Emulated Stator Voltage-Oriented Vector Control of DFIM-SPS With Coupling Effect Elimination for Electric Ship Applications

The dilemma between high control performance and high fault tolerance for a power electronic penetrated shipboard propulsion system (SPS) impedes the development of more-electric ships (MESs). In this article, with a doubly fed induction machine (DFIM) electric drivetrain adopted, a partially power decoupled SPS structure is presented to enhance the system robustness to solid-state device failure. Two electric machines, which are the synchronous generator (SG) and DFIM, generate and consume power in a DFIM-SPS, respectively. However, the coupling effect between their controls results in potential threats to the system stable operation. The phase-locked loop (PLL) functions as the key factor of interacting their operation, and its mechanism is illustrated in detail for DFIM-SPS to explain the deteriorated performance. This article proposes an emulated stator voltage-orientated vector control (ESVO-VC) strategy with coupling effect elimination to realize separate control of SG and DFIM electric drivetrain. The proposed ESVO-VC strategy is verified by simulation in MATLAB/Simulink for a 10-MW DFIM-SPS, in which three-stage mechanical load torque changes are presented to indicate different working conditions. Moreover, the power circuits of SG and back-to-back power converter (BTBPC) are simulated in a real-time digital simulator (RTDS), and the proposed ESVO-VC is further validated by a control-hardware-in-the-loop (CHIL) setup.