CONSTANT SAMPLING TYPE CURRENT CONTROL SYSTEM FOR 3-PHASE SELF-EXCITED AC/DC CONVERTER

摘要

PROBLEM TO BE SOLVED: To extend a sampling period and enable the application to a 3-phase 3-wire AC system by a method, wherein when the comparison results between the real currents of interlinking points and target functions are out of a predetermined range, the switching modes of the respective main elements of an AC/DC converter are selected and operated by the values of an error function only. ;SOLUTION: 3-phase AC currents at interlinking points are detected and compared with target functions ja (tn), jb (tn) and jc (tn), which are composed of predetermined balanced 3-phase sine waves by comparators 14, 14-1 and 14-2. If the comparison results are out of a predetermined target range in a lower direction, an upward switching mode is selected. If the comparison results are out of a predetermined range in an upper direction, a downward switching mode is selected. Such control is repeated for every current sampling time, and the balanced 3-phase target functions ja (tn), jb (tn) and jc (tn) are followed. For this purpose, the gate commands of respective switching elements can be selected only according to the values of an error function at the respective sampling times.;COPYRIGHT: (C)1998,JPO