Magnetic field simulation in the air gap of DC electric motor - QuickField simulation example
In the lab air space is modelled by the current layer ef, magnetic permeability of steel assumed to be infinite. Problem field is replaced by the sheet of conducting paper of proper shape (abcdefg). Obtaining the lines of magnetic field is replaced by the lines of equal electric potential in the conducting sheet. This replacement is correct, as the picture of the field H in the air and field U in the sheet looks the same. Current flows in at line ef and goes out from line ab. Lines of equal electric potential are measured by digital voltmeter.
How to find air gap magnetic field in DC motor?
Answer Typical applications Geometry
Given
Task
Solution
Results
Engineering question
Set up a plane-parallel QuickField DC Magnetics problem for a DC motor air gap and evaluate magnetic field distribution from computed field results.
DC motor air gaps, commutator motors, motor pole assemblies
Download
Simulation problem
Problem Type
Liner plane-parallel magnetostatic problem.
Air region is defined by contour abcdefg. Dimensions: ab=2 mm, ag=32o, cd=68 mm, bc=45o, de=30o, ef=55 mm. Action of other parts of the motor is modeled by boundary conditions.>
Relative magnetic permeability of steel of rotor and stator μ=1000.
Relative magnetic permeability of air μ= 1.
Current density in the coil j=1 A/mm².
Electric power of motor 45 kW.
Draw the lines of magnetic field in DC electric motor in the non-ferromagnetic region. Calculate pole dissipation coefficients for two formulations. First - the coil is defined by current distribution, the magnetic permeability of steel is finite. Second - simplified formulation: steel assumed to be with infinite permeability and the coil is modeled by current layer.
Flux density in DC electric motor:
Model type
Leakage flux
Full flux
Ratio
Realistic model
1.11 mWb
52.93 mWb
0.021
Simplified model (laboratory unit)
3.39 mWb
78.87 mWb
0.043
Related examples