Electromagnetically coupled battery charger

• US 4,031,449 A
• Filed: 11/20/1975
• Issued: 06/21/1977
• Est. Priority Date: 11/20/1975
• Status: Expired due to Term

• Current Assignee: Arthur D. Little, Inc.
• Original Assignee: Arthur D. Little, Inc.
• Inventors: Trombly, John E.
• Primary Examiner(s): Hickey, Robert J.
• Application Number:
  US05/633,987
• Time in Patent Office: 579 Days
• Field of Search: 320/2-5, 320/20-24, 320/39, 320/40, 320/59, 320/43, 336/211, 336/229, 323/45
• US Class Current: 320/108
• CPC Class Codes: H02J 2207/20 Charging or discharging characterised by the power electronics converter
• 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 50/12 of the resonant type
• CPC Class Codes: H02J 50/402 the two or more transmitting or the two or more receiving devices being integrated in the same unit, e.g. power mats with several coils or antennas with several sub-antennas
• CPC Class Codes: H02J 50/90 involving detection or optimisation of position, e.g. alignment
• CPC Class Codes: H02J 7/02 for charging batteries from ac mains by converters
• CPC Class Codes: Y10S 320/12 Precharging analysis, e.g. determining presence of battery
• CPC Class Codes: Y10S 320/29 Transformer having plural secondaries

Abstract

A solid state electronic battery charger which is electromagnetically coupled to one or more batteries. A charging circuit energizes a drive winding to produce an alternating field received by an associated coupler and operative to convey charging current to a battery connected thereto. A sense winding monitors the level of the alternating field to derive a signal representative of the battery charge level and which causes a tapered charge to be supplied to the battery and an indication of a sensed fully charged state. A proximity sensor can be provided to denote the presence of a coupled battery and by which charging operation is commenced.

Claims

1. A battery charger comprising:

a first electromagnetic assembly having a drive winding and a sense winding;

a charging circuit operative to energize said drive winding to provide a predetermined alternating field;

a control circuit connected to said sense winding and to said charging circuit and operative in response to a signal from said sense winding to control the charging level of said charging circuit;

an electromagnetic receiver assembly connectable to a battery to be charged and adapted for electromagnetic coupling to said assembly; and

means operative in response to the presence of said receiver assembly in coupling relationship with said first assembly to enable full power operation of said charging circuitry, including;

a proximity winding operative to provide a signal upon coupling of said receiver assembly and said first assembly; and

means operative in response to said proximity winding signal to provide an enabling signal to cause full power operation of said charging circuit.

2. The battery charger of claim 1 wherein said charging circuit includes:

means for providing a charging current to said drive winding;

means for switching said current through said drive winding to provide said predetermined alternating field;

and wherein said control circuit includes;

means for providing an error signal representative of the magnitude of the signal from said sense winding; and

means for applying said error signal to said current providing means to control the magnitude of said charging current.

3. The battery charger of claim 1 wherein said charging circuit includes:

means operative in response to an AC source to provide a rectified and filtered signal;

voltage regulator means receiving said rectified and filtered signal and providing an output signal of predetermined magnitude to said drive winding; and

means for switching said output signal through said drive winding to provide said predetermined alternating field.

4. The battery charger of claim 3 further including:

current sensing means in feedback connection with said voltage regulator means to limit the maximum current supplied to said drive winding; and

means for indicating the operating state of said charger.

5. The battery charger of claim 4 wherein said control circuit includes:

rectifier means connected to said sense winding and operative to provide a signal representative of the magnitude of said alternating field; and

comparator means operative in response to said signal from said rectifier means to provide an error signal to said voltage regulator means for controlling the magnitude of current applied to said drive winding.

6. The battery charger of claim 1 wherein said first electromagnetic assembly includes:

a magnetic core having said drive winding and sense winding each disposed thereon;

said drive winding providing said alternating field from a predetermined face of said core, and said sense winding being disposed to sense said alternating field.

