An Optimized Compensation Strategy of Direct Matrix Converter-Fed PMSM Drives with Field Weakening under Unbalanced Supply Conditions

This paper presents an optimized compensation strategy for direct matrix converter (DMC) - fed permanent magnet synchronous motor (PMSM) drives with special consideration of the modification in field weakening control under unbalanced supply conditions. The imbalance of input voltage conditions in a three wire system are analysed and considered to be composed of positive and negative sequence components. To determine unbalance factor of the grid and decompose the positive and negative sequence components, the dual second order generalized integrator (DSOGI) and positive sequence calculator (PSC) algorithm are introduced. In order to achieve balanced output while optimizing the input current to be sinusoidal, the modulation index based on direct modulation method and the field weakening regulator are then adjusted according to unbalance factor of the input voltage conditions. The principle of the proposed compensation strategy is explained in detail. Simulation results are used to verify this proposed strategy. A low voltage laboratory platform consisting of DMC and servo motor is implemented and controlled using hybrid hardware concept based on field-programmable gate array (FPGA) and digital signal processor (DSP). Experimental studies on the laboratory prototype confirm the feasibility and effectiveness of the proposed method.