How to obtain 4th order transfer function in simulink

I have a circuit for which transfer function has to be obtained to check the stability

Answer 1

[Aneela]

Hi @Swetha

To obtain a 4th order transfer function, refer to the below steps:

1. Create a "Discrete Transfer Fcn" block.
2. Double click the block and navigate to the block's properties.
3. The length of the "numerator" and "denominator" vectors in the "Data" section of the "Main" determines the order of transfer function block.
4. To obtain a 4th order transfer functiton block, set numerator and denominator to a five-length vector.
5. The order of the denominator must be greater than or equal to the order of the numerator.

Refer to the below screenshots:

Block Parameters:

Transfer Function Block:

Answer 2

[Swetha]

Hi Andreas

I dont have the numerator and denominator coefficients, i have attached the circuit below for which i am looking to determine the poles, zeroes, phase margin, gain margin

In the circuit i am using LC components for which the transfer function and stability parameters has to be derived

Hope you got my point

[Aneela]

Hi Swetha, could you please share the entire circuit?

[Swetha]

Screen shot i have attached that is the circuit

[Swetha]

[Aneela]

Please share it in the ".SLX" format, so that I can reproduce at my end.

[Swetha]

Hi Aneela i am working to create the model in simulink

Answer 3

[Yifeng Tang]

This example from the System Identification Toolbox should address what you need.

https://www.mathworks.com/help/ident/ug/estimating-transfer-function-models-for-a-boost-converter.html