POWER SUPPLY PHASE ORDER DECISION UNIT FOR THREE-PHASE PWM CONVERTER

摘要

PROBLEM TO BE SOLVED: To prevent failure due to reverse connection and to operate a controller normally even under reverse connection by determining the phase order of a power supply being connected with a three-phase PWM converter based on the polarity of a determined phase order decision reference value. SOLUTION: A first means 5 determines the two-phase voltage value of an input voltage through three-phase/two-phase conversion of a three-phase input voltage value. A second means 6 determines the differentiated value of a two-phase voltage value determined by the first means 5. A third means 7 determines a phase order reference value (J) using the two-phase voltage value determined by the first means 5 and the differentiated value thereof determined by the second means 6. Phase order of power supply is determined from the polarity of J. More specifically, phase order of a power supply being connected with a converter can be determined from the polarity of J determined by the third means 7 such that positive J represents forward phase whereas negative J represents reverse phase.