| 摘要 |
PROBLEM TO BE SOLVED: To improve profitability by conducting rational insulation coordination protection, by determining the rated breakdown strength of a self arc- extinguishing type switching element and a reverse blocking diode by setting specified margins at each protective level. SOLUTION: When this power converter is adapted to an ozone generator, the protective levels of self arc-extinguishing type switching elements 14-1-14-4 and reverse blocking diodes 13-1-13-4 are selected in relation to the operating voltage of an inverter circuit 5 while rated voltage is determined in cooperation with the protective levels. A thyristor 9 is not ignited by an output from an overvoltage protective circuit 8 and also does not conduct operation unnecessary for operating voltage at a normal time, and is operated surely at the time of a fixed value or more of overvoltage and the IGBTs 14-1-14-4 and the reverse blocking diodes 13-1-13-4 are protected. Since rated voltage has a rational margin to the protective level of the overvoltage protective circuit 8, sufficient protection is performed against overvoltage. Accordingly, profitability can be improved by conducting rational insulation cooperation protection. |
