axial flux permanent magnet generator .....

[mallikarjun]

hi this mallikarjun i m making a generator ,"axial flux permanent magnet generator " of 230 watts   using Ne-Feb magnet of 42 grade ,

i have designed a rotor of outer diameter 236mm and inner diameter 116 mm

magnets shape is trapezoidal of 60mm in height and 47.5mm x 39.5mm top and bottom in length  ..

i m using 8 pole rotor single sided not dual rotor   so..


i need design the stat-or using toroidal coil winding three phase star connected  single layer ..

i dont how to calculate the number  of coils need and and number of turns per coil and thickness of wire to be used 

for toroidal coil ... pls do help me out ..

[GoVertical]

http://www.6pie.com/faradayslaw.php
Hi, this should help. Make a test coil before you cast a stator.

[Flux]

Toroidal machines are not usually considered here and they need to be looked at rather differently.

With a torus the flux is at right angles to a conventional air gap machine so you can always wind it as a single layer winding. The obvious way to wind an 8 pole is with 8 coils per phase ( 24 coils total). Each 3rd coil will be in the same phase and I think it will need to be reversed as it will be under an opposite pole.

For best results you would make it dual rotor with magnet discs on either side with like poles facing, but it works fine with one magnet rotor, you have double the resistance so you done't get best use.

You don't mention magnet thickness and that affects the flux.

I strongly suggest that you wind a test coil same dimensions as one of the 24 final coils and see what you get. Bear in mind that in the final thing wou will get 8 times that voltage per phase and 1.73 times that line to line in star.Factor in the 1.4 times factor for the rectifier to bring to dc mean and you can equate that to your battery volts.

This type of winding is well cooled and you can use possibly one or probably two layers in your coils. This will keep the air gap short and even with thin magnets you may bet over 800mT in the gap.

If you want to try it by calculation then I don't see why the conventional equations won't work.

E=4.4 ( Phimax) x f x N where f is frequency and N is the total number of turns per phase

The flux bit is not so simple as your flux is travelling circumferentially through the core but as it is coming from the magnets it should be the same so I assume if you take your gap density and multiply by magnet surface area it will work out. For a machine fed from both sides the flux would be double.

Hope this gives you a starting point, just don't expect things that apply to axial air gap machines to work out in this case and certainly don't try messing with 6 coils on the 4 magnet 3 coil basis for axial air gap single layer windings.

Flux

[GoVertical]

http://egdk.ttu.ee/files/kuressaare2007/kuressaare2007_186kallaste-kilk.pdf

[mallikarjun]

sir .. thank you for your suggestion .. i will do normal coil winding for generator of 80v

magnet thickness will 5mm
 
magnet area A sq.m   =2160 x 10^-6

for star connected
total flux = magnet area A sq.m x flux density B
=2160 x 10^-6 x1.29=2.8mwb.

.The  flux obtained is sufficient or not

Average voltage (which is 80V/ 2.732for star connected AC)
= 4.44 x total flux x number of turns x revolutions per second
= (4.44 x 2.8 x 10^-3x number of turns x 360)/60

= 392 turns total
so if use 24 coil
8 coils/phase =392/8 which is 49 turns per coil.
so i can take 49 turn per coil … .. 3 coil per magnet ..


how should i make coil connection??


i taught of making connection like this ..
 3 phase connection the for r phase  1 st coil end would connect  4 end and 4 start to 7end ,7 start  to 10 end ,10 start to 13end

..so  similar for y phase 2  st coil end would connect  5 end and 5  start to 8 end ,8 start  to 11 end ,11 start to 14end ..so 

similar for b phase 3 st coil end would connect  6 end and 6 start to 9 end ,9 start  to 12 end ,12 start to 15 end ..

is my above theory correct .. if not please comment ...

i need to know the gauge of wire to be taken ..

[GoVertical]

Hi, are you planning to use a power conversion circuit?? Like a MPPT or a Buck converter with a varaible duty cycle.

Do not consider the hardware used but the info at about 1 minute and 30 seconds explains why you will need a power conversion circuit. Using a lot of coils will make the stator internal resistance very high and most of the power generated  will be lost as heat at the stator.
Corrections welcome

[mallikarjun]

yes i am using buck converter i need know the ic available for 2 amps current

[mallikarjun]

i am bit confused can any one of u help me with winding connection with drawing please for the above design as i am getting confused .. please help

[electrondady1]

my understanding of three phase requires all the coils of each phase to be wired in series so the end of coil 1 would connect to the start of coil 2 and the end of coil 2 would connect the the start of coil three.