Boost converter estimated transfer function and actual model do not match

Hi all,

I have completed the example "Estimating Transfer Function Models for a Boost Converter". After obtaining the estimated transfer function model, I have compared the response of the Simscape model with the output of the transfer function. Theoretically, both systems should show a similar output using as input the equlibrium point chosen for the estimation. However, both responses differ during the transient and the steady state. What am I missing here??

Answer 1

[sai charan sampara]

Hello Raúl,

I understand that you are trying to find the reasoning behind mismatch between the estimated and the original output in the example Simulink model.

This is because the connection made to the LTI block is wrong. The LTI system block’s input should be connected to the input of the model which in this case is voltage. An LTI system block applies the transform corresponding to the transfer function on the input signal. The voltage from the controlled voltage source is the input of in this case and hence it should be treated as input to the LTI system.The scope in the Simulink model is a measure of the output voltage and not the transfer function of the system. The constant block that you have connected is a control signal of the gate of the MOSFET and is not the desired input signal. Hence the output voltage and the output of the LTI block do not match.

You can refer to the below documentation to learn more:

https://www.mathworks.com/help/control/ref/ltisystem.html