Analysis of Output Voltage Spectra in a Hybrid Diode-Clamp Cascade 13-level Inverter

This paper presents a novel hybrid diode-clamp cascade 13-level inverter. The inverter is based on the series connection between two inverter modules with higher and lower DC bus voltage. According to a hybrid control scheme in the topology, it is the fact that higher voltage devices and faster devices operate in synergism. Subharmonic PWM method is employed in lower voltage module. In the case of three carrier dispositions, mathematic models of the modulation process are constructed. The rigorous analytic solution is derived from an extension of Bennet´s method, which facilitates the evaluation of spectra accurately. We gather up spectral characteristics of output waveforms including all operation conditions. Experiment is performed to confirm the feasibility of the proposed approach