Rolls Royce permanent magnet thruster questions

[Yogi71]

Hello,
I am considering an attempt at building or modifying a device inspired by the following, as well as others:



I don't know how I would make a driver for such a thing. Would it need to be software driven for example? Any input to point me in the right direction would be very helpful to me and deeply appreciated.
Thanks!

 

[berkeman]

Welcome to the PF.

Could you compare and contrast this modality of electric motor with other modalities? What would you say is the main advantage of this modality for the marine propeller application?

I don't know how I would make a driver for such a thing.

What do you mean by that? Are you asking about whether you need some closed-loop control capability to figure out how to time the changing coil currents in the stator? If so, what are your thoughts? When you do more Google searching and reading about this electric motor modality, how are they controlling the speed of the rotor? Do they use feedback, or just drive it open-loop?

 

[CWatters]

Basically it's a large permanent magnet brushless motor. Plenty are used for all sorts of other applications even model aircraft, drones etc

Yes some sort of electronic device is required to control the speed and to commutate the motor. Brushless motor controller ICs are available but I don't know if any support the number of poles you are talking about and you will need additional electronics (eg power FETs) to interface them to the motor windings. Worth looking at their application notes/design guides.

 

[Yogi71]

Hi berkman,..." how are they controlling the speed of the rotor?"

I do not yet know how their controller works. I am, at this point, assuming is to be an open loop system, however at least a monitored one. Likely equipped with some emergency controls.

 

[berkeman]

Hi berkman,..." how are they controlling the speed of the rotor?"

I do not yet know how their controller works. I am, at this point, assuming is to be an open loop system, however at least a monitored one. Likely equipped with some emergency controls.

Did you see the good reply by @CWatters ?

 

[Yogi71]

Hi berkeman,
The main advantage spoken of in the video was about using less power. More efficiency! As far as "how are they controlling the rotor speed" , at this point I am assuming it is open loop and they slow the firing of the coils. Yet this at some point may need to balance with power to the coils being adjusted.
Not sure exactly how their system works.

 

[Yogi71]

Yes I saw that post. I also have pondered that-number of poles- obviously a custom design.

 

[berkeman]

Not sure exactly how their system works.

Well, just keep doing your research and reading, and you'll learn a lot more about this electric motor and other modalities of electric motors.

Hint -- For this marine application, not having to seal the drive shaft that drives the propeller is a big advantage for efficiency and reliability. After you have done more reading, you should be able to explain that hint back to us.

 

[berkeman]

some kind of weird attitude...I did enough reading just now. Here's a hint------delete my account! see ya

Hmm, strange. Fun project and lots of great things to learn doing it. Not sure what the problem is, but I'll close this thread for now. PM me if you'd like it re-opened after you've done more reading. Keep on experimenting and learning.

 

[berkeman]

(Note -- there has been some cleanup in the thread)

 

[berkeman]

The OP is on a 10-day vacation from the PF. He/she can start a new thread showing more of their research and reading when they return, if they want our help. This thread will remain closed.