A novel noninverting boost-buck dc-dc converter
topology is presented, applicable when both sides of the
converter need to have the same grounding. It is based on the
back-to-back connection of two n-level diode-clamped converter
legs, and allows bidirectional power flow. A simplified topology
is proposed for unidirectional power flow applications. Two new
pulse width modulation strategies with different advantages are
proposed to operate the converter guaranteeing dc-link
capacitor voltage balance in every switching cycle for all
possible operating conditions and using small capacitance
values. The semiconductor device losses are analytically
compared to the losses in a conventional two-level boost-buck
converter. The analysis yields a higher efficiency for the
multilevel converter, especially as the number of levels
increases. Experimental results are presented to validate the
good converter performance in a five-level converter prototype.
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