Optimal design of multilevel Uninterruptible Power Supply

In this paper, an optimization regarding power density and efficiency of 30kVA multilevel Uninterruptible Power Supply (UPS) is presented. The key design parameters, including switching frequency, converter topologies, number of levels, modulation schemes, and passive values, are selected by considering their impacts on losses, harmonics, and Electro Magnetic Interference (EMI). The optimization is performed for a switching frequency range of 10-40kHz and for two, three and four level converters and considering ferrite, amorphous, nanocrystalline and powder core materials. Also, The new concept of using Coefficient Diagram Method (CDM) controller in output filter design is introduced.