Crossover frequencies for specified gain
wc = getGainCrossover(sys,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
Find the 0dB crossover 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 crossovers 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.
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 = 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 systemdynamic system model
Input dynamic system, specified as any SISO or MIMO dynamic system model.