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VESC for turbomachine testing - max ERPM?

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Tue, 2019-08-13 16:58

#1

batdan

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VESC for turbomachine testing - max ERPM?

I'm eventually going to conduct some testing of some hydrodynamic air bearings with turbomachine test rig. The nominal operating speed is 164,000 rpm however it may have to go as high as 181,000 rpm. It probably won't run for very long so high reliability isn't super important.

Currently we are planning to use a Celeroton controller for this however it costs tens of thousands of dollars so we have to interrupt another test to borrow this. I want to be certain there isn't anything cheaper and more compact that could work. The version of the Celeroton controller is designed for a 24-48 VDC input and a max of a 1000W, however the air bearing test rig probably won't draw more than 100W in the steady-state.

https://www.celeroton.com/en/products/converters.html

I saw that the high-end VESC seems like it won't have any problem with the voltage and current requirements, but the listed ERPM limit of 150,000 is a little too low to work. Does anyone know if there is any way this can be increased to maybe 200,000? If not, does anyone have any recommendations for something that might be able to work that isn't obnoxiously expensive?

This is everything I know about the motor:

Single pole pair
46 V line-to-line peak (19 VRMS line-to-neutral) which I think is at the nominal speed of 161,000 rpm

I don't have any coil inductance or resistance info yet, unfortunately.

Wed, 2019-08-14 09:00

#2

frank

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Maybe the 75/300 can go up that fast on a motor with a single pole pair (inrunner). I'll check that for you.

Frank

Tue, 2019-08-27 16:21

#3

batdan

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The TampaBoards website states that it is "150k ERPM driveable" which is not enough for this application. However, this comment that benjamin made in a previous thread seems to imply that it can possibly get up to 200k erpm which should be sufficient:

"The latest firmware and VESC Tool is out since yesterday. To run at 60 kHz, sample in V0 and V7 has to be disabled (essentially running the control loop at half the switching frequency). That should be enough to run motors at 200K ERPM, and decrease the current ripple when the inductance is extremely low. The switching losses increase quite significantly when switching that fast though. "

Also, I received some additional information about the motor/alternator & device from the manufacturer:

Single pole pair rotor magnet (cylindrical SmCo magnet glued inside a hollow rotor shaft)
The nominal speed is 161,000 rpm, max is probably 180,000 rpm
Sensorless operation
The line-to-line-phase voltage is 18.6 Vrms (I presume at the nominal 161,000 RPM)
the EMF voltage is 19.3 Vrms
the room temp coil resistance is 0.12 Ohms
and the coil inductance is 95 uH
expected ~100 W for steady state operation. Of course it'll be much higher during acceleration, but I expect less than 1000w even there.
Hydrodynamic air bearing machine so it can't spend much time spinning slowly.

The VESC 75/300 is pretty expensive ($600 US) so there's no way I could get permission to buy one unless I could be pretty certain that it can work for my application. Could one of the cheaper designs posisbly go up to that erpm as well? I'm not going to need much power.