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  1. K

    MATLAB nyquist plot help needed

    Hi MATLABdude, That is the problem. I have tried that before but it generates the following error: "??? Cell contents reference from a non-cell array object." Do you have any resolution to the above error?
  2. K

    MATLAB nyquist plot help needed

    i understand that the "nyquist" command in matlab requires one to key in the transfer function.. however, i am stuck here as i am unable to form a transfer function from the following numerator and denominator: num = s-3/2-1/2*(-24*s+1)^(1/2) den = 1.25*s^2 +3.75*s + 2.5 i know that...
  3. K

    Engineering DC Motor

    Homework Statement A separately excited DC motor with 220V, 970rpm, 100A and Ra=0.05ohms. It is braked by plugging from an initial speed of 1000rpm. I need to calculate i)the resistance to be placed in the armature circuit to limit braking current to twice the full load value, ii)the...
  4. K

    Transfer Function

    Hi rock.freak667, sorry i don't get you. do you mean shift the disturbance D(s) to the left of G1(s) as in in the block diagram? or do you mean the equation Y(s) - G2(s)D(s) = U(s)G1(s)G2(s)? please advise. thank you.
  5. K

    Transfer Function

    U(s) is my input, Y(s) is the output. I have two plants, G1(s) and G2(s). Between these two plants, i have a disturbance input, D(s). Am i right to say Y(s) = U(s)G1(s)G2(s) + G2(s)D(s)? If that is the case, how can i get the overall transfer function Y(s)/U(s)? Please advise. Thank you.
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