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Introduction

Multiphysics simulation is a computational discipline that covers any simulations which combine multiple physical models or multiple simultaneous physical phenomena. For example, combining magnetic, fluid/solid mechanics and thermal transfer using finite element software. Multiphysics typically involves solving coupled analysis systems of partial differential equations using finite element method(FEM).

Many physical simulations involve coupled systems, such as electric and magnetic fields for electromagnetism, pressure and velocity for acoustic, etc…

The first example of Multiphysics simulation solved by JMAG is the Induction heating which combines Magnetic, thermal and mechanical analysis.

 
 

Specific Analysis Types dedicated to Induction Heating and Multiphysics simulations

The following studies can be used for Multiphysics simulation with JMAG:

  • 2D/3D Magnetic Field Analysis (Static, Transient, Frequency)

  • 2D/3D Iron Loss Analysis (Transient, Frequency)

  • 2D/3D Thermal Analysis (Static, Transient)

  • 2D/3D Structural Analysis (Static, Eigenmode, Transient, Frequency)

  • 3D Electric Field Analysis (Static, Frequency, Current distribution)

  • 2D/3D Thermal Stress Analysis (Static, Transient)

Some examples of the results obtained into JMAG after performing these analyses are listed below:
Magnetic flux, flux line, Magnetic field, Flux linkage, Voltage, Current, eddy current distribution, Electromagnetic force, Lorentz force, Magnetostriction force, Joule losses, Hysteresis losses, Iron losses, Dielectric losses, Electric field, Electric potential, Electric Charge, Electric power, Temperature distribution, Heat flux generation, Heat flow, Heat source, heating efficiency, Thermal resistance, Displacement, Deformation, Stress, Strain, Sound pressure and Sound Pressure level.

 

CAD modelling for Induction Heating and Multiphysics simulations

JMAG-Designer has many tools with different methods to create and import CAD geometry for induction Heating and Multiphysics.

  • JMAG-Designer has many tools with different methods to create and import CAD geometry for induction Heating and Multiphysics.
  • Geometry Editor: Create a CAD models directly from JMAG CAD modeler interface.

CDA formats

 
 

Specific features dedicated to Induction Heating

It is the process of heating an electrically conducting a metal by electromagnetic induction, through heat generated in the object by eddy currents. An induction heater consists of an electromagnet, and an electronic oscillator that passes a high-frequency alternating current (AC) through the electromagnet. The rapidly alternating magnetic field penetrates the part, generating electric currents inside the conductor called eddy currents. The eddy currents flowing through the resistance of the material heat it by Joule heating. In ferromagnetic materials like iron, heat may also be generated by magnetic hysteresis losses. The frequency of current used depends on the size of part, material type, coupling (between the work coil and the part to be heated) and the penetration depth.

An important feature of the induction heating process is that the heat is generated inside the part itself, instead of by an external heat source via heat conduction. Thus objects can be heated very rapidly. Induction heating is used in many industrial processes, such as heat treatment in metallurgy, crystal growth and zone refining used in the semiconductor industry, and to melt refractory metals which require very high temperatures. It is also used in induction cooking for heating containers of food.

 

Material modeling

For induction heating analysis, accounting for temperature dependency in the material being heated is important from the standpoint of accuracy. Generally, the problem is that it is difficult to obtain magnetic properties taking account of temperature dependence in magnetic materials. Simplified methods are also needed for analyzing composite materials with complex structure.

Temperature curves

It has been reported that it is important in terms of accuracy to take account of the temperature dependence of the B-H curve when doing analyses of billet heaters that are used, for example, for the shaft of a car. This can serve as a useful reference for the temperature dependence of carbon steel. Induction heating is being used for heat treatment of carbon fiber reinforced polymer composites, which have high mechanical and chemical resistance per unit weight. Issues regarding how to model and simulate an induction heating problems and ways to handle anisotropy material properties for analysis have been treated and developed into JMAG.

