An indirect variable structure model reference adaptive control applied to the speed control of a three-phase induction motor

An indirect approach to the variable structure model reference adaptive control (VS-MRAC) is proposed. This approach is applied to the speed control of a three-phase induction motor. In the direct approach, the switching laws are designed for the parameters of the controller, and in this case the main difficulty is to find the bounds, which must be used in the control laws. On the other hand, in the indirect approach, the switching laws are designed for the plant parameters, which are uncertain, but their bounds can be easily found, since they are related to physical parameters of the system. The idea is to design an indirect variable structure approach and to apply it to the speed control of a three-phase induction motor.