A new sensorless start-up method of LCI system for gas-turbine

This paper proposes a new senseless start-up method by using a terminal voltage/current without position sensor. A flux estimator consisting of field flux model, P controller and flux voltage model is proposed and rotor angle/speed is estimated by using a phase locked loop. Furthermore, initial rotor angle is estimated rapidly and accurately by using the same flux voltage model during the initial build-up time of field current. The LCI system uses a closed loop current control method to accelerate the machine from zero speed to a speed until an enough back-emf voltage builds up. Performance of the proposed start-up method is evaluated by Simpower/Matlab simulation at low speed and high speed range. To verify a feasibility of the proposed method, a 5kVA prototype of load commutated inverter system is implemented. Experimental results show the proposed sensorless start-up method works well in the initial start-up at the zero speed, forced commutation mode at low speed and natural commutation mode at high speed range.