A MATLAB-based graphical technique for amortization study of adjustable speed drives

Economic justification of electric drives is the primary reason for many applications. However, the cumbersome trial-and-error calculations necessary to present this aspect often leads to omission of the topic in electric drives courses. This paper presents a MATLAB-based program that generates plots of input power and shaft torque for variable-frequency operation of three-phase induction motors. Based on these graphs, an example is presented illustrating how a cost amortization study for an adjustable speed drive application can be presented with minimal effort and lecture time.