Hi,
I rewind motors for high end performance. Hope you like the my latest which will be a NEU 4638 YYYY-DDDD . If you need rewind service or prop matching Kv for the larger out runners contact me.

I specialize in new winds utilizing high fill and multiple layer in the FSCW format designed to lower ripple, improve the power factor and efficiency, It does this by removing the sub harmonic fundamental which reduced the magnets and rotor cores temperature significantly and boosting the working harmonics. I can also rewind motors for lower Kv to turn larger props for big planes. The winds also quiet the motors and reduce vibrations. These are some of the newest wind proposals for 2020. PM me for specifics. about NEU outrunners in the large sizes for big planes.

Thanks.
Hubert

Happy new year! These all fit the HK 5020 Scorpion

I have the lathe now so my next quest is to build my own permanent magnet flux switching machine. No conventional machine will compare to its torque profile.

The strait slot design is not clean when it comes to tooth top frequency
A skewed slot design is far superior for a clean passing frequency
Harmonic distortion will also be less
What is the projected cogging and cusping efficiencies / relationships

Depends on the goal. If it is truly a BLDC and driven by a 6 step inverter it isn't at all a problem. Skewed slots produce less torque U see no hobby motor uses them. The design is already optimized by lehner with formed litz wire and sinusoidal shaped segmented magnets . 93% efficient pictured here. A real analysis will involve mathematics a knowledge of the material and winding scheme involved. U will need alot more than an eye test here. Questing for a sinus waveform only makes sense if you are using a sinus inverter and that power system will not generate the same torque output as a true BLDC machine and inverter. Running them mismatched only bring ripple and at WOT there is no real advantage in efficiency. In fact at high speed sinus drives may run onto trouble with high pole count commutation. A properly designed parallel slot does a better job of equalizing the current density of the coil conductors from the bottom to the top of the slot. The other advantages it can give in terms of torque production . It also has the potential of much better fill with a rectangular or square conductor that round wire and radial slots. Rotor losses are attenuated buy pm segmets an pm shape. You see 100 percent pm coverage. They already have the design working well.

Originally Posted by rooman

The strait slot design is not clean when it comes to tooth top frequency
A skewed slot design is far superior for a clean passing frequency
Harmonic distortion will also be less
What is the projected cogging and cusping efficiencies / relationships

.....Also

I have not had the chance to look at the Fourier analysis of the generated wave forms with these different geometries and the factory scorpion HK rotor system. We hope the theory of the hybrid winding system holds true here and we run with a cooler rotor and attenuated 2 pole harmonics without fancy rotors and a special magnet Haus preparation. However, I'd expect the parallel slot stator and factory rotor configuration to have a coarser cogging. For my experiments though, I hope it in particular produces a true triangle or trapezoidal BEMF waveform. There is some newer empiric work out there that shows with 50/50 duty cycle triangle or trapezoidal excitation the plug-in coefficients for the Steinmetz core loss equation actually were less than those for sinus excitation. When I capture the generated wave forms at the different or expected fundamental frequencies of operation and take some cogging torque measurements, I will share them. Even though the slots here are also parallel the complete power system goals for electromechanical efficiencies are drastically different. I hope there is something to be learned from the upcoming experimentation.

Thank you for your interest and advice.
Hubert.

The interchange

The core loss by Stienmetz's theory , pertains mainly to grain structure within silicon steel lamination , I use this theorem for core loss in turbine generators when performing impedic efficiency upgrades of robel windings
Ive not experimented with a suspended metal core that has no grain structure .....
However -
If making the core from scratch i see no reason why a ferrite grain structure couldn't be obtained
A way to control ferrite linearity would be to apply a mag field while the core cures , this would aid in armature axial flux efficiency ....eg lower hysteresis

Originally Posted by rooman

The core loss by Stienmetz's theory , pertains mainly to grain structure within silicon steel lamination , I use this theorem for core loss in turbine generators when performing impedic efficiency upgrades of robel windings
Ive not experimented with a suspended metal core that has no grain structure .....
However -
If making the core from scratch i see no reason why a ferrite grain structure couldn't be obtained
A way to control ferrite linearity would be to apply a mag field while the core cures , this would aid in armature axial flux efficiency ....eg lower hysteresis

And all this is why I love my spark plugs!
It is very interesting but I am waiting for battery tech to catch up with gas for flight times.

Originally Posted by rooman

The core loss by Stienmetz's theory , pertains mainly to grain structure within silicon steel lamination , I use this theorem for core loss in turbine generators when performing impedic efficiency upgrades of robel windings
Ive not experimented with a suspended metal core that has no grain structure .....
However -
If making the core from scratch i see no reason why a ferrite grain structure couldn't be obtained
A way to control ferrite linearity would be to apply a mag field while the core cures , this would aid in armature axial flux efficiency ....eg lower hysteresis

With respect to bars or hairpins 2 KPI's for a slot design would be minimal joule losses and the lowest % average change in multiple inductor impedances in the slot . While slot opening width alone does more for lowering the average percentage impedance across multiple conductors, the tooth width is also important in affecting the total joule losses. A good slot depth width ratio for a start might be 1.5. Interchangeable cores make it a lot easier to test that in reality. The suspended metal core in this case like most composite cores has the downfall that it does not have the the magnetic susceptibility as silicon steel , however the iron particles are truly insulated from one another which should localize eddy current in the core. The issue here is the density and thermal properties of the substrate the iron is suspended in. A laser sintered armature isnt exactly a new idea but one that can be utilized and further perfected in a motor design concept such as this I suppose. I guess with composite cores you could also narrow the air gap or utilize larger or stronger pm to compensate for their lower susceptibility.

Originally Posted by Festivus

And all this is why I love my spark plugs!
It is very interesting but I am waiting for battery tech to catch up with gas for flight times.

I think if you carefully plan out your electrified power delivery system that technology already exist in what's available. It's all about the utilization of the technology.

Are you looking to use oxygen free or beryllium based copper wires ?
O/F would be the preference due to the clocked-up frequency of the speed controller , surface resistivity would also be improved , very little skinning affect
As you know the robel square section wires on the market today provide for an improved cross sectional area and lower impedance
C220 Amid-Imide coatings or a Kapton wire will handle the temperatures inparticular of an over fluxed asymmetric dropped phase condition
Sinus is duely affected when this situation happens

Brusa Switzerlang AG holds the patent for ( FLW) formed litz wire. In their study at less than 500 hz there was not a significant difference in copper losses between it and square hairpins and again it has been shown that triangular or trapezoidal commutation with a bldc motor actually had lower core losses. If I am running a high pole outrunner at over 1.5 kilo then I can expect some iron losses as compared to a 2 or 4 pole inrunner. Imho they are best utilized as direct drive options to replace geared inrunners that run at much higher voltage constants and rpms. I'd hope I dont need to run a 60 mm external 10 pole rotor at over 1.5 kilo Its easy to see that the hairpins have the potential to be the best rectangular slot filler.

Roo and Boho,
You boys are way above my pay grade! I’m amazed at all the electric activity in the modeling world. It just wasn’t for my way of flying. I’m more of a dump gas in the tank and go fly kind of flying enthusiast. The technical knowledge needed to fly electrics never excited me so flying glow and gas eventually won me over…..
In reading the technical jargon you two posted I’m reminded of a smattering of things you’d hear if you’d listen to the YouTube video about the Rockwell Turbo Encabulator. Anyway…. Maybe I can incorporate one of those flux slot thingys in one of my gassers! Happy flying!
WT 👍👍