Article on Hall sensors in BLDC motors

NoSmoke

1 mW
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This Digi-Key article is a good description of how the Hall sensors work in a BLDC motor:

https://www.digikey.com/en/blog/using-bldc-hall-sensors-as-position-encoders-part-1

One thing though I noticed in particular is the following:

'Summary

No matter which single sensor output square wave is examined following a transition, one of the remaining sensors is trailing while the other is leading (one is high while the other is low). It is for this reason that it does not matter which arrangement of sensor outputs you use when reading values. The only effected calculation is direction of rotation.'

Unless I'm misunderstanding it, the above implies that ordering of the wiring of the three signal wires of the Hall sensors to the motor controller doesn't matter for operation of the motor (except for direction of rotation).

I have however seen several posts describing how the six possible wiring configurations (of the three wires) might have to be tried (by trial and error) for configuring a controller. What am I missing here??
 
The article states "The following information is intended to assist in interpreting Hall sensor logical output for the purposes of determining position, direction and speed. Although the output can be used for motor commutation, that aspect of BLDC motor operation is not explained here. ".

In ebike/etc controllers, however, the halls *are* used for motor commutation, and *that* does require a specific order of hall signals to phase drive.

However, it still doesn't matter if you are writing your own code to read the sensors (which is what the article is describing usage for), because you can take the order and put it in any order you want in your code. That's what the self-learn controllers do. They can also fire the phases in any order they like, so it doesn't matter what order those are wired in, either.

If you have a hardware controller with no self-learn function, it matters a great deal which order the sensors are wired in because the order the signals occur in must match where the phase signals are so the phases can keep pulling and/or pushing the magnets on the rotor (which the halls are tracking) with the correct speed and timing.

The trial and error wiring order of phase/hall combinations is only needed for that type of controller, which is less and less common these days. More and more of them, even the really cheap ones, use a self-learning / autodetecting method, usually when setting it up in the first place.

A really smart controller could even tell which order to use on every motor startup, but with higher power it's possible to damage things if the controller applied that level of power during the process, instead of waiting till it "knows" what order signals appear in...and regardless of power level, the motor must turn a certain amount to get signals from every hall relative to every phase to use that to determine the right combo. That might not be possible depending on the application, without unloading the driven wheel(s), like taking them off ground during the calibration. (that's why teh regular self-learn is done during setup rather than in-use).
 
OK, thanks - I kinda expected there was more to it than I first expected. You may recall from a recent previous thread that I am attempting to mate a Kelly controller to a motor of somewhat unknown characteristics. I am concerned that the color coding of the Hall and phase wiring on the motor does not correspond directly to that on the controller.

I gather then that the Kelly (KLS6030N) is not a self-learning controller and, that is why the "Identification angle" procedure is needed(?). If that is the case, I'm also wondering how one knows if the Hall and phase wiring are incorrect - do you have to wait until the procedure completes (which I gather can take two or three minutes) and gives a fail indication or, can one tell sooner (such as the motor does not move at all or maybe only a bit one way of the other)?

It surprises me that the color coding is not apparently consistent between manufacturers - the colors themselves seem to be pretty consistent but the wiring not so.

BTW, I think I have narrowed down the manufacturer of the motor on the ATV. It appears to be the same as the controller - UniteMotor. They manufacture both controllers and motors and I think I have this motor:

http://motors-manufacturer.com/2-12-1200-1500w-drive-motor-pmdc-brushless-motor-tf133ah.html

The look and dimensions are the same but I am a bit bummed as it says it is a 1,500 W motor (rated) with 3,000 W (max) and the Kelly I bought is rated for a 3,000 W motor. The ATV vendor told me it was a 3,000 W motor which seemed odd at the time as the original controller is 1,500 W. Looks like I may have bought a controller twice as large as necessary? :( Oh well, the vendor also told me it was a three pole motor so go figure...

Thanks again amberwolf, your comments have been very helpful to me.
 
NoSmoke said:
I am concerned that the color coding of the Hall and phase wiring on the motor does not correspond directly to that on the controller.
I can virtually guarantee that it's very unlikely for them to match. ;)

I gather then that the Kelly (KLS6030N) is not a self-learning controller and, that is why the "Identification angle" procedure is needed(?).
AFAIK, that's what the IA process *is*: self-learn. ;)

The SL process is usually done on basic controllers by connecting a wire pair with the powered wheel offground; once the motor spins normally its disocnnected. If it spins the wrong way, just do it again. That's all there is. But the rest of the controller isn't configurable or tunable, so...if you need that stuff, more programmable things like Kellys, Sabvotons, Fardriver, etc, are a better option.

Even more advanced controllers also exist, like Sevcon, ASI, etc., but they don't support DIYers so you're on your own setting one up, or even trying to get the software and hardware needed to do so...and without that, the controller is an expensive brick becuase it has to be tuned to the motor and system you use it with to even work at all.

DIY controllers exist with more configurability but still with support, but they're DIY, so you'd need to build it and set it up, or best case get one premade and isntall the firmware and set it up.

If that is the case, I'm also wondering how one knows if the Hall and phase wiring are incorrect - do you have to wait until the procedure completes (which I gather can take two or three minutes) and gives a fail indication or, can one tell sooner (such as the motor does not move at all or maybe only a bit one way of the other)?
The test can cause the motor to jerk all over the place and make some scary noises (just like doing it manually), so until it's over you cant' usually tell what's really going on.

I have a broken Kelly here that just smokes motors trying to do the IA test; I haven't tried to skip the IA and just manually determine a good phase/hall combo to see if it can be used at all; it may have damaged FET drivers or FETs, or a problem with it's brain; dunno. Kinda hoping for it to be a brain problem, because then I can use the powerstage driven from a Lebowski brain chip instead.


