Control of Doubly-Fed Induction Motor Based Shipboard Propulsion System for More-Electric Ships

In this paper, a doubly-fed induction motor (DFIM) based shipboard propulsion system (SPS) is proposed for more-electric ships (MESs). Two power flow paths are presented, which are based on direct AC power transmission and power decoupling with back-to-back converter (BTBC). This type of SPS minimizes unnecessary power conversion and increases the system robustness to power converter faults. The synchronous generator (SG) and DFIM are the main power components in the proposed DFIM-SPS. An emulated stator voltage orientated vector control (ESVO-VC) strategy without using phase-locked loop (PLL) is proposed. The simulation study is carried out in Matlab/Simulink to verify the performance of the proposed DFIM-SPS, with frequent load variations taken into consideration. By employing the proposed ESVO-VC scheme, high quality of input three-phase currents, high power factor, and superior torque tracking performance are presented. Furthermore, a control-hardware-in-the-loop (CHIL) setup is used to implement the proposed ESVO-VC with the power circuits of SG and BTBC simulated in a realtime digital simulator (RTDS) to verify the system control performance in the almost practical environment.