Single motor on dual VESC

[ziploc]

Should I change the title? That’s when I thought we had a dual-VESC.

[ziploc]

Or maybe I should start a new thread for this question. I was just adding to this thread because it’s the same controller we were trying to sort out.

[b264]

@ziploc

If we run in FOC mode, it gets up to a mid-RPM and then immediately locks up and chatters until you release throttle.

If we run in BLDC mode, it appears to act normally, but will only draw a max of about 35 amps. Also, if I hold it at full throttle for about 10 seconds, it starts to do the sort of chatter you see when it’s having trouble starting. I thought I had all the current settings in order, but I’m guessing I don’t.

Do these symptoms sound familiar to anyone?

What is the motor Kv?

Did you do the motor detection? On FOC using the wizard, but also manually for BLDC and write the values? What are the values for FOC (I, R, L, λ) and BLDC (integrator limit, BEMF coupling)?

Did you try disabling Motor Settings > FOC > Advanced > Current Controller Decoupling?

What is your Motor Settings > FOC > Advanced > Switching Frequency?

Are you using sensors or encoders?

How many poles does your motor have?

Did you try an older firmware version? Are you using 5.2? VESC Tool or variESC Tool?

Which control app are you using? Which control mode?

[b264]

@ziploc

Should I change the title? That’s when I thought we had a dual-VESC.

Probably, if you can.

[ziploc]

Lots of good questions. I’m helping a buddy, and it’s his unit. I’ll invite him to come here and answer the questions I can’t. But here’s what I know…

What is the motor Kv?

I’m almost sure he said it’s 120

Did you do the motor detection? On FOC using the wizard, but also manually for BLDC and write the values?

I ran motor detection for both using the Wizard. I think I also run BLDC detection through the regular UI. Is that what you mean by “manually”? I saved the BLDC config.

What are the values for FOC (I, R, L, λ)

Unfortunately, we didn’t save the FOC config because we were having better luck with the BLDC config. But we can re-run the FOC detection and get those parameters if that will help. These are what I’m finding in the BLDC config I saved; so I’m hoping they’re left over from the FOC config…

<foc_current_kp>0.0190835</foc_current_kp>
<foc_current_ki>22.0532</foc_current_ki>
<foc_f_sw>30000</foc_f_sw>
<foc_pll_kp>2000</foc_pll_kp>
<foc_pll_ki>30000</foc_pll_ki>
<foc_motor_l>1.90835e-05</foc_motor_l>
<foc_motor_r>0.0220532</foc_motor_r>

and BLDC (integrator limit, BEMF coupling)?

I hope this is what you mean…

<sl_min_erpm_cycle_int_limit>1100</sl_min_erpm_cycle_int_limit>
<sl_cycle_int_limit>375</sl_cycle_int_limit>

<sl_bemf_coupling_k>900</sl_bemf_coupling_k>

Did you try disabling Motor Settings > FOC > Advanced > Current Controller Decoupling?

Nope. Not familiar with that. But happy to try it. What’s it do?

What is your Motor Settings > FOC > Advanced > Switching Frequency?

Dunno didn’t save the FOC settings.

Are you using sensors or encoders?

Neither. It’s running sensorless.

How many poles does your motor have?

He said 6. I suspect that means “6 pole pairs”. But that seems like a surprising number.

Did you try an older firmware version? Are you using 5.2? VESC Tool or variESC Tool?

We’re using VESC_Tool.2.06.exe
I don’t recall which firmware is on the FSESC. But easy enough to check.

Which control app are you using? Which control mode?

Current control, no reverse, with brake. Not sure which app. I guess it’s the default.

Sorry I don’t have better answers, but I will happily dig them out. Thanks for the help!

[ziploc]

Unfortunately, it doesn’t look like I can edit the title. But I can start a new thread if that’s more appropriate.

[FreedomBoogie]

Hi, I am ziploc’s friend. I’ll add a bit more to his answers

1. What is the motor Kv?

• The motor is 120KV. Here is the specs for the motor

• Voltage range: 6-20S (25.2-84V)
• Max Spin Speed(RPM): 16380
• KV(RPM/V): 120KV/100KV
• Max Power:6000W
• Peak current: 200A
• The number of pole: 6
• Max torque at 60%:9NM
• Dimension: D65*L161mm
• Max working temperature: 120︒C
• Insulation voltage & leak current: AC500V/10MA/3S
• Lead wires extension: 8AWGx1300mm
• Waterproof level:IP68
• Weight:3kg
• Plug: 8.0mm
• Motor wire: 8AWG

2. How many poles does your motor have?
   6 poles

[b264]

What voltage are you using?

Have you checked for faults? Rebooting the ESC clears those, so check before a reboot.

Maybe try Ackmaniac 3.103 firmware and see if the same thing happens or not.

[ziploc]

We did check for faults. Usually we got nothing, but once we got this…

[ziploc]

We learned more today. We tweaked the BLDC parameters, and have the motor behaving much better. It no longer locks up and stutters. But we’re still struggling with the current limit. But we now have some interesting hints.

We’re nominally running on a 14S 15P pack (actually 3 14S5P packs in parallel). So this gives us about 56V. And when we run this setup, we hit a ceiling at about 30A. So we unplugged those packs and plugged in a 6S Lipo (about 24V). Interestingly, the motor actually seemed happier and smoother with this pack. Now we were pulling about 50A.

So I assumed the other packs just could not deliver the current (despite the fact that their specs indicate they should do it easily). So we tried a 3rd configuration. We took two of my 6S lipo packs and put them in series to get about 48V. I figured if one 6S pack was getting us 50A, two would probably push significantly higher (I know for a fact these packs can push more than 50A). But we found just the opposite.

The more volts we supply, the less current we pull. It’s as if there’s a limit on input power, or output power. Or maybe there’s a limit on ERPM. With all configurations, we’re getting a top ERPM right around 6000. But I think we have all our limits WAY wide of these marks.

Does this turn on a lightbulb for anyone?

Thanks.

[b264]

@ziploc

Or maybe there’s a limit on ERPM.

I was thinking about this yesterday, but you shouldn’t be anywhere close.

Are you 100% positive the motor is 6 poles?

Is it inrunner or outrunner?

[ziploc]

Are you 100% positive the motor is 6 poles?

I’ve never been absolutely certain about anything in my life. But Girish says those are the specs of the motor. Frankly, I hate the terminology. Because I’m pretty sure they usually mean “pole pairs” when they say poles. But even then I don’t think we’re near any of our limits. Also, I’m almost certain they mean magnetic poles, but I suppose it could be either the electric or magnetic poles.

Is it inrunner or outrunner?

The specs say inrunner.

[b264]

@ziploc

<foc_f_sw>30000</foc_f_sw>

Try lowering the FOC frequency and note what happens, if anything. Try 12k instead of 30k maybe. If that works well, try something lower.

Motor Settings > FOC > Advanced > Switching Frequency

The 19μH motor inductance seems a little high, and a higher voltage battery would lower the duty cycle so all I can think right now is to try switching it slower.

[ziploc]

We’re currently running BLDC. Is there a similar parameter for that?

[b264]

Motor Settings > BLDC > Advanced > Maximum Switching Frequency

[ziploc]

Thanks. We’ll give that a try. Incidentally, we did try increasing that frequency. It never occurred to me to try lowering it.

[ziploc]

I’ve got another dumb question. There’s a min and max switching frequency. I thought the switching frequency remained constant in general and only the duty-cycle changes. I must be wrong. Can you explain how it does work?