Modified approach to stability margin for lower order perturbed systems: Applications to dc-dc converter and servo system

In this paper, an alternative improved technique is proposed for determining the stability margin of low-order perturbed systems. This approach is based on the results on Hurwitz invariance of uncertain polynomials and also results on the stability margin of low-order perturbed systems. Further, this approach is applied for determining stability margin of PWM push-pull dc-dc converter and PD controller based perturbed servo system. The previously published work on the perturbed PWM push-pull dc-dc converter gives absolute stability and conservative stability margin, whereas proposed technique gives efficient stability margin and thus reduces the conservatism of the existing methods. Further, real time validation is carried out on experimental setup of Qube servo system. This approach is verified by checking responses of the original and the modified perturbed systems using time domain and frequency domain analysis. The proposed technique is a quick improved method of determining stability margin of the system without performing time domain and frequency domain analysis. The proposed analysis will be very much useful to electrical engineers, since the technique is very quick, simple and computationally efficient.