Electric power converter/inverter and power control apparatus using the same

摘要

PURPOSE:To prevent the breakdown of controlled rectifier elements by providing voltage limiter means in inversely parallel with the controlled rectifier elements, detecting means which detect electric currents when the voltage limiter means operate, and protective means which are operated by the detected signals of the detector means. CONSTITUTION:First to fourth controlled rectifier elements 4-7 are connected in series between both terminals of capacitors 2a and 2b which are connected to a DC side 1 and have a neutral point 3 and first and second clamp diodes 16 and 17 are respectively connected between the connecting point between the first and second controlled rectifier elements 4 and 5 and the neutral point 3 and between the connecting point between the third and fourth controlled rectifier elements 6 and 7 and the neutral point 3. In such a power converter, voltage limiter means 4b-15b which are connected in inversely parallel with controlled rectifier elements 4-15, detecting means 26-37 which detect electric currents when the means 4b-15b operate, and protective means which stop the operations of the elements 4-15 by using the detected signals of the means 26-37 are provided.