Radial state space vector modulation-a new space vector technique for reducing DC link capacitor harmonic currents in three level converters

Three level diode clamped converters exhibit significant low frequency harmonics in the neutral point current with classical modulation methods. A new space vector strategy that eliminates low frequency ripple from the DC link capacitors of a three level converter is proposed in this paper. The strategy redistributes the duty cycles of six states in the three level switching state diagram onto two adjacent states. States where each phase is connected to three separate DC levels are not chosen. This modified modulation method eliminates the low frequency harmonic content from the DC link capacitors with cost and size benefits.