Title:
METHOD AND APPARATUS FOR CONTROL OF CONSTANT MARGIN ANGLE IN THYRISTOR AC-DC CONVERTER
Document Type and Number:
Japanese Patent JP3428845
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To eliminate the failure of a commutation operation even when the frequency of an AC system is changed by a method in which a desired margin angle is changed by using a specific expression so as to be porportional to the frequency of the AC system.
SOLUTION: An apparatus is composed of a cosine computing unit 1 which computes the cosine of a margin-angle instruction value γref, of a multiplier 2 in which a commutation reactor Xi is multiplied by a DC current Id, of a scale multiplier 3 in which the output of the multiplier 2 is multiplied by a factor and of a multiplier 8 in which the margin-angle instruction value γref is multiplied by the output of a scale multiplier 7 so as to output its result to the cosine computing unit 1. Then, by using an expression of cosγ-cosβ=(21/2).Xi.Id/Ei, a desired margin angle is changed so as to be proportional to the frequency of an AC system. In the expression, represents a commutation reactance for one phase portion, Id represents a DC current, and Ei represents a transformer-valve-winding voltage. When the margin-angle instruction value γref is corrected in this manner, a constant-margin-angle control apparatus at an AC-DC converter does not generate the failure of a commutation operation even when the frequency (f) of the AC system is changed, and it continues a stable operation.
Inventors:
Toshiyuki Fujii
Naoki Morishima
Naoki Morishima
Application Number:
JP956697A
Publication Date:
July 22, 2003
Filing Date:
January 22, 1997
Export Citation:
Assignee:
Mitsubishi Electric Corporation
International Classes:
H02M7/155; H02M7/12; (IPC1-7): H02M7/155
Domestic Patent References:
| JP5103482A | ||||
| JP7327373A | ||||
| JP8140361A |
Attorney, Agent or Firm:
Hiroaki Tazawa (1 person outside)