Construction of Bode Plots

Rules for Construction of Bode Plots

Follow these rules while constructing a Bode plot.

·        Represent the open loop transfer function in the standard time constant form.

·        Substitute, s=jω in the above equation.

·        Find the corner frequencies and arrange them in ascending order.

·        Consider the starting frequency of the Bode plot as 1/10^th of the minimum corner frequency or 0.1 rad/sec whichever is smaller value and draw the Bode plot upto 10 times maximum corner frequency.

·        Draw the magnitude plots for each term and combine

·        these plots properly.

·        Draw the phase plots for each term and combine these plots properly.

Note − The corner frequency is the frequency at which there is a change in the slope of the magnitude plot.

Example

Consider the open loop transfer function of a closed loop control system