| 摘要 |
PROBLEM TO BE SOLVED: To prevent causing improper actions in a current balance mechanism, when power is turned on/off of an electric power unit included in a parallel operation system. SOLUTION: An output current detection circuit 9 generates a voltage signal, corresponding to a current value flowing into a load 16 from a switching power circuit 4. An output of this detection circuit 9 is connected to a current comparison bus connection terminal 6 via a series circuit of a resistor 10 and an FET 11. The fellow terminals 6 of two sets of devices 1 are connected by a common current comparison bus 15, the fellow outputs of the output current detection circuit 9 butt on the bus 15 respectively via the resistor 10. When the voltage signals output from the two detection circuits 9 are unequal, an intermediate value of these voltage signals is generated on the bus 15. Based on the differential component from the voltage on the bus 15, output voltage of the switching power circuit is controlled. Based on a signal from an input voltage detection circuit 14, if inputting of input power 2 to the switching power circuit 4 is detected, the FET 11 is inverted from the off to on, using a delay by a suitably preset time.
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