Forums

PreWraping in Lead/Lag

Started by Toro August 10, 2006
Hello

I need to convert a lead/lag filter to a z transform function. I'll be 
using the bilinear method. 

Question, what equation do I use for prewraping the lead and lag times?? 
For the other filters i've converted i was prewrapping the frequency and 
using rads/sec. For the lead/lag filters I only have a time constant input.

Transfer function is 

      T1*s + 1
g(s) ----------
      T2*s + 1



Thanks
Toro wrote:
> Hello > > I need to convert a lead/lag filter to a z transform function. I'll be > using the bilinear method. > > Question, what equation do I use for prewraping the lead and lag times?? > For the other filters i've converted i was prewrapping the frequency and > using rads/sec. For the lead/lag filters I only have a time constant input. > > Transfer function is > > T1*s + 1 > g(s) ---------- > T2*s + 1
T = 1/ω = 1/2πf -- Engineering is the art of making what you want from things you can get. ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
Jerry Avins <jya@ieee.org> wrote in news:bdWdnaHIL-VdyUbZnZ2dnUVZ_t-
dnZ2d@rcn.net:

> > T = 1/&#2013265944;% = 1/2&#2013265944; f > --
That got real messed up in plain text, Jerry. -- Scott Reverse name to reply
Scott Seidman wrote:
> Jerry Avins <jya@ieee.org> wrote in news:bdWdnaHIL-VdyUbZnZ2dnUVZ_t- > dnZ2d@rcn.net: > >> T = 1/&#2013265944;% = 1/2&#2013265944; f >> -- > > That got real messed up in plain text, Jerry.
UTF 8, Western (ISO8859-1) Tau = 1/omega = 1/2pi*f Thanks for the heads up. Jerry -- Engineering is the art of making what you want from things you can get. &#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;
Jerry Avins <jya@ieee.org> wrote in 
news:UJWdnbn2RsCXwEbZnZ2dnUVZ_rydnZ2d@rcn.net:

> Scott Seidman wrote: >> Jerry Avins <jya@ieee.org> wrote in news:bdWdnaHIL-VdyUbZnZ2dnUVZ_t- >> dnZ2d@rcn.net: >> >>> T = 1/&#2013265944;% = 1/2&#2013265944; f >>> -- >> >> That got real messed up in plain text, Jerry. > > UTF 8, Western (ISO8859-1) > > Tau = 1/omega = 1/2pi*f > > Thanks for the heads up. > > Jerry
Thanks for the response. Is the 'f' in Hz or in radians/sec? If in Hz then all I need to do is take the invers of T1 and T2 inputs, is this correct? How about if in rad/sec, do I take the inverse and multiply by 2*pi??? Or am I missing something here??? thanks again
Toro wrote:
> Jerry Avins <jya@ieee.org> wrote in > news:UJWdnbn2RsCXwEbZnZ2dnUVZ_rydnZ2d@rcn.net: > >> Scott Seidman wrote: >>> Jerry Avins <jya@ieee.org> wrote in news:bdWdnaHIL-VdyUbZnZ2dnUVZ_t- >>> dnZ2d@rcn.net: >>> >>>> T = 1/&#2013265944;% = 1/2&#2013265944; f >>>> -- >>> That got real messed up in plain text, Jerry. >> UTF 8, Western (ISO8859-1) >> >> Tau = 1/omega = 1/2pi*f >> >> Thanks for the heads up. >> >> Jerry > > Thanks for the response. Is the 'f' in Hz or in radians/sec? If in Hz > then all I need to do is take the invers of T1 and T2 inputs, is this > correct? > > How about if in rad/sec, do I take the inverse and multiply by 2*pi??? Or > am I missing something here???
f is cycles per second. w is radians per second. (It should really be ?; lower-case omega, but not everyone sees that properly.) w = 2*pi*f. That's EE 101. Glad to help, but I assumed I didn't need to. My error. Jerry -- Engineering is the art of making what you want from things you can get. &#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;
Jerry Avins <jya@ieee.org> wrote in news:---
dnZc50eODBn_ZnZ2dnUVZ_o6dnZ2d@rcn.net:

> That's EE 101.
But if I had a dime for every time I've been off by a factor of 2pi .... -- Scott Reverse name to reply