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Direct current power supply device for battery charging

  • US 4,147,970 A
  • Filed: 12/20/1976
  • Issued: 04/03/1979
  • Est. Priority Date: 12/25/1975
  • Status: Expired due to Term
First Claim
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1. A direct current power supply device for rectifying an a-c voltage of external power supply and supplying d-c power to a battery and/or a d-c load characterized in that it comprises:

  • a current detecting means to detect a current component flowing to said battery,a voltage detecting means to detect a terminal voltage of said battery,a control means controlled by said current detecting means and said voltage detecting means,a leakage transformer functioning by external a-c power supply, anda charging converter means for supplying d-c power to said battery,said charging converter means being controlled by said control means and supplied power from the output of said leakage transformer,said control means comprising a maximum value detecting circuit to combine the output voltage of said current detecting means and said voltage detecting means, a switching circuit controlled by said maximum value detecting circuit, a pulse generating circuit in which pulse rise time is controlled by said switching circuit, and a switching control circuit controlled by said pulse generating circuit,whereby said direct current power supply device is provided a determined current-voltage characteristic, said characteristic being such that a constant current state is kept until a terminal voltage of said battery reaches a desired level and a constant voltage state is kept when the terminal voltage of said battery reaches said desired level,said control means further including an excessive input voltage detecting means for detecting the output voltage of said external a-c power supply, said excessive input voltage detecting means controlling said switching control circuit decreasing the output power of said charging converter means when the output voltage of said external a-c power supply is high,said excessive input voltage detecting means comprises circuit elements having non-linear voltage and current characteristics comprising a voltage divider and Zener diode having one end thereof connected to a division point of said voltage divider and the other end thereof connected to said switching circuit, a d-c voltage having a value proportional to the output voltage of said external a-c power supply is applied to both ends of said voltage divider.

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