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Asked by chethan
on 4 May 2013

Hello,

when i simulate the model using simplified synchronous machine the output frequency is not proper. The parameters which i am supposed to use to get a frequency of 400Hz is N=6000(the input to the model is 628rad/s), pole pairs=4. when i give this parameter i don't get a freq of 400Hz, why is this? is there any other parameters that i have to change? if so please help me.

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Answer by John Doe
on 6 May 2013

Edited by John Doe
on 6 May 2013

Accepted answer

The electrical frequency is, as stated in the comments:

f_elec = poles * f_mec / 2

I was wondering what you were doing, because I can't see where you get in trouble. In a synchronous machine, the output frequency is only a function of the number of poles, and the rotor frequency, nothing else.

Since I don't know how you achieved 0.153Hz, I asked to see your model, so that I could try to figure out where your error is.

Thus, the answer to your question: "Is there any other parameters that i have to change?" is No, nothing else must be changed.

Best of luck!

## 8 Comments

## John Doe (view profile)

Direct link to this comment:http://www.mathworks.com/matlabcentral/answers/74608#comment_147262

It is hard to tell with no information regarding your model. Can you describe it / provide it? What is input, and what is the output? Is the input the frequency of the rotor, and output is the frequency of the voltage? What is N? The number of windings (how is that relevant)? What output frequency do you get now? The electrical frequency should be 4 times the mechanical frequency for the data provided here.

## chethan (view profile)

Direct link to this comment:http://www.mathworks.com/matlabcentral/answers/74608#comment_147353

i need a synchronous generator which give 115vrms, 400hz. The input to the machine is speed(N) and the field voltage(Vf). my problem is, i am getting the desired output voltage but the output frequency is not 400Hz.

## John Doe (view profile)

Direct link to this comment:http://www.mathworks.com/matlabcentral/answers/74608#comment_147367

Could you show your work? It's impossible to give an answer without it. Using the information you have given above, your output frequency will be 400Hz, thus your model is incorrect (not the data). What frequency are you getting? The output frequency should be (if your model is correct):

Which is equal to 8 * 100 / 2 = 400 Hz.

## John Doe (view profile)

Direct link to this comment:http://www.mathworks.com/matlabcentral/answers/74608#comment_147408

There is no photo here. Please also include your equations...

## chethan (view profile)

Direct link to this comment:http://www.mathworks.com/matlabcentral/answers/74608#comment_147410

here is tthe photo copy of my simullation, m getting the freq of 0.153Hz

## John Doe (view profile)

Direct link to this comment:http://www.mathworks.com/matlabcentral/answers/74608#comment_147415

It's not easy to help you when don't even check if your uploads work. Again, no photo copy, and no code...

## chethan (view profile)

Direct link to this comment:http://www.mathworks.com/matlabcentral/answers/74608#comment_147607

sorry, i don't know how to upload the pic here. and my simulation is very simple. i have a simplified generator connected to the RLC load. and for an electrical engineer the above given information is enough for him to just build the model in less than 2min. i thought you would do tat and give some useful solution. Anyways thanks Robert :) thanks for your consideration.

## syed zia (view profile)

Direct link to this comment:http://www.mathworks.com/matlabcentral/answers/74608#comment_150475

I also need da same thing ,want to measure the frequency...and its variation after increasing load.........plz help me tnx....