How Many Poles

Electric Motors and Controllers
Post Reply
dwkayaks
100 µW
100 µW
Posts: 7
Joined: Mar 18, 2017 6:09 am

How Many Poles

Post by dwkayaks » Aug 28, 2017 11:57 am

Just installing a Cycle Analyst and Grinfineon Controller up-grade . The CA set-up requires an entry for the number of poles that are in my 250W 36V geared hub motor.

Grin's Cycle Analyst V2.4 Quick Start Guide page 6 , suggests that I can figure out how many poles my geared hub motor has " by measuring the hall signal with a voltmeter and counting how many times it toggles to 0V during a full turn of the wheel" .

My question is where to place my voltmeter probes for this test ? :roll:

User avatar
teklektik
1.21 GW
1.21 GW
Posts: 3521
Joined: Mar 26, 2011 1:15 pm
Location: CT, USA

Re: How Many Poles

Post by teklektik » Aug 28, 2017 1:14 pm

Most geared motors have a built-in freewheel clutch making accurate speed/distance measurement from the halls impossible since hall signals to not alternate when coasting. For gearmotor or other applications where a freewheel is in play, you should purchase a CA-DPS (S=speed pickup) instead of a CA-DP. Here the wheel pickup provides the signal instead of the halls and you configure the CA pole count according to the number of spoke magnets you have (typically 1).

No problem if you have the wrong sex CA since they are identical except for a minor wiring change. See "Appendix B. Add/Remove Wheel Speed Pickup Sensor" of the CA3 User Guide. The instructions there apply to any model CA with minor changes for PCB connection layout. A pickup can be had from Grin or you can use a pickup from a cheapie bike computer (that you might obtain locally). These are basically little magnetic reed switches, so no magic in there... Wind the pickup lead with a couple of dozen turns of waxed dental floss as a blob inside the case so it won't pull out the hole in the case if you snag it.

Otherwise, if you have one of the very few gearmotors without a clutch, then place your negative meter lead on the call connector black wire (GND) and the positive lead on any of the YEL/GRN/BLU hall leads. It's generally easiest to probe the connector pins from the back (make have to remove heatshrink on connector). Power up the controller and the voltage should toggle between 0V and about 5V - the exact voltage isn't important in this case. Gear motor rotation is geared up for this exercise so you will need to move the wheel VERY VERY slowly as you count the positive transitions. Pole counts in the neighborhood of 80 are not unusual (e.g. 5:1 gearing by 16 true motor poles = 80 effective poles per revolution). Unfortunately, the CA only allows something like 60 poles, so if you find a higher number your best bet will be to switch to wheel pickup in any case.
  • FWIW: The same problem on a CA3 can be addressed without a meter. Go to the Speedometer Setup Preview screen and just watch the little arrow next to the "p" (for poles). It will point up/down as the input speed signal changes state.
Last edited by teklektik on Aug 28, 2017 1:29 pm, edited 3 times in total.
Visit Grin Technologies at www.ebikes.ca
Build Thread: 2WD Yuba Mundo V4

User avatar
fechter
100 GW
100 GW
Posts: 11804
Joined: Dec 31, 2006 3:23 pm
Location: California Bay Area, USA

Re: How Many Poles

Post by fechter » Aug 28, 2017 1:22 pm

If you turn the wheel backward, you can spin the rotor and see the halls toggle. This still wouldn't solve the problem of no speed when you are coasting.
"One test is worth a thousand opinions"

User avatar
amberwolf
100 GW
100 GW
Posts: 23900
Joined: Aug 17, 2009 6:43 am
Location: Phoenix, AZ, USA, Earth, Sol, Local Bubble, Orion Arm, Milky Way, Local Group
Contact:

Re: How Many Poles

Post by amberwolf » Aug 28, 2017 9:25 pm

The easiest way to solve the problem is as Teklektik describes, with an external speed sensor. (I use one even though I could use the motor halls, simply because it's easier to setup and use when I either change motors or move the CA from bike to trike, etc.)

