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A transformerless multicellular dc-dc converter has been newly proposed. The capacitively isolated dc-dc cell converters have been applied to develop the multicellular converter without using high frequency transformers. The high voltage transformation ratio is achieved by the ISOP (Input Series Output Parallel) connection topology of the cell converters and the realization of the highly efficient cell converter is expected because of no transformers. A 144 V-24 V, 200 W prototype of the multicellular dc-dc converter using 3 cell converters based on the capacitive isolation has been developed, and the feasibility of the transformerless multicellular converter has been confirmed.

Tetrahedral amorphous-carbon (ta-C) without hydrogen is the hardest in diamond-like carbon (DLC), and expected of the application to coating on dry cutting tool for aluminum. The only method to prepare ta-C on an industrial scale is cathodic vacuum arc deposition. The authors have been developed T-shape filtered arc deposition (T-FAD) system with efficient droplet reduction. However, ta-C usually requires a binding interlayer between the workpiece and film, since the internal stress of the film is very high and adhesion to the substrate is not good. In the present study, in order to prepare DLC and metal film on the superhard alloy depositing from same direction, the authors developed on X-shape filtered arc deposition (X-FAD) apparatus. First of all, the authors verified the droplet reduction function, and then the appropriate duct bias voltages and deposition rate. DLC was also prepared with substrate heating. By considering and following these results, 1 a thick ta-C film was prepared on a superhard alloy with interlayer by X-FAD