| 摘要 |
PROBLEM TO BE SOLVED: To reduce the frequency of motor stop due to thermal protection and thus avoid loss arising from motor stop. SOLUTION: A thermal load Q is estimated from the actual value 1 of motor current. When the magnitude of the estimated thermal load approaches the level Q1 of stopping the motor, a current limiting value I1 is reduced. When some margin of thermal load is produced, the current limiting value is increased and brought close to the original value I1max. |
