Cascaded Modular Converter With Reduced Output Voltage Ripple

In this paper, two cascaded modular converter configurations are compared: CMC and MLC. The non-isolated version offers a simpler construction, control method, better modularity and better power management architecture. The isolated version is considered better in a photovoltaic (PV) application as it can handle the difference in irradiance conditions i.e. due to partial shading without affecting the symmetry of its output voltage and current. Combining the advantages of differential-mode converters and multilevel inverters, CMCs can produce naturally filtered output voltage and current with lower voltage stress across its components while allowing for better power management. Moreover, a modified switching pattern is introduced to further reduce the sizing of the passive components (LC filters). This is done by shifting the triangular carrier associated with each dc-dc module which results in much lower average output ripples. Thus, lower switching frequency and / or converter size can be achieved. A brief description of the converters construction and operation is introduced. Then, Matlab / Simulink model is constructed to validate the converters ability to produce lower output ripples.