Hybrid Model Predictive Control for Modified Modular Multilevel Switch-Mode Power Amplifier

Abstract

This article proposes a hybrid model predictive control (HMPC) for a modified modular multilevel switch-mode power amplifier (M3-SMPA). The M3-SMPA consists of two parts connected in series including modular multilevel converter (MMC) and full-bridge converter (FBC). Different from available MPC methods that only apply either finite control set MPC (FMPC) or modulated MPC (MMPC), the proposed HMPC method synthesizes the merits of both FMPC and MMPC on different timescales. First, the optimal control option (CO) for MMC is calculated by FMPC with the multiple control objectives, including output voltage control, circulating current control, and submodules (SMs) capacitor voltages balance control. Then, based on the above-mentioned optimal CO, the optimal duty cycle for FBC is calculated by MMPC with a single objective of output voltage control. In this case, the FMPC achieves the multiobjective control of MMC while the MMPC eliminates the tracking error of output voltage using FBC with a fixed switching frequency. Furthermore, a circulating current injection method is presented to balance the SMs capacitor voltages and an improved adjacent search method is introduced to reduce the evaluated COs for MMC in each control period. The effect of dc-link voltage configuration for FBC on output steady-state performance is also analyzed. Finally, the effectiveness of the proposed HMPC method is verified by experimental results.