Design of parallel resonant DC link PWM inverter

Resonant topologies in the dc link of conventional converters are able to provide soft switching and therefore theoretically eliminate switching losses. A major drawback of most of these topologies is that PWM operation is not possible due to fixed switching instants. Although higher switching frequencies are obtainable, the use of sigma delta modulation yields undesirable subharmonics in the output spectrum. The parallel-resonant dc link (PRDCL) circuit under consideration in this paper allows the use of PWM, thus combining the benefits of hard and soft switched inverters. The operational principles are analyzed and results obtained through simulation as well as experiment are given.