Complex physical phenomena in reality need to be tackled from multifaceted approaches including magnetic, thermal and structural aspects in product design. However, when these designs are performed by each division in most cases, a need to fulfill the demand for the trade-off for each request item may cause a lot of hassle when trying to obtain optimal design values. To solve this problem, a cooperated/coupled analysis simulation via CAE dealing with complex phenomena would be an effective measure, but users also tend to hesitate to use this due to prioritizing preliminary learning of each analysis step.
The Multiphysics function newly introduced for Ver. 13 allows even magnetic circuit designers to easily handle an analysis taking into consideration the impact of both centrifugal force and heat (small multiphysics).
We have also added a new level on the JMAG-Designer treeview for coupling analysis functions, presenting a comprehensive coupling analysis environment that's easy to use.
Vibration analyses can now also handle items such as vibration phenomena due to having added an analysis function to the time region.
With the concept of multiphysics analysis functions that anybody can use easily, there is a small multiphysics function that enables coupling analyses accounting for centrifugal force analysis or heat during drive time in a magnetic field analysis.
1. Magnetic Field Analysis/Centrifugal Force Calculation
Centrifugal force can be calculated when concurrently running a magnetic field analysis for motors (Figure 7). Electric/magnetic circuit design such as torque and induced voltage under the specified rotational speed can be examined besides strength design to check if it has sufficient robustness to withstand the centrifugal force. Furthermore, the function to render and check physical quantity concurrently based on different phenomena such as stress/displacement distribution and magnetic flux distribution helps us to understand the phenomena in an objective manner.
Fig. 7 Mises Stress Distribution of IPM Motor Rotor
2. Magnetic Field Analysis/ Thermal Equivalent Circuit Calculation
What is vital in a thermal analysis is heat exchange and heat release phenomena through parts which are not modeled in the magnetic field analysis, such as the bobbin and case. Detailed modeling which is often required in the magnetic field - thermal coupled analysis was an encouraging factor for users to perform an analysis.
In the newly created magnetic field-thermal coupled analysis using the heat equivalent circuit, settings in the heat equivalent circuit from the circuit editing screen for the magnetic field analysis enables an analysis taking into account the heat generation phenomena due to copper and iron losses. This shows, without using a complicated 3D thermal model and by employing a heat equivalent circuit, how increasing the coil heat generation and resistance values lowers the torque (Fig. 8). This analysis can be specified and run from a magnetic field analysis, allowing even non-experts such as electric/magnetic circuit designers to easily handle an analysis taking into consideration the heat generation.
Fig. 8 Easy Evaluation of the Heat Generation Effect using Heat Equivalent Circuit
Thermal Stress Analysis Study
Heat generation phenomenon due to factors such as eddy current brings structural deformation of objects due to thermal stress, as well as has an impact on the physical property value such as electrical conductivity.
With the thermal stress analysis study, if the coefficient of thermal expansion in material properties is defined, it's possible for the temperature distribution as a load creating heat that outputs stress distribution and displacement distribution (Fig. 9). For conductors like bus bars that are subject to heat deformation in large currents, we provide an effective evaluation method.
Fig 9 Temperature Distribution and Thermal Deformation caused by Eddy Current Loss as a Heat Source
New Framework for Coupled Analyses
1. Direct Execution of Coupled Analysis
A coupled analysis combines multiple analysis types such as magnetic field analysis and thermal analysis, but conventional JMAG-Designer did not support a framework for the coupled analysis and from Ver. 13 there is a new framework for coupling analysis. Preparing a new hierarchy called the analysis group in the new framework, magnetic field analysis studies and thermal analysis studies which are necessary for a coupled analysis are collectively managed within a group. This framework also supported parametric analyses during coupled analyses, greatly enhancing operability during coupled analysis.
Fig. 10 Adding Analysis Group
2. Geometry data sharing between different analysis types
Target parts to be analyzed in the coupled analysis differ depending on the magnetic field analysis, thermal analysis and structural analysis. For example, in the high frequency induction heating, although heating coils are modeled for the magnetic field analysis to handle work piece's heat generation phenomena, only work piece is handled without modeling the heating coils for thermal analysis. Nonmagnetic objects which are omitted in the magnetic field analysis will be included as targets in the structural analysis.
As requirements differ regarding part data for coupled analyses or analysis types like this, each study is divided up into its own different solid model.
Ver.13 provides the shared solid model under new coupled analysis framework, which was divided by each analysis type in earlier versions (Fig. 11). Depending on the analysis type, parts not needed for an analysis can be directly controlled from the JMAG-Designer main window. For this reason, as a CAD model is a convenient function as it enables selection of the necessary parts for each particular type of analysis, so preparing a single, detailed, solid model in advance it will ensure there is enough for the geometry.
Fig. 11 Data Sharing in the Magnetic Field-Thermal Coupled Analysis (Gear Quenching)
Vibration Transient Analysis
A transient response analysis function is added to the Ver. 13 vibration analysis, a structural analysis module (DS).
However, there are many cases requiring response sensitivity to a more instantaneous vibratory force of the type that can only damage equipment instead of a steady vibration phenomena. Even for users who deal with the electric/mechanical system, there is an increasing demand for acquiring a real time response of stress and displacement to the transient changes based on the electromagnetic phenomena.
This newly added new transient response analysis function enabled users to grasp stress and displacement variation overtime depending on the electromagnetic force generated instantly (Fig. 12).
Fig. 12 Variations in Suction Core Vibration Speed due to Moving Electromagnet
Vibration Transient Analysis