ABSTRACT
In this paper a new dc source less topology has been introduced for multilevel inverters. It uses crossover switches to generate the maximum output voltage levels. The Crossover Switches Cell (CSC) multilevel inverter can generate all possible voltage level among the DC supply and regulated DC voltage capacitor. A voltage controller has been proposed to keep the DC capacitor voltage regulated in case of load changes. The CSC provides maximum voltage levels and the controller balances the capacitor voltage even if the DC supply voltage changes. The number of voltage levels are increased to 11 by increasing the number of capacitors. The proposed system is simulated in MATLAB/Simulink software.
INTRODUCTION
Nowadays, research is focused and oriented toward more efficient energy conversion power electronics converters for high power applications which facilitates the integration of renewable energy resources into the grid supplying therefore high power loads and industrial consumers. The power rating limit of semiconductor switches leads to low efficiency of conventional voltage source inverters (VSI) in high power applications. Therefore, multilevel inverters are widely developed that employs medium voltage switches in order to deliver high power and high voltage from DC side to the AC side. Multilevel inverters are mostly employed in high power systems like: mining applications as regenerative conveyor, medical purposes like MRI gradient coil driver, hydro pump storage, STATCOM, FACTS, distributed generation, ship propulsion, train traction, aerospace and renewable energy conversion (wind and photovoltaic). Recently, low and medium power application using multilevel inverter is reported in applications like active filters because of the smooth output waveform. Many topologies have been introduced while most of them have not attracted the industries. The most popular topologies are cascaded H-bridge (CHB) and neutral point clamped (NPC) which are mainly used in machine drives. Introducing new topologies of multilevel inverters that produce more levels at the output while using less switches and DC supplies, is a challenging part of research in this field. Optimizing the numbers of switches used in multilevel inverters reduces the required gate driver’s boards and consequently, the manufacturing cost will become cheaper. Pack U cell (PUC) is another topology for multilevel inverters that have lower switches and DC sources while generating more voltage levels. It uses six switches, one DC supply and one DC capacitor to generate seven-level inverter; however the maximum voltage value of the PUC cannot exceed the DC source voltage magnitude.

Block Diagram