| 摘要 |
PROBLEM TO BE SOLVED: To quickly stop the operation of an inverter, when a load having a half-wave rectifying circuit is connected to a half-bridge type inverter. SOLUTION: An inverter 24 is provided with a capacitor circuit 5, consisting of the serial connection of two capacitors 4, 5 to which a DC power supply voltage is applied from a DC power supply circuit 1 and a half-bridge type inverter main circuit 11 consisting of serial connection of two IGBTs (switching elements) 7, 8 connected in parallel to which capacitor circuit 6, in order to supply an AC power to a load 23 from the common connecting point of two capacitors 4, 5 and common connecting point of two IGBTs 7, 8. A protection device 26 is composed of an output voltage detecting circuit 15 for detecting the AC output voltage of the inverter 24, mean value detecting circuits 27 and 28 in the positive and negative voltage sides for respectively detecting the mean value of the positive output voltage of an output voltage detecting circuit 15 and the mean value of negative output voltage thereof and the difference detecting circuit 29 for stopping the operation of the inverter 24, when the difference between the absolute values of mean values of the positive and negative output voltages reaches a prescribed value. |
