Modulated Finite-Control-Set Model Predictive Current Control for Five-Phase Voltage-Source Inverter

Due to the fixed and limited sampling period in the real-time system, three-phase inverters using finite-control-set model predictive current control (FCS-MPCC) usually suffer from large ripples of phase current. Moreover, the extension of FCS-MPCC scheme to a multiphase system always faces another challenge, which is to simultaneously regulate the fundamental and the low-order harmonic current components. For the case of the five-phase voltage source inverter that has been widely investigated recently, the existing literature has solved the harmonic currents issues with the utilization of virtual voltage vectors. But these virtual voltage vectors are still limited to the fixed angles and magnitudes in the space coordinate and lack effective current ripples suppression means. Therefore, this paper first applies virtual vectors to reduce the lower order harmonic currents and thus eliminates the weighting factor in cost function. Then, based on duty-cycle optimization, a modulated control set synthesized through virtual voltage vectors is employed to attain a smoother phase current waveform. Compared to existing methods, the vector selection and duty-cycle determination can be implemented simultaneously. Finally, a comparison of the proposed modulated FCS-MPCC scheme and the other FCS-MPCCs is presented. Simulation and experimental results verify that the proposed scheme can remain the simplified structure, fast dynamic performance, constant switching frequency, and achieve minimal current ripples.