Power decoupling with autonomous reference generation for single-phase differential inverters

Abstract

The second-harmonic power ripple in single-phase inverter may introduce the issue of low reliability and low power density. In order to replace the bulky dc-link capacitor, an alternative approach is to use active power decoupling so that the ripple power can be diverted into other energy storages. However, the performance of existing active power decoupling methods depends heavily on certain control references, which unfortunately are parameter dependent. In this paper an autonomous reference generation technique is proposed for single phase differential inverter without relying on the system parameters. A unified average switching model is firstly derived for Buck, Buck-Boost and Boost differential inverter, which is apparently have nonlinear characteristics. Then, dual-loop cascading control and a feedback linearization method is employed to design the inner- and outer loop controllers, which are used for realizing an improved power decoupling control, capacitor voltage and inductor current regulation. By substituting the corresponding parameter into unified model, the proposed control loop can be applied to different inverter types (Buck, Buck-Boost and Boost). Finally, detailed laboratory prototype experimental results have been done to verify the effectiveness of this power decoupling method.