Alternate Search Pattern for Parallel Sphere Decoder in Long Prediction Horizon FCS-MPC

The sphere decoding algorithm (SDA) is used in power electronics as a solver of the optimization stage for long prediction horizon finite control set model predictive control (LPH-FCS-MPC). In the literature, a parallel SDA was proposed to enable concurrent search. This strategy increases the number of candidates explored per time, improving the likelihood of finding the optimal solution in real time. In this work, an alternate search pattern for the parallel SDA is proposed. The main idea is that each parallel sphere decoder block explores a region of the search space following a different search pattern, increasing diversification of candidates before a solution has to be delivered. This approach improves the average optimality of parallel SDA, which in turns enhances the control performance.