Control strategy to start a shaft generator system employing DFIM under power take me home mode

Abstract

Comparing to the traditional synchronous or induction electric machines, the doubly-fed induction machine (DFIM) with the partially rated converter is a good solution for a shaft generator system which normally operates within a relatively small adjustable speed range. However, the application of DFIM is limited in the real systems due to the lack of self-start capability under the power take me home (PTH) mode when the main engine fails. To overcome this problem, an approach is proposed in this paper. The basic idea is first to start the machine in the induction machine (IM) mode feeding from the ship-borne power grid (SPG) and then to switch over into the DFIM mode when the speed reaches its normal speed range. The hardware scheme, start procedure and control algorithm of the start approach are presented in the paper. Simulation and experimental studies were carried out to validate the feasibility and effectiveness of the approach.