Power Compensation-Oriented SVM-DPC Strategy for a Fault-Tolerant Back-to-Back Power Converter Based DFIM Shipboard Propulsion System

Abstract

For safety critical transportation applications like all-electric ship propulsion systems (SPS), the reliable system operation is definitely the primary concern. In this paper, a fault-tolerant back-to-back power converter based on the four-switch three-phase (FSTP) topology is applied to a doubly-fed induction machine (DFIM) based all-electric SPS. A power compensation-oriented space vector modulation direct power control (PCSVM-DPC) strategy with dc-bus voltage unbalance elimination is proposed to ride through the single bridge arm open-circuit fault in the source-side converter (SSC) and improve the system dynamic performance simultaneously. Besides, the DFIM-SPS is endowed with excellent steady-state performance by applying the proposed control strategy. The dc-bus voltage deviation is suppressed based on the calculation of active and reactive power compensation terms to increase the dc-bus voltage utilization rate. Moreover, good post-fault system operation performance can be achieved with fast active power and electromagnetic torque tracking speeds. The proposed PCSVM-DPC strategy for the fault-tolerant FSTP SSC based DFIM-SPS is easy to implement without high computational burden. The SVM-DPC method is also presented for the load-side converter. The proposed control strategy is verified by experiments on a 1.5 kW DFIM-SPS experimental platform.