Fork vibration with Mac hub motor

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AHicks   100 W

100 W
Posts: 262
Joined: Jul 24 2018 10:53am

Re: Fork vibration with Mac hub motor

Post by AHicks » Sep 01 2019 8:20am

Is this a solid front fork, or one with a suspension of some sort? If not solid, I think the MAC is going to destroy it.

Jatem   100 mW

100 mW
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Joined: Jun 03 2019 3:08pm

Re: Fork vibration with Mac hub motor

Post by Jatem » Sep 01 2019 3:08pm

It's a rigid surly cromoly fork.

It would be good to hear an audio recording of a "normal" Mac hub motor running on a workstand, without background wind noise or freehub noise.

Here's one clip I found with an BAC FOC controller, and it sounds to me like it has similar resonance to what I'm seeing...
https://www.youtube.com/watch?v=JG50inFee1I

AHicks   100 W

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Joined: Jul 24 2018 10:53am

Re: Fork vibration with Mac hub motor

Post by AHicks » Sep 01 2019 7:30pm

That's pretty similar to what I get when the wheel is unloaded like that, but not at all what I get when riding.

Unloaded like that, my guess is the controller senses the wheel is bumping into the max speed setting and shutting the power off until the wheel slows a hair, then hitting it with voltage again to bring it back up to speed. This cycle happening/repeating over an over again very quickly. Because it disappears completely when riding, I don't view it as an issue at all. -Al

Jatem   100 mW

100 mW
Posts: 43
Joined: Jun 03 2019 3:08pm

Re: Fork vibration with Mac hub motor

Post by Jatem » Sep 01 2019 9:42pm

AHicks wrote:
Sep 01 2019 7:30pm
That's pretty similar to what I get when the wheel is unloaded like that, but not at all what I get when riding.

Unloaded like that, my guess is the controller senses the wheel is bumping into the max speed setting and shutting the power off until the wheel slows a hair, then hitting it with voltage again to bring it back up to speed. This cycle happening/repeating over an over again very quickly. Because it disappears completely when riding, I don't view it as an issue at all. -Al
What value of P1 are you using, 160?
I'm hearing that pulsing noise in the mid range while riding, similar to 38 seconds into that BAC clip above when the motor is still increasing speed (and isn't yet freewheeling).

Jatem   100 mW

100 mW
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Joined: Jun 03 2019 3:08pm

Re: Fork vibration with Mac hub motor

Post by Jatem » Sep 29 2019 3:31am

AHicks wrote:
Aug 29 2019 8:21am
I'm using a heavier KT controller with the MAC 12t. It's a 12 mosfet rated for 35a max. I have it limited to about 1300w (+-) using the parameters over concern for the battery. Plenty of grunt available with that for my purposes.

It sounds like you have the color sequence figure out, but I'll show what I used so you can confirm.

Phase Firing order    Motor    Controller     
A                    Blue          Yellow           
B                    Green        Blue           
C                    Yellow       Green 

Hall sensors fire in the same order, so they match the phase motor/controller color sequence.

After listening to the sound recording, wondering if you're getting that same resonance when actually out riding?
My KT and Mac 10T is a lot quieter and smoother with the following wiring combination (phase and hall sensors in the same order):

Phase Firing order    Motor    Controller     
A                    Blue          Green          
B                    Green        Yellow         
C                    Yellow       Blue

With this wiring combination, it's much more pleasant to ride. It's no longer making a racket. Now it makes a smooth electrical purr at high speed.

The motor still causes the forks to wiggle back and forth at 20kmhr in PAS 2/3, but it's much quieter sounding - the pronounced chuff chuff sound is essentially gone.

The thing is, according to all the motor wiring discussions there should be three good forward combinations and there good reverse combinations. This gyb order shouldn't be any different to bgy. The original BGY order, the order I'm now using, and the order you've been using, are exactly the same firing order - just bgybgybgybgy... However, it makes a difference to smoothness/noise if the controller phase A starts at a different point around the motor. Perhaps it's due to poorly aligned sensors in the motor, or resonance with the PWM timing.

One day I might try the open source firmware by stancecoke / casainho. I'd be interested in the settings with phase angle, if someone else has got it working with the Mac.

AHicks   100 W

100 W
Posts: 262
Joined: Jul 24 2018 10:53am

Re: Fork vibration with Mac hub motor

Post by AHicks » Sep 29 2019 9:24am

Weird as hell, but it sounds like you have your issue on the run.

I have to wonder if KT is consistent with the firing order from model to model, or even during a production run?

Bottom line is, ours are different for sure!

Jatem   100 mW

100 mW
Posts: 43
Joined: Jun 03 2019 3:08pm

Re: Fork vibration with Mac hub motor

Post by Jatem » Sep 29 2019 2:15pm

There shouldn't be any difference between bgy, gyb, and ybg with the halls and phases matching, they should all be the same firing order. It's odd, that's for sure.

Jatem   100 mW

100 mW
Posts: 43
Joined: Jun 03 2019 3:08pm

Re: Fork vibration with Mac hub motor

Post by Jatem » Nov 27 2019 8:14pm

I'm tired of the vibration, it seems to be a known issue with the KT controller on some geared hubs. I wish I had known that in advance. It's not losing sync at high speed, the problem is at low to mid speed with low PAS. It is more tolerable when the controller is in speed control mode, but I want to be using current control (torque simulation), so that I can pedal it faster.

I'm getting a phaserunner instead. I would not recommend using a pswpower kt 6 fet sine wave controller to drive a Mac 10t.

AHicks   100 W

100 W
Posts: 262
Joined: Jul 24 2018 10:53am

Re: Fork vibration with Mac hub motor

Post by AHicks » Nov 28 2019 9:51am

Sorry it didn't work out for you. Interested in how well you do with the Phaserunner. Please keep us updated!

Aquakitty   100 W

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Re: Fork vibration with Mac hub motor

Post by Aquakitty » Nov 28 2019 5:24pm

Jatem wrote:
Nov 27 2019 8:14pm
I'm tired of the vibration, it seems to be a known issue with the KT controller on some geared hubs. I wish I had known that in advance. It's not losing sync at high speed, the problem is at low to mid speed with low PAS. It is more tolerable when the controller is in speed control mode, but I want to be using current control (torque simulation), so that I can pedal it faster.

I'm getting a phaserunner instead. I would not recommend using a pswpower kt 6 fet sine wave controller to drive a Mac 10t.
While I agree the phaserunner is a good idea, did you think about trying the custom firmware for KT Controllers?
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Hardtail made from random bits I had laying around, ginormous old Marzocchi fork, BBS02

Jatem   100 mW

100 mW
Posts: 43
Joined: Jun 03 2019 3:08pm

Re: Fork vibration with Mac hub motor

Post by Jatem » Nov 28 2019 5:52pm

Stancecoke said it would make no difference to the resonance issue.

Jatem   100 mW

100 mW
Posts: 43
Joined: Jun 03 2019 3:08pm

Re: Fork vibration with Mac hub motor

Post by Jatem » Jan 24 2020 2:09pm

I switched from the KT controller to a Phaserunner, and now it's running smooth as silk. It would have been a lot easier to get a phaserunner for the Mac the first place. I'm pleased to say the fork judder is gone.

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