Modelling and control of a power electronic cascade for the multi‐DC bus supply

Abstract

PurposeThe purpose of this paper is to describe the control and regulation of input DC voltages of nine‐level neutral point clamping (NPC) voltage source inverter (VSI).Design/methodology/approachThe analysis and simulation of a cascade made up of three‐phase five‐level PWM rectifier‐nine levels NPC VSI are treated. This cascade is used to feed a permanent magnet synchronous machine (PMSM) drive. First, the five‐level PWM rectifier is presented. Then a topology of nine‐level NPC VSI and the associated PWM control strategy are described. In order to discard the problem of DC link voltage fluctuations, a clamping bridge with a PI regulation has been added to the cascade. Then a field‐oriented control strategy has been implemented in the PMSM.FindingsThe obtained results are full of promise to use the inverter in high voltage and great power applications such as electric naval propulsion systems.Originality/valueThe application of the proposed feedback control algorithm to the studied cascade offers the possibility of stabilizing the DC voltages. The studied cascade absorbs network currents with low‐harmonic content and unity power factor. In all, the instability problems associated with use of multilevel inverters are solved.