VESC as multirotor ESC?

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jlcortex
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VESC as multirotor ESC?

Postby jlcortex » 26 Feb 2018, 08:40

Hello, we have been testing this 80A FOC ESC for multicopters and there are a huge diference with old BLDC ESCs
hw.JPG
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Now we have a bigger project but this FOC ESC only works with its motor and it is not configurable.
So i am thinking in VESC.

- Do someone use VESC on multicopters?

I am thinking to use about 40 inches propellers and i have calculated about 2500W per motor at hover and about 6000W of peak power.
I am doing some calculations for 3 diferent configurations, 12S (44.4V), 14S (51,8V) and 20S (74V)

I have calculated the drivers dissipation, very basic calculation W=I * R (Rds) and it seems every configuration dissipates exactly the same:

drivers.JPG
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- Can i change original driver for a 100V mosfet and use with 20S?

I am thinking to buy 4 VESC 4.12 version and do some tests.

- Is it good idea? it seems the secret of a good ESC is the speed with which the esc apply the changes of the control signal to the motor.

My fear is that although the FOC control is much faster than the BLDC, however the VESC is not designed for this application and there are delays or filters in the input signal that slow down the control.

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TheFallen
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Re: VESC as multirotor ESC?

Postby TheFallen » 26 Feb 2018, 08:51

Stock VESCs will only accept up to 60V. Battery packs above 12-13S will cause the VESC to burn. This is a limitation of the driver chip and FETs, while changing the FETs is possible, there are no compatible alternative chips for the driver chip.

jlcortex
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Re: VESC as multirotor ESC?

Postby jlcortex » 26 Feb 2018, 12:26

Ok, I understand 100V is impossible with this driver,

But 14S by changing mosfet to IRFS7730-7PPBF???
14S is 58.8V (full charged)

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TheFallen
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Re: VESC as multirotor ESC?

Postby TheFallen » 26 Feb 2018, 13:39

You can certainly try it. But any voltage spikes from the motor will blow up the VESC. You want ~5V of headroom.

arvidb
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Re: VESC as multirotor ESC?

Postby arvidb » 27 Feb 2018, 16:56


jlcortex
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Re: VESC as multirotor ESC?

Postby jlcortex » 06 Mar 2018, 20:41

yes, i have a VESC6, but i have not tested too much.

I have realized the ERPM limit could be a problem

This kind of big multicopters motors have a 36N42P scheme, 42 magnets is 21 pole pairs?
60000erpm /21 = 2850rpm?

Is it correct this calculation?

arvidb
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Re: VESC as multirotor ESC?

Postby arvidb » 07 Mar 2018, 00:12

The calculation is correct, but the limit of 60000 erpm is for VESC4. VESC6 can do much more - I seem to recall I've read at least 150000 erpm somewhere?

jlcortex
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Re: VESC as multirotor ESC?

Postby jlcortex » 07 Mar 2018, 00:37

arvidb,

Thanks, yes, you are right, "VESC Six will remove the 60k ERPM limit and has been tested around 150k ERPM from what i've heard and seen on Benjamin's test videos"

15000/21 = 7140rpm is enought!!!

Motors are 100 or 110kv *52V = never more than 5500rpm

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TheFallen
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Re: VESC as multirotor ESC?

Postby TheFallen » 07 Mar 2018, 07:55

Arvidb is talking about electronic RPM, the number of 'turns' the ESC sees for each motor rotation. This is the number of poles multiplied by the number of rotations.

Your suggested motors have a high pole count, 21 pole pairs, so it would be 110kv * 52V * 21 pole pairs = 120,120 electrical RPM.

The VESC6 has a much higher erpm limit, but VESC4 get some extra erpm with the latest firmware.

ThierryGTLTS
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Re: VESC as multirotor ESC?

Postby ThierryGTLTS » 07 Mar 2018, 08:26



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