Sensorless start-up method of LCI system for gas-turbine

This paper proposes a senseless start-up method of load commutated inverter system by using a modified integrator with an adaptive compensation. The sensorless algorithm is composed of flux estimator by a modified integrator with an adaptive compensation and rotor angle/speed estimator based on phase locked loop. The flux estimator consists of low pass filter, quadrature detector and PI controller. The quadrature detector is used to detect the phase difference between the machine voltage and estimated flux through modified integrator. The modified integrator is used instead of the pure integrator to eliminate DC offset and DC drift problems. Operation modes of LCI system are investigated, and the performance of sensorless algorithm and operation modes is verified by simulation results. To verify feasibility of the algorithm, 5kVA prototype of load commutated inverter system has been implemented. The performance of operation mode and sensorless algorithm is verified through experiment results at all speed range.