New Multilevel Converters With Coupled Inductors: Properties and Control

International audienceIn the paper, a new five-level (5L) converter is presented. It is called 5L-active-neutral-point-clamped with coupled-inductor (5L-ANPC-CI) and consists of a three-level bidirectional (3L-B) commutation cell connected to two parallel basic commutation cells. The proposed topology can be seen as two cascaded current stages controlled at different frequencies. The high-current stage is specific to the 3L-B cell controlled at low-frequency, while the low-current stage corresponds to the parallel cells with coupled-inductor controlled at high-frequency (HF). Due to this advantage, the new converter appears as a useful solution to increase the output current, while the switched current through the HF power devices is reduced. The operation principle of the new structure is verified by simulations both for single- and for three-phase topologies. Experimental results for single-phase 5L-ANPC-CI converter on a low-voltage test bench are also provided to validate the proper operation of this concept

Loss balancing for Active-NPC and Active-Stacked-NPC multilevel converters

International audienceThe paper is focused on the numerical calculation of total losses in each power device of 3L-ANPC (Active-NPC) and 3L-ASNPC (Active-Stacked-NPC) multilevel converters in a STATCOM application. Due to the symmetry of the structures the conduction and switching losses are calculated only for half of power devices. The modulation functions and the conduction/switching intervals are elaborated in order to calculate the total losses. These are specific for each power device depending on the structure's type and on the PWM strategy. The obtained results for conduction currents (average and RMS values) are validated using PSIM simulations

New Multilevel Converters Based on Stacked Commutation Cells with Shared Power Devices

International audienceIn this paper, a new three-level (3L) converter is presented. It is called 3L Vienna neutral-point-clamped (3L-VNPC) converter and consists of two stacked high-frequency (HF) commutation cells working with a shared power device. The HF cells are connected to a single-phase switched bridge controlled at low frequency. The 3L-VNPC topology is extended to 3L active VNPC (3L-AVNPC) concept, which is generalized for five levels (5L) and N odd voltage levels (N L). The proposed multilevel converters can be seen as two cascaded voltage stages. The high-voltage stage is specific to the single-phase switched bridge, while the low-voltage (LV) stage corresponds to the stacked HF cells with shared power devices. The new concept AVNPC is a useful and suitable solution for medium-voltage applications, where small modulation index (M) is as crucial as large M. The analyses of the new converters are verified by simulations both for 3L and for 5L topologies, and their features are generalized for NL. Experimental results for single-phase 3L-AVNPC converter on an LV test bench are also provided to validate the proper operation of the new concept