Simplified stability analysis of a V/f controlled closed-loop induction motor drive system

The paper deals with the stability determination of a three-phase induction motor drive which operates in closed-loop constant V/f control mode. The presented work carries out stability analysis using a very efficient method called Parameter Plane Technique which sometimes also referred as “D-Partition technique”. The effect of parameter variation on the stability which may be the time constant, the gain of inverter and PI controller etc. of the induction motor drive system is investigated using the presented technique. The graphs are plotted in terms of parameters of the drive in parameter planes which give the relative idea about the degree of stability. The presented stability analysis for the drive helps in determining the relative stability of the drive and also enables to find the drive parameter values for which fastest transient response is obtained. With the available technique it is also possible to design the drive for the values the particular values of parameters which gives the most stable performance of the drive system with fastest transient response i.e. the settling time of the drive is minimum. This is a necessary requirement of the high fidelity drive system or high performance drive system. Analytical approach is used in the paper using MATLAB code.