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BATTERY CHARGING CIRCUIT

  • US 20100327817A1
  • Filed: 02/05/2009
  • Published: 12/30/2010
  • Est. Priority Date: 02/06/2008
  • Status: Active Grant
First Claim
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1. A battery charging circuit comprising:

  • a rectifier circuit that rectifies a three-phase alternate-current voltage outputted from an electric power generator and generates a charge voltage for charging a battery;

    a voltage detection circuit that detects that a voltage of the battery becomes equal to or higher than a predetermined voltage;

    a switching circuit that charges, in an off-state, the battery through the rectifier circuit and that short-circuits, in an on-state, the electric power generator through the rectifier circuit;

    a switch control circuit that switches the switching circuit to the on-state when the voltage detection circuit detects that the voltage of the battery becomes equal to or higher than the predetermined voltage; and

    a control circuit that controls the switching circuit to switch from the on-state to the off-state and to maintain the off-state,wherein the control circuit comprises a capacitor that is charged when the switch control circuit controls the switching circuit to switch to the on-state, the capacitor discharging when the switch control circuit controls the switching circuit to switch to the off-state,the voltage detection circuit comprises a first transistor, a base of the first transistor being reverse-biased by the capacitor discharging, andthe switch control circuit comprises a second transistor, a base of the second transistor being connected to a collector of the first transistor, the switch control circuit controlling the on-state and the off-state of the switching circuit based on a collector current through the collector.

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