That said:

While you generally can't use the hall sensors on a typical geared hubmotor to monitor anythign other than internal motor speed while it's being powered and driving the bike (rather than wheel or bike speed):

There are some geared hubs that have a separate speed sensor wire on them, where a separate sensor just for speedometer is installed inside it.

If you have one of these, there would be either 9 active wires on your motor cabling (3 phase, 5 hall, 1 speed), 10-11 wires (3 phase, 5 hall, 2-3 speed), or 5-6 wires (3 phase, 2-3 speed).

If you post the details of your motor, controller, and system, we can help you determine this.



I have a Fusin sensorless geared hub that has 3 wire speedo (hall) sensor, and I have worked on a few bikes for Cvin (local member0 with 8Fun and Bafang and unnamed sensored geared hubmotors that also have a separate speedo sensor and wire, so I know they're out there.

I also have an Ezee and a couple other Fusin sensored geared hubmotors that *don't* have a separate speedo sensor on them, that would require the external wheel-mounted speedo sensor for the CA.

dwkayaks
100 µW
100 µW
Posts: 7
Joined: Mar 18, 2017 6:09 am

Re: How Many Poles

Post by dwkayaks » Aug 29, 2017 8:40 am

Gee Teklektic , a Big T Y for your reply ,,, thinking your advice in quotes below , should be included in the CA V2.3 User Manual as this would have saved me time, money, and frustration .

"Most geared motors have a built-in freewheel clutch making accurate speed/distance measurement from the halls impossible since hall signals to not alternate when coasting."

I will take your suggestion and install the spoke magnet and leave the Hall connector un-plugged . :cry:

T Y to Fechter for confirming this in your reply , :)

Also a Big T Y to Amberwolf too ,,,,, " If you post the details of your motor, controller, and system, we can help you determine this. " ,,,,, My entry level Ebike only has this info printed on the gear motor hub : 36v26" 16122081 with a spoiled controller model # X813-AA007A-5T . I was trying to up-grade with Grin products , but with a limited budget , Ouch !

User avatar
teklektik
1.21 GW
1.21 GW
Posts: 3521
Joined: Mar 26, 2011 1:15 pm
Location: CT, USA

Re: How Many Poles

Post by teklektik » Aug 29, 2017 10:57 am

dwkayaks wrote: I will take your suggestion and install the spoke magnet and leave the Hall connector un-plugged . :cry:
I'm pretty sure this is just a bit of a nomenclature issue, but just to be sure:
  • You need to leave the controller hall connector plugged in for the motor to run, but you need to disconnect the yellow Spd wire in the CA-DP cable from the CA PCB and replace it with the wheel pickup connections.
Anyhow - an annoying but easy one - I think you have a handle on the issue. :D
Visit Grin Technologies at www.ebikes.ca
Build Thread: 2WD Yuba Mundo V4

dwkayaks
100 µW
100 µW
Posts: 7
Joined: Mar 18, 2017 6:09 am

Re: How Many Poles

Post by dwkayaks » Aug 29, 2017 11:41 am

Thank You again Teklektic , the reason I want to un-plug the Hall connector is that when I plug it into the motor Hall connector , the motor just shutters and barely turns the wheel when I advance the throttle . When un-plugged the motor works fine , except on start-up when a loud clunk is heard when applying the throttle to start off .

I was thinking that the motor studdering was caused by out of phase controller signals to the motor , and that brings my thoughts to, is this fixed by entering the correct number of poles in the CA ?

