Phaserunner v6 + Shengyi SX2, shuddering start

[Bush mechanic]

Hi crew, would love to get some thoughts on this: Shengyi sx2 rear geared hub (5:1, 72 effective pole pairs), runs beautifully once at speed, but shudders and is super rough and weak on take off. As per title, I have a v6 PR.

The most obvious potential issue I can think of is phase and hall combinations error due to my splicing of an L1019 cable (PR) to Z910 cable (this is what the Shengyi uses) - I’ve based this on wire colour alone, however, I’m tentatively ruling this out as a problem because the system DOES run well once it gets moving.

Would any of the following observations suggest any issues?


-static test, spinning test are fine, returns valid hall pattern
-oddly the motor unit did spin backwards in the initial test, fixed this by using the flip option but I’ve not had this happen before
-hall sensors seem to fire in normal sequence when I slowly spin the wheel backwards when looking at the PR suite dashboard
-currently set to hall sensors only, not sensor less
-I’ve realised the torque up ramp is very short (50ms). I did use this controller on a GMAC a few years ago, I don’t recall changing the setting but it might be a left over from that

I’ll try a few more combinations later when I get home, but if anyone has had similar issues with the Shengyi + PRv6, or thoughts on possible causes that would be awesome.

 

[neptronix]

This controller has lots of problems with geared motors like the Shengyi and Mac because it cannot handle as high of eRPM as it should. What i do know is that some tuning helps it, and the Shengyi has a bit lower eRPM so it has a better prognosis than the MAC.

Does Grin provide a premade tune for this in the software? you probably want to start from that tune, if so.

What winding, wheel size, and voltage are you running?

 

[Bush mechanic]

This controller has lots of problems with geared motors like the Shengyi and Mac because it cannot handle as high of eRPM as it should.

Hi nep, I’m really hoping this isn’t the issue, but I actually went back to using the V3 phaserunner on my Mac cargo bike because the V6 caused so many weird issues that I couldn’t make sense of.

I have the standard wind, 700c rim, 52v, limited to 25A battery current (I know it’s a bit on the high side, will drop this to 20 I think).

I had this same “notchy” shuddering, hammering effect on the Mac amongst other issues with this controller at very low speed. This isn’t very technical, but it feels like the coils are just not quite firing at the correct time, like the phases are slightly out - but the weird thing is that once at speed it’s totally fine.

RE tuning files, I think the software suite might have some issues as I’ve tried using the download function and it claims to have no connection. I might email Grin and see if they can send a list of exact settings, but I know they are very busy these days.

 

[slaphappygamer]

There is a default setting for that motor. Give it a shot.

I have a similar motor. The DGW22. I had the same issue. I reset the controller settings and the trouble persisted UNTIL I loaded default parameters for the SX motor. Still, I had the shuttered start as you describe.

The fix was to play with the Feedback Bandwidth Tuning. This will be a VERY tedious task as you have to ride the bike after each adjustment. I would start with adjusting Current Regulation Bandwidth. It may be too high. Half the number and try again. Half the number again until you feel good change. You might get to a point where you have to adjust by 100s, or/then 10s. Then do the same with PLL Bandwidth and Padding, but the values will be much lower. You may want to skip the halving process.

Once you have the vehicle launching consistently well, you can use the Cycle Analyst to adjust the throttle ramping.

 

[Bush mechanic]

There is a default setting for that motor. Give it a shot.

I have a similar motor. The DGW22. I had the same issue. I reset the controller settings and the trouble persisted UNTIL I loaded default parameters for the SX motor. Still, I had the shuttered start as you describe.

The fix was to play with the Feedback Bandwidth Tuning. This will be a VERY tedious task as you have to ride the bike after each adjustment. I would start with adjusting Current Regulation Bandwidth. It may be too high. Half the number and try again. Half the number again until you feel good change. You might get to a point where you have to adjust by 100s, or/then 10s. Then do the same with PLL Bandwidth and Padding, but the values will be much lower. You may want to skip the halving process.

That’s awesome, thank you! For some reason I can’t access any default profiles, but I’ll try those parameters.

Did you end up resolving it completely and get totally smooth starts?

 

[slaphappygamer]

Yes. My bike runs nicely now. Check my post, and attached documents regarding Feedback Bandwidth Tuning, here.

I did turn the sensorless start off, since I have hall sensors. I also feel that turning off sensorless start lets the motor ramp up a tab bit faster. Mostly just disabled it so the controller has one less thing to calculate.

 

[Bush mechanic]

Yes. My bike runs nicely now. Check my post, and attached documents regarding Feedback Bandwidth Tuning, here.

I did turn the sensorless start off, since I have hall sensors. I also feel that turning off sensorless start lets the motor ramp up a tab bit faster. Mostly just disabled it so the controller has one less thing to calculate.

That’s great, will have another try later- thanks again

 

[Bush mechanic]

Yes. My bike runs nicely now. Check my post, and attached documents regarding Feedback Bandwidth Tuning, here.

Can’t thank you enough, this is perfect. Probably still need to fine tune, but feedback bandwidth tuning is where it’s at: experimentally just tried the same settings you had for yours (110/200/2.00) and there is a very clear instant improvement. Still a little bit of stutter but it’s gone from 7/10 annoying to 2/10 bearable. I’ll try adjusting a bit more in the coming days but I’m convinced this will solve it.

Thanks again!

 

[slaphappygamer]

Can’t thank you enough, this is perfect. Probably still need to fine tune, but feedback bandwidth tuning is where it’s at: experimentally just tried the same settings you had for yours (110/200/2.00) and there is a very clear instant improvement. Still a little bit of stutter but it’s gone from 7/10 annoying to 2/10 bearable. I’ll try adjusting a bit more in the coming days but I’m convinced this will solve it.

Thanks again!

Awesome! I’m glad you are finding resolution. Just remember that after you achieve a smooth take off you can adjust throttle ramping on the Cycle Analyst to find the right acceleration speed for you.

Also, watch for the Instantaneous Phase Over Current error. You may get this when adjusting the PLL Bandwidth. I just cleared the fault and continued to further adjust PLL Bandwidth.

I’m not sure how, but while I was making adjustments in the Feedback Bandwidth Tuning, my motor did start to spin backwards. I could hear the gears moving, but no tire rotation. If this happens to you, then reload the Default Parameter for your motor. That cleared the issue for me. You may have to rerun the autotune again.

 

[alfy22]

Can’t thank you enough, this is perfect. Probably still need to fine tune, but feedback bandwidth tuning is where it’s at: experimentally just tried the same settings you had for yours (110/200/2.00) and there is a very clear instant improvement. Still a little bit of stutter but it’s gone from 7/10 annoying to 2/10 bearable. I’ll try adjusting a bit more in the coming days but I’m convinced this will solve it.

Thanks again!

hi @Bush mechanic, i just got a shengyi SX2 and have the same stuttering start issue. just wondered if you managed to fine-tune the parameters further or ended up with 110/200/2.0 ? thanks