A Variable Structure Approach for Finite-Control-Set Model Predictive Current Control of a Household Appliance

A finite control set model predictive control (FCS-MPC) strategy is investigated for the speed regulation of permanent magnet synchronous motors (PMSMs). A cascaded control structure is implemented, consisting of an inner FCS-MPC current loop, enhanced by a variable structure (VS) approach, and an outer discrete-time VS control (DTVSC) speed loop. The adoption of FCS-MPC for current regulation in industrial PMSMs is driven by its inherent fast dynamic response, ability to enforce constraints, and the potential for modulator-less operation. Furthermore, DTVSC has proven to be an effective PMSM control strategy, particularly valued for its robustness in the face of model inaccuracies and external disturbances. The proposed control methodology, compared to the industry-standard PI cascaded control implemented by Whirlpool in domestic appliances, provides an improvement in control performance and robustness characteristics.