Mathematical Problems in Engineering / 2013 / Article / Tab 3

Research Article

Design and Analysis of a Novel Speed-Changing Wheel Hub with an Integrated Electric Motor for Electric Bicycles

Table 3

Rated conditions, magnet’s material properties, and design results for an exterior-rotor BLDC hub motor.

ItemsSymbolValues

Rated conditions
Rated power (W) 350
Rated speed (rpm) 300

Magnet’s material properties (NdFeB BNP12)
Remanence (T) 0.76
Relative permeability 1.26
Coercivity (A/m) −480000
Direction of magnetizationParallel
Magnet thickness (mm) 2
Magnet arc (degree) 27

Design results
Number of phases 3
Number of magnet polesP 12
Number of armature slotsS 18
Air-gap length (mm)g 0.5
Slot opening (mm) 2.6
Inner radius of rotor (mm)Rri50.5
Outer radius of rotor (mm) 60
Inner radius of stator (mm) 20
Outer radius of stator (mm) 50
Tooth width of stator (mm) 7
Shoe depth (mm) 2
Shoe ramp (degree) 0
Number of coils per armature tooth (turn) 54
Stack length (mm)L 80
Rated phase current (A) 8.3

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