Power Decoupling Control of the Two-Stage Single-Phase DC-AC Power Conversion System to Eliminate the Double Line Frequency Ripple

In two-stage single-phase inverters, inherent double line frequency ripple is present at both input and output of the frontend converter. Generally large electrolytic capacitors are used to eliminate the double line frequency ripple. It is well known that the low frequency ripple shortens the lifespan of the capacitor hence the system reliability may get worse. In order to eliminate the double line frequency ripple additional hardware combined with an energy storage device is required in most of the methods developed so far. In this paper, a novel power-decoupling control method is proposed to eliminate the double line frequency ripple at the front-end converter of the DC /AC power conversion system. The proposed control algorithm is composed of two loops, a ripple compensation loop and an average voltage control loop, and no extra hardware is required. Since the proposed method does not require any information from the phase-locked-loop (PLL) of the inverter it is independent of the inverter control. In order to prove the validity and feasibility of the proposed algorithm a 5kW Dual Active Bridge DC/DC converter and a single-phase inverter are implemented. The effectiveness of the proposed method is verified through the simulation and experimental results.