BLDC tool parameter configuration help

General topics and discussions about the VESC and its development.
anroop
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BLDC tool parameter configuration help

Postby anroop » 28 Feb 2017, 13:53

Hi,
I'm using your ESC for a custom application that involves accelerating the motor from 200 RPM to 12000 RPM in < 1.5 seconds with a maximum load of 200 grams on the motor.

Tried using my self built ciruit got burnt several times and dropped my idea and purchased the VESC from Maytech.

ESC : http://www.maytech.cn/en/mtvesc50a/10331.html (source vesc, supplier Maytech)
Motor : http://www.maxonmotor.com/medias/sys_ma ... 283-EN.pdf (303 KV, Hall sensored)
Power source : 52 VDC (Regulated power supply for gradual acceleration testing to achieve 12,000 RPM), 39 VDC (battery, for immediate acceleration)
Software : BLDC tool

I have been trying to detect the motor and its parameters under the BLDC motor configuration (sensored/sensorless) and it always fails and the motor heats up (motor is low inductance). Then I tried detecting the motor parameters under FOC tab (motor was configured to BLDC sensorless) and it was a success (measured R, L, lamda with 1 A, 0.05 duty cycle (DC), else the motor was not running smooth or not at all). Hall sensor detection was also successful and I uploaded all the values to the ESC. the motor was able to run under Sensored /Sensorless mode (BLDC delay mode, FOC detection parameters) to a minimum RPM of 2000 at 18% DC, and with further tweaking of low speed ERPM value under BLDC tab I was able to achieve 215 RPM (Which was great for me).

Tried running it to 12,000 RPM with gradual acceleration and was successful

Then the next part was the acceleration.
Tried accelerating the motor from 2,000 to 10,500 RPM (@39 VDC using battery from power inverter) with 50 grams load on it and it was successful.
Tried accelerating the motor from 215 RPM to 10,500 RPM with 50 grams load on it, but the motor got stalled and burnt, Currently I have burnt 2 motors costing me ~30,000 INR. I have currently stopped the experimenting as it seems I'm not operating the ESC and motor at their perfect spots that'll keep the motor & ESC safe.

The Motor manufacturer has qualified the motor with their controller rated until 60 VDC (costing way beyond I could afford) and had confirmed me that it was working with 50 gram load from 215 RPM to 12,000 RPM in < 0.5 second. He is yet to Qualify it for 200 grams load.

So I would like to some get help with this so that I could run the motor with VESC safe.

Could some one please mentor and guide me from the basics on using this motor with the VESC.

I was controlling the speed only using duty from BLDC tool

I am attaching the setting screen shots FYR.

Your inputs and efforts are much appreciated.

rew
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Re: BLDC tool parameter configuration help

Postby rew » 28 Feb 2017, 20:36

That motor can do "70W" and max about 35V according to the specs. That means that the motor is built to run on 2A.

This is a VERY low current for the VESC. You will need to replace the current sensing resistor by a bigger value.

On the "standard" VESC, 50A gives 50mV, multiplied by 10 gives 500mV and then a factor of three of overcurrent/peak current can be measured.

So if you normally want to stay, say under 3A, you need 1.5V at the ADC at 10A. So 0.150V = 150mV over the shunt at 10A, so 15mOhm. Double check: 150mV * 10A = 1.5W is acceptable.

Then the VESC would be much better adjusted to measuring the state of your motor.

The thing is.... If 70W or 100W is enough to accelerate your load to 12000 RPM in 1.5 seconds depends on the moment of inertia. (not on the weight).

pf26
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Re: BLDC tool parameter configuration help

Postby pf26 » 01 Mar 2017, 13:08

From the datasheet, the nominal motor current is 2.43A. With a thermal constant of 28.1sec, you can probably use currents up to something like 5-8 amps during very short times. I think 10mOhm shunts should be fine. And you really have to set a low max motor current in BLDCtools and on your PSU.

The ability to accelerate your load depends how the load is to be moved. If you can overpower your motor to 200W during 1.5s with 50% efficiency, you have 150 Joules to accelerate your motor rotor (24 gcm²) + your load. With 150J, you can get a 0.2kg load to 100km/h..

anroop
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Re: BLDC tool parameter configuration help

Postby anroop » 01 Mar 2017, 13:22

Thanks rew,

I hope that could solve my motor burnout issue. I have some queries in your suggestion below, FYR I have not yet started exploring the Hardware/Firmware of this VESC. A complete beginner on the BLDC front. Really sorry if am asking too much of the basics.

[*]On the "standard" VESC, 50A gives 50mV, multiplied by 10 gives 500 mV and then a factor of three of overcurrent/peak current can be measured - why do you multiply 50 mV by 10 (related to this specific hardware/Firmware)

[*]So if you normally want to stay, say under 3A, you need 1.5V at the ADC at 10A. So 0.150V = 150mV over the shunt at 10A, so 15 mOhm. Double check: 150mV * 10A = 1.5W is acceptable - How is < 3A related to 1.5 VDC on ADC at 10A (and why at 10 A), and could you sort out for me of which Resistor (Rxy) & how much value i should replace for my motor spec

[*]Then the VESC would be much better adjusted to measuring the state of your motor - Do you mean it would help me detect my motor parameters under BLDC sensored (Integrate mode) which would make my motor run safe without burning out

[*]The thing is.... If 70W or 100W is enough to accelerate your load to 12000 RPM in 1.5 seconds depends on the moment of inertia. (not on the weight) - currently exploring the inertia part. please send any basic links if possible

Anybody with possible relations and help are welcome...

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TheFallen
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Re: BLDC tool parameter configuration help

Postby TheFallen » 01 Mar 2017, 13:52


anroop
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Re: BLDC tool parameter configuration help

Postby anroop » 09 Mar 2017, 11:18

Hey Guys,
@rew, @pf26 @ TheFallen - Thanks for the info. I have got both 10 and 15 milli ohm resistors @ 2 watt. let me the test with them and will let you know the outcome.

Hope this doesn't burn the third motor :)

rew
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Re: BLDC tool parameter configuration help

Postby rew » 12 Mar 2017, 08:14

It would be more useful to spend a day in the books to try and figure out if what you're trying to do is physically possible.

You want to spin something up to high RPM in a short time. This is likely going to cost some amount of energy, and you should do the calculations to determine if this is even remotely possible with the motor you have.

anroop
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Re: BLDC tool parameter configuration help

Postby anroop » 13 Mar 2017, 13:30

Last edited by anroop on 15 Mar 2017, 07:50, edited 1 time in total.

artteth
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Re: BLDC tool parameter configuration help

Postby artteth » 13 Mar 2017, 15:40


anroop
Posts: 13
Joined: 28 Feb 2017, 12:45
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Re: BLDC tool parameter configuration help

Postby anroop » 14 Mar 2017, 10:59

Last edited by anroop on 15 Mar 2017, 07:55, edited 5 times in total.


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