Candidate Modulation Patterns Solution for Five-Phase PMSM Drive System

Model predictive control (MPC) schemes applied in multiphase permanent magnet synchronous motors (PMSMs) should provide the precise torque output and suppress the harmonic currents at the same time. Then, the trade-off between precise torque output and harmonic currents suppression is inevitable in the finite control set model predictive control (FCSMPC). To provide an alternative of this problem, this paper presents a new extension strategy of FCS-MPC applied in multiphase PMSMs. The novelty of this paper includes two parts. Firstly, the control sets are extended from the candidate voltage vectors to the candidate modulation patterns. These modulation patterns consist of switching signals with specific rules. The second one is the new cost function which realizes the harmonic currents suppression with the modulation patterns selection. Two groups of modulation patterns are developed to assess the performance of this structure. The first group is called “semi-controlled modulation pattern” which could provide the precise voltage vectors in the αβ subspace. The second group is called “fundamental torque-controlled modulation pattern” which could further suppress the harmonic currents. These two groups of modulation patterns could realize the required performance with a much lower switching frequency. Moreover, the parameter mismatches in the harmonic subspace caused by the uncertainties of the system and errors in the parameter values are also compensated in proposed MPC. Finally, the comparative experiments show the performance differences among two modulation patterns and those existing controllers.