Thermal issues in the design of permanent magnet based electrical motors
36 poles brushless DC motor with NdFeB permanent magnets.
Problem Type:
A nonlinear plane-parallel problem of magnetostatics and heat transfer.
Geometry:
Stator
Name |
Parameter |
Value |
Stator internal diameter |
D |
400 mm |
Stator tooth zone external diameter |
DS |
430 mm |
Stator external diameter |
DE |
446 mm |
Stator axial length |
LE |
300 mm |
|
Rotor
Name |
Parameter |
Value |
Rotor shaft diameter |
DH |
355 mm |
Rotor core diameter |
DN |
386 mm |
Rotor external diameter |
DR |
398 mm |
Rotor axial length |
LX |
300 mm |
|
Given:
DC motor power P = 12 kW
Voltage U = 600 V;
Speed Nn = 200 rpm;
Torque Mn = 573 N·m;
Insulation class: F (155°C);
Steel power loss (50 Hz, 1.6 T) pf = 5 W/kg;
Air temperature T = 40°C.
Problem:
Which temperature will afford the magnets under the following working conditions:
Cooling: natural / forced
Load: permanent / periodic (50%)
Results:
Rotor final temperature.
|
Natural convection
Periodic load |
Natural convection
Permanent load |
Forced convection
Periodic load |
Forced convection
Permanent load |
Winding |
335°C |
375°C |
142°C |
155°C |
Magnets |
335°C |
385°C |
125°C |
140°C |
Hub |
342°C |
395°C |
133°C |
147°C |
 
One has to keep in mind the use of forced air circulation as a normal procedure. The controller could offer additional options to pose a limit to currents and/or temperatures.
Student's version |
Professional version |
- |
dc_motor.zip (16925 nodes) |
|
