Outer iron type power transformer and power converter using the same

摘要

PROBLEM TO BE SOLVED: To provide a shell type power transformer which can prevent an uneven magnetization as a problem in practical use and uses a no-cut thin-band wound magnetic core which has a low magnetic core loss and is compact, and a highly efficient and reliable power converter. SOLUTION: In this shell type power transformer, a shell type magnetic core comprises at least more than two wound magnetic cores wherein an angular ratio Br/Bs which is a ratio of residual magnetic flux density Br to saturated magnetic density Bs in a d.c. magnetic characteristic when the peak value of a magnetizing force is measured at 800 A/m, is 0.7 or less, the peak value of magnetizing force is 0.05 A/m, and an a.c. -to-initial permeability ri is =10,000 and =90,000 at a frequency of 20 kHz. A primary winding having no center tap in the intermediate leg of the shell type magnetic core, or a primary winding having at least more than one set of bifilar wound center tap, and a full-wave rectification secondary winding having at least one set of bifilar wound center tap are provided, and two indexes of coupling at 20 kHz between the primary winding and each of the full-wave rectification secondary windings as a main output are 0.9997 or more respectively.