| 摘要 |
PURPOSE:To effect the trailing of load current in the required space of time, by providing a switch in series on load side from a chopper and providing a diode of reversed polarity and a resistor in parallel. CONSTITUTION:A power unit is composed of a transformer 2 for rectifier, a rectifier 3, a reactor 4, a capacitor 5, a chopper circuit 6, a diode 7, a DC current detector 9, a constant current control circuit 11, a pulse width modulation circuit 12, a driver circuit 13, etc. It feeds current to an electromagnet coil 8, the load. On this occasion, provided are a resistor 14 to attenuate the load current in trailing the current, a diode 15, a switch 16 to turn off in trailing the current. The load current thereby circulates the diode 15 through the resistor 14, so that it trails in high speed. It is therefore possible to perform the trailing and leading of the current in a short cycle by the proper choice of the constant number of the resistant values of the resistor 14 at discharge time.
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