What Is Magnetic Field Analysis Software?
Magnetic Field Analysis Software is the use of numerical analysis methods to simulate the magnetic fields generated in electronic devices and other equipment.
Magnetic field analysis software includes time-domain analysis methods, frequency-domain analysis methods, and equivalent concentrated constant network methods.
Magnetic field analysis software is used from the design stage of electronic equipment to avoid interference between electronic equipment. These are called EMC countermeasures.
The magnetic field is reproduced by numerically solving Maxwell’s equations, and reproducing the conditions of the structure of the device and the current to be given to it on a computer.
Uses of Magnetic Field Analysis Software
Magnetic field analysis software is widely used in the design and development of electronic equipment and other products to implement EMC countermeasures.
EMC stands for Electromagnetic Compatibility, which describes the absence of electromagnetic interference or interference, and the design of products to operate properly even when subjected to interference.
With the rapid development of electronic equipment, it is necessary to ensure EMC-free performance immediately on the computer. Therefore, magnetic field analysis software simulations play an important role in the design stage of circuits, circuit boards, and housings.
Types of Magnetic Field Analysis Software
Typical simulation methods used in magnetic field analysis software are either time-domain or frequency-domain analysis methods.
The former includes the finite-difference time-domain method (FDHD), while the latter includes the method of moments (MoM) and the finite element method.
1. Finite-Difference Time-Domain Method
The finite-difference time-domain method is excellent for analyzing transient conditions because the analysis is performed in the time domain. It is characterized by intuitive and easy-to-understand calculations. On the other hand, it requires a large amount of memory and takes a long computation time because a large space is used as the computation target.
2. Moment Method
The conductor to be analyzed is divided into a mesh shape, and the current values of the price blocks are calculated, taking into account the electromagnetic interaction between the blocks. This method is suitable for EMC analysis of uniform conductors. However, it is difficult to model the non-uniform structure of conductors. This method is often used to calculate radiation from antennas.
3. Finite Element Method
This method divides the entire area of the structure to be analyzed into a mesh. This method has the advantage of modeling non-uniform structures, but it is difficult to extend to the calculation of radiation like the method of moments.
Principle of Magnetic Field Analysis Software
This section explains the principles of magnetic field analysis software using the finite-difference time-domain method as an example.
1. Finite-Difference Time-Domain Method
Maxwell’s equations are simplified using the finite-difference method (time division using finite time), and the time response of the electromagnetic field is obtained by numerical calculation. The entire space to be analyzed is divided into a mesh, and Maxwell’s equations and the difference method are applied to each divided block. This method is excellent for modeling the transient response of magnetic fields and inhomogeneous structures.
2. Difference Method
This is one of the discretization methods in which the derivative is replaced by a difference approximation (difference quotient). This method has been used for a long time as one of the numerical analysis methods. The differential equation is called a difference equation when the derivative of a differential equation is replaced by the difference.
In the finite-difference time-domain method, the time response of the electromagnetic field is numerically obtained by expanding Maxwell’s equations into difference equations.
3. Maxwell’s Equations
Maxwell’s equations are the basic equations of classical electromagnetism that explain electromagnetic fields. It consists of four equations explained below:
The first equation is Gauss’s law. It states that the presence of an electric charge generates lines of electric force from its surroundings.
The second equation states that magnetic flux is a loop and that the magnetic flux that springs out always returns to its source.
The third equation is Faraday’s law of electromagnetic induction. It shows that when the magnetic flux changes, an electric field is generated to prevent the change, and an electromotive force is generated.
The fourth equation is Ampere’s law. It shows that when a current flows, a magnetic field is generated around it.
4. Modeling
When conducting an analysis, a model is created by dividing the area to be analyzed into a mesh. The fineness and scale of the mesh affect the accuracy of the analysis.
The finer the mesh is divided, the more accurate the calculation results can be.
On the other hand, this has the disadvantage of requiring high processing power and processing time due to the high computational processing load.
Although it is necessary to set up a mesh with appropriate coarseness, care should be taken because the space between meshes is excluded from the calculation.