matlab中bode,MATLAB中bode函数的使用及实例

分析频率响应特性适用。

bode

Bode diagram of frequency response

Syntax

bode

bode(sys)

bode(sys,w)

bode(sys1,sys2,...,sysN)

bode(sys1,sys2,...,sysN,w)

bode(sys1,'PlotStyle1',...,sysN,'PlotStyleN')

Description

bode computes the magnitude and phase of the frequency response of LTI models. When you

invoke this function without left-side arguments, bode produces a Bode plot on the screen. The

magnitude is plotted in decibels (dB), and the phase in degrees. The decibel calculation for mag is

computed as 20log10 (|H(jω)|), where |H(jω)| is the system's frequency response. You can use

bode plots to analyze system properties such as the gain margin, phase margin, DC gain,

bandwidth, disturbance rejection, and stability.

bode(sys) plots the Bode response of an arbitrary LTI model sys. This model can be continuous

or discrete, and SISO or MIMO. In the MIMO case, bode produces an array of Bode plots, each

plot showing the Bode response of one particular I/O channel. The frequency range is determined

automatically based on the system poles and zeros.

bode(sys,w) explicitly specifies the frequency range or frequency points for the plot. To focus on

a particular frequency interval [wmin,wmax], set w = {wmin,wmax}. To use particular frequency

points, set w to the vector of desired frequencies. Use logspace to generate logarithmically

spaced frequency vectors. Specify all frequencies in radians per second (rad/s).

bode(sys1,sys2,...,sysN) or bode(sys1,sys2,...,sysN,w) plots the Bode responses

of several LTI models on a single figure. All systems must have the same number of inputs and

outputs, but they can include both continuous and discrete systems. Use this syntax to compare

the Bode responses of multiple systems.

bode(sys1,'PlotStyle1',...,sysN,'PlotStyleN') specifies the color, linestyle, and/or

marker for each system's plot. For example:

bode(sys1,'r--',sys2,'gx')

produces a red dashed lines for the first system sys1 and green 'x' markers for the second

system sys2.

When you invoke this function with left-side arguments, the commands

[mag,phase,w] = bode(sys)

[mag,phase] = bode(sys,w)

return the magnitude and phase (in degrees) of the frequency response at the frequencies w (in

rad/s). The outputs mag and phase are 3-D arrays with the frequency as the last dimension (see

"Arguments" for details). To convert the magnitude to decibels, type