Inductively Coupled Ballast Circuit

• US 20070085487A1
• Filed: 11/28/2006
• Published: 04/19/2007
• Est. Priority Date: 06/21/1999
• Status: Active Grant

• Current Assignee: Philips IP Ventures B.V. (Koninklijke Philips N.V.)
• Original Assignee: Access Business Group International LLC (Alticor Incorporated)
• Inventors: Denen, Dennis, Kuennen, Roy, Baarman, David, Mollema, Scott, Markham, Ronald
• Granted Patent: US 7,385,357 B2
• Time in Patent Office: Days
• US Class Current: 315/209.R
• CPC Class Codes: A61L 2/10 Ultraviolet radiation
• CPC Class Codes: C02F 1/001 Processes for the treatment of water whereby the filtration technique is of importance C02F1/44 takes precedence; construction of filters in general B01D24/00 - B01D41/00
• CPC Class Codes: C02F 1/008 Control or steering systems not provided for elsewhere in subclass C02F
• CPC Class Codes: C02F 1/32 with ultraviolet light
• CPC Class Codes: C02F 1/325 Irradiation devices or lamp constructions
• CPC Class Codes: C02F 2201/3228 Units having reflectors, e.g. coatings, baffles, plates, mirrors
• CPC Class Codes: C02F 2201/326 Lamp control systems
• CPC Class Codes: C02F 2209/005 Processes using a programmable logic controller [PLC]
• CPC Class Codes: C02F 2209/008 comprising telecommunication features, e.g. modems or antennas
• CPC Class Codes: C02F 2209/40 Liquid flow rate
• CPC Class Codes: C02F 9/20 Portable or detachable small-scale multistage treatment devices, e.g. point of use or laboratory water purification systems
• CPC Class Codes: H01F 38/14 Inductive couplings for wireless supply or distribution of electric power using inductive coupling H02J50/10
• CPC Class Codes: H02J 50/10 using inductive coupling
• CPC Class Codes: H02J 50/80 involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices
• CPC Class Codes: H02J 50/90 involving detection or optimisation of position, e.g. alignment
• CPC Class Codes: H05B 41/24 in which the lamp is fed by high frequency ac, or with separate oscillator frequencyH05B41/26 takes precedence
• CPC Class Codes: H05B 41/36 Controlling
• CPC Class Codes: H05B 47/10 Controlling the light source
• CPC Class Codes: H05B 47/11 by determining the brightness or colour temperature of ambient light
• CPC Class Codes: H05B 47/19 via wireless transmission
• CPC Class Codes: H05B 47/20 : Responsive to malfunctions or to light source life; for protection
• CPC Class Codes: Y02B 20/00 : Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
• CPC Class Codes: Y02B 20/40 : Control techniques providing energy savings, e.g. smart controller or presence detection

Abstract

A ballast circuit is disclosed for inductively providing power to a load. The ballast circuit includes an oscillator, a driver, a switching circuit, a resonant tank circuit and a current sensing circuit. The current sensing circuit provides a current feedback signal to the oscillator that is representative of the current in the resonant tank circuit. The current feedback signal drives the frequency of the ballast circuit causing the ballast circuit to seek resonance. The ballast circuit preferably includes a current limit circuit that is inductively coupled to the resonant tank circuit. The current limit circuit disables the ballast circuit when the current in the ballast circuit exceeds a predetermined threshold or falls outside a predetermined range.

Claims

1. A ballast circuit, comprising:

a primary subcircuit having a primary coil;

a current sensor connected to said primary subcircuit, said sensor sensing a characteristic of a current in said primary subcircuit;

a control circuit supplying current to said primary coil, said control circuit varying a characteristic of the current supplied to said primary coil as a function of said characteristic sensed by said current sensor;

a secondary coil inductively coupled with said primary coil, wherein said primary coil inductively energizes said secondary coil; and

a load electrically connected to said secondary coil, whereby power is provided to said load by said secondary coil.

2. The ballast circuit of claim 1, wherein said load is further defined as a resonant lamp circuit.

3. The ballast circuit of claim 1, wherein said primary coil is disposed in a series resonant tank circuit, said resonant lamp circuit and said series resonant tank circuit resonating at about the same frequency.

4. The ballast circuit of claim 1, wherein said resonant lamp circuit includes an electromagnetic radiation emitting device.

5. The ballast circuit of claim 1, wherein said electromagnetic radiation emitting device is one of an ultraviolet lamp, an incandescent lamp, a light emitting diode lamp, a pulsed white light lamp and a dielectric barrier discharge lamp.

6. The ballast circuit of claim 1 further including an oscillator, wherein said oscillator includes a buffer circuit that prevents load changes from pulling the frequency of oscillation of said oscillator.

7. The ballast circuit of claim 1 further including a driver, wherein said driver comprises a multi-winding transformer.

8. The ballast circuit of claim 1 further including a half-bridge switching circuit, wherein said half-bridge switching circuit comprises a MOSFET totem pole half-bridge switching circuit.

9. The ballast circuit of claim 3, wherein said series resonant tank circuit further includes a pair of tank capacitors, a pair of diodes and a capacitor.

10. The ballast circuit of claim 2, wherein said resonant lamp circuit comprises a capacitor and a starter circuit.

11. A method for supplying power to a load through an inductive coupling, comprising the steps of:

supplying a current at a frequency to a primary subcircuit containing a primary coil of an inductive coupling;

generating power within a secondary coil across the inductive coupling, the generated power being applied to the load;

monitoring at least one characteristic of the current in the primary subcircuit, the monitored characteristic being affected by a characteristic of the load reflected through the inductive coupling; and

adjusting a characteristic of the current supplied to the primary coil as a function of the monitored characteristic.

12. The method of claim 11 wherein the monitored characteristic is further defined as at least one of the phase and the amplitude of the current supplied to the primary subcircuit.

13. An inductive coupling, comprising:

a primary circuit having;

a subcircuit containing a primary coil,

a sensor for sensing a characteristic of power in said subcircuit, and

a control circuit means for supplying power to said primary coil, said control circuit means varying a characteristic of the power supplied to said primary coil as a function of said characteristic sensed by said sensor; and

a secondary circuit having;

a secondary coil inductively coupled with said primary coil, wherein said primary coil inductively energizes said secondary coil, and

a load electrically connected to said secondary coil, whereby power is provided to said load by said secondary coil.

14. The inductive coupling of claim 13 wherein the sensed characteristic is further defined as a characteristic that varies in response to a characteristic of said secondary circuit reflected from said secondary circuit to said primary circuit through the inductive coupling.

15. The inductive coupling of claim 13 wherein the sensed characteristic is further defined as at least one of a phase and a magnitude of the current in said subcircuit.

16. The inductive coupling of claim 13 wherein said varied characteristic of said power supplied to said primary coil is further defined as a frequency of a voltage applied to said primary coil.

17. The inductive coupling of claim 13 wherein said sensor is further defined as a current sensor.

18. The inductive coupling of claim 13 wherein the sensed characteristic is further defined as a characteristic affected by a reflected impedance of said secondary circuit.

19. The inductive coupling of claim 13 wherein said varied characteristic of said power supplied to said primary coil is further defined as a frequency of a voltage applied to said primary coil;

and

wherein the sensed characteristic is further defined as a characteristic affected by a reflected impedance of said secondary circuit.

20. The inductive coupling of claim 13 wherein said sensed characteristic is further defined as a magnitude of the current in said subcircuit, said sensor being further defined as a current sensor;

and

wherein said varied characteristic of said power supplied to said primary coil is further defined as a frequency of a voltage applied to said primary coil.