2kw hub motor vibration when accelerating

[jozobozo]

I have a 2kw rated hub motor and a vesc controller and I noticed significant vibrations coming from the rear wheel under more than half throttle acceleration at around the 2.2kw point and after that it's all good (it goes to around 5kw max).

I suspected that there might be play in the rear dropouts so i tried loosening the rear wheel and getting it into the dropouts as much as I can but still the same issue. The wheel isn't perfectly true also so I'll try that later when i get the spoke tool.

What I also noticed is that when i lower the motor current there's less vibration but it's still present at around 2kw. Am i just overclocking the motor too much? I have it set to 80A battery current and i tried 130A-150A motor current on a 16s battery and as i understand it, the phase current is the highest when accelerating because the duty cycle is at the lowest so could it just be too much phase amps that's causing the motor to vibrate under heavy acceleration?

 

[neptronix]

It would be very helpful to know the make and model of motor, and if it had this vibration problem the whole time, or did it just develop.

 

[jozobozo]

It's a generic unbranded 2kw motor from China, non-geared. The controller is makerbase 75200v2. I've maybe done 150km so far on the motor and had it running on a 14s battery at 60A and 120A motor current and it was mostly fine, i felt slight vibration sometimes under acceleration but I assumed it was because the wheel wasn't true when i got it from factory. Then a friend crashed the bike and cracked the battery holder slightly so decided to put on the 16s battery I just made that's capable of 6kw+ and when testing it today it started vibrating really bad when giving it a lot of throttle under acceleration so I don't know if higher phase current is the problem or is it mechanical and just becomes more pronounced under higher torque. It only happens under load, in the air is fine. I can give it throttle gradually and let of a bit at one point at around 2kw or like 20km/h when accelerating to minimize the vibration and after that I can do full throttle and it's fine. I'll try to get a video of it tomorrow.

 

[E-HP]

It's a generic unbranded 2kw motor from China, non-geared. The controller is makerbase 75200v2. I've maybe done 150km so far on the motor and had it running on a 14s battery at 60A and 120A motor current and it was mostly fine, i felt slight vibration sometimes under acceleration but I assumed it was because the wheel wasn't true when i got it from factory. Then a friend crashed the bike and cracked the battery holder slightly so decided to put on the 16s battery I just made that's capable of 6kw+ and when testing it today it started vibrating really bad when giving it a lot of throttle under acceleration so I don't know if higher phase current is the problem or is it mechanical and just becomes more pronounced under higher torque. It only happens under load, in the air is fine. I can give it throttle gradually and let of a bit at one point at around 2kw or like 20km/h when accelerating to minimize the vibration and after that I can do full throttle and it's fine. I'll try to get a video of it tomorrow.

Have you checked your phase conductions and their connectors? The one time I had this type of symptom ended up being a slightly loose phase wire connector, that only happened under acceleration, when the phase amps were highest.

Using the info you provided and a Crystalite DD hub (2kW), the phase current running the 16S battery remains higher than the 14S system until around 14mph. If the symptoms are phase current related, then in the example, it would much more pronounced between 0 and 14mph

 

[scianiac]

It's the current PI controller becoming unstable. Basically what is happening is the controller is trying to keep the phase current at the level you are asking, the current setting in the controller if at max throttle or some percentage of that based on the throttle setting. The problem is it's having a hard time keeping it there, the phase current is oscillating up and down and you feel that as a fast pulsing feeling. At lower power levels like under low load it can keep things in check but once you start pushing the power it has to work a lot harder, the more current you put it the electrical noise and such it has to deal with.

The cause of why it can't keep the current level stable is probably several factors. First it's it's a shit controller that is poorly designed, and I'm not saying that just to shit on makerbase, I have a Flipsky 75200 Pro V2 (basically identical) with a hub motor that does exactly what you are describing and I can see from the logs that is what is happening and I've seen plenty of evidence on where they cheapened out on the controller to cause it to be noisy. They put almost no ceramic caps, the circuit design is meh, they opamps get fed noisy power from the voltage regulators, etc.

Second factor is tuning, you can tune around the hardware issues to improve things.

The good news is unless you have the ABS current set really high or Slow ABS current on it means it's stable enough to run, it if was too unstable it would be tripping OC faults. If you do have the ABS current set really high and Slow ABS on, well first turn slow ABS off, that's how you blow up controllers.

First thing that seems to work the best is to turn the Zero Vector Frequency down. You can turn it down by say 1-2khz at a time and see if it improves, you might find somewhere around 18-22 to be a good area. This seems to make these controllers run much more stable. I have a post somewhere where I go over a bunch more tuning settings that helped, specifically with that VESC and a hub motor at high current.

