| 摘要 |
<p>PROBLEM TO BE SOLVED: To protect load drive means, definitely detect sort-circuit troubles of load, and prevent erroneous detection of short-circuit troubles due to a transient overcorrent by judging a load to be short-circuited if a state, where the detected value of a load current exceeds a predetermined value within a first predetermined time, has continued for a second predetermined time. SOLUTION: A current flowing to a motor 4 is detected by load current detecting means 6, and this load current is controlled by load current control means 7 so as to make this load current to be followed by a target current. Then, at the load short circuit failure judging means 9, the maximum value of load current detected values is retained for a first predetermined time by the maximum current retaining means 10, then by short-circuit current judging means 13, a short-circuit current is judged when the maximum current retaining value has exceeded the predetermined current value. Next, by the short-circuit continuation time judging means 14, if this short-circuit continuation time judging results continue more than the second predetermined time and indicate a short- circuit trouble of load, the drive of motor 4 by the load drive means 8 is stopped and alarm means 15 is operated.</p> |
