A Study on Model Predictive Control of 3-phase Inverter with Output LC Filter

Traditionally, in order to control output voltage of the Three-Phase Inverter, the proportional-integral (PI) controller using dual-loop voltage control strategy has been used. However, physical input constraints were not considered in the design of the PI controller, and there was no analytical method to determine the control gain. This paper presents a dual-loop inverter voltage control strategy for uninterruptible power supply (UPS) utilizing an one-step ahead model predictive control in the inner-loop. The proposed MPC optimizes the cost function of the error state through a simple online membership test; any numerical method is not necessary. Moreover, any off-line optimization is not required. It is shown that the proposed MPC makes the closed-loop system globally asymptotically stable in the presence of input constraints. Following the conventional dual-loop strategy, the PI controller is used in the outer-loop to regulate the output voltage.

The effectiveness of the proposed MPC scheme is simulation shown under an unexpected load changes.