| 摘要 |
<P>PROBLEM TO BE SOLVED: To effectively utilize a rectifying element and a switch element of a converter by providing different overcurrent levels at power drive and at regeneration when there is a difference in an energizing capability of the rectifying element and the switch element, and to perform a positive protecting operation. <P>SOLUTION: A bus voltage detector 70 detects an increase or a decrease in a bus voltage which is the voltage between a positive voltage bus and a negative voltage bus. An operating state discrimination unit 90 discriminates whether a motor 30 is in a regenerative state or in a power drive state based on an increased or decreased result of the bus voltage from the detector 70 during stopping period of regenerative switch elements SW1-SW6. An overcurrent protective controller 80 forcibly stops the drive of the switch elements SW1-SW6 only for a predetermined period when the input phase current detected by an input phase current detector 60 reaches the overcurrent level, and decides whether the operation of the converter 10 is an emergency stop or a forcible stop of the elements SW1-SW6 are released and reset to the normal operation based on the decision result of an operating state decision unit 90 during stopping period. <P>COPYRIGHT: (C)2004,JPO |