 

Mesh modeling

Optimizes local heating, it requires accurate management of the eddy currents concentrating near the surface of the work piece. Our skin mesh function generates mesh and accurately predicts eddy current distribution, which is vital to simulate the high-frequency quenching process. The specialized mesh functions have been developed such as the skin Depth Mesh. This innovative function can be used to generate a layered mesh of a specified thickness on the surface of a part. Firstly, this makes it possible to accurately express offsets in magnetic flux distribution caused by the skin effect, and secondly, to generate an optimal high quality mesh capable of evaluating the effects of eddy currents.

 

Multiple High-Frequencies Induction Heating Analysis of a Gear

Gears are created in such a way that the surfaces of their teeth are hard in order to resist the wear and tear that occurs when they come into contact with the teeth of other gears. these teeth are heated rapidly on only their surface by a high frequency power source using high-frequency induction heating, which is a type of surface hardening method.

analysis of a gear

Two-way coupling simulation between thermal and magnetic field analysis accounting for temperature variations can be setup to handle this king of induction heating model because as a precision component, a gear requires an accurate evaluation of dimensional tolerance due to thermal deformation resulting from induction hardening.

JMAG software offers a magnetic and thermal analysis solutions based on the finite element method that can be successfully applied for design of induction heaters for hardening of leading gear wheel. To handle the detailed phenomena, users can analyse and optimize the induction heater system with its elevated temperature process in order to heat efficiently the gear's surface uniformly, and obtain the optimum heating coil's geometry, arrangement, current frequency and size of parts. So, users will confirm the eddy current losses and temperature distributions of the gear.

temperature and joule loss of a gear

User can set and control multiple frequencies for power supply in magneto-thermal analysis when heating both the gear tip of the wheel and the gear base:

  • Estimation of dual wave properties in high-frequency induction heating
  • Respective losses from different superimposed frequencies can be analyzed by specifying multiple magnetic field analysis.

 

magnetic field analysis

 

 

Induction cooking system

The cooking heater system cooks food by heating a conductive pot body with an induction heating method based on electromagnetic induction.

JMAG software offers a magnetic and thermal analysis solutions that uses the finite element method for studying and optimizing the induction cooking heater for heating efficiency. User can simulate the magnetic flux density surrounding the heater that uses high frequency induction heating. He can find the optimal ways to control the leakage flux around the cooking system and evaluate the temperature distribution on the iron pot. User can also estimate the uniformity of temperature distribution on the pot bottom which can be led from the loss distribution, and confirm if no flux leakage is causing malfunctioning of his electric devices surrounding the cooking system by checking the 3D flux lines.

induction cooking system

distribution on cooking system

 
 
 

Specific features dedicated to Multiphysics simulations

 

Small Multiphysics

  • Centrifugal Force Calculation

2D magneto-structural analysis can be ran to confirm the mechanical behaviour of the electric machine. The example below shows the Interior Permanent Magnet (IPM) machines designed to minimize the amount of flux traveling between magnets by using very thin bridges. However, mechanically, a thin bridge may not be able to withstand the centrifugal forces in the rotor. So, sample 2D model can be performed just by adding the “Centrifual Force Calculation” condition into the magnetic analysis.

centrifugal force analysis

 
 
  • 1D Thermal Circuit calculation

2D magneto-thermal analysis can be performed by easily calculating the temperature evaluation during motor operation using a 1D heat equivalence circuit. A simple temperature increase prediction is available in magnetic field analysis. No additional license is requiring, usable only with a magnetic field analysis license.

thermal circuit calculation

 

 

JMAG Coupled Analysis

Available coupled analysis for Multiphysics simulations that POWERSYS performed by using only the JMAG interface listed below:

JMAG coupled analysis

 

 

  • Thermal stress analysis

Thermal Stress study can be setup by combining the magnetic analysis (losses, electromagnetic forces), thermal analysis (losses are set as heat generation, temperatures) and structural analysis (deformation, stress depend on temperature).

