Investigation of Conduction and Switching Power Losses in Modified Stacked Multicell Converters

Considering the advantage of the modified stacked multicell converter over flying capacitor and stacked multicell converters, and noting that investigation of the conduction and switching power losses can be advantageous in the design of multilevel converters, an analytical approach to calculate and analyze conduction and switching power losses in modified stacked multicell converter is presented in this paper. First, rms and average currents flowing through the insulated-gate bipolar transistors (IGBTs) and antiparallel diodes are analytically calculated by considering the duty cycle of each IGBT and diode in terms of converter modulation index, load current, and power factor. For validation, numerical results of the derived closed-form equations for computation of the rms and average currents are compared with simulation results and experimental measurements. Numeric computations of the closed-form equations match the simulation results and experimental measurements very well, which verifies the analytic equations. Next, derived equations for rms and average currents computation are utilized to calculate the conduction power losses. Finally, switching power loss analysis is performed by numeric approach and curve fitting method.