5-phase brushless motor

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Oct 18, 2021
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I am searching for information on this, and what I find indicates that 5 phases would give higher efficiency than 3 for various reasons.

I realize it is slightly more complex and the motor controller would cost more, but really I don't think the cost difference justifies it. For power generation such as wind turbines, the cogging would be much lower too.

So, why not 5 phase (and higher) motors? For sensorless, 4 of the 5 are powered which gives obvious higher efficiency. There are less eddy losses, more usable torque, and even more precision for servo applications. The efficiency gain of (possibly 2-3%) is pretty significant when these motors are already fairly efficient. What is holding us back?

What would be the ideal stator/pole count? 15s20p?

There are also (dual 3 phase or 6 phase) with reportedly higher efficiency. Can someone explain why the 2 sets of 3 phase windings are 30 degrees out of phase?
 
I don't know if Falco is still in business, but...they advertised a 5-phase hubmotor.

My hesitancy was the proprietary 5-phase controller. Motors generally are robust, abuse-friendly, and reasonably repairable.

Controllers operate by voodoo, and are filled at the factory with the "Magic Smoke".
 
I would like to see that. Reminds me of a similar idea I had for electric DC car motors. Why have 400 volts DC going into just 3 phases when you could have 6 or 12 phases, the same amount of current going into each stator but at a lower voltage? Sure it would mean a much more complicated controller but it would reduce or eliminate the need for such high voltages. What if there were 24 motor phases for example and just one controller for each phase with communications between all the controllers so they could synchronize?
 
There has been a six-phase motor where the phases were split so the user can use two 3-phase controllers.

All it takes is money to develop a prototype to your specs...
 
[youtube]msJJQcrYd4E[/youtube]



Rakesh Dhawan, (pwezident,flounder & chief bottle washer of falco emotors) had prior worked on wavecrest labs' 7-phase motor & has openly admitted on-line that he got most of his 5-phase know-how from open source info & patents published by texas a&m.
notably these might be a good place for you to start.
Vector Control of Five-Phase Synchronous Reluctance Machine with the Third Harmonic Current Injections for High Specific Torque
Enhanced Rotor Field Oriented Control of Five-Phase Induction Motor with the Combined Fundamental and Third Harmonic Currents
Parameter estimation of vector controlled induction machine
A Low-Cost Low-Loss Brushless Permanent Magnet Motor Drive

https://ieeexplore.ieee.org/document/1348542

someone on E*S had once pointed out that an odd number of phases is preferable without 'splaining exactly why.
mxlemming said:
The fundamental frequency will travel with the rotor synchronously, whereas higher harmonics will not.
i'd presumed it has to do with harmonic resonance.
in that case, then the nearest non-proprietary odd-phase config lands on number9 ringo.
https://repositories.lib.utexas.edu/bitstream/handle/2152/30659/PR_348.pdf;sequence=1
https://www.danatm4.com/blog/5-benefits-multi-phase-motors-inverters/

news-electric-aviation-ascend-reeach-02Sept2020.jpg

https://engineering.tamu.edu/news/2...y-for-transformational-energy-technology.html


R. Shi, H. Toliyat, A. El-Antably
Published 2001
Engineering
Conference Record of the 2001 IEEE Industry Applications Conference. 36th IAS Annual Meeting (Cat. No.01CH37248)

It is shown that third harmonic current injection can produce higher shaft torque than conventional sinusoidal current regulation in five-phase synchronous reluctance machines with salient-pole rotors. This paper investigates the field oriented control (FOC) including the hysteresis-type PWM current regulator of such machines under flexible third harmonic current injection. It is concluded that the sinusoidal current injection can be viewed as a special case of combined fundamental plus third harmonic current injection with 0 percent of third harmonic current. The flexible FOC control algorithm is designed and the developed model is confirmed by the simulation results in Matlab/Simulink environment. The complete strategy has been implemented on a digital signal processor based five-phase synchronous reluctance motor drive fabricated in the authors' laboratory. The experimental results verify the developed flexible fundamental plus third harmonic FOC.



http://www.hindawi.com/journals/mse/2014/686373/
It is also shown that the torque ripple in five-phase PMBLDC motor is low compared to its three-phase counterparts. It is concluded that the average torque produced in a five-phase motor running at 1500 rpm is 1.6 times the torque of a three-phase motor having the same D/L, and the torque ripple of the five-phase motor is 50.29% less than that of the three-phase motor.

