A High-Frequency Link Matrix Rectifier With a Pure Capacitive Output Filter in a Discontinuous Conduction Mode

High-frequency link matrix rectifier (HFLMR) is an isolated single-stage three-phase ac-dc converter, which originates from the three-phase matrix converter and inherits the advantages of matrix rectifier such as no dc-link components. In this paper, an HFLMR for more electric aircraft system is proposed. The proposed HFLMR consists of a three-phase input LC filter, a matrix rectifier, a high-frequency transformer, a diode bridge rectifier, and a purely capacitive output filter. The elimination of output filter inductor clamps the output rectifier device off-state voltage to the output voltage and eliminates any RC snubber across the rectifier. A novel symmetric modulation scheme based on space vector modulation is implemented to regulate the switching sequences and provide selective natural zero voltage switching and zero current switching of the devices of the matrix bridge. The proposed converter is more power-dense since it eliminates the dc-link components, output filter inductor, and lossy snubber across the output rectifier devices. A TI digital signal processor TMS320F28379D is used to process the converter signals and generate the gating logic. The proposed converter is validated on a laboratory prototype powered by 115 V-rms ac with frequency of 400 Hz. The isolated dc output voltage is regulated at 270 V dc and the maximum output power is 600 W.