Converters for drives

Abstract

This chapter presents the most popular dc -ac inverter topologies, two -level and three -level NPC inverter, used for the electric drives. It focuses on the SPWM and SVPWM methods for the two -level and three -level NPC inverters. The emphasis is given to the implementation aspect of these PWM methods. It is shown that the SVPWM method can be implemented in the same way as the SPWM method with small modification in the sinusoidal reference signals. Furthermore, the problem of neutral -point voltage unbalance associated with the three -level NPC inverter is discussed. A popular method to balance the neutral -point voltage is also discussed.