| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem of being unable to surely protect a switching element, if an output frequency is lowered sharply. SOLUTION: To thermally protect the switching elements Q1 -Q6 of a conversion circuit 3 of an inverter unit, a radiator 6 is provided. A temperature detector 7 is coupled with the radiator 6. An allowable temperature with which a detected temperature is compared, is not made as a fixed value but is corrected with an output frequency fo and a switching frequency fc . |
