Power electronics applications started with the purpose of driving electric motors. The nature of this application generally implies no need of a neutral cable. In consequence classic inverters have three legs, one for each phase. However, in medium and low voltage energy distribution, it is common to use three phases plus a fourth neutral wire. This case becomes especially relevant for renewable energy and distributed generation. The use of three leg inverters for four wire applications has a number of drawbacks which could be improved by using the four leg NPC topology. In this book these...