steady state. The total simulation duration will be the sum of this parame-
ter and one period of the base frequency signal.
Avector containing the lowest and highest frequency of the multitone per-
turbation signal. The highest frequency is rounded up towards the next
integer multiple of the lowest frequency.
In a multitone analysis, the frequencies are linearly spaced (see “Multi-
tone Analysis” (on page 148)). Since the Bode plot has a logarithmic scale,
PLECS thins out the higher frequency values to accelerate the analysis.
If the lowest and highest frequencies are far apart, i.e. separated by sev-
eral orders of magnitude, the multitone analysis may become slow. One
reason is that the simulation times become long and the simulation steps
small, since they depend on the lowest and highest frequencies, respec-
tively. You may try to speed up the analysis by specifying intermediate
frequency values, i.e. by entering a frequency vector with more than two
elements. Each intermediate value must be greater than ten times the
preceding value. If the frequency vector contains n elements, n 1 sepa-
rate multitone analyses are performed and the Bode plot is composed of
the respective results. Since the frequency range of each individual multi-
tone analysis is smaller than the overall range, the total time needed may
The amplitude of the perturbation signal. Note that the actual perturba-
tion signal may have a sightly different amplitude due to its composition
from the different tones.
The Small Signal Perturbation block that will be active during the analy-
sis. All other perturbations blocks will output 0.
The Small Signal Response block that will record the system response dur-
ing the analysis.
Extraction of State-Space Matrices
PLECS allows you to extract the state-space matrices describing the linear
portion of a circuit model for a given combination of switch positions. The
commands used for this purpose are listed below. These commands can be
used both in a Simulation Script (see page 201) and on the Octave console. In
each of the commands circuit is the name of the circuit model.