ELECTRIC POWER CONVERSION DEVICE

PURPOSE:To feedback energy and improve efficiency by connecting a surge absorbing circuit in parallel with GTO (gate turn off) thyristors that are connected in parallel and connecting a converter for feedback and a diode for feedback between the surge absorbing circuit and the electric power source. CONSTITUTION:CTO thyristors 19a and 19b are connected in parallel through a reactor 18 for balancer, and they are connected to a power source 21 through a reactor 20. Furthermore, to the CTO thyristors 19a and 19b surge absorbing circuits 24a, 25a, 25b are respectively connected in parallel, and converters for feedback, 26a, 26b, and diodes for feedback, 27a and 27b are connected between each surge circuit and the power source, and at the time the intermediate taps of the converters for feedback 26a and 26b are connected to the power source 21. In this arrangement, balance of electric current is improved when the GTO thyristors are operated in parallel, and the energy of the surge absorbing circuits with the GTO thyristors on is fed back to the power source by the converters for feedback, and with the GTO thyristors off the energy accumulated in the reactor 20 is fed back to the power source with the result of raised efficiency.