 

[jozobozo]

Have you checked your phase conductions and their connectors? The one time I had this type of symptom ended up being a slightly loose phase wire connector, that only happened under acceleration, when the phase amps were highest.

Using the info you provided and a Crystalite DD hub (2kW), the phase current running the 16S battery remains higher than the 14S system until around 14mph. If the symptoms are phase current related, then in the example, it would much more pronounced between 0 and 14mph

View attachment 388221

Thanks for the insight. Yeah it seems like phase current is the problem. The phase wires are really thin on the motor, like 14awg and they do get hot. The connectors are one of those round sp28 50A rated waterproof connectors. I have some thick bullet connectors laying around that i could use but not sure it would do anything considering the thin phase wires. I tried it set to 70A battery and 130A motor current and the vibration is barely noticeable with a few pedal strokes from a standstill so I'll keep it like that until i upgrade the motor.

 

[jozobozo]

It's the current PI controller becoming unstable. Basically what is happening is the controller is trying to keep the phase current at the level you are asking, the current setting in the controller if at max throttle or some percentage of that based on the throttle setting. The problem is it's having a hard time keeping it there, the phase current is oscillating up and down and you feel that as a fast pulsing feeling. At lower power levels like under low load it can keep things in check but once you start pushing the power it has to work a lot harder, the more current you put it the electrical noise and such it has to deal with.

The cause of why it can't keep the current level stable is probably several factors. First it's it's a shit controller that is poorly designed, and I'm not saying that just to shit on makerbase, I have a Flipsky 75200 Pro V2 (basically identical) with a hub motor that does exactly what you are describing and I can see from the logs that is what is happening and I've seen plenty of evidence on where they cheapened out on the controller to cause it to be noisy. They put almost no ceramic caps, the circuit design is meh, they opamps get fed noisy power from the voltage regulators, etc.

Second factor is tuning, you can tune around the hardware issues to improve things.

The good news is unless you have the ABS current set really high or Slow ABS current on it means it's stable enough to run, it if was too unstable it would be tripping OC faults. If you do have the ABS current set really high and Slow ABS on, well first turn slow ABS off, that's how you blow up controllers.

First thing that seems to work the best is to turn the Zero Vector Frequency down. You can turn it down by say 1-2khz at a time and see if it improves, you might find somewhere around 18-22 to be a good area. This seems to make these controllers run much more stable. I have a post somewhere where I go over a bunch more tuning settings that helped, specifically with that VESC and a hub motor at high current.

The ABS current is at 200 and slow ABS is off. I tried putting the ABS to 300 and motor current at 200 for one pull and it vibrates like crazy. I'll check out your post with the settings but i think i'll keep the phase current conservative with this hub motor. But yeah the controllers aren't great, I had a flispky 75100 pro v2 and now the makerbase but I'd love to try the makerx g300 controller with a higher rated motor in the future.

 

[Gika]

La corrente dell'ABS è a 200 e l'ABS lento è disattivato. Ho provato a impostare l'ABS a 300 e la corrente del motore a 200 per una tirata e vibra tantissimo. Darò un'occhiata al tuo post con le impostazioni, ma penso che manterrò la corrente di fase su valori conservativi con questo motore a mozzo. Comunque, i controller non sono il massimo, avevo un Flispky 75100 Pro V2 e ora il MakerBase, ma mi piacerebbe provare il controller MakerX G300 con un motore di potenza superiore in futuro.

Ciao, hai provato ad abbassare il guadagno dell'osservatore? Il mio Flipsky 75200 V2 Pro ha funzionato molto meglio. Inoltre, usa l'Ortega originale o l'MX Lemming.

 

[neptronix]

Here's my thoughts:

- 50A rated power connectors with 120a phase current is bad news and may even cause a controller to detect wrong ( too high resistance in the wire )
- If you are running sensorless, there's some special tuning needed to make it NOT run like crap from a stall + low rpm, almost every controller does a poor job until you can tune it ( VESC based controllers are one of the few capable of doing a good job after tuning )
- if the controller is tripping due too high phase current or something else, it should have an indicator light somewhere, or you may be able to observe it in the software with a tuning cable and laptop while riding!
- 120A phase / 60A batt is a little low, throw some more phase amps at it if you can, this will result in weak initial torque ( and some fun wobbly noises ) on most motors, it's more ideal to have a 2.25:1 ratio or higher