Alternator BLDC Mod ~7kw

[Sauger-Junky]

Hi,
we build am Electric motor bike and the game is for us most power we can handle with MTB parts
https://endless-sphere.com/forums/viewtopic.php?f=28&t=96858

at the beginning we just convert a bosch alternator with 103x40mm rotor to a BLDC but at 70 volt and 50 amp the magnetic field jump over
nearly the same as the rotor get 12 volt or16 volt

so we build a new rotor with 12 pole eatch 2 magnets with 40x10x5mm neodym 45n
the ari betwen magnets and stator is ~0.4mm
we fix the magnets with secondglue and later we put aramid and epoxy around it
i breake nearly my finger to but the magnets on the rotor till the secondglue hold them on place you have to push them with ~8 kg
the magnetig surface is 85% so it is perfect for the sensorless controller

at 70 volt we put 100 amp in and at 5°c outside the stator has 25°c after 15min testing
next test will be 100,8 volt and 100 amp

the weight of the motor will be around 4kg

on star it tourn 28 u/min per Volt
on triangle it tourn 48 u/min per Volt

 

[Sauger-Junky]

https://youtu.be/52ufo_kanYs

 

[j bjork]

Nice work :thumb:

Can you use the fan from the old rotor?

 

[ZevEst]

Hello,

Nice work, I see that this alternator has 6 coils also, can you tell me more about how did you wire them?

 

[Sauger-Junky]

Thanks

the fan was weldet on the old rotor

at the moment we use it without fan but ther are 17mm space for a new fan

 

[Sauger-Junky]

you have to measure witch both are a pair an then you do it like
tchangly21 in his video


https://youtu.be/wgXS6YynEVE

 

[Ianhill]

Good work and top effort.

Looking at the rotor and its good effort but using alloy in the centre is not helping complete the magnetic circuit of the neodymium, plus it's one large piece of iron so the magnets seating area is going to get hot with eddys when running plus the lack of steel in that area means there will be more magnetism leaked down the motors shaft to the sprocket, I noticed there's a gap between the magnets where iron can be used to help complete the magnetic circuit, this gap needs to be calculated to carry both sides flux so a good magnetic carrying steel could be 1 for 1 with the magnets width, so magnet height ×2 equals the gap and fill it with the iron to get a better complete circuit and raise the magnets strength at its surface.

I would be looking at imitation of the tesla model 3 motor it's possible you could see 12kw + If you get them magnets under the surface to get a completed loop you can make it an IPM have a Google of these rotors and have a look what you can come up with you seem to have decent tooling have a bash you may make something quite desirable for a small diy motorbike it has the potential to rev very high.

 

[Sauger-Junky]

Thanks

yes the Tesla rotor looks good and i think we can build a rotor like this but i can`t find a seller for the
electro sheet and i do not undestod how they magnets cascade

 

[Ianhill]

Tech ingredients.
Very powerful magnets
He has a few videos explaining the basics to get your head around what they are doing on the rotor.

Without accurate dimensions and knowing the layout of the coil id struggle to recommend the magnets size and how-to place them but remember not to saturate the iron and keep them close to the surface as you can amdnuse the yoke affect so the opposing magnets strengthen each other.

The model 3 uses this opposing yoke effect with the halbach effect to greatly improve the rotors magnetic tesla at its surface, so less magnet material can be used in a lighter more efficient rotor or pack that thing full and get massive amounts of dense power there's so much to consider on a rotor windage etc but your effort is damn good I bet it results in a decent motor as is just watch you don't overheat the magnets in heavy use.

 

[Ianhill]

Tech ingredients.
Very powerful magnets
He has a few videos on youtube explaining the basics to get your head around what they are doing on the rotor.

Without accurate dimensions and knowing the layout of the coil id struggle to recommend the magnets size and how-to place them but remember not to saturate the iron and keep them close to the surface as you can amdnuse the yoke affect so the opposing magnets strengthen each other.

The model 3 uses this opposing yoke effect with the halbach effect to greatly improve the rotors magnetic tesla at its surface, so less magnet material can be used in a lighter more efficient rotor or pack that thing full and get massive amounts of dense power there's so much to consider on a rotor windage etc but your effort is damn good I bet it results in a decent motor as is just watch you don't overheat the magnets in heavy use.

 

[Ianhill]

From my research it appears when there's any sort of reluctance torque from magnets beneath the rotor surface the brushless esc will not be able to control the rotor, a vesc maybe able to run the motor with an encoder but I'm not sure.

When ever the magnets are below the surface like the rotors I showed then the controller needs to be matched to cope next on my list is vesc's and reluctance motors see what's happening in that area dig beneath the surface excuse the pun.

A laminated rotor with surface mount magnets in a halbach array arragnment would still run fine from a standard controller though, it will just need more magnet area for the same tesla at its surface and the IPM motor has more tesla for the same magnet mass but the controller needs to be tuned to run the setup im sure there's more on here that could chip in some experience with running one on a custom controller.

 

[Sauger-Junky]

until now we run the motor sensorles and if we build a rotor like the tesla it will run sensorles

 

[Sauger-Junky]

we did some tests with 100v and 100a it runs nice but the controller reatch his rpm limit and past 6 minutes full trottle we had on the stator 25 degree centigrade but the st52 iron rotor was 52 degree centigrade

the ceap 96v 1500w controller gets an shunt and conductor path upgrade

we are neve had more then 30 degree centigrade on it

 

[Ianhill]

we did some tests with 100v and 100a it runs nice but the controller reatch his rpm limit and past 6 minutes full trottle we had on the stator 25 degree centigrade but the st52 iron rotor was 52 degree centigrade

the ceap 96v 1500w controller gets an shunt and conductor path upgrade

we are neve had more then 30 degree centigrade on it

Confirmed my observations with the magnet ring it's sounds a more than capable motor mind dis you have it under any load ?

I've got a hub motor from a dualtron scooter good for 4kw + bursts its an outrunner design but the magnets are the same sat on solid magnetic steel ring pressed into a alloy outer ring.

Few pics by here https://endless-sphere.com/forums/viewtopic.php?f=35&t=97557&start=25