they come with are sensorless. They will startup from a complete stop in the correct direction. They do sometimes make "grinding" sounds as the controller works out which way to spin it.


I *think* the Mac / BMC geared hubs have hall sensors, but I cant' remmeber for sure (never had one, but thye're popular here on ES).

Dunno about the EZee geared hubs, or the MXUS/etc. geared hubs.

There's others I cant' remmber the names of you can find by poking around ES.

 

[agrumpinthedust]

That sounds good, thanks!

If I happen to buy sensorless motors, it's good to know that I can probably find a decent controller to run it from a standstill state.

If you were to buy the cheapest $30 controllers on ebay, would you expect them to be able to start from stopped or is that feature only on more expensive controllers?