• The Challenge EM Simulation

    The Challenge EM Simulation

    Are you faced with such tasks: Are innovations permanently required? Measurements and experiments are not satisfactory? Is the Physics Complex? Time is short? Then we are here for you! On these pages we demonstrate MAGNETICS, an outstanding electromagnetic FE solver product that we develop for you. MAGNETICS, integrated in NX / Simcenter or as standalone, well known as NX Magnetics, is a comprehensive FEM software package to simulate and optimize electromagnetic devices. It is used by industry and science and either Read More
  • Circuit Breakers

    Circuit Breakers

    Outstanding Features for the coupling of electromagnetic, elasticity, motion and thermal allow realistic simulations of circuit breakers and switchgears. The animation demonstrates the FEM simulation of a low-voltage circuit breaker. A voltage is applied to a coil (below), whereupon the plunger is pulled into the coil. The four contact bridges (above) are connected to the plunger and then press on their contact partners, whereupon the AC current flows through the lines. The Lorenz forces lead to small mechanical vibrations with Read More
  • High-Frequency

    High-Frequency

    Thanks to the capability of a full wave solver, the analysis of antennas, waveguides or microwave ovens is another application area for electromagnetic simulation with Magnetics for NX/Simcenter. The picture shows as an general example the model of a microstrip patch antenna and its electric field result. Such antennas are becoming increasingly useful because they can be printed directly onto a circuit board. They are becoming very widespread within the mobile phone market. Patch antennas are low cost, have a Read More
  • Individual Motor Designs

    Individual Motor Designs

    The application to simulate is a linear motor to be used in a future magnetic levitation railway. We publish this with kindly permission by HARDT GLOBAL MOBILITY. Download as PDF Read More
  • Transformers

    Transformers

    This example deals with a three phase medium power transformer. Goal is to find the main characteristics e.g. power and efficiency under normal operating conditions. Download as PDF Read More
  • Lightning Strikes

    Lightning Strikes

    Lightning strikes that occur in wind turbine towers can be analyzed to help for dimensioning of arrestors and to estimate the electric and magnetic field strengths that appear.This example shows how this kind of analysis can be done in Magnetics for NX/Simcenter. The tower is made of steel bars that conduct the lightning current down into the ground. Inside is a cable with an resistor in which we want to analyze the specific energy. Download as PDF Download NX Files Read More
  • EMC, Electromagnetic Compatiblity

    EMC, Electromagnetic Compatiblity

    This example shows a FEM analysis of a Circuit Breaker that is placed in a carbon fiber box. Induced eddy currents and the shielding effect are investigated. Download as PDF     Download NX Files Video Read More
  • Customer Presentations

    Customer Presentations

    Following we demonstrate some presentations or papers published by industrial users and ourselves. Temperature Field and Power Loss Calculation With Coupled Simulations for a Medium-Voltage Simplified Switchgear. Electrica, 23(1), 107-120, 2023, A. Efe Şeker, B. Çelik, D. Yıldırım, E. Aslan Sakacı and A. Deniz. Optimierung eines PMSM Motors bezüglich Drehmoment und Ripple mit NX Magnetics und HEEDS. Presentation of Peter Binde at 2022 PLM Connection. Electrostatic discharge simulation using a GPU-accelerated DGTD solver targeting modern graphics hardware. COMPUMAG 2021. Jan. Read More
  • 1
  • 2
  • 3
  • 4
  • 5
  • 6
  • 7
  • 8

3 Phase Transformer

This example deals with a three phase medium power transformer. Goal is to find the main characteristics e.g. power and efficiency under normal operating conditions.

Download as PDF

Initial Situation

Find Transformer Characteristics

This example deals with a three phase medium power transformer. Goal is to find the main characteristics e.g. power and efficiency under normal operating conditions through FEM simulation. Also of interest is the shielding effect of the housing. In further simulations one could also simulate for power up behavior and electric short circuit conditions. Also acoustics and thermal conditions may be of interest and can be simulated.

The following picture shows definitions of the phase currents

Picture: Scheme of TransformerPicture: Scheme of Transformer

  • Three Coils: High Voltage (active), Medium Voltage (active) and Low Voltage (passive).
  • Three Phases: Phase A, Phase B and Phase C.
  • Magnetic Core: With non-linear Material.

