A controller for an LCI to extend the operating range of single-phase brushless exciter synchronous motors

Abstract

This thesis proposes a control scheme for a load commutated inverter-based drive for a single- phase brushless exciter synchronous motor, which represents a modification to a conventional field-oriented control that (i) improves the pulse generation accuracy including a load synchro- nized pulse generation scheme based on the estimated stator fluxes; (ii) effectively regulates the rotor speed and the estimated stator flux magnitude considering a simplified model of the single- phase brushless exciter; and (iii) extends the rotor speed and load torque operating range through the online calculation of the inverter firing angle based on the commutation model, which obeys the reduction, on average, of the exciter field current and stator current during the overall process. Hardware-in-the-loop tests show the response of the rotor speed and stator flux under a typicalmilling load profile.