Flux-coupled iron directed battery charger

• US 4,912,391 A
• Filed: 05/01/1989
• Issued: 03/27/1990
• Est. Priority Date: 05/01/1989
• Status: Expired due to Fees

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Meadows, Vernon
• Primary Examiner(s): HICKEY, ROBERT
• Application Number:
  US07/346,444
• Time in Patent Office: 330 Days
• Field of Search: 320/2-5, 320/51
• US Class Current: 320/108
• CPC Class Codes: H02J 50/005 Mechanical details of housing or structure aiming to accommodate the power transfer means, e.g. mechanical integration of coils, antennas or transducers into emitting or receiving devices
• CPC Class Codes: H02J 50/10 using inductive coupling
• CPC Class Codes: H02J 7/00 Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
• CPC Class Codes: H02J 7/0044 specially adapted for holding portable devices containing batteries H02J7/0045 takes precedence

Abstract

A flux-coupled, iron directed battery charger charges a battery while avoiding physical contact between the charger and the battery and uses a control circuit that substantially reduces the flow of charging current to the battery when said battery is fully or nearly fully charged.

Claims

1. A battery charger for charging at least one electric cell, comprising:

a substantially u-shaped first iron-core material;

a substantially u-shaped second iron-core material magnetically coupled to the first iron-core material;

a primary transformer winding, having a first terminal and a second terminal, magnetically coupled to the first iron-core material and wound around the second iron-core material, for establishing magnetic flux through the first iron-core material in response to a varying voltage applied between the first and second terminals

a secondary transformer winding coupled to the first iron-core material having a first terminal and a second terminal for establishing a potential between the first terminal and said second terminal, in response to the magnetic flux flowing through the first iron-core material;

a rectifier coupled to the secondary transformer winding, for rectifying current flowing from the secondary transformer winding for charging of the electric cell;

control means coupled to the rectifier for controlling the amount of current flowing from the rectifier, whereby the amount of current flowing into the electric cell is substantially reduced when the electric cell is substantially charged;

a third transformer and winding coupled to said first iron core material for increasing the reluctance of the first iron-core material when the electric cell is substantially charged.

2. The battery charger of claim 1, the terminals of the third transformer winding are shorted together when the electric cell is substantially charged, thus increasing the reluctance of the first iron-core material.

3. The battery charger of claim 2, wherein the first iron-core material has a plurality of air gaps therein, for increasing the reluctance of said first iron-core material.

4. The battery charger of claim 1, further comprising a first housing for holding the first iron-core material.

5. The battery charger of claim 4, wherein said first housing also holds the control means.

6. The battery charger of claim 5, wherein said first housing also holds the electric cell.

7. The battery charger of claim 1, further comprising a second housing for holding the second iron-core material.

8. The battery charger of claim 3, further comprising a first housing for holding the first iron-core material.

9. The battery charger of claim 8, wherein said first housing also holds the control means.

10. The battery charger of claim 3, further comprising a second housing for holding the second iron-core material.

11. The battery charger of claim 10, wherein the second housing also holds the primary winding.

12. The battery charger of claim 11, wherein the second housing has a port wherein the first housing may be inserted for charging of the electric cell.

13. An electric battery comprising:

an electric cell;

a housing for holding said electric cell;

a substantially u-shaped iron-core material;

a first secondary transformer winding coupled to the iron-core material having a first terminal and a second terminal for establishing a potential between the first terminal and the second terminal, in response to magnetic flux flowing through the iron-core material;

a rectifier, coupled to the first secondary transformer winding and to the electric cell, for rectifying current flowing from the first secondary transformer winding for charging of the electric cell;

a control means coupled to the rectifier for controlling the amount of current flowing from the rectifier for charging of the electric cell, whereby the amount of current flowing into the electric cell is substantially reduced when the electric cell is substantially charged;

a second secondary transformer winding having first and second terminals the second secondary transformer being wound around the iron core material for increasing the reluctance of the iron-core material when the electric cell is substantially charged; and

means for connecting the first terminal of the second transformer winding to the second terminal of the second transformer winding when the electric cell is substantially charged, thus increasing the reluctance of the iron-core material.

14. The electric battery of claim 13, wherein the iron-core material has a plurality of air gaps therein, for increasing the reluctance of the iron-core material.

15. The electric battery of claim 14, wherein the housing also holds the rectifier.

16. The electric battery of claim 15, wherein the housing also holds the control means.