7. A battery charger comprising:

a first electromagnetic assembly having a drive winding and a sense winding;

a charging circuit operative to energize said drive winding to provide a predetermined alternating field, including;

means operative in response to an AC source to provide a rectified and filtered signal;

voltage regulator means receiving said rectified and filtered signal and providing an output signal of predetermined magnitude to said drive winding; and

means for switching said output signal through said drive winding to provide said predetermined alternating field;

a control circuit connected to said sense winding and to said charging circuit and operative in response to a signal from said sense winding to control the charging level of said charging circuit, including;

rectifier means connected to said sense winding and operative to provide a signal representative of the magnitude of said alternating field; and

comparator means operative in response to said signal from said rectifier means to provide an error signal to said voltage regulator means for controlling the magnitude of current applied to said drive winding;

current sensing means in feedback connection with said voltage regulator means to limit the maximum current supplied to said drive winding;

means for indicating the operating state of said charger;

an electromagnetic receiver assembly connectable to a battery to be charged and adapted for electromagnetic coupling to said first assembly; and

means operative in response to the presence of said receiver assembly in coupling relationship with said first assembly to enable full power operation of said charging circuitry, including;

a proximity sensor operative to detect the presence of said receiver assembly in coupling relationship with said first assembly to provide a signal indication thereof; and

means operative in response to said signal indication to control the magnitude of said error signal in accordance with the coupled condition of said receiver assembly and first assembly.

8. The battery charger of claim 7 wherein said proximity sensor is an electromagnetic proximity sense winding operative to sense the presence of said receiver assembly and first assembly in coupling relationship.

9. For use in a battery charger electromagnetically coupled to a battery and including means for providing an alternating field by which charging current is supplied to said battery, and means for sensing said alternating field to control the magnitude of said charging current in accordance with the level of charge of said battery, an electromagnetic assembly comprising:

a high permeability magnetic core having an outer annular wall and a coaxial cylindrical portion defining an annular space therebetween, said annular wall and cylindrical portion terminating in an end face;

a drive winding coaxially disposed within said annular space about said cylindrical portion and providing in response to an energizing signal an alternating field emanating from said end face; and

a sense winding coaxially disposed in said annular space in association with said drive winding and operative to provide a signal representative of the magnitude of said alternating field.

10. The invention of claim 9 further including:

a proximity sense winding disposed in said cylindrical portion of said core and operative to sense the fringing field of said drive winding in the absense of a receiver assembly coupled to said core.

11. The invention of claim 9 further including:

a proximity sense winding coaxially disposed with respect to said drive and sense windings and outwardly extending from said end face and operative to sense the fringing field of said drive winding in the absence of a receiver assembly coupled to said core.

12. A battery charger comprising:

a first electromagnetic assembly having a drive winding and a sense winding, including;

a magnetic core having said drive winding and sense winding each disposed thereon;

said drive winding providing said alternating field from a predetermined face of said core, and said sense winding being disposed to sense said alternating field;

a charging circuit operative to energize said drive winding to provide a predetermined alternating field;

a control circuit connected to said sense winding and to said charging circuit and operative in response to a signal from said sense winding to control the charging level of said charging circuit;

an electromagnetic receiver assembly connectable to a battery to be charged and adapted for electromagnetic coupling to said assembly; and

means operative in response to the presence of said receiver assembly in coupling relationship with said first assembly to enable full power operation of said charging circuitry, including;

a proximity sense winding disposed with respect to said core to sense the fringing field of said drive winding in the absence of coupling between said receiver assembly and first assembly.

13. For use in a battery charger electromagnetically coupled to a battery and including means for providing an alternating field by which charging current is supplied to said battery, and means for sensing said alternating field to control the magnitude of said charging current in accordance with the level of charge of said battery, an electromagnetic assembly comprising:

a high permeability magnetic core having an outer annular wall and a coaxial cylindrical portion defining an annular space therebetween, said annular wall and cylindrical portion terminating in an end face;

a drive winding coaxially disposed within said annular space about said cylindrical portion and providing in response to an energizing signal an alternating field emanating from said end face;

a sense winding coaxially disposed in said annular space in association with said drive winding and operative to provide a signal representative of the magnitude of said alternating field; and

a proximity sense winding coaxially disposed with respect to said drive and sense winding and outwardly extending from said end face and operative to sense the fringing field of said drive winding in the absence of a receiver assembly coupled to said core.

14. A battery charging comprising:

a first electromagnetic assembly having a drive winding disposed on a magnetic core;

a charging circuit operative to energize said drive winding to provide a predetermined alternating field;

an electromagnetic receiver assembly connectable to a battery to be charged and adapted for electromagnetic coupling to said first assembly; and

means operative in response to the presence of said receiver assembly in coupling relationship with said first assembly to enable full power operation of said charging circuitry, including;

a proximity winding disposed with respect to said core to sense the fringing field of said drive winding in the absence of coupling between said receiver assembly and first assembly and operative to provide a signal upon coupling of said receiver assembly and said first assembly; and

means operative in response to said proximity winding signal to provide an enabling signal to allow full power operation of said charging circuit.