Fundamental characteristics of a photoe]ectrochemical cell using p-type porous-St layer (PSL) as a semiconductor photoe]ectrode were measured. The PSL electrode exhibited stable photodiode characteristics. The increase in the PSL thickness was very useful in suppressing the dark current, although it resulted somewhat in reducing the photosensitivity, due to the increase in surface recombination losses of photogenerated carriers.

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SUMMARYWe have developed a prototype of a 3 kV/200 A SiC hybrid module, which is equipped with Si IGBTs and SiC Schottky barrier diodes. We achieved a reduction in the recovery loss and turn-on loss by using an SiC hybrid module and decreasing the turn-on time by lowering the gate resistance. Moreover, we estimated that the total energy loss in the converter and inverter was reduced to approximately 30% by using the developed SiC hybrid module. Additionally, the inverter succeeded in driving an induction motor for a train. C⃝

Transformers are used in power converter systems in order to isolate input circuit and output circuit of the system and to obtain a suitable output voltage to loads. Ideal AC power sources do not include DC component, however some time output voltage of the power converters include DC component in its output voltage because of difference of switching behaviour of power devices which are used in the power converters. Also offset error of voltage transducers, current transducers, analog circuits and A/D converters produce the DC component in the output voltage. The component leads the magnetic field saturation of the transformers, which causes loss and acoustic noise from them. Then it is required to prevent the DC component. However, it is difficult to achieve to select switching devices, which have some switching behaviour. It is achievable to prevent the DC component if the component can be measured and compensate it. However it is difficult to measure the DC component because it is very small compare to the output voltage and offset of the measuring system cannot be ignored.In this paper, a novel magnetic field saturation of the transformers detecting method, which is based on a correlation function to exciting current of it is proposed and effectiveness of the DC component compensation in accordance with the value measured by the novel method is shown.