Calculating the phase shift of the output compare to the input in matlab

[mtnkh]

Hi,

I have a system which its impedance, z = |z|∠θ, is variable and unknown and I want to estimate the impedance in this case I inject a sine current with a known amplitude and frequency to the system, I = sine(2*pi*f*t) and measured the output voltage.
So in this case we will have this equation:
Vout = I*|z|∠θ
I used a DAQ to sample the data and process it in PC. I wanted to know how can I measure the phase shift between "Vout" and "I" which is equal to the phase of the impedance using matlab?

 

[FvM]

It's a classical impedance meter setup. The usual method is quadrature detector, multiplying the measured signal with sin and cos reference, integrating the product over full cycles. Noise and harmonics are supressed, complex impedance respectively magnitude and angle can be calculated by basic trigonometric relations.

 

[danadakk]

This might help :

Agilent - Impedance Measurement Handbook, 2nd Edition (5968-1947E, 2000-06) : Agilent Technologies : Free Download, Borrow, and Streaming : Internet Archive

Agilent - Impedance Measurement Handbook, 2nd Edition (5968-1947E, 2000-06)

archive.org

Example project, see attached, done on a PSOC 3 SOC. I think this could be ported to PSOC 5LP which is M3 ARM.

Regards, Dana.

 

[thannara123]

View attachment 186210

Regards, Dana.

Hi Dana what software is this ?

 

[danadakk]

Its a PSOC 3 in the example, IDE and compiler are free, PSOC Creator 4.4,

https://www.infineon.com/cms/en/design-support/tools/sdk/psoc-software/psoc-creator/

low end board for ARM is ~ $ 15 , CY8CKIT-059 (top part is snap off programmer/debugger) :

Resources on part (varies by family), below us typical, multiple copies in many cases :

Note cores available are 8051 for PSOC 3, ARM for PSOC 5LP.


Regards, Dana.