A Novel Approach to Induction Motor Transfer Functions

The scope of static ac drives is increasing rapidly, and with this increase has evolved the need to devise control strategies for a variety of new applications. Purely analytical approaches to design of control systems for ac drives are hindered by the highly coupled nature of the ac induction motor equations which, in the past, necessitated lengthy manual derivations of transfer functions. This paper presents an alternative approach using a state variable formulation. The equations are arranged in a form such that the entire derivation procedure can be relegated to a digital computer. Transfer function poles, zeros, and gain for any practical input-output pair of variables can be rapidly obtained.