Shigeru Hamada

Analysis and design considerations for a saturable reactor assisted soft-switching full-bridge DC-DC converter are presented. The converter has advantages such as low switching losses with no substantial increase in conduction losses, wide load range, and constant frequency operation. To show how to utilize the analysis results, a 350 W, 500 kHz converter is chosen as a design example. The results are verified experimentally on a prototype converter.< <ETX xmlns:mml="http://www.w3.org/1998/Math/

A novel zero-voltage and zero-current switching PWM DC-DC converter with low conduction losses is presented in this paper. A new interleaved two-switch forward soft-switching converter topology is developed to minimize circulating current with no additional auxiliary circuits. This converter has many advantages such as less components, better efficiency, high power density and cost efficiency for high power applications. The principle of operation is illustrated together with steady-state analys

A family of saturable-reactor-assisted soft switching pulse-width-modulated (PWM) DC-DC power converters is presented. It uses saturable reactors to achieve efficient soft switching in a wide load range, from no-load to full-load, with no substantial increase in conduction losses. An approximate analysis and key experimental results are presented. In addition, a summary of voltage conversion ratios and voltage and current stresses for this family of converters is provided.< <ETX xmlns:mml="http:

The authors describe a power converter which incorporates saturable reactors as nonlinear elements to perform effective zero-voltage switching under large load and wide voltage-regulation ranges. Its steady-state characteristics are evaluated and discussed on the basis of computer simulation and experiments carried out with a 0.5-kW, 500-kHz breadboard. A power conversion efficiency of more than 88% was obtained. The results demonstrated that electromagnetic interference can be reduced.< <ETX xm

A constant-frequency, phase-shifted-mode, PWM (pulse-width-modulated) DC-DC power converter is described which incorporates two-stage inverters with high-frequency transformer links and saturable reactors as nonlinear elements. The proposed converter performs efficient zero-voltage switching over a large load range (no limitation for load range) and a wide voltage regulation range. Its steady-state characteristics are evaluated and discussed on the basis of computer simulation and experimental r

A new soft-switching converter technique is introduced which employs small saturable reactors and phase-shift modulation. This considerably reduces switching losses with no substantial increase in conduction losses. The proposed soft-switching concept and its modifications to full-bridge DC-DC power convertors are shown and discussed. These convertors can be realised by only a few additional small magnetic components with conventional full-bridge PWM convertors. The steady-state characteristics

In order to evaluate the fatigue limit of lamellar pearlitic steel used for railroad rails, tensile tests and fatigue tests are performed. Although the fatigue ratio of the lamellar pearlitic steel is lower than that of general steels, the reason for this has not been clarified. The fatigue cracks of the pearlitic steel initiate at a very early stage during the fatigue test. It is speculated that the steel should be treated as a steel with initial defects. In order to determine the initial defec