Crossover frequencies for specified gain
wc = getGainCrossover(
wc of frequencies at which the frequency
response of the dynamic system model,
principal gain of
gain. For SISO systems, the
principal gain is the frequency response. For MIMO models, the principal
gain is the largest singular value of
Unity Gain Crossover
Find the 0dB crossover frequencies of a single-loop control system with plant given by:
and PI controller given by:
G = zpk(,[-1,-1,-1],1); C = pid(1.14,0.454); sys = G*C; wc = getGainCrossover(sys,1)
wc = 0.5214
The 0 dB crossover frequencies are the frequencies at which the open-loop response
sys = G*C has unity gain. Because this system only crosses unity gain once,
getGainCrossover returns a single value.
Notch Filter Stopband
Find the 20 dB stopband of
sys is a notch filter centered at 10 rad/s.
sys = tf([1 0.05 100],[1 5 100]); gain = db2mag(-20); wc = getGainCrossover(sys,gain)
wc = 2×1 9.7531 10.2531
db2mag command converts the gain value of -20 dB to absolute units. The
getGainCrossover command returns the two frequencies that define the stopband.
sys — Input dynamic system
dynamic system model
Input dynamic system, specified as any SISO or MIMO dynamic system model.
gain — Input gain
positive real scalar
Input gain in absolute units, specified as a positive real scalar.
sysis a SISO model, the gain is the frequency response magnitude of
sysis a MIMO model, gain means the largest singular value of
getGainCrossover computes gain crossover frequencies using
structure-preserving eigensolvers from the SLICOT library. For more information about
the SLICOT library, see http://slicot.org.