Non resonant inductive power transmission system and method

• US 8,188,619 B2
• Filed: 07/02/2009
• Issued: 05/29/2012
• Est. Priority Date: 07/02/2008
• Status: Active Grant

• Current Assignee: Powermat Technologies, Ltd.
• Original Assignee: Powermat Technologies, Ltd.
• Inventors: Azancot, Yossi, Ben-Shalom, Amir, Greenwald, Oola, Rofe, Arik, Leibovitz, Alfred, Ashery, Moti
• Primary Examiner(s): Barnie, Rexford
• Assistant Examiner(s): PARRIES, DRU M
• Application Number:
  US12/497,088
• Publication Number:
  US 20100066176A1
• Time in Patent Office: 1,062 Days
• Field of Search: 307/104
• US Class Current: 307/104
• CPC Class Codes: H01F 2038/143 for signals
• CPC Class Codes: H02J 50/10 using inductive coupling
• CPC Class Codes: H02J 50/12 of the resonant type
• 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: H02M 3/3376 with automatic control of output voltage or current
• CPC Class Codes: H02M 7/4815 Resonant converters H02M7/4811 and H02M7/4826 take precedence
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

Non-resonant inductive power transmission wherein the driving voltage across a primary inductor oscillates at a frequency significantly different from the resonant frequency of the inductive coupling system. Embodiments of the invention include systems and methods for: power regulation using frequency control, fault detection using voltage peak detectors and inductive communication channels.

Claims

1. An inductive power transfer system comprising at least one inductive power outlet comprising at least one primary inductive coil wired to a power supply via a driver;

said primary inductive coil for forming an inductive couple with at least one secondary inductive coil wired to an electric load, said secondary inductive coil associated with an inductive power receiver wherein said driver is configured to provide a driving voltage across said primary inductive coil, said driving voltage oscillating at a transmission frequency higher than the resonant frequency of said inductive couple, and wherein;

said primary inductive coil is further wired to a reception circuit comprising a voltage monitor for monitoring the amplitude of a primary voltage across said primary coil, and

said secondary inductive coil is further wired to a transmission circuit for connecting at least one electric element to said secondary inductive coil thereby increasing said resonant frequency;

such that a control signal may be transferred from said transmission circuit to said reception circuit.

2. The system of claim 1 wherein said driver comprises a switching unit for intermittently connecting said primary inductive coil to said power supply.

3. The system of claim 1 wherein said transmission frequency lies within a range in which induced voltage varies approximately linearly with frequency.

4. The system of claim 1 said inductive power outlet comprising a signal detector adapted to detect a first signal and a second signal, and said driver is configured to:

increase said transmission frequency when said first signal is detected by the detector, and

decrease said transmission frequency when said second signal is detected by the detector.

5. The system of claim 4 wherein said detector is selected from the list consisting of:

optical detectors, radio receivers, audio detectors and voltage peak detectors.

6. The system of claim 1 said driver being configured to adjust said transmission frequency in response to said control signal.

7. The system of claim 6 wherein said control signal carries data pertaining to the operational parameters of said electric load.

8. The system of claim 7 wherein said operational parameters are selected from the group consisting of:

required operating voltage for said electric load;

required operating current for said electric load;

required operating temperature for said electric load;

required operating power for said electric load;

measured operating voltage for said electric load;

measured operating current for said electric load;

measured operating temperature for said electric load;

measured operating power for said electric load;

power delivered to said primary inductive coil;

power received by said secondary inductive coil, and

a user identification code.

9. The system of claim 1 wherein said driver further comprises a voltage monitor for monitoring the amplitude of a primary voltage across said primary coil.

10. The system of claim 9 wherein said voltage monitor is configured to detect significant increases in primary voltage.

11. The system of claim 1 comprising a power converter selected from the group consisting of:

a transformer, a DC-to-DC converter, an AC-to-DC converter, an AC-to-AC converter, a flyback transformer, a flyback converter, a full-bridge converter, a half-bridge converter and a forward converter.

12. The system of claim 1, said secondary inductive coil being wired to two inputs of a bridge rectifier and said electric load being wired to two outputs of said bridge rectifier wherein said transmission circuit is wired to one input of said bridge rectifier and one output of said bridge rectifier.

13. The system of claim 1 wherein said transmission circuit further comprises a modulator for modulating a bit-rate signal with an input signal to create a modulated signal and a switch for intermittently connecting an electrical element to said secondary inductive coil according to said modulated signal.

14. The system of claim 1 wherein said voltage monitor further comprises a correlator for cross-correlating the amplitude of said primary voltage with said bit-rate signal for producing an output signal.

15. The system of claim 1, said control signal for transferring a feedback signal from said secondary inductive coil to said primary inductive coil for regulating power transfer across an inductive power coupling.

16. The system of claim 1 said driver being configured to adjust said transmission frequency in response to said feedback signals.

17. The system of claim 1 adapted to transfer a first signal and a second signal, and said driver being configured to:

increase said transmission frequency when said first signal is received by the receiver, and

decrease said transmission frequency when said second signal is received by the receiver.

18. The system of claim 1 incorporated into at least one application selected from a group consisting of:

inductive chargers, inductive power adaptors, power tools, kitchen appliances, bathroom appliances, computers, media players, office equipment, implanted devices, pace makers, trackers and RFID tags.

19. A method for transferring a signal from a secondary inductive coil to a primary inductive coil of an inductive power transfer system, said method comprising the following steps:

Step (i)—

connecting said primary inductive coil to a voltage monitor for monitoring amplitude of a primary voltage across said primary coil;

Step (ii)—

connecting said secondary inductive coil to a transmission circuit for selectively increasing resonant frequency of said inductive power transfer system;

Step (iii)—

providing an oscillating voltage to said primary inductive coil at an initial transmission frequency higher than an initial resonant frequency of said inductive power transfer system, thereby inducing a voltage in said secondary inductive coil;

Step (iv)—

using said transmission circuit to modulate a bit-rate signal with said input signal to create a modulated signal and connecting an electrical element to said secondary inductive coil intermittently according to said modulated signal, and

Step (v)—

using said voltage monitor to cross-correlate said amplitude of said primary voltage with said bit-rate signal thereby producing an output signal.