transformer modeling webinar1
TRANSCRIPT
Transformer and Inductor
Modeling
© 2012 COMSOL. COMSOL and COMSOL Multiphysics are registered trademarks of COMSOL AB. Capture the Concept,
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Magnus Olsson
COMSOL
• Overview of COMSOL Multiphysics
• Inductor modeling
• Transformer modeling
• Q&A
Agenda
The Multiphysics Approach
Multiphysics in Transformers and Inductors
Inductive coupling
Magnetic saturation
Skin effect
Resistive and Inductive heating
Fluid flow and
convective cooling
Magnetostriction
Capacitive coupling
Noise and vibration
Thermal expansion
External loads and circuits
Devices and Industries
• Transformers
• Inductors
• Litz wire
• Motors/Actuators
• Generators
• Sensors
• Loudspeakers
• Transducers
• ... many more
• Aerospace
• Audio
• Automotive
• Electrical Power
• generation
• Distribution
• Electronics
• Steel and Metal
• ... many more
Types of Devices Industries
Poll Question 1
Essentials for Inductor Modeling
• Inputs
– Device geometry
– Material properties
– Material orientation
– Coupling with other physics?
– Appropriate set of boundary conditions
– Determine analysis type
• Outputs
– Frequency Domain
• Inductive coupling
• Inductive loss / skin effect
– Stationary response
• Static saturation
– Time Domain
• Dynamic saturation
Time to solution increases
2D or 3D?
• High numeric
precision
• Easy drawing
• Quick results
• Resolve skin effect
• Resolve details -
many individual
turns
• Full geometry
• Use 3D CAD
• ”3D effects”
• 3D Visualization
• Homogenized
coils / materials
• Demanding
• Difficult to resolve
• Complementary
2D 3D
Modeling features
• Domain level features
• Boundary level features
Example: Inductive Heating
• 3 turn primary coil
– water cooled
• Secondary
– solid copper cylinder
• Embedded in FR4
Model parameters
Model set up
Results
Coil resistance
Modeling option:
Convective boundary heat flux
Poll Question 2
Coil features and skin effect
r0
2
(Iron) mm 34.01012.1
4000
(Aluminum) mm 1210774.3
1
(Copper) mm 9105.998
1
7
7
7
r
r
r
• Multiturn Coil Domain (no skin effect)
• Sigle Turn Coil Domain (solid)
• Coil Group Domain (solid, many turns)
Boundary layer meshing helps resolving the skin depth
by progressive growth from boundaries
Use triangular and/or mapped meshing elsewhere.
Meshing tips
Transformer with skin effect
Frequency Sweep
Results for 1Hz
Results for 50Hz
Circuits
Simple example
Add circuit elements
with settings
Single Phase E-core Transformer
E-core transformer
E-core
Primary winding
Secondary winding
• Full non-linear time domain analysis at a constant
frequency of 50 Hz is modeled.
• Non-linear magnetic material (with saturation effect) is
used for magnetic core.
• The primary and secondary windings are modeled as
homogenized current carrying domains. Individual wires
are not resolved.
• Skin effect in windings and core is not included.
Model Features
• The model assumes that the primary and secondary windings are made
of thin wire and multiple number of turns.
• If the wire diameter is less than the skin depth and there are “many”
turns, then the coil can be assumed to be a homogeneous current
carrying domain.
Assumption – Coil with thin wire
Coil with thin
wires and
many turns
≈
Equivalent
homogenous
current-carrying
domain
Results (Case 1)
• Number of turns in the coils Np = Ns
• Only induction but no step up/down of voltages
Results (Case 1)
• Ip and Is are different by roughly 4 orders of magnitude
which is also the difference between Rp and Rs
• Is/Ip ≠ Rs/Rp because Is depends only on Vis but Ip
depends on both Vip and Vp
Magnetic flux density distribution (slice plots)
Magnetic flux density distribution
Arrow plot showing
magnetic flux
concentration through
transformer core
Case 2 – Step down transformer
• Global Definitions > Parameters - Rp = Rs (to visualize step down
simulation)
- Np/Ns = 1000
• Model 1 > Definitions > Variables 2 - Vp (peak) = 25000 volt
Results (Case 2)
Vip/Vis = Np/Ns = 1000
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