A Three-Phase, Five-Level Multilevel Inverter with Output Voltage Boost

Splitting of a dc voltage source with two capacitors has been the approach in generating 5-level output voltage with three-phase full-bridge circuit and added bidirectional switch. Associated with this configuration are the problem of voltage imbalance between the splitting capacitors and output voltage limitation to the value of the input voltage source. This paper proposes a unit topology for three-phase, 5-level multilevel inverter, MLI. In each phase-leg, it consists of H-bridge circuit, a capacitor, charge-discharge unit and de source. The charge-discharge unit with the capacitor is the interface between the H-bridge and the dc source. The proposed unit cell can generate 5-level phase leg output voltage waveform, whose peak value is twice the input voltage value; resulting in the syntheses of 9-level output line voltage waveforms. The salient feature of the proposed circuit is its output voltage boosting capability. Simulation and prototype experimental results are presented.