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How to compensate the phase error introduced by a low pass filter?

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powersys

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The first figure below shows the MATLAB/Simulink model of a low-pass filter (LPF). The cut-off frequency of the LPF is fc=10Hz. The sinewave frequency is fe=2Hz. As shown in the 2nd figure below, the LPF introduces a phase error at fe=2Hz, resulting in a filtered sinewave with phase error (see 3rd figure below).

Is there a method to compensate the phase error (which is applicable in Simulink or a microcontroller based application)?

Thanks.

93_1341319008.png


65_1341319125.png


44_1341319008.png
 

You can follow your LPF with an all-pass filter (or some other phase-compensating network) to adjust the phase.
 

You can add more phase shift with an all-pass filter, but you can't remove the phase shift added by the low-pass filter.
 

godfreyl said:
You can add more phase shift with an all-pass filter, but you can't remove the phase shift added by the low-pass filter.
Click to expand...

Of course. If your requirement is to have the input->output phase=0 (or. really, 360) then you can do it. Otherwise you need a time machine.
 

Powersys,

are you really sure that your application requires to compensate this phase "error" ?
By the wy, I wouldn´t call it "error" because it is a natural physical phenomenon, see Bode`s fundamental formula for the gain-phase relationship.
 

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