DC-to-AC inversion using quasi-resonant techniques

It is demonstrated that two basic approaches can be taken to achieve DC-to-AC inversion. The first, the differential load excitation (DLE) scheme, uses two converters, driven out of phase, to drive a load differentially. Unfortunately, this scheme requires a large number of components when it is implemented using quasi-resonant techniques. A more component-effective approach uses switched source excitation (SSE) schemes. One SSE approach uses two converters, each handling one polarity of the signal. By appropriate switching, an amplified signal is reconstructed at the output. The second SSE approach entails only one converter but with a slightly more involved switching requirement. It allows a significant overall reduction in the number of components needed and reduced performance requirements on most of the switches, since most switch at the lower inversion-frequency rate. A number of quasi-resonant inverter topologies from two broad categories are presented. For applications that require inverters to supply reactive power, three schemes which can be applied to various inverters, thus affording them reactive load handling capability, are discussed