moving from z domain to w domain, transfer function

hello,

I want to know G as function of w where G is G(z)=(0.003569z+0.003395)/(z^2-1.861z+0.8607) and z is (1+0.025w)/(1-0.025w)

thanks,

[darova]

I think it's too complicated to express w explicitly. Are you trying to find roots? Use fsolve

Answer 1

[Ameer Hamza]

MATLAB control system toolbox have d2c function to convert transfer function from discrete (z-domain) to continuous (s-domain). However, you need to specify the sample time period in the discrete domain. Try this

ts = 0.1;
z = tf('z', 0.01);
Gz = (0.003569*z+0.003395)/(z^2-1.861*z+0.8607);
Gw = d2c(G);

Gz
Gw

Result

Gz =
 
  0.003569 z + 0.003395
  ----------------------
  z^2 - 1.861 z + 0.8607
 
Sample time: 0.01 seconds
Discrete-time transfer function.


Gw =
 
  -2.348e-07 s + 0.7499
  ---------------------
  s^2 + 1.5 s - 0.03231
 
Continuous-time transfer function.

s-domain is equivalent to w-domain when .