Bode Stability Criterion
Stability conditions are given below:
- For a Stable System: Both the margins should be positive or phase margin should be greater than the gain margin.
- For Marginal Stable System: Both the margins should be zero or phase margin should be equal to the gain margin.
- For Unstable System: If any of them is negative or phase margin should be less than the gain margin.
Gain Margin
The gain margin refers to the amount of gain, which can be increased or decreased without making the system unstable. It is usually expressed as a magnitude in dB.
Phase Margin
The phase margin refers to the amount of phase, which can be increased or decreased without making the system unstable. It is usually expressed as a phase in degrees.
https://lpsa.swarthmore.edu/Bode/Bode.html