System and method for controlling power transfer across an inductive power coupling

• US 8,749,097 B2
• Filed: 09/21/2009
• Issued: 06/10/2014
• Est. Priority Date: 03/22/2007
• Status: Active Grant

• Current Assignee: Powermat Technologies, Ltd.
• Original Assignee: Powermat Technologies, Ltd.
• Inventors: Azancot, Yossi, Ben-Shalom, Amir, Greenwald, Oola, Rofe, Arik
• Primary Examiner(s): Barnie, Rexford
• Assistant Examiner(s): INGE, JOSEPH N
• Application Number:
  US12/563,544
• Publication Number:
  US 20100072825A1
• Time in Patent Office: 1,723 Days
• Field of Search: 307/104
• 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 primary inductive coil being connected to a reception circuit configured to detect a plurality of control signals and the secondary inductive coil being connected to an electrical load and a transmission circuit configured to transmit said plurality of control signals,

wherein the transmission circuit comprises at least one ancillary load selectively connectable to the secondary inductive coil and further comprises a switching unit for intermittently connecting the ancillary load to the secondary inductive coil,

wherein said control signal is generated by the ancillary load being intermittently connected to the secondary coil at a determined rate;

wherein the transmission circuit further comprises a half-wave rectifier, and a reception circuit configured to detect second harmonic signals in the power supplied to the primary inductive coil; and

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.

2. The signal transfer system of claim 1, wherein the switching unit comprises:

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 1, the reception circuit comprising at least one power monitor for monitoring power provided to the primary inductive coil.

4. The signal transfer system of claim 3 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.

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

6. The signal transfer system of claim 1 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

provide the coupled primary inductive coil with a higher power.

7. 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.

8. An electrical device comprising an electric load connected to a secondary inductive coil, said secondary inductive coil being configured to form an inductive couple when brought into proximity with a primary inductive coil associated with an inductive power outlet such that power is provided to said electric load from said inductive power outlet, wherein:

said secondary inductive coil is further connected to a transmission circuit configured to transmit a plurality of control signals detectable by a reception circuit associated with said inductive power outlet, said control signals being usable to regulate the power provided from the inductive power outlet to the electric load, said transmission circuit comprising;

at least one ancillary load, and

at least one switch for intermittently connecting said ancillary load to the secondary inductive coil at a determined rate thereby encoding data pertinent to regulating power transmission from said inductive power outlet to said electric