Transformerless battery charger in combination with a battery, and method of charging a battery

• US 4,774,449 A
• Filed: 03/03/1986
• Issued: 09/27/1988
• Est. Priority Date: 03/03/1986
• Status: Expired due to Term

• Current Assignee: Intel Corporation
• Original Assignee: Robin K. Elkins
• Inventors: Elkins, Robin K.
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): Ault, Anita M.
• Application Number:
  US06/835,159
• Time in Patent Office: 939 Days
• Field of Search: 320/2, 320/15, 320/21, 320/57, 320/59, 320/DIG. 2, 320/33, 307/66
• US Class Current: 320/129
• CPC Class Codes: H02J 2207/20 Charging or discharging characterised by the power electronics converter
• CPC Class Codes: H02J 7/007182 in response to battery voltage
• CPC Class Codes: H02J 7/02 for charging batteries from ac mains by converters

Abstract

A transformerless battery charger having a circuit for connecting the battery to an A.C. power source to supply charging current to the battery including: an inductive impedance in series with the battery for limiting the charging current through the battery. An electronic switch in the form of a TRIAC or SCR is connected in series with the battery, and the electronic switch is normally non-conductive thereby keeping open the charging circuit for the battery. An electronic trigger for turning on said electronic switch is provided to close the charging circuit for the battery as a function of the difference between the instantaneous voltage from said A.C. power source and the battery voltage. The electronic switch and the electronic trigger jointly operating to provide a pulsed charging current to the battery during the A.C. power cycle which is long enough to produce a significant battery-charging effect but short enough to avoid harmful internal heating of the battery. The electronic trigger advantageously includes an R--C element driving a Diac.

Claims

1. In combination with a battery, a transformerless battery charger comprising circuit means for connecting said battery to an A.C. power source to supply charging current to the battery, said circuit means comprising:

inductor means in series with said A.C. power source;

electronic switch means in series with said A.C. power source, said electronic switch means being normally non-conductive, to thereby open the charging circuit for the battery;

and electronic trigger means for turning on said electronic switch means to close the charging circuit for the battery as a function of the difference between the instantaneous voltage from said A.C. power source and the battery voltage;

said electronic switch means and said electronic trigger means being jointly operable to provide a charging current to the battery during the A.C. power cycle long enough to produce a significant battery-charging effect but short enough to avoid harmful internal heating of the battery;

said electronic switch means being a Triac having a control electrode connected to said electronic trigger means;

said circuit means also including a full-wave rectifier bridge having a pair of opposite input terminals, one of which is connected to said Triac and the other to said A.C. power source, and a pair of opposite output terminals connected across the battery being charged.

2. The combination of claim 1 wherein:

said electronic trigger means comprises a Diac and a resistance-capacitance timing network connected to said control electrode of said Triac.

3. The combination of claim 2 wherein said A.C. power source is a 60 Hz., 110-120 volt power supply;

and said resistance-capacitance timing network includes resistance means adjustable to provide non-destructive charging of batteries with different nominal voltages.

4. The combination of claim 3 wherein said inductor means is a toroidal inductor.

5. In combination with a battery, a transformerless battery charger comprising circuit means for connecting said battery to an A.C. power source to supply charging current to the battery, said circuit means comprising:

inductor means in series with said A.C. power source;

electronic switch means in series with said A.C. power source, said electronic switch means being normally non-conductive to thereby open the charging circuit for the battery;

and electronic trigger means for turning on said electronic switch means to close the charging circuit for the battery as a function of the difference between the instantaneous voltage from said A.C. power source and the battery voltage;

said electronic switch means and said electronic trigger means being jointly operable to provide a charging current to the battery during the A.C. power cycle long enough to produce a significant battery-charging effect but short enough to avoid harmful internal heating of the battery;

said electronic switch means being an SCR having a control electrode connected to said electronic trigger means.

6. The combination of claim 5 wherein:

said electronic trigger means comprises a Diac and a resistance-capacitance timing network connected to said control electrode of said SCR.

7. The combination of claim 6 wherein:

said A.C. power source is a 60 Hz., 110-120 volt power supply; and

said resistance-capacitance timing network includes resistance means adjustable to provide non-destructive charging of batteries with different nominal voltages.

8. The combination of claim 7 wherein said inductor means is a toroidal inductor.

9. The combination of claim 5 wherein said electronic switch means is an SCR connected directly between one terminal of said battery and said A.C. power source, said SCR having a control electrode.