Multilevel inverter by cascading industrial VSI Academic Article uri icon


  • In this paper, the modularity concept applied to medium-voltage adjustable speed drives is addressed. First, the single-phase cascaded voltage-sorce inverter that uses series connection of insulated gate bipolar transistor (IGBT) H-bridge modules with isolated dc buses is presented. Next, a novel three-phase cascaded voltage-source inverter that uses three IGBT triphase inverter modules along with an output transformer to obtain a 3-p.u. multilevel output voltage is introduced. The system yields in high-quality multistep voltage with up to four levels and low dv/dt, balanced operation of the inverter modules, each supplying a third of the motor rated kVa. The concept of using cascaded inverters is further extended to a new modular motor-modular inverter system where the motor winding connections are reconnected into several three-phase groups, either six-lead or 12-lead connection according to the voltage level, each powered by a standard triphase IGBT inverter module. Thus, a high fault tolerance is being achieved and the output transformer requirement is eliminated. A staggered space-vector modulation technique applicable to three-phase cascaded voltage-source inverter topologies is also demonstrated. Both computer simulations and experimental tests demonstrate the feasibility of the systems.

published proceedings


altmetric score

  • 3

author list (cited authors)

  • Teodorescu, R., Blaabjerg, F., Pedersen, J. K., Cengelci, E., & Enjeti, P. N.

citation count

  • 141

complete list of authors

  • Teodorescu, R||Blaabjerg, F||Pedersen, JK||Cengelci, E||Enjeti, PN

publication date

  • August 2002