Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.
Measurement of magnetic field density in the air gap of electrical machine
Posted Jan 16, 2017, 8:01 a.m. EST Low-Frequency Electromagnetics, Results & Visualization Version 5.2a 10 Replies
Please login with a confirmed email address before reporting spam
Can any one help me with the measurement of radial magnetic field density in the air gap of an electrical machine along a circle at each point with respect to time.
I tried to follow this step,
Data set --> More data sets--> average.---> selected boundary of the circle where I want to calculate magnetic field density
Now I go to
Derived values --> Point evaluation ----> data sets-->Average1---expression -->sqrt(rmm.Bx^2+rmm.By^2)
But I am not able to get the magnetic field density at each point along the circle.
Can any one help me?
With best regards,
Gaurav
Please login with a confirmed email address before reporting spam
Once you have set up your parametric curve, you can right click on Derived Values, then select Average, then select Line Average. Select the Parametric curve data set as your data source for the calculation.
Please login with a confirmed email address before reporting spam
Thank you! I could implement this. However I am still getting single value with respect to time. I want to calculate radial flux density at different points along the circle. For example 36 points (in between 0 to 2 pi). So at each of these 36 points I should be able to calculate radial flux density with respect to time.
With best regards,
Gaurav
Please login with a confirmed email address before reporting spam
Please login with a confirmed email address before reporting spam
I have uploaded the model. I have given a simple 3 phase supply and trying to measure the flux density along a circle of 40mm. I am not able to attach the file. Would it be possible for you to download from this link,
drive.google.com/open?id=0B2tw-aRna17LRVFpT2FGWW9ZdW8
With best regards,
Gaurav
Please login with a confirmed email address before reporting spam
Are you sure the plot is using the correct data set for its source? If you are using a Parametric Curve 3D to define the circle on which you want to plot, is that curve using the correct Data Set for it's source?
Please login with a confirmed email address before reporting spam
Thank you! I have uploaded the model now. I am using Parametric Curve 2d to define the circle and later trying to evaluate the solution in table 6 and later I am plotting it to 1D Plot Group 19. It seems, since I am using line average so it is giving an average flux density along the circle at a particular time. What I want is, flux density at different locations along the circle.
With best regards,
Gaurav
Attachments:
Please login with a confirmed email address before reporting spam
You have your steel structure, the rest should be air as a single air domain. You can create a circular region at your 40mm radius and define it as a mesh control domain, that way, you have a contiguous but refined mesh in the region you are interested in. You can then define a Cut point 2D data set with the following values (assuming you want data points every 36 degrees in this example case, adjust the formula to suit your needs):
x: 40*cos(range(0,2*pi/10,1.8*pi))
y: 40*sin(range(0,2*pi/10,1.8*pi))
This will create points (within your refined mesh domain) at which you can evaluate time averaged values for the array of points in the data set.
You do this by right clicking on Derived Values, choose Point Evaluation, then enter your desired expression (in your case "sqrt(rmm.Bx^2+rmm.By^2)"), then at the bottom of the settings screen for the point evaluation, choose the Average operation under the Data Series operation section.
This will give you a table of the time averaged field at the desired points.
Hope this helps...
Please login with a confirmed email address before reporting spam
Thanks a lot! I could evaluate radial flux density at different data points. I have removed circle 28 and kept only one circle at 40mm radius to have a refined mesh in that domain. Is it the same you wanted to convey? I have one more doubt. I want to calculate this expression at each instant of time. I can choose them manually from the time selection in point evaluation. Is there any way by which I can calculate at each point with respect to time? Please have a look to my model.
With best regards,
Gaurav
Attachments:
Please login with a confirmed email address before reporting spam
To create a table of point values as a function of time, you can duplicate the previously created derived value group, but choose "none" in the "data series operation" section. Right click the new derived value definition and choose Evaluate/New Table. A table of point values will appear showing the values of each point at all of the different time points.
Please login with a confirmed email address before reporting spam
Thank you! It is working now.
With best regards,
Gaurav
Note that while COMSOL employees may participate in the discussion forum, COMSOL® software users who are on-subscription should submit their questions via the Support Center for a more comprehensive response from the Technical Support team.
Suggested Content
- BLOG Analyzing Electric Motor and Generator Designs with COMSOL®
- BLOG Modeling Linear Motors or Generators in COMSOL Multiphysics
- FORUM Magnetic Continuity - Contact Impedance to model air gap
- KNOWLEDGE BASE Using Symmetries in COMSOL Multiphysics
- KNOWLEDGE BASE The Magnetic and Electric Fields Interface with Electrical Circuit Gives an Unexpected Error for Transient Studies