| 摘要 |
PURPOSE:To improve protection by a method wherein the AND of an overcurrent detecting signal, obtained by comparing a current detecting signal with a reference value signal, and an operation starting commanding signal is utilized as the overcurrent detecting signal. CONSTITUTION:A voltage type inverter device is constituted of a converter 3, converting 3-phase AC power source 1 into DC power, a smoothing capacitor 4 and an inverter 5 and drives ac AC motor 6. A protecting device for the inverter device is constituted of a current detector 7, a reference value generating circuit 8, a comparing circuit 9, a circuit 10 for holding the result of comparison or an overcurrent detecting signal 9a and an inverter control device 11. In this case, an AND element 12 is inserted between the comparing circuit 9 and the hold circuit 10 to input newly the AND of the overcurrent detecting signal 9a and an inverter operation starting commanding signal 11b into the hold circuit 10 as the overcurrent detecting signal 12a. According to this constitution, an output from an AND element 12 is not outputted even when the overcurrent detecting signal 9a is outputted due to the generation of noise. |
