Investigation and verification of a cascade double Γ-CL current source resonant inverter

The current source resonant inverter (CSRI) is at the heart of many systems and equipment (e.g. uninterruptible power supply (UPS) and high-frequency annealing (HFA) equipment). Many topologies shown in open literature are series resonant converters (SRC) and parallel resonant converters (PRC) that consist of two or three energy storage elements. However, they have a number of limitations. These limitations of two- or/and three- element resonant topologies can be overcome by adding a fourth energy storage element. This paper introduces a cascade double Γ-CL CSRI, which has very smooth waveforms for output voltage and current, and a very low total harmonic distortion (THD) value. It effectively reduces the power losses and largely increases the power transfer efficiency. Simulation and testing results verified the authors´ design and analysis