| 摘要 |
PROBLEM TO BE SOLVED: To enable judgment with small scale constitution and that at the optional time by converting a temperature difference signal into the temperature difference signal in the case where a fixed current is made to flow, based on the current detection value of a current detector, and comparing the outputs at the different times with each other, and judging whether a self extinguishing element is abnormal or not. SOLUTION: A current flowing to an inverter 6 is measured with a current detector 9, and it is converted into a temperature rise value where current application current conditions are made equal, based on a curve of current vs. saturation temperature set beforehand. At the first drive of a power converter, the temperature rise value after this conversion is written into the specified address 15a of a storage device 15, and it is preserved as an initial value for comparison. Then, a comparison judging means 16 compares the initial value for comparison with the temperature rise value at judgment, and issues abnormality judgment output in the case that the difference gets over the specified threshold. Accordingly, the system can be constituted in small scale, and the judgment at the optional time is made possible. |
