| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To solve the problem that an AC switch ACSW 1 is not cut-off completely and left as communicated to a system 200 when a converter 100 is switched to the UPS control of CVCF upon the reception of an abnormal signal Se=1 of the system 200, thus causing the converter 100 to be fed with an excessive current and causing the possibility of an operation not to be continued. <P>SOLUTION: When the converter is switched to the UPS control from communicative control upon the detection of an abnormality in the system, following measures are provided: (1) a current-control system that leads a current flowing in the AC switch ACSW to zero is constituted, and UPS voltage control is started upon the detection of zero cross; (2) a period in which an operation is conducted at a fixed percentage modulation is provided; or (3) an operation- stop period is provided. <P>COPYRIGHT: (C)2003,JPO</p> |
