| 摘要 |
PURPOSE:To quicken the rise-up of a conduction current by the high voltage of a capacitor by a method wherein an accumulated energy is converted into the electrostatic energy of the small-capacitance capacitor to reduce the conduction current quickly while a switching element is conducted when the conduction current has been reduced to a predetermined value. CONSTITUTION:The accumulated energy of a load 1 tends to circulate to the positive pole 2a of a power source by diodes 4a, 4b, however, the circulation is precluded by a diode 6 and a capacitor 5 is charged. The capacitance of the capacitor 5 is small and, therefore, the voltage thereof is increased and an exciting current is reduced quickly. When the exciting current is reduced to a predetermined value, an output is returned to a high level due to the hysteresis characteristics of an operational amplifier 11. Accordingly, transistors 3a, 3b are conducted, the exciting current is increased suddenly and is increased further by a power source voltage nextly. When the exciting current has exceeded a reference voltage, transistors 3a, 3b in a chopper circuit become non-conductive again. |
