I am trying to implement the following block diagram using Simulink in Matlab.

I am having trouble getting the high pass filters to work properly.

To do the filtering, I am using the First and Second order filters from the SimScape toolbox.

Using a step source I am getting a sort of result, but I cannot work out how to adjust the cut off frequency for the first order and damping ratio for the second order filter.

Are these the best blocks to use, or is there a better one. If so, how do I tune the filters to work as I require?

## Best Answer

Those blocks are fine to use.

You vary the cutoff frequency via the TimeCostant input block.

Please note the cutoff is in \$\omega\$ so for 50Hz cutoff you will need to enter in the period of \$\frac{1}{2*\pi*50}\$

Try the "Plot Freq Response" checkbox to check the step-response & view the bode plot for a particular filter setting

A similar process exists for the 2nd order filters, but with the additional damping factor