fourbanger
100 W
Trying to figure out the relation between the amount of surface area passing a magnet and the amount of power a motor can reasonably be expected to produce.
These figures are derived by calculating the stator diameter * 3.14 * stator width.
Here are some examples [numbers are in centimetres squared]:
225.29 1500W Leaf Hub Motor [20.5cm(dia.) * 3.14 * 3.5cm(width)]
131.88 40H Scooter Hub Motor [10.5 * 3.14 * 4.0]
62.01 450W GNG Mid Drive [7.9 * 3.14 * 2.5]
179.35 Mini Conhis Hub Motor [13.5 * 3.14 * 4.2]
98.91 8.5" Scooter Hub Motor [10.5 * 3.14 * 3.0
76.87 eZee Geared Hub Motor [13.6 * 3.14 * 1.8]
OK. Easy peasy, but all this tells me is how much stator surface area is passed by a given magnet for 1 rpm. So I need to factor in a rotational speed to get some idea of power produced, right?
Using the same examples:
225.29 1500W Leaf Hub Motor [20.5cm * 3.14 * 3.5cm] x 652rpm = 146892 [cm.sq. per minute]
131.88 40H Scooter Hub Motor [10.5 * 3.14 * 4.0] x 1000rpm = 131880
62.01 450W GNG Mid Drive [7.9 * 3.14 * 2.5] x 3000rpm = 186030
179.35 Mini Conhis Hub Motor [13.5 * 3.14 * 4.2] x 600rpm = 107610
98.91 8.5" Scooter Hub Motor [10.5 * 3.14 * 3.0 x 1000rpm = 98910
76.87 eZee Geared Hub Motor [13.6 * 3.14 * 1.8] x 937.5 = 72065.625
EDIT: Pretty sure the 1500W Leaf has .35mm lams but we're just going to pretend that it doesn't here...
: )
[RPM is derived from dividing 250hz (the frequency at which a motor with 0.5mm laminations begins to lose efficiency, apparently) by number of pole pairs multiplied by 60 (number of seconds in a minute)]
Ok, so, my question is: Is this an OK way to APPROXIMATE the amount of power produced by a given motor and, if not, why not? I know I'm omitting a bunch of things like magnet thickness, airgap, heat shedding and a whole whack of other details I don't even know about. But it would be neat if I could use numbers like these as a quick benchmark for performance.
What do you guys think?
Kind regards as always.
These figures are derived by calculating the stator diameter * 3.14 * stator width.
Here are some examples [numbers are in centimetres squared]:
225.29 1500W Leaf Hub Motor [20.5cm(dia.) * 3.14 * 3.5cm(width)]
131.88 40H Scooter Hub Motor [10.5 * 3.14 * 4.0]
62.01 450W GNG Mid Drive [7.9 * 3.14 * 2.5]
179.35 Mini Conhis Hub Motor [13.5 * 3.14 * 4.2]
98.91 8.5" Scooter Hub Motor [10.5 * 3.14 * 3.0
76.87 eZee Geared Hub Motor [13.6 * 3.14 * 1.8]
OK. Easy peasy, but all this tells me is how much stator surface area is passed by a given magnet for 1 rpm. So I need to factor in a rotational speed to get some idea of power produced, right?
Using the same examples:
225.29 1500W Leaf Hub Motor [20.5cm * 3.14 * 3.5cm] x 652rpm = 146892 [cm.sq. per minute]
131.88 40H Scooter Hub Motor [10.5 * 3.14 * 4.0] x 1000rpm = 131880
62.01 450W GNG Mid Drive [7.9 * 3.14 * 2.5] x 3000rpm = 186030
179.35 Mini Conhis Hub Motor [13.5 * 3.14 * 4.2] x 600rpm = 107610
98.91 8.5" Scooter Hub Motor [10.5 * 3.14 * 3.0 x 1000rpm = 98910
76.87 eZee Geared Hub Motor [13.6 * 3.14 * 1.8] x 937.5 = 72065.625
EDIT: Pretty sure the 1500W Leaf has .35mm lams but we're just going to pretend that it doesn't here...
: )
[RPM is derived from dividing 250hz (the frequency at which a motor with 0.5mm laminations begins to lose efficiency, apparently) by number of pole pairs multiplied by 60 (number of seconds in a minute)]
Ok, so, my question is: Is this an OK way to APPROXIMATE the amount of power produced by a given motor and, if not, why not? I know I'm omitting a bunch of things like magnet thickness, airgap, heat shedding and a whole whack of other details I don't even know about. But it would be neat if I could use numbers like these as a quick benchmark for performance.
What do you guys think?
Kind regards as always.