Abstract: A power converting device converts any of DC voltages outputted from at least two DC power supplies and outputs a converted voltage. A control unit of the power converting device determines whether a first contact and a second contact of a switch are melted and joined together based on a detection signal, before a second DC power supply outputs a second DC voltage.

Abstract: A power converting device converts any of DC voltages outputted from at least two DC power supplies and outputs a converted voltage. A control unit of the power converting device determines whether a first contact and a second contact of a switch are melted and joined together based on a detection signal, before a second DC power supply outputs a second DC voltage.

Abstract: A bidirectional DC-DC converter comprises: a first low voltage-side input/output terminal and a second low voltage-side input/output terminal; a low voltage-side rectifying circuit connected to the first low voltage-side input/output terminal and the second low voltage-side input/output terminal; a first high voltage-side input/output terminal and a second high voltage-side input/output terminal; a high voltage-side rectifying circuit connected to the first high voltage-side input/output terminal and the second high voltage-side input/output terminal; a transformer connected between the low voltage-side rectifying circuit and the high voltage-side rectifying circuit; and a controlling circuit that controls operations of switching elements in the low voltage-side rectifying circuit and the high voltage-side rectifying circuit. The controlling circuit achieves soft switching of a switching element in the high voltage-side rectifying circuit in a step-down operation.

Abstract: A bidirectional DC-DC converter comprises: a first low voltage-side input/output terminal and a second low voltage-side input/output terminal; a low voltage-side rectifying circuit connected to the first low voltage-side input/output terminal and the second low voltage-side input/output terminal; a first high voltage-side input/output terminal and a second high voltage-side input/output terminal; a high voltage-side rectifying circuit connected to the first high voltage-side input/output terminal and the second high voltage-side input/output terminal; a transformer connected between the low voltage-side rectifying circuit and the high voltage-side rectifying circuit; and a controlling circuit that controls operations of switching elements in the low voltage-side rectifying circuit and the high voltage-side rectifying circuit. The controlling circuit achieves soft switching of a switching element in the high voltage-side rectifying circuit in a step-down operation.

Abstract: A diaphragm for use in speakers in which a center dome is provided with a plurality of ribs in one of axial symmetry and non-axial symmetry patterns, for thereby dispersing the divisional resonance occurring in the center dome during the vibration and lowering the sound pressure specifically in higher sound range frequency characteristics, as well as a speaker comprising the particular diaphragm, are provided.