NON RESONANT INDUCTIVE POWER TRANSMISSION SYSTEM AND METHOD

• US 20120212073A1
• Filed: 04/27/2012
• Published: 08/23/2012
• 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, Ashery, Moti, Lei-Bovitz, Alfred
• Granted Patent: US 8,427,012 B2
• Time in Patent Office: Days
• 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 having a characteristic resonant frequency 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 significantly different from said characteristic resonant frequency of said inductive couple.

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 1, said driver being configured to adjust said transmission frequency in response to said feedback signals.

6. The system of claim 5 wherein said feedback signals carry data pertaining to the operational parameters of said electric load.

7. The system of claim 6 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.

8. The system of claim 4 wherein said detector is selected from the list comprising optical detectors, radio receivers, audio detectors and voltage peak detectors.

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 comprising:

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 driving voltage oscillating at a transmission frequency higher than the resonant frequency of said inductive couple, 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 decreasing capacitance of the system;

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

13. The system of claim 12, 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.

14. The system of claim 12 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 said electrical element to said secondary inductive coil according to said modulated signal.

15. The system of claim 12 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.

16. The system of claim 12, 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.

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

18. The system of claim 16 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.

19. 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.

24. The system of claim 1, said driving voltage oscillating at a transmission frequency higher than the resonant frequency of said inductive couple, 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 decreasing inductance of the system;

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

25. The system of claim 24, 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.

26. The system of claim 24 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 said electrical element to said secondary inductive coil according to said modulated signal.

27. The system of claim 24 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.

28. The system of claim 24, 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.

29. The system of claim 28 said driver being configured to adjust said transmission frequency in response to said feedback signals.

30. The system of claim 28 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.

20. A method for regulating power transmission inductive from a primary inductive coil, wired to a power supply via a driver, to a secondary inductive coil, wired to an electric load, said method comprising:

(a) providing an oscillating voltage to said primary inductive coil at an initial transmission frequency ft which is substantially different from a characteristic resonant frequency f_R of the system;

(b) inducing a secondary voltage in said secondary inductive coil;

(c) monitoring power received by said electric load;

(d) sending a feedback signal when the monitored power deviates from a predetermined range;

(e) said driver receiving said feedback signal;

(f) said driver adjusting said transmission frequency; and

(g) repeating steps (b) to (f).

21. The method of claim 20 wherein step (d) further comprises:

(d1) sending a feedback signal of a first type S_a to said driver, whenever said power drops below a predetermined lower threshold, and

(d2) sending a feedback signal of a second type S_b to said driver, whenever said power exceeds a predetermined upper threshold.

22. The method of claim 20 wherein said initial transmission frequency f_t is higher than the characteristic resonant frequency f_R.

23. The method of claim 22 wherein step (f) further comprises:

(f1) said driver reducing said transmission frequency by an incremental value −

δ

f₁ when the received feedback signal is of the first type S_a, and

said driver increasing said transmission frequency by an incremental value +δ

f₂ when the received feedback signal is of the second type S_b.