SYSTEM AND METHOD FOR CONTROLLING POWER TRANSFER ACROSS AN INDUCTIVE POWER COUPLING

• US 20100072825A1
• Filed: 09/21/2009
• Published: 03/25/2010
• Est. Priority Date: 03/22/2007
• Status: Active Grant

• Current Assignee: Powermat Technologies, Ltd.
• Original Assignee: Powermat Ltd.
• Inventors: Greenwald, Oola, Ben-Shalom, Amir, Azancot, Yossi, Rofe, Arik
• Granted Patent: US 8,749,097 B2
• Time in Patent Office: Days
• US Class Current: 307/104
• CPC Class Codes: G01V 3/08 operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices with electromagnetic waves G01V3/12
• 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 50/20 using microwaves or radio frequency waves
• 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 50/70 involving the reduction of electric, magnetic or electromagnetic leakage fields
• 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: H02J 7/00045 Authentication, i.e. circuits for checking compatibility between one component, e.g. a battery or a battery charger, and another component, e.g. a power source
• CPC Class Codes: H02J 7/00309 Overheat or overtemperature protection
• CPC Class Codes: H02J 7/00712 the cycle being controlled or terminated in response to electric parameters
• CPC Class Codes: H02J 7/007192 in response to temperature
• CPC Class Codes: H02M 1/0058 by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current flow is zero using an auxiliary actively switched resonant commutation circuit connected to an intermediate DC voltage or between two push-pull branches of an inverter bridge H02M7/4811; in resonant inverters H02M7/4815; in inverters operating from a resonant DC source H02M7/4826
• CPC Class Codes: H02M 3/3376 with automatic control of output voltage or current
• 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

A signal transfer system for controlling power transfer across an inductive power coupling. A transmission circuit associated with an inductive power receiver is configured to transmit a control signal to a reception circuit associated with an inductive power outlet. The transmission circuit includes an ancillary load and a switching unit for modulating power drawn by a secondary inductive coil according to the control signal. The reception circuit is configured to monitor power provided to a primary inductive coil thereby detecting the modulated control signal. The signal transfer system may be used to regulate the power supplied by the inductive coupling and to detect the presence of the secondary coil.

Claims

1. A signal transfer system for controlling inductive power transfer between a primary inductive coil and a secondary inductive coil, the signal transfer system comprising a transmission circuit configured to transmit control signals, wherein the transmission circuit comprises at least one ancillary load selectively connectable to the secondary inductive coil.

2. The signal transfer system of claim 1, wherein the transmission circuit comprises at least one switching unit comprising:

a modulator configured to modulate a bit-rate signal with an input signal producing a modulated signal; and

a switch for intermittently connecting the ancillary load to the secondary inductive coil according to the modulated signal.

3. The signal transfer system of claim 2 wherein the switching unit further comprises a controller configured to encode data into the input signal.

4. The signal transfer system of claim 2 wherein the switching unit further comprises a frequency divider.

5. The signal transfer system of claim 2 wherein the primary inductive coil is configured to operate at a driving frequency and the modulator is configured to generate a bit-rate signal having a frequency that is an integer fraction of the driving frequency.

6. The signal transfer system of claim 2 further comprising a reception circuit configured to detect the control signals, the reception circuit comprising at least one power monitor for monitoring power provided to the primary inductive coil.

7. The signal transfer system of claim 6 wherein the reception circuit further comprises

at least one current monitor for monitoring a primary-current drawn by the primary inductive coil, thereby producing a primary current-signal, and

at least one correlator configured to cross-correlate the primary-current signal with the bit-rate signal, thereby producing an output signal.

8. The signal transfer system of claim 1 wherein the primary inductive coil is galvanically isolated from the secondary inductive coil.

9. The signal transfer system of claim 1 wherein the inductive power coupling is a device 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.

10. The signal transfer system of claim 1, wherein:

the transmission circuit further comprises a half-wave rectifier, and

a reception circuit is configured to detect second harmonic signals in the power supplied to the primary inductive coil.

11. The signal transfer system of claim 10 wherein a plurality of primary inductive coils are connected to a driver, the driver being configured to operate the primary inductive coils sequentially, and the reception circuit is configured to detect second harmonic signals in the power supplied to at least one primary inductive coil, indicating that the primary inductive coil is coupled to a secondary inductive coil

12. The signal transfer system of claim 11 wherein each primary inductive coil is operable at a plurality of power levels and the driver is configured to:

provide low power pulses to each primary inductive coil until a coupled primary inductive coil is identified, and

to provide the coupled primary inductive coil with a higher power.

13. The signal transfer system according to claim 1, the control signal for carrying encoded data pertaining to at least one of the group comprising:

presence of the electric load;

location of the primary inductive coil;

location of the secondary inductive coil;

required operating voltage for the electric load;

required operating current for the electric load;

required operating temperature for the electric load;

required operating power for the electric load;

measured operating voltage for the electric load;

measured operating current for the electric load;

measured operating temperature for the electric load;

measured operating power for the electric load;

power delivered to the primary inductive coil;

power received by the secondary inductive coil, and a user identification code.

14. An electrical device incorporating the signal transfer system of claim 1.

15. The electrical device of claim 14 being selected from a group consisting of:

computers, telephones, personal digital assistance (PDAs), cameras, media players, computers, keyboards and mice.

16. An inductive power outlet incorporating a reception circuit for receiving control signals produced by the transmission circuit of the signal transfer system of claim 1.

17. A method for transferring a signal through an inductive energy coupling, the inductive energy coupling comprising a primary coil connected to a power source and a secondary coil connected to an electric load, the method comprising:

providing an input signal;

providing a bit-rate signal;

modulating the bit-rate signal with the input signal to create a modulated signal;

connecting an ancillary load to the secondary coil intermittently according to the modulated signal;

monitoring a primary current drawn by the primary coil and producing a primary current signal; and

cross-correlating the primary current signal with the bit-rate signal to generate an output signal.

18. The method of claim 17 wherein the input signal is provided by monitoring at least one operating parameter of the electric load and encoding data pertaining to the operating parameter into the input signal.

19. A method for detecting the presence of a secondary inductive coil coupled to a primary inductive coil the method comprising:

providing a power monitor for monitoring power provided to the primary inductive coil;

providing an ancillary load connectable to the secondary inductive coil via a frequency divider, and

the power monitor detecting harmonic signals in the power supplied to the primary inductive coil indicating power being drawn by the ancillary load.

20. The method of claim 19 wherein the frequency divider comprises a half-wave rectifier and the harmonic signals comprise second harmonic signals.