Hybrid modulation and new technologies for high-frequency high-power multiphase power system

Recent R& D advances on megawatt power, high-frequency nanocrystalline transformer [1] and high-voltage, high-frequency SiC based semiconductor devices [2] present possibility of a shift in the design of high-power inverters from a one based on complicated structure with line-frequency switching to the one based on simple topology and operates at 10 - 20 kHz frequency. In line with these ongoing advancements, in this paper, a summary of performance for a multiphase high-frequency-link (HFL) high-power inverter using a new innovation (here after referred to as ldquohybrid modulationrdquo [3] - [5]) have been outlined in the presence of hard-switched and soft-switched front-end. Unlike conventional constant-dc-link inverters, the hybrid-modulation-based inverter applies a high-frequency pulsating dc link voltage to the output ac/ac stage, whose structure is identical to a three-phase voltage source inverter (VSI). The former has comparable bus voltage utilization and total harmonic distortion (THD) performance as the conventional constant dc-link VSI but possesses other additional advantages such as: 1) elimination of dc filter; 2) reduced switching and conduction losses of high-voltage switches; and 3) reduced RMS current and di/dt stress of high-voltage devices. Finally, straightforward topological scalability using the hybrid modulation based converters is also demonstrated.