Model Predictive Control Based Controller for Grid-Connected Ripple-Port Inverters

Single-phase grid-tied inverters have a characteristic double-line-frequency power ripple. Dual-frequency ripple interferes with the maximum power point tracking functionality and reduces the energy harvest from photovoltaic systems. Using capacitor banks to filter out double frequency ripple reduces system reliability. An active filtering technique, such as the ripple port module integrated inverter (RP-MII), has shown a significant reduction in the capacitor size required at the dc link. This paper presents a model predictive control (MPC) technique for dc-link voltage regulation. Controlling the RP-MII using a modulator-based regulator requires multiple control loops and tuning numerous gains. Using a multiobjective MPC cost function relies on a single loop capable of grid current control and dc-link voltage regulation. Results show that the MPC controlled RP-MII requires significantly lower capacitance to achieve the same ripple results. Without losing generality, the proposed controller could be implemented to other power decoupling and active filtering techniques.