Inductive power transmission system and method for concurrently transmitting digital messages

• US 9,065,489 B2
• Filed: 10/22/2014
• Issued: 06/23/2015
• Est. Priority Date: 10/11/2012
• Status: Active Grant

• Current Assignee: Powermat Technologies, Ltd.
• Original Assignee: Powermat Technologies, Ltd.
• Inventors: Mach, Elieser, Rofe, Arik, Greenwald, Oola, Raveh, Guy, Moshkovich, Oz, Podkamien, Ian, Koren, Yuval, Burdo, Rinat
• Primary Examiner(s): DEBERADINIS, ROBERT L
• Application Number:
  US14/520,632
• Publication Number:
  US 20150035381A1
• Time in Patent Office: 244 Days
• Field of Search: 307/104
• US Class Current: 1/1
• CPC Class Codes: H02H 3/38 responsive to both voltage and current; responsive to phase angle between voltage and current
• CPC Class Codes: H02H 5/041 additionally responsive to excess current H02H5/048 takes precedence
• 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: H02J 7/00034 Charger exchanging data with an electronic device, i.e. telephone, whose internal battery is under charge
• CPC Class Codes: H04B 5/79 for data transfer in combination with power transfer

Abstract

A control circuit for an inductive power outlet configured to transfer power to an inductive power receiver includes a resonant circuit having a characteristic resonant peak and connected to a primary coil configured to inductively couple with a secondary coil of the inductive power receiver, a frequency driver operable to provide a driving voltage oscillating at an operating frequency higher than the characteristic resonant peak of the resonant circuit across the primary coil, a magnitude detector operable to monitor primary coil voltage, and a data demodulator operable to detect modulated peaks in primary coil voltage indicating that a communications modulator of the inductive power receiver has transitioned from a first state to a second state. The communications modulation determines a characteristic frequency of the peaks and extracts modulated data sent in communication signals from the inductive power receiver.

Claims

1. A control circuit for an inductive power outlet configured to transfer power to an inductive power receiver, said control circuit comprising:

a resonant circuit connected to a primary coil configured to inductively couple with a secondary coil of said inductive power receiver, said resonant circuit having a characteristic resonant peak;

a frequency driver operable to provide a driving voltage across said primary coil, said driving voltage oscillating at an operating frequency higher than said characteristic resonant peak of the resonant circuit;

a magnitude detector operable to monitor primary coil voltage;

a data demodulator operable to detect modulated peaks in primary coil voltage indicating that a communications modulator of said inductive power receiver has transitioned from a first state to a second state, to determine a characteristic frequency of said peaks and thereby to extract modulated data sent in communication signals from said inductive power receiver.

2. The control circuit of claim 1 wherein said data demodulator is operable to detect communication signals comprising a pulse comprising a fixed duration t_s of high logical state followed by a second duration (1/f−

t_s) of low logical state.

3. The control circuit of claim 1, wherein said data demodulator is operable to distinguish between at least a power decrease signal, and a power increase signal.

4. The control circuit of claim 3 wherein said frequency driver is further operable to decrease said operating frequency when a power increase signal is detected.

5. The control circuit of claim 3 wherein said frequency driver is further operable to increase said operating frequency when a power decrease signal is detected.

6. The control circuit of claim 3 wherein said frequency driver is operable to decrease said operating frequency within 50 microseconds of the end of a series of two or more power increase signals.

7. The control circuit of claim 3 wherein said frequency driver is operable to provide said driving voltage at a minimum operating frequency after a series of 24 consecutive said power increase signals.

8. The control circuit of claim 3 wherein said frequency driver is operable to provide said driving voltage at a maximum operating frequency after a series of 180 consecutive power said increase signals.

9. The control circuit of claim 1, wherein said data demodulator is operable to distinguish between at least a power decrease signal, a power increase signal and a power perpetuation signal.

10. The control circuit of claim 1, wherein said data demodulator is operable to distinguish between at least a power decrease signal, a power increase signal and a termination signal.

11. The control circuit of claim 1 wherein said characteristic frequency is selected from 250 Hz, 500 Hz, 1 kHz, 4 kHz, 6 kHz and 8 kHz.

12. The control circuit of claim 1 wherein said inductive power outlet is operable to transmit a ping signal upon detection of said inductive power receiver and to terminate power transmission if no valid signal response is received.

13. The control circuit of claim 1 wherein said frequency driver operable to perform a frequency sweep upon detection of said inductive power receiver and to terminate power transmission if no valid signal response is received.

14. The control circuit of claim 13 wherein said valid signal response comprises a communication signal having a characteristic frequency of 8 kHz.

15. An inductive power outlet configured to transfer power to an inductive power receiver said inductive power outlet comprising:

a resonant circuit connected to a primary coil configured to inductively couple with a secondary coil of said inductive power receiver, said resonant circuit having a characteristic resonant peak;

a frequency driver operable to provide a driving voltage across said primary coil, said driving voltage oscillating at an operating frequency higher than said characteristic resonant peak of the resonant circuit;

a magnitude detector operable to monitor primary coil voltage;

a data demodulator operable to detect modulated peaks in primary coil voltage indicating that a communications modulator of said inductive power receiver has transitioned from a first state to a second state, to determine a characteristic frequency of said peaks, and thereby to extract modulated data sent in communication signals from said inductive power receiver; and

a detection unit operable to detect placement of an inductive power receiver on said inductive power outlet.

16. The inductive power outlet of claim 15 wherein said detection unit comprises a Hall Effect sensor.

17. The inductive power outlet of claim 15 wherein said detection unit is configured to detect a 40 Gauss difference in magnetic field.

18. A method for transferring power inductively from an inductive power outlet to an inductive power receiver, said inductive power transmitter having a primary coil, a resonant circuit, a frequency driver, a magnitude detector, and a data demodulator, said method comprising:

said inductive power outlet transmitting a ping signal;

said inductive power outlet receiving a valid signal response;

said frequency driver providing a driving voltage across said primary coil,

said magnitude detector monitoring primary coil voltage;

said data demodulator extracting modulator from communication signals sent from said inductive power receiver;

said frequency driver increasing power level if said data modulator detects a power increase signal;

said frequency driver decreasing power level if said data modulator detects a power decrease signal; and

said frequency driver terminating power transmission if said data modulator detects a termination signal.

19. The method of claim 18 wherein said ping signal comprises a frequency sweep.

20. The method of claim 18 wherein said valid signal response comprises a communication signal having a characteristic frequency of 8 kHz.