Multi-pulse rectifiers feeding h-bridge inverter

This article presents a comparative analysis of 12-, 18-, 24-, and 36-pulse rectifier topologies supplying 3-phase three-level H-bridge inverters as active loads. The analysis comprises the total harmonic distortion data of the inverter and grid currents and voltages, including inter-modulation harmonics. This article shows that the rectifier-inverter connection produces inter-modulation harmonics between the grid and inverter frequencies. As a result, intermodulation and sub-harmonics are present in the grid currents. This article presents an analysis and comparison of these inter-modulation effects for the mentioned topologies. Moreover, it is shown that the inter-modulation effects can be reduced by increasing the capacitance of DC-link capacitors, increasing grid series inductance, and using rectifiers with high number of pulses. The analysis is validated by extensive simulation results.