| 摘要 |
PURPOSE:To prevent the starting delay of a smoothing capacitor and to prolong the life of a contactor by operating a converter for a given period of time, when the DC side voltage of said converter lowers and the speed of an electric car increases and there is no operating command of said converter. CONSTITUTION:When PWM converter CONV interrupts operation, the voltage of a capacitor C1 starts lowering. In this case, when a rolling stock is coasting and its speed is higher than a certain value, the conditions of an AND circuit AND are satisfied if DC (VD) is lower than a set point corresponding to the peak value of AC voltage. Then, power is outputted from a one-shot timer T for a given period of time and the PWM converter CONV operates only for said period of time via a converter control circuit CONT to charge the capacitor C1 with electricity. At the time of starting said converter control circuit CONT and stopping said electric car, said conditions are not satisfied so that said operation is not performed. |