BTW the ebike Grinfieon controller doesn't need the ebrake inhibitors connected , to run the motor , so was thinking to not connect these as well . :pancake:

I hope you know just how important your advice and knowledge is to us newbe's ,,,,,,

User avatar
amberwolf
100 GW
100 GW
Posts: 23900
Joined: Aug 17, 2009 6:43 am
Location: Phoenix, AZ, USA, Earth, Sol, Local Bubble, Orion Arm, Milky Way, Local Group
Contact:

Re: How Many Poles

Post by amberwolf » Aug 29, 2017 2:30 pm

dwkayaks wrote: the reason I want to un-plug the Hall connector is that when I plug it into the motor Hall connector , the motor just shutters and barely turns the wheel when I advance the throttle .
This probably means that the hall and phase wire combination is not correct for that motor/controller combination. If the controller and motor did not come together pre-installed on the bike (working from the factory), then even if they came as a "kit" it is possible they are not yet wired to work together.

Alternately it could just be a loose or bad connection on one of the hall wires, so the signals are not quite right and the controller isn't able to sense the motor's position correctly. I'd check that first, but if there's no connection problem, then:

There's 36 possible combinations between the 3 blue/green/yellow wires between both connectors, and only one of them is likely to work on a geared hubmotor (the other would spin it backwards which wont' move the wheel on-ground, and off-ground might just barely spin it backwards from friction in the clutch).

The other combinations would have various other effects but aren't usable. There is a thread How To Determine The Wiring For A Brushless Motor that can help you fix that.

When un-plugged the motor works fine , except on start-up when a loud clunk is heard when applying the throttle to start off .
That's probably the controller first spinning the mtoor backwards then finding no load on it it spins it the other way, and as the clutch and gears engage it thunks. My bigger Fusin kit (sensorless) always does that.

If it does what you want without the halls connected, I'd just leave them disconnected and save the troulbe of figuring out what combination of hall and phase wires you'd need for it.
I was thinking that the motor studdering was caused by out of phase controller signals to the motor , and that brings my thoughts to, is this fixed by entering the correct number of poles in the CA ?
The CA has nothing to directly do with what the controller does to operate the motor, only what speed it operates the motor at (assuming the CA's throttle output is connected to the controller's throttle input).

The problem is between the cotnroller and motor.

User avatar
teklektik
1.21 GW
1.21 GW
Posts: 3521
Joined: Mar 26, 2011 1:15 pm
Location: CT, USA

Re: How Many Poles

Post by teklektik » Aug 29, 2017 5:02 pm

dwkayaks wrote:...the reason I want to un-plug the Hall connector is that when I plug it into the motor Hall connector , the motor just shutters and barely turns the wheel when I advance the throttle . When un-plugged the motor works fine , except on start-up when a loud clunk is heard when applying the throttle to start off .

I was thinking that the motor studdering was caused by out of phase controller signals to the motor , and that brings my thoughts to, is this fixed by entering the correct number of poles in the CA ?

BTW the ebike Grinfieon controller doesn't need the ebrake inhibitors connected , to run the motor , so was thinking to not connect these as well . :pancake:
The problem is that the new Grinfineons don't do automagic self-learning to figure out the phases as did the older Grinfineons - so you have to do it yourself. This was the price of getting the sinusoidal drive - only so much code room in the controller.

As mentioned above, there are posts about this, but I would recommend starting with the Grinfineon Manual so you are on the same page as the vendor should you contact them for assistance (always recommended as a first source...). Grin has links to download docs on their site - here's the link for your controller: http://www.ebikes.ca/documents/Grinfineon_V2.1.pdf.

As the manual points out, be gentle on the throttle when mapping halls/phases to avoid cooking the controller with a bad hookup. Go to open throttle only after things appear finished and running smoothly, and only to actual riding after full throttle works successfully on the stand.

Also - with a gear motor, when you are figuring out the phases be advised that if the motor runs backwards (normal during phase experimenting) you will only hear a little whirring as the clutch will be disengaged so the wheel will not be turning. DD motors (no clutch) actually spin the wheel backwards as expected.

Don't worry about the ebrakes. These are pretty much required for PAS systems to kill the automatic power or on a DD motor to get regen, but for a gear motor they are really optional, so no worries there unless you have sub-normal hand coordination... :D
Visit Grin Technologies at www.ebikes.ca
Build Thread: 2WD Yuba Mundo V4

Post Reply