Research on Dual Voltage Vector Predictive Control of Three-phase Four-Switch Fault-Tolerant Converter

With the development of inverter technology, three-phase four-switch fault-tolerant converters are widely used in power systems. However, the traditional single-vector control strategy has limitations in terms of current tracking accuracy and total harmonic distortion (THD), and the system control performance declines when faults occur. In this paper, a current prediction model of a three-phase four-switch dual voltage vector fault-tolerant converter is constructed in the αβ stationary coordinate system. Combined with the predictive control principle of the modulation model, a dual voltage vector predictive control strategy is proposed. This strategy optimizes the selection and combination of dual voltage vectors, reduces current harmonic distortion, and improves the control accuracy and stability of the system. Through Matlab/Simulink simulation, the open-circuit fault of phase a was set, compared with the fault-free situation, and verified by using both static and dynamic control strategies. The results show that in the static experiment, the THD of the improved phase currents a, b, and c were 2.77%, 3.07%, and 2.77% respectively, and the harmonic distortion was significantly improved. In the dynamic experiment, when the current jumps at 0.5 seconds, the THD of phases a, b, and c is 2.73%, 3.15%, and 2.85% respectively. The response speed is fast and there is no harmonic distortion. The simulation results strongly confirm the effectiveness of this strategy in improving the current tracking accuracy, reducing THD and ensuring the reliable operation of the converter.