The CAD model for this transformer is set up as a half model that is sufficient for doing FEM simulations.

Picture: CAD Model of TransformerPicture: CAD Model of Transformer

Main characteristics for this task are these:

  • Dimensions: Transformer 200 mm x 600 mm; and Housing 300 mm x 800 mm,
  • Coils: Stranded Coils with 230 (HV blue), 115 (MV cyan) and 55 (LV green) Windings,
  • Shielding: Nu-Metal Shielding (red) with a thickness of 5mm,
  • Surrounding Air: Sufficiently large Volume with surrounding Air (transparent blue).

 

Appropriate Method

3D FEM Model with Circuit

To set up a 3D simulation the half CAD model is meshed with either hexahedral or tetrahedral elements or mixtures of these. We use mostly hexahedral elements because of the quite simple CAD shape of the core and also the coils. The following picture shows this mesh.

Picture: FEM Model of TransformerPicture: FEM Model of Transformer

In a next step a housing is modeled also in CAD and meshed in the FEM environment of Simcenter. The material type mu-metal for best shielding effects (red) with a thickness of 5mm is applied.

Picture: Housing of Transformer (red)Picture: Housing of Transformer (red)

The surrounding air is modeled as a sufficient large sphere volume (transparent blue in next picture).

Picture: Surrounding air (transparent blue) and corresponding air mesh

Picture: Surrounding air (transparent blue) and corresponding air mesh

Picture: Surrounding air (transparent blue) and corresponding air mesh

Finally a circuit network is defined to connect the coils in the desired way. Corresponding to the following two pictures different types of connections or cables are used:

On the primary side of the transformer we use these:

  • Cable Networks: Cable connectors network between HV (blue) and MV (cyan) coils
  • Cross Connectors: Switchable resistance between respective HV and MV coils (for short circuit simulation only)
  • Current Cable: Connectors for imposing the respective currents IA, IB and IC.

Picture: Circuit network on the primary sidePicture: Circuit network on the primary side

On the secondary side of the transformer we use these:

  • Cable Networks: Cable connectors network between LV (coils)
  • Resistive Cable: Resistive RL cable connectors between LV coils and Mass

Picture: Circuit network on the secondary sidePicture: Circuit network on the secondary side

 

Result

Power Up, Normal Operation, Short Circuit

The setup of the solution is as follows:

Phase 1: Normal operation

  • HV and MV coils are still connected via a low resistance cables.
  • HV and MV coils are driven by a constant driving current.
  • LV coils are connected via high resistance cable connectors.

This general procedure is the same for the transient and frequency simulations.

Following the results of power and efficiency for normal transformer operation are shown.

Picture: Power ResultPicture: Power Result

  • Increasing Power: Between 0 and 8 Ohms
  • Maximum Power: Peak appears at (roughly) 8-10 Ohms
  • Stagnation:  At higher loads >35 Ohms

Picture: Efficiency ResultPicture: Efficiency Result

  • Maximum Efficiency: Peak appears at (roughly) 1-3 Ohms
  • Decreasing Efficiency:  At higher loads >3 Ohms

A result of the magnetic flux density over time in the core can be seen in the following picture.

Picture: Magnetic Flux Density and Coil CurrentPicture: Magnetic Flux Density and Coil Current

Following to phase 1 there can be solutions for two additional simulations which are not shown here.

Phase 2: Power up (results not shown here)

  • HV and MV coils are connected via a low resistance cables.
  • HV and MV coils are driven by a non-constant driving current.
  • Until a first time T1 the driving Current is increased to simulate the powering up.
  • LV coils are connected via high resistance cable connectors.

Phase 3: Short Circuit (results not shown here)

  • HV and MV coils are still connected via a low resistance cables.
  • HV and MV coils are driven by a constant driving current.
  • After a second time T2 the high resistance cable connector connecting the LV coils are rapidly decreased to simulate a short circuit.

Conclusion: It has been shown that using these methods in NX Magnetics it is simply possible to analyze transformers, find power and efficiency. In further simulation types there can be checked for temperatures, structural stresses and acoustics.

We use cookies

We use cookies on our website. Some of them are essential for the operation of the site, while others help us to improve this site and the user experience (tracking cookies). You can decide for yourself whether you want to allow cookies or not. Please note that if you reject them, you may not be able to use all the functionalities of the site.