Hello,
I'm investigating the use of Induction dd hub motors, and would like to know more about the advantages and drawbacks vs PSMS motors. I found this paper quite intersting: https://pdfs.semanticscholar.org/bc07/e5e0273735ab4b657603955a88d7bb0b70fa.pdf
Basically, the main drawback of direct drive hub motors are their narrow optimal efficiency spectrum. Each PSMS is designed to work at a given RPM, anything outside that range will significantly decrease efficiency, and hence lead to lower battery range. Just drive a DD motor uphill, and than a geared hub or a mid drive and you'll see for yourself.
One possibility would be to use an induction motor, and vary both magnetic fields according to usage. Strong overdrive a start for increased torque, and weak fields at high speed to decrease drag.
Of course induction motors come with a lot of drawbacks, like more weight (for the second coiling), overheating issues (because you pump power through 2x coils) and lower efficiency than PSMS (because you have to power 2x coils).
So the main question would be: would the increase in efficiency do to varying magnetic fields offset the drawbacks ?
I'm investigating the use of Induction dd hub motors, and would like to know more about the advantages and drawbacks vs PSMS motors. I found this paper quite intersting: https://pdfs.semanticscholar.org/bc07/e5e0273735ab4b657603955a88d7bb0b70fa.pdf
Basically, the main drawback of direct drive hub motors are their narrow optimal efficiency spectrum. Each PSMS is designed to work at a given RPM, anything outside that range will significantly decrease efficiency, and hence lead to lower battery range. Just drive a DD motor uphill, and than a geared hub or a mid drive and you'll see for yourself.
One possibility would be to use an induction motor, and vary both magnetic fields according to usage. Strong overdrive a start for increased torque, and weak fields at high speed to decrease drag.
Of course induction motors come with a lot of drawbacks, like more weight (for the second coiling), overheating issues (because you pump power through 2x coils) and lower efficiency than PSMS (because you have to power 2x coils).
So the main question would be: would the increase in efficiency do to varying magnetic fields offset the drawbacks ?