Currently, however, all analyses in FEMM are of mechanically static configurations. An induction machine with a moving rotor with can be modeled using a relatively simple circuit model. The purpose of the static FEMM analyses is then to identify the parameters in the circuit model.

This circuit model can then be used under a wide variety of conditions e. Although circuit parameters can often be approximated by closed-form expressions in explicit terms of the motor geometry, the point of identifying these parameters via finite element analyses is to validate the approximations and simplifications that inevitably must be made in the derivation of the analytical design formulas.

The purpose of this example is to demonstrate, in a relatively step-by-step manner, how one goes about building and identifying an induction machine model using FEMM.

This example will specifically consider a V, 50 Hz, 2 HP motor. The files referred to in this article are available here. A reasonable model of an induction motor must first be identified before the parameters in that model can be deduced. A reasonable model to assume might be the one pictured in Figure 1. This model is meant to represent one phase of an induction machine operating in steady state i.

In this model, all leakage is lumped on the stator side of the circuit in inductance L l. The coupling to the rotor and the currents on the rotor are represented by parallel paths through the inductor, Mrepresenting the inductance of the magnetic circuit linking the rotor and stator and through resistor R rrepresenting work dissipated as heat in the rotor and delivered to the load as mechanical power. In this circuit equation, v represents the phase voltagethe RMS voltage applied across each phase of the machine, and i represents the phase currentthe RMS current through each phase of the machine.

These are important distinctions, because depending on how the motor is wired i. To remove any ambiguity, this note will deal with a model represented exclusively in terms of phase current and phase voltage. Figure 1: Simple steady-state per-phase induction motor model.

Now that we have a model of the motor, we can use this model to derive some useful relationships between phase current, phase voltage, and torque. The impedances of the motor can be added together in the same fashion as resistors, using the same rules for parallel and series configurations. In case, the total impedance of the motor could be represented by Zwhere:. A result that will be useful later on in the note is the flux linkage of any particular phase.

Dividing by current, we can obtain a slip frequency-dependent inductance. This result can be separated into real and complex components as:. The dependency of this inductance on slip frequency provides us with a mechanism that we will later use to identify motor parameters.This course covers basic design principles of electrical machines. You will be able to design main parameters of an electric machine such as magnetic and electric loading, number of slots, winding dimensions.

Thermal and structural design of electric machines will be also covered. You will use FEA software and optimization tools to determine the best parameters. For details of the projects, please visit the GitHub page. Please choose one topic from below, and fill in the online spreadsheet to book your topic and date. One topic should be presented only once. First-come first served. You will be evaluated by you classmates using the following score sheet.

The main idea of this project is to get you familiar with FEA finite element analysis methods. You have the following options:. You are supposed to model the induction machines you designed in the 2nd projects. The outputs of the projects are as follows:. If you are tired of designing induction machines, you have another option: to design a direct-drive permanent magnet generator for a wind turbine.

## Dave, David and Linear induction motors

Here are the specifications:. You are supposed to design a synchronous reluctance motror for the BMW i3which is a full-electric car with a hybrid-synchronous motor.

Although the motor is rated at 75 kW, it can produce instantaneous power up to kW, and torque up to Nm. Although the original motor is PM assisted, you can design a classical synchronous reluctance motor. Here are some useful links:.

**FEMM 사용법**

In this projects you are supposed to design an induction motor the options are given below. Please spend some time to learn the software and read the documentation.

The motor you need to design is a traction asynchronous squirrel cage induction motor with the following specifications:. Design the induction motor that is used in Tesla Model Swhich has a few different variations. To keep things simple, use the RWD 85 Modelwith rear wheel drive, which has the following specs:. You can find some specs of the motor from here and hereyou can find more information on the internet. The specifications of the wind turbine are as follows:.

Additionaly, you are free to use any software listed below during your design stage. In the report please describe how you decided on the following aspects of the prroject. For example, you can vary one of the following:. You are supposed to design a high-frequency, high-voltage transformer that will be used in a X-Ray device. Here are some links to get you familiar with the topic:.

In this project you are supposed to design an eddy current brake design which will be used as a mechanical damper. Here are some links on the eddy current brakes:.Induction Motor Example. David Meeker dmeeker ieee. August 20, Generally, one would like to use the program to model the performance of an induction machine at speed and under load.

Currentl y, however, all analyses in FEMM are of. An induction machine with a moving rotor with can be modeled using a relatively simple circuit model. The purpose of the static FEMM analyses is then to identify the.