  • Coupling analysis of loss (magnetic), thermal, stress
  • Thermal stress study requires magnetic, thermal, and structural analysis licenses

 

thermal stress analysis

 

 

JMAG Coupling Interface (Co-simulation)

Multi-physics simulation is becoming a requirement for design, optimization and development of the new and future electromechanical systems.
JMAG provides multi-physics solutions using different CAE software interfaces. In this case, the available coupling interfaces for Multiphysics simulation that POWERSYS performed by coupling JMAG interface with other CAD/CAE software’s are listed below:

JMAG coupling interface

 

 

  • JMAG and ABAQUS coupling

The link between JMAG and ABAQUS brings a new Multiphysics solution for our users in the simulation of Fluid-Structure Interaction. POWERSYS can advise and support all users who want to setup a Multiphysics simulation by coupling JMAG with Simulia ABAQUS.

JMAG vs ABAQUS

 

  • The direct interface for Abaqus and JMAG-Designer has been improved by JSOL.
  • JMAG allows large deformation analysis to be performed with electromagnetic force.
  • The time intervals for Abaqus' explicit method procedure (Dynamic Explicit), which is required in a large deformation analysis, are too short in the transient response magnetic field analysis, and when these intervals are used in a magnetic field analysis, the number of calculations increases enormously. The subcycling coupling is now supported, and a two-way coupled analysis can be performed without requiring the time intervals to match in Abaqus and JMAG-Designer.
  • Calculations are more stable, and electromagnetic force and displacement can be passed with the required timing, enabling a coupled analysis with large deformations, such as an electromagnetic forming analysis. The deforming part due to electromagnetic force can now be captured with high precision.

 


 

Co-simulation Case 1: Electromagnetic Metal Forming analysis

electromagnetic metal forming analysis

disp and temp abaqus CSE heat and force

Others example

others example

 

 

  • JMAG and Star CCM+ coupling

The link between JMAG and STAR-CCM+ brings a new Multiphysics solution for our users in the Computational fluid dynamics (CFD) domains. POWERSYS can also advice and support all users who plan to perform a Multiphysics simulation by coupling JMAG with Star-CCM+.

  • With a link to STAR-CCM+, magnetic performance and thermal effect can be evaluated in detail accounting for thermal-fluid phenomena that cannot be modelled in JMAG
  • STAR-CCM+ and JMAG coupling interface provide two-way analysis environment

 

JMAG vs Star CCM+

 

 


 

Co-simulation Case 2: Cooling Analysis of Reactor

  • With the miniaturization of motors and such, the operating frequency of the power control unit (PCU) equipped with EV/HV has reached tens of kHz.
  • To pursue limit design, magnetic performance evaluation is required using a detailed analysis accounting for not only reducing loss, but also an environment in PCU.
  • Prediction of accurate hot spot using CSE achieved thermal countermeasures including cooling system of the substrate.

 

Cooling analysis of reactor

 


 

Co-simulation Case 3: Cooling System of EV/HV Drive Motor

  • Since PM motors are mainstream for EV/HV drive, high-power consumption density has become more and more in demand.
  • Characteristics of the permanent magnet change greatly depending on temperature.
  • The cooling system is extremely important to maintain motor performance.
  • By linking with detailed air cooling analysis, a performance evaluation accounting for temperature rises during motor operation was achieved.

 

Cooling system of EV/HV drive motor

 


 

Co-simulation Case 4: Temperature Analysis of Oil-Immersed Transformer

This case shows the heat distribution in a magnetic field analysis for a forced circulation type oil-immersed transformer after mapping the thermal distribution to thermal fluid analysis model, and then obtain the temperature by handling the insulating oil as a fluid in a thermal fluid analysis.

Temperature analysis of oil-immersed transformer

The software JMAG is developed by JSOL Corporation and distributed in Europe and USA by Powersys.
JMAG is simulation software developed by the JSOL Corporation for the design and development of electrical equipment’s.

 

Today, numerical methods are increasingly used for the solution of electromagnetic fields and there is a variety of commercial computer programs based on the finite element method (FEM) used for electric machine design. JMAG are dedicated tool for this king of purpose, it’s useful during the FEA simulation and optimization process of an electrical machine because it provides more advanced methods to assess more accurately the final optimal characteristics of the design. This innovative software offers very suitable solutions for motor designers, engineers, and manufacturers, as well as graduate students, and academic researchers, and it covers the design and design-related issues, modeling and simulation, engineering studies, testing process, and performance characteristics of electric machines.

 

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