2. 2
Global definitions
Parameter
Numeral
Fixed
Used for parameter sweep
Variable
Can change during simulation
To simplify expressions and operators
Function (Versus time/parameter/etc)
Waveform/signal/etc
root >
8. 8
Physics
Magnetic Fields (mf):
Dependent variable: magnetic vector potential (A)
Full field / Background field
Nearfields
Powerful coil analysis
Not for static calculation (or you will need non-zero conductivity)
Magnetic Field Formulation
Dependent variable: magnetic fields (H)
Good for time-domain magnetic modeling of materials
with a strongly nonlinear E-J characteristic such as superconductors
Magnetic and Electric Fields
Dependent variable: magnetic vector potential (A) & electric potential (V)
Good for static calculation
Coil analysis
Electromagnetic Waves, Frequency Domain (emw)
Dependent variable: electric fields (E)
Time-harmonic electromagnetic field distributions
Wideband analysis
No coil analysis
Components > Add Physics
9. 9
Background medium
Infinite Element Domain
Background
Null
Definition> Infinite Element Domain
Infinite Element Domain
Background (Air)
Null
Air spec. for physics “mf”
10. 10
Define sources (Tx)
Coil
Multi/single turn
Excited by current/voltage
Set excitation by V, I or a circuit
External current density
Surface current
Edge current
Lumped Port
Between two PEC boundaries
Faster computation
Magnetic fields > Coil
11. 11
Define receptors (Rx)
Coil
Multi/single turn
Set excitation to zero volt
Lumped port
Define conductive material in Materials
In this case, make sure to make fine meshing so that you can measure
induced currents using “Derived values” (explained in post-processing)
Magnetic fields > Coil
Magnetic fields > Lumped Port
13. 13
Define impedances
Lumped element
Uniform / Cable / User defined
Par/Ser RLC
Effective conductivity (define in Materials)
1
𝜎 𝑐𝑢
𝑙𝑒𝑛𝑔𝑡ℎ
𝑐𝑟𝑜𝑠𝑠 𝑎𝑟𝑒𝑎
+ 𝑗𝜔𝐿 𝑒𝑥𝑡 +
1
𝑗𝜔𝐶 𝑒𝑥𝑡
→
1
𝜎 𝑒𝑓𝑓
𝑙𝑒𝑛𝑔𝑡ℎ
𝑐𝑟𝑜𝑠𝑠 𝑎𝑟𝑒𝑎
𝜎𝑒𝑓𝑓 =
1
1
𝜎 𝑐𝑢
+ 𝑗𝜔𝐿 𝑒𝑥𝑡+
1
𝑗𝜔𝐶 𝑒𝑥𝑡
×
𝑐𝑟𝑜𝑠𝑠 𝑎𝑟𝑒𝑎
𝑙𝑒𝑛𝑔𝑡ℎ
Lumped element
Coil (PEC)
Coil (PEC)
Usually
faster computation
…
Magnetic fields > Lumped element
14. 14
Nonlinear materials
First, add a nonlinear material
Then, add a new “Ampère's Law” for the nonlinear
core with magnetic field from the BH curve
16. 16
Studies
Each study includes at lest 1 step, such as:
Coil Geo. Analysis
Stationary (DC)
Frequency domain
Time domain
You can add several parameter sweeps to your study
You may change the solver configurations, e.g.:
Iterative
Direct
root > Add Study
17. 17
Parameter sweep
Adding parameter sweep to the Study
Study extensions
Adding parameter sweep without adding!
Study > Parametric Sweep
18. 18
Optimization
First, add Physics “opt”
Define parameters in Global Control Variables
Add and set objectives
Do NOT define optimization parameters is Pa
rameters/Variables
Then add Optimization to the Study
You may add Global Inequality Constraint
20. 20
Results types
Numeral
• Derived values
• Tables
1D plot
• X-Y plots
• Smith charts
• Cut lines
2D plot
• Single slice
• Cut planes
3D plot
• Multi-slice
DataSets
Results > Data Sets
Solution
21. 21
Variable types in Comsol
This is a typical variable:
You can search among valid variables:
You can use Matlab syntax in Comsol
Comp1.mf.normH
Component’s name Physic’s
name
Variable’s
name
NecessaryNot necessary
22. 22
Buckle down,
do it yourself.
And feel free to ask me your questions!
meemar@gmail.com