Soft-transition three-phase PWM conversion technology

By recognizing common topological properties of PWM converters and of available semiconductor switches, a new generalized soft-switching principle (soft-transition (ST) principle) is developed for the elementary PWM switching cell. Application of the ST principle opens a way of implementing many different new soft-switching PWM topologies. Its application is especially valuable in three-phase converters where the circuit complexity and presence of AC variables can often obscure possible ways of applying the ST technique. The generalized ST principle was successfully used for the development of two novel ZVT rectifier topologies.