A Single Phase AC/DC/AC Converter With Unified Ripple Power Decoupling

In single phase ac/dc/ac converters, the low frequency ripple powers exist both at the source and load sides. Usually, large dc-link filter components are used to buffer the ripple powers, which increases volume and weight. To overcome the drawback, this paper presents a single phase ac/dc/ac current source converter with unified ripple power decoupling. The converter only consists of three bridge arms and a decoupling circuit. The three bridge arms play the role of rectification and inversion with sharing a bridge arm. And the decoupling circuit is in series with the dc-link energy storage unit to buffer the ripple powers. The circuit configuration and operation principles are introduced first. Then, a modulation strategy based on Cartesian space is developed to achieve sinusoidal input and output currents. The control idea that the dc-link current is regulated by the decoupling circuit and the averaged decoupling capacitor voltage is maintained by the rectifier is adopted. The ripple power buffer is automatically achieved. Finally, the theoretical analysis is favorably verified by the simulations and experimental results.