Abstract: A switching power supply device includes a full-bridge circuit, a transformer, a rectifier circuit, a filter circuit, a first series connection of a snubber capacitor and a first diode, and a second diode. The full-bridge circuit includes switching elements which are controlled to be driven under phase-shift control. The first series connection is connected in parallel with the smoothing reactor, where one terminal is connected to a terminal on positive side of the rectifier circuit, and the other terminal is connected to an anode of the first diode. A cathode of the first diode is connected to one terminal of the smoothing capacitor which is applied with positive voltage. The second diode is provided between a terminal on negative side of the rectifier circuit and a connecting point of the snubber capacitor and the first diode. A cathode of the second diode is connected to the connecting point.

Abstract: A battery charger includes a primary side circuit, a transformer, a secondary side circuit and a control circuit. The secondary side circuit includes a first output unit and a second output unit. The battery charges a main battery and an auxiliary battery. The first output unit, which is connected to a main battery, includes an integrated rectifier-converter and a smoothing circuit. The integrated rectifier-converter is formed using MOSFETs. When charging the auxiliary battery with power from the main battery, power from the main battery is converted by the integrated rectifier-converter to AC power which induces power in an output winding of a transformer connected to the auxiliary battery.

Abstract: An improved working vessel such as a dredger or the like of the type including a working apparatus at one end of the vessel body and a spud serving as a turning shaft member for the vessel body at the other end, includes the improvement wherein the turning staff member comprises an arm shaft extending toward the bottom of the sea from the vessel body at a downward inclination angle and a lowermost end member adapted to penetrate the bottom of the sea. The arm shaft is pivotally connected to the vessel body by way of a horizontally extending shaft at the upper end thereof and is hung up from a gantry fixedly mounted on the vessel body with the aid of a wire extending downwardly from the gantry.