Active power decoupling method based on dual buck circuit with model predictive control

Abstract

Single phase inverter and rectifier systems have double line frequency ripple power which is inherent to the ac-side of the circuit but adversely affects the dc-side performance. Typically, an aluminum electrolytic capacitors is placed at the dc side to absorb this power ripple, but reduces the power density and reliability of the converter. Therefore, active decoupling methods have been proposed in the literature to transfer the ripple power to smaller storage components by extra switches to the converter. However, the existing active power circuits are mostly composed of half bridge circuit, which has inherent shoot-through potential problem and could degrade the system reliability. Moreover, the existing active power decoupling methods are normally implemented through predetermined voltage of storage component using conventional PI control method, which limits the decoupling dynamic performance of the system. In this paper, a novel active power decoupling method based on dual buck circuit and model predictive control is proposed. The dual buck circuit is composed of two separate buck converters operating in each half cycle and two split small dc-link capacitors to eliminate the dc-link voltage ripple. The topology is free of shoot-through and deadtime concern and the control is independent with that of the main power stage circuit, which makes the design simpler and more reliable. By applying model predictive control, the proposed control strategy is proved to have good dynamic performance by both simulation and experimental results.