Toshiba Toko Meter Systems Co., Ltd.

Mitsubishi Electric Corporation

Masaaki Ishino

Yoshito Sameda

Kenji Nakano

Yukio Takanohashi

Hiroto Uyama

Nobuya Nishida

A three-level I-type inverter includes first to fourth switching devices between first and second potentials, first to fourth diodes, and fifth and sixth diodes. The first to fourth diodes are respectively connected to the first to fourth switching devices in anti-parallel. Between a connection node of the first and second switching devices and a connection node of the third and fourth switching devices, the fifth and sixth diodes are connected in series and in anti-parallel with series connection of the second and third switching devices. A connection node of the fifth and sixth diodes is connected to an input node having intermediate potential. A connection node of the second and third switching devices is connected to an output node. The second switching device and diode are formed of a first reverse conducting IGBT. The third switching device and diode are formed of a second reverse conducting IGBT.

Three-level I-type inverter and semiconductor module

A gas appliance judgment apparatus and method by which a type of gas appliance in use and the existence of a gas leak can be identified. In operation, noise is removed from measured instantaneous flow volume, whereupon the 'length', 'initial flow volume' and &#x201c;sequence of transited regions&#x201d; of the variable portion of the flow volume and the &#x201c;length&#x201d;, &#x201c;average value&#x201d; and &#x201c;gradient&#x201d; of the flat portion of the flow volume are extracted. A rule having characteristics data which matches the characteristics of the variable portion and the flat portion of the flow volume is then searched, and points are added respectively for the type of gas appliance and for the existence of a gas leak. When the added points are not less than a previously established threshold value, then the type of gas appliance in use is determined, and appliance type information is output as a judgment result.

Gas appliance judgment apparatus and method

According to the present invention, mistaken detection of a gas leak can be prevented even when using an appliance which has been newly installed in a dwelling receiving a gas supply, and whereby a gas leak can be detected rapidly, efficiently and accurately. The characteristics extraction meansextracts characteristics of a gas flow including a combination of the instantaneous flow volume data and the instantaneous flow volume time differential value, on the basis of the data obtained by the flow volume measurement means, pressure measurement means, instantaneous flow volume time differential operation meansand pressure time differential operation means. The leak detection meanscompares the characteristics data for respective types of gas appliance or for a gas leak registered in the storage meanswith the characteristics extracted by the characteristics extraction means, and if a matching is not achieved, further judges whether there is a flow volume variation or nozzle variation, and whereby it judges whether there is a gas leak or whether an unregistered appliance is in use. If occurrence of a gas leak, the warning meansissues a warning. If an unregistered appliance is in use, the characteristics data forming the basis of the judgment is registered as a new characteristics data in the storage meansby the characteristics data registration means

Growing community of inventors

Tokyo, Japan

Masaaki Ishino