It surprises me that the color coding is not apparently consistent between manufacturers - the colors themselves seem to be pretty consistent but the wiring not so.

There's no reason for them to care. People buy the stuff anyway (probably not having any idea about this stuff and not knowing they will have to match the wires by function, not color) and now that self-learn is a fairly common thing, there is virtually no reason to do so. Some controllers don't even use colored wire anymore for the phase and hall signals, just for the hall power and ground. Motors still seem to color theirs, but even that will go away eventually to save money (3 rolls (or one bigger) of the same color will be (a little) cheaper than 3 different colors, in quantity).


Pardon the "rant" below; it's something most people don't think about; it's very simplified, but essentially how it works:

THere are many other incompatible things between manufacturers of basically the same stuff, and there isn't any benefit to them to change those, either, so generally they don't. If it would suddenly make or save them a lot of money to change to the same system some other manufacturer uses, and keep making them that money, they'd do it.

Always keep in mind that companies as a general rule don't make things we need. They make us need things they make. They make things that cost enough less to make and distribute that they can profit maximally by doing so.

So they don't really care what we need or what we want; they look at what other people are already selling successfully, and either just make those, or they copy that in their own incompatible version (so you have to buy all the parts from them, until someone else copies theirs, then they update it to make all the previous stuff (and the clone(s)) incompatible, and sell more new things. (see Bafang for a reference)

There's a few exceptions...but not many.


BTW, I think I have narrowed down the manufacturer of the motor on the ATV. It appears to be the same as the controller - UniteMotor. They manufacture both controllers and motors and I think I have this motor:

http://motors-manufacturer.com/2-12-1200-1500w-drive-motor-pmdc-brushless-motor-tf133ah.html

The look and dimensions are the same but I am a bit bummed as it says it is a 1,500 W motor (rated) with 3,000 W (max) and the Kelly I bought is rated for a 3,000 W motor. The ATV vendor told me it was a 3,000 W motor which seemed odd at the time as the original controller is 1,500 W. Looks like I may have bought a controller twice as large as necessary? :(

The "good" news is a bigger controller will be more able to handle a load without running near it's limits. Many e-parts are sold as rated higher than they are actually able to deal with; right at the limits of their specifications, rather than leaving a large safety margin like they should.

So the seller calls a 3000w *peak* motor a 3000w motor, even though it can't sustain that for more than a few seconds at a time. Same for just about every part you can find out there.

Some sellers do actually rate things realistically, like QSMotor's motors. (dunno about their controllers; seen plenty of exploded ones on the forum...but the motors are nice. :)

So if you setup the controller to not sustain 3kw, or you install a thermal sensor inside the motor (BBQ thermometer, etc) and use your own judgement on when to let off throttle, or conditions you ride in, the motor can probably handle the bursts of 3kw it may see.

You can also use forced-air cooling on the outside of the motor to increase the frequency of those bursts, or ventilate the motor and use that FA cooling to increase the sustained power it can handle.

Oh well, the vendor also told me it was a three pole motor so go figure...
Best guess is they don't speak English as a first language and/or they aren't technical enough to know the difference between "pole" and "phase".
 
Thanks again for all the help. :D

I guess then I'll just hook it up color to color and let'er rip. Hopefully the IA procedure will sort it all out.

BTW, I emailed UniteMotor earlier today asking how many poles the motor has and they just replied - 4 pole pairs. That doesn't jibe with my Hall sensor state switches measurement (which suggested 10 poles) so maybe I'll start with 8 poles and switch to 10 if it doesn't work.

I guess I'll be OK with the apparently too large controller as it can be current limited and I'm not a hot-dog rider anyhow.

As far as help from the vendor (I probably should have said "retailer") Venom Motorsports, they all speak good English and seem eager to please but aren't really well versed on the electrical details of what they sell (I expect they are better dealing with their gas engine products). Anyhow, when I pointed out to them that 3 poles could not be correct and maybe they were referring to phases, they sent an image of a generic, brushed DC motor which happened to have three poles - I guess they didn't know the difference. They then told me the motor has 8 poles but when I asked how they specifically know for my motor they said it is similar to golf cart motors which have 8 poles. :confused: Fun and games.....

Meanwhile, the controller has been languishing in Memphis for four days now, was supposed to be delivered Monday, and it appears impossible to contact FedX to find out what's wrong and when delivery can be expected (their web site says nothing except where it is now and no expected delivery date is available, as far as I can tell).
 
NoSmoke said:
They then told me the motor has 8 poles but when I asked how they specifically know for my motor they said it is similar to golf cart motors which have 8 poles. :confused:
That would depend on the GC motor--most of those that I've seen are brushed motors (many series-wound non-permanent-magnet), such as these:
https://ddmotorsystems.com/GolfCartMotorPage.php
whcih don't use the term for the same thing, so that wouldn't apply at all to your question. Those use poles as number of brushes on the commutator, and most of them are 2 pole or 4 pole. (4pole is half the speed but twice the torque of an otherwise identical 2pole motor).

There are brushless upgrade kits to replace some of those, but they vary widely as to type, design, size, etc.
 
Yes, I suspected the golf cart motor thing was probably bogus as well.

Anyway, UniteMotor got back to me and said the motor has 4 pole pairs (8 poles) so I guess I'll go with that even though my Hall sensor state change measurement suggested 10.

As well, they have a Canadian rep who they passed my query on to - he sent me an image of one of their motor/axle combos which matches exactly with what I have so it looks like I have the motor correctly identified. :)

Now, if FedEx would get things going (package still in Memphis since Friday with no scheduled delivery date). Crap, paid $55 for air delivery and this is what happens...
 
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