[youtube]16Kv_a8E0vg[/youtube]
 

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Toorbough ULL-Zeveigh said:
Rakesh Dhawan, (pwezident,flounder & chief bottle washer of falco emotors) had prior worked on wavecrest labs' 7-phase motor & has openly admitted on-line that he got most of his 5-phase know-how from open source info & patents published by texas a&m.
notably these might be a good place for you to start.
Vector Control of Five-Phase Synchronous Reluctance Machine with the Third Harmonic Current Injections for High Specific Torque
Enhanced Rotor Field Oriented Control of Five-Phase Induction Motor with the Combined Fundamental and Third Harmonic Currents
Parameter estimation of vector controlled induction machine
A Low-Cost Low-Loss Brushless Permanent Magnet Motor Drive

https://ieeexplore.ieee.org/document/1348542

someone on E*S had once pointed out that an odd number of phases is preferable without 'splaining exactly why.
i'd presumed has to do harmonic resonance.
in that case, then the nearest non-proprietary odd-phase config lands on number9 ringo.
https://repositories.lib.utexas.edu/bitstream/handle/2152/30659/PR_348.pdf;sequence=1
https://www.danatm4.com/blog/5-benefits-multi-phase-motors-inverters/

news-electric-aviation-ascend-reeach-02Sept2020.jpg

https://engineering.tamu.edu/news/2...y-for-transformational-energy-technology.html
Why would you object third harmonics into a 5 phase system? Surely you'd want to inject 5th harmonics? :confused:
 
Yes it was tried it wasn't the wonder motor of Wonder motors. Plus when everything's proprietary like the falco you're asking for a headache.
 
so you dont know much about FALCO
it is not proprietary as BIONX and others
can you connect any battery to BIONX - NO
can you connect any battery to SHIMANO, BOSH.. - NO
that is prorietary
Falco will run on any battery of your choice
so it is not your typical proprietary!!!
 
Toorbough ULL-Zeveigh said:
someone on E*S had once pointed out that an odd number of phases is preferable without 'splaining exactly why.
mxlemming said:
The fundamental frequency will travel with the rotor synchronously, whereas higher harmonics will not.
i'd presumed it has to do with harmonic resonance.
in that case, then the nearest non-proprietary odd-phase config lands on number9 ringo.
https://repositories.lib.utexas.edu/bitstream/handle/2152/30659/PR_348.pdf;sequence=1
https://www.danatm4.com/blog/5-benefits-multi-phase-motors-inverters/
I see you've edited your post to quote me as the one saying odd numbers of phases are preferable.
However, the thing you've quoted has absolutely nothing to do with that, it's commentary on the harmonics on the backemf profile of a motor, not on the number of phases.
 
mxlemming said:
it's commentary on the harmonics on the backemf profile of a motor, not on the number of phases.
the bemf harmonics distribution ("profile" :roll: ) varies with the number of phases, they're inseparable.
you are not the 'someone' on ES i'm trying to find (unable to locate the post which seems to have been pruned) but wuz closest supporting evidence.
i did say it wuz a presumption based on erroneous (as it turns out) tacoma narrows bridge line of thought.
if i read too much into your comment, then i still don't have a satisfactory answer to why odd # of phases are the only configurations (higher than 6-phase) ever seriously pursued.


Researchers in the Naval University of Engineering analysed the 15 phase induction motor system under non-sinusoidal power supply, and proposed the field-circuit coupled finite element method for the multi-phase motor, which provides a theoretical basis for motor design optimisation and control, and successfully developed the 15-phase advanced induction motor drive system.
https://ietresearch.onlinelibrary.wiley.com/doi/10.1049/joe.2017.0789



mxlemming said:
Why would you object third harmonics into a 5 phase system? Surely you'd want to inject 5th harmonics? :confused:
maybe you would object but i would inject.
no longer confused?
the field-oriented vector control method for a five-phase induction motor with the third-harmonic current injection was proposed. Finally, simulation by MATLAB/Simulink and experiment is implanted on the five-phase induction motor. The results indicate that the air-gap magnetic field gets improved, and the power density of five-phase induction motor is enhanced without any increase of power switch capacity and machine size.
 
Toorbough ULL-Zeveigh said:
mxlemming said:
it's commentary on the harmonics on the backemf profile of a motor, not on the number of phases.
the bemf harmonics distribution ("profile" :roll: ) varies with the number of phases, they're inseparable.
you are not the 'someone' on ES i'm trying to find (unable to locate the post which seems to have been pruned) but wuz closest supporting evidence.
i did say it wuz a presumption based on erroneous (as it turns out) tacoma narrows bridge line of thought.
if i read too much into your comment, then i still don't have a satisfactory answer to why odd # of phases are the only configurations (higher than 6-phase) ever seriously pursued.


Researchers in the Naval University of Engineering analysed the 15 phase induction motor system under non-sinusoidal power supply, and proposed the field-circuit coupled finite element method for the multi-phase motor, which provides a theoretical basis for motor design optimisation and control, and successfully developed the 15-phase advanced induction motor drive system.
https://ietresearch.onlinelibrary.wiley.com/doi/10.1049/joe.2017.0789



mxlemming said:
Why would you object third harmonics into a 5 phase system? Surely you'd want to inject 5th harmonics? :confused:
maybe you would object but i would inject.
no longer confused?
the field-oriented vector control method for a five-phase induction motor with the third-harmonic current injection was proposed. Finally, simulation by MATLAB/Simulink and experiment is implanted on the five-phase induction motor. The results indicate that the air-gap magnetic field gets improved, and the power density of five-phase induction motor is enhanced without any increase of power switch capacity and machine size.
Your pedantry for my mobile autocorrect typo doesn't change the fact that third harmonic injection in 5 phase systems makes no sense.

No one makes many phase motors because they don't actually offer tangible improvement. There's always snake oil salesmen though.

They used to make marginal sense back when electronics were garbage, switching was difficult, computation was difficult etc... But that's not the world we live in any more.

I guess the kind of people who want to try multi phase motors make assumptions that don't really hold , you can make arbitrary and even phase motors wound in star.

Also, 6 phase motor for example is electrically the same as 3 phase with half the windings connected in reverse.

8 phase is like a 4 phase with some windings backwards
10 phase like a 5 phase.....
See a patern?
 
mxlemming said:
Also, 6 phase motor for example is electrically the same as 3 phase with half the windings connected in reverse.

To reduce torque ripple on square wave or quasi-square wave inverters (almost irrelevant now), 6 phase machine should have 2 set of 3 phase windings with the two sets being 30 degree out of phase as per OP's query. Searching older ES threads, Lebowski also has mentioned about 30 degree shift.

seandepagnier said:
Can someone explain why the 2 sets of 3 phase windings are 30 degrees out of phase?

Quoting P.C.Krause et al., "Induction machine analysis for arbitrary displacement between multiple winding sets", IEEE Trans. on IA, Vol. 93, May 1974

The required angular spacing between multiple winding sets for best performance is pi/n for an even number of sets and 2*pi/n for an odd number of sets, where n is the total number of phases

So here it will 180/6 = 30 degrees

I have done a minor project on multi phase induction machines during my masters >15 years back. Matlab/Simulink simulation as well as real world test was done (using a generalized machine, IIRC, it was called Kron's generalized machine, which can be converted to almost any type of electrical machine). Results showed 9 times reduction in torque ripple & frequency of pulsating torque was shifted from 6 to 12 times the supply frequency when fed by a square wave inverter, while there was no difference in torque ripple when fed by a sinusoidal input.
 
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