Primary-Current Controlled Flyback Micro-Inverter for PV Applications

Abstract

Photovoltaic (PV) modular inverter (MI) has gained in popularity due to the rise of distributed generation. The merits of distributed maximum power point tracking (MPPT) for each panel is very appealing since partial shading has always been an issue in centralized PV power systems. The concept of the one-panel-one-generator also improves system reliability since one MI failure does not affect other panels. Many topologies had been proposed for the task, however, to date, research has focused on the reduction of cost, efficiency enhancement, and system reliability. This thesis offers an insight into producing a conventional flyback converter topology as the MI. In order to improve its power density, this study focuses on controlling the averaged switch current in continuous conduction mode (CCM) using the PI type 2 controller. The first order pole transfer function is separated from the controller body and implemented as a dynamic amplifier to facilitate the discrete controller. Modulating the primary-side current allows the system to share its output-side components with other modules and its dynamic excludes the problematic non-minimum phase zero contained in the primary-to-output transfer function. A prototype of 200W capacity has also been designed and constructed for experimental evaluation.

Date of Award	May 2015
Original language	American English
Supervisor	Michael Weidong Xiao (Supervisor)