Modelling and power quality enhancement of induction motor with soft starter using synchronous reference frame theory

An This paper presents a method for obtaining the desired reference current for Voltage Source Inverter (VSI) of Shunt Active Filter fed Induction motor using Synchronous Reference Frame (SRF) theory. The modeling is based on the a-b-c stationary frame to 0-d-q rotating frame transformation of the ac system variables. The cur rents injected by the active filter are controlled in the synchronous orthogonal 0-d-q frame using a decoupled nonlinear control strategy. The reference harmonic components are extracted from the sensed nonlinear load currents by applying the synchronous reference frame method, where an AC voltage controller fed three-phase Induction motor is taken as the nonlinear load. To improve the performance of the PI controller, the feedback path to the integral term is introduced to compensate the winding up phenomenon due to integrator. The Phase Locked Loop (PLL) with PI filter is used for Synchronization, with much emphasis on minimizing delays. The results confirm the performances considered theoretically for the shunt active filter topology and to comply with IEEE 519 recommended harmonic standards.