This circuit model can then be used under a wide variety. Alt hough circuit parameters can often be. The purpose of this example is to demonstrate, in a relatively step-by-step manner, how one goes about building and identifying an induction machine model using FEMM. This example will specifically cons ider a V, 50 Hz, 2 HP motor. Induction Motor Model. A reasonable mode l to assume might be the one pictured in. Figure 1.

This model is meant to represen t one phase of an induction machine operating. In this circuit equation, v represents the phase voltagethe RMS voltage applied across ea ch phase of the machine, and i represents the phase currentthe RMS current through each ph ase of the machine. These are important distinctions, because de pending on how the motor is wired i.

To remove any ambiguity, this note. Figure 1: Simple steady-state per-phase induction motor model. Now that we have a model of the motor, we can use this model to derive some useful relationships between phase curr ent, phase voltage, and torque.

Motor Impedance. The impedances of the motor can be added to gether in the same fashion as resistors, using the same rules for parallel and series configurations. In case, the total impedance of the motor could be represented by Zwhere:.

The voltage is then related to the current via:. Per-Phase Flux Linkage.If you are a first-time user, the best way to start is by completing the FEMM tutorial.

What's going on? How do I fix this? There's no fee or special license required for simply using the results of the codes that are up on the website as part of an analysis done for some commercial purpose.

Like it says in the [License] :. Functional use running of the Program is not restricted, and any output produced through the use of the Program is subject to this license only if its contents constitute a work based on the Program independent of having been made by running the Program. In other words, you can use the results of the program for pretty much any purpose. However, you do need a special license to resell the program itself or to include pieces of the source in a commercial product.

More specifically, for AC problems, all quantities currents, fluxes, etc. For example, if a was a complex number representing the magnetic vector potential at some point, we could explicitly represent vector potential as a function of time, A tusing the equation:.

FEMM will only give reasonable results if you are interpolating between defined points on the B-H curve for the material. Depending on your particular problem, you may need to add points to your B-H curves so that you are always interpolating rather than extrapolating. For nonlinear AC problems, there is also another factor at play. In this type of problem, FEMM is solving for the amplitude of the fundamental part of the field, which allows bigger values of flux density to appear than would be possible in a magnetostatic solution.

For example, consider a material that saturates at about 2 Tesla. Imagine that at some point in the material, the flux density is traversing a a square wave versus time, varying between -2 Tesla and 2 Tesla. This would be analogous to an AC problem in which the material was subjected to a high degree of saturation. Although the peak value considering all harmonics is 2 Tesla, it is reasonable for significantly higher flux densities to appear when just the fundamental is considered.

Although the amplitude values produced by the nonlinear time harmonic simulation seem intuitively odd, the forces and losses resulting by these calculations are typically reasonable. See Question 3. Make sure that the materials that you are using have reasonable values for conductivity i.A linear induction motor LIM is an alternating current ACasynchronous linear motor that works by the same general principles as other induction motors but is typically designed to directly produce motion in a straight line.

Characteristically, linear induction motors have a finite primary or secondary length, which generates end-effects, whereas a conventional induction motor is arranged in an endless loop. Despite their name, not all linear induction motors produce linear motion; some linear induction motors are employed for generating rotations of large diameters where the use of a continuous primary would be very expensive.

### Calculation of Induction Motor Model Parameters Using Finite Element Method

As with rotary motors, linear motors frequently run on a three-phase power supply and can support very high speeds. However, there are end-effects that reduce the motor's force, and it is often not possible to fit a gearbox to trade off force and speed.

Linear induction motors are thus frequently less energy efficient than normal rotary motors for any given required force output. LIMs, unlike their rotary counterparts, can give a levitation effect.

They are therefore often used where contactless force is required, where low maintenance is desirable, or where the duty cycle is low. Their practical uses include magnetic levitationlinear propulsion, and linear actuators. They have also been used for pumping liquid metals. The history of linear electric motors can be traced back at least as far as the s to the work of Charles Wheatstone at King's College in London, [3] but Wheatstone's model was too inefficient to be practical.

A feasible linear induction motor is described in US patent ; inventor Alfred Zehden of Frankfurt-am-Mainand is for driving trains or lifts. German engineer Hermann Kemper built a working model in In a single-sided version, the magnetic field can create repulsion forces that push the conductor away from the stator, levitating it and carrying it along the direction of the moving magnetic field. Laithwaite called the later versions a magnetic river.

These versions of the linear induction motor use a principle called transverse flux where two opposite poles are placed side by side. This permits very long poles to be used, and thus permits high speed and efficiency. A linear electric motor's primary typically consists of a flat magnetic core generally laminated with transverse slots that are often straight cut [6] with coils laid into the slots, with each phase giving an alternating polarity so that the different phases physically overlap.

The secondary is frequently a sheet of aluminium, often with an iron backing plate. Some LIMs are double sided with one primary on each side of the secondary, and, in this case, no iron backing is needed. Two types of linear motor exist: a short primarywhere the coils are truncated shorter than the secondary, and a short secondarywhere the conductive plate is smaller.

Short secondary LIMs are often wound as parallel connections between coils of the same phase, whereas short primaries are usually wound in series. The primaries of transverse flux LIMs have a series of twin poles lying transversely side-by-side with opposite winding directions.

These poles are typically made either with a suitably cut laminated backing plate or a series of transverse U-cores. In this electric motor design, the force is produced by a linearly moving magnetic field acting on conductors in the field. Any conductor, be it a loop, a coil, or simply a piece of plate metal, that is placed in this field will have eddy currents induced in it thus creating an opposing magnetic field in accordance with Lenz's law. The two opposing fields will repel each other, creating motion as the magnetic field sweeps through the metal.

For a slip of sthe speed of the secondary in a linear motor is given by.

The drive generated by linear induction motors is somewhat similar to conventional induction motors; the drive forces show a roughly similar characteristic shape relative to slip, albeit modulated by end effects.Create an AI-powered research feed to stay up to date with new papers like this posted to ArXiv. Skip to search form Skip to main content You are currently offline. Some features of the site may not work correctly.

Bose and Anshuman Bhattacharjee and R. BoseAnshuman BhattacharjeeR. Prem Sudha Published Physics. The paper attempts to model a three phase squirrel cage induction motor and using Finite Element Method to obtain the finite element field solutions. The linear time harmonic vector field potential solution is used for the inductance determination. Save to Library. Create Alert.

Launch Research Feed. Share This Paper. Figures from this paper. Citations Publications citing this paper. Analysis in the parameterization of the inductances and resistance of the rotor of a three phase induction motor using finite elements method D.

Supriya A. PandeAishwarya A. Apte IqbalVaibhav Agarwal References Publications referenced by this paper. Calculation of two-axis induction motor model parameters using finite elements Drago DolinarR.Now the time has come to do that! A C shaped electromagnet is pretty much what the name says: a C shaped bloc of iron or other ferromagnetic material with a coil wrapped around the body of the C.

A C shaped electromagnet can be found, for instance, in a shaded pole motor. In FEMM we can easily model such simple geometry as follows. Both these parameters can be changed according to the materials available in the materials library of the program. After running the mesh generator, if everything is fine, we should obtain a full mesh.

Setting a boundary condition is not required the program runs anyway but strongly suggested for better resutls. Note that the following magnetic circuit assuming no flux leakage can be obtained from the equation stated above:. In the case of ferromagnetic materials, this relationship is non-linear, while in the case of the air it is.

If you make this assumption, then all the magnetic energy stored in the system is concentrated in the air gap. We will see that this is not the case in this simulation. This simplifying assumption is fine for getting a rough idea of how the system behaves though.

First off, we can note that some flux lines are outside the magnetic core. These flux is called leakage flux. The induction field is stronger in the core and becomes weaker near the air gap, however, the induction field varies between 1.

The magnetic flux is 0. Again, note that the flux can be reasonably assumed to be constant. The flux can be calculated by using the integration function of FEMM. How much stronger you may ask. Not bad, huh? The magnetic voltage drop can be found by integrating the magnetic field over the desired contour.

The magnetic tension drop in the air gap is about A while in the whole iron core it is about A. Again our expectations are met by the simulation. The induction field is at its lowest in the air gap, while the magnetic field is mostly concentrated in the air gap as expected.

It can help you calculate electromagnetic forces, induced currents and much more. As a simple example, below you can find the results of the simulation of the induction field of a 4 poles synchronous machine. Usually, the induction field is generated using a constant current or permanent magnets.

This simulation appliesfor example, to a synchronous generator that is rotating with the stator windings open in that case, no magnetic field is generated by the stator since no current is flowing through those windings. The generator is modelled using M22 steel.

### Calculation of Induction Motor Model Parameters Using Finite Element Method

The following pictures represent a 90 degree turn of a synchronous generator with no load attached. Note how the field lines change. The head of the poles tend to be saturated much faster than the air gap. I hope you enjoyed this overview of some of the functions of FEMM for magnetics simulations. The files of the simulations can be downloaded here. Please do share this post if you have found it useful or interesting or even in the case you liked the pretty pictures :D.

Your article helped me a lot, great content, thanks for making it available as simulations!

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