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What is the gain margin in dB?
Gain margin is defined as the amount of change in open-loop gain needed to make a closed-loop system unstable. The gain margin is the difference between 0 dB and the gain at the phase cross-over frequency that gives a phase of −180°.
How do you determine gain from root locus?
Key Concept: Properties of Open Loop Gain Used to Draw Root Locus
- The loop gain is KG(s)H(s) which can be rewritten as KN(s)/D(s).
- N(s), the numerator polynomial, is mth order; D(s) is nth order:
- K>0, a0>0, b0>0.
- N(s) has zeros at zi (i=1..
- The difference between n and m is q, so q=n-m.
How is the phase margin of root locus calculated?
Gain Margin : We define gain margin by which the design value of the gain factor can be multiplied before the system becomes unstable. Phase Margin : Phase margin can be calculated from the given formula: Symmetry of Root Locus : Root locus is symmetric about the x axis or the real axis.
How to increase the compensator gain in root locus?
To create a faster response, increase the compensator gain. In the Root Locus Editor, right-click the plot area and select Edit Compensator. In the Compensator Editor dialog box, specify a gain of 20. In the Root Locus Editor plot, the closed-loop pole locations move to reflect the new gain value.
Why do the poles move in root locus editor?
In the Root Locus Editor plot, the closed-loop pole locations move to reflect the new gain value. Also, the Step Response plot updates. The closed-loop response does not satisfy the settling time requirement and exhibits unwanted ringing. Increasing the gain makes the system underdamped and further increases lead to instability.
How to make the root locus diagram easier to read?
To make the root locus diagram easier to read, zoom in. In the Root Locus Editor, right-click the plot area and select Properties. In the Property Editor dialog box, on the Limits tab, specify Real Axis and Imaginary Axis limits from -500 to 500.