A novel approach on a parameter self-tuning method in an ac servo system

Abstract This paper describes a newly developed parameter identification method for three-phase induction machines. The identification is performed in two steps corresponding to the two states of the machine, namely the initial standstill state and the normal operating state. In each step, on-line identification of parameters indispensable to description of the machine dynamics can be realized by observing the behaviour of the stator current and voltage. These parameters are stator winding self-inductance, transient inductance, rotor circuit time constant and stator winding resistance. At standstill state, they are identified from the stator voltage waveform, when a ramp current is supplied to the stator by a dc power amplifier. At the operating state these parameters are identified by solving a set of equations obtained from the phasor relationship between stator current and voltage. This identification technique is applied to a PWM drive system and can lead to parameter self-tuning in an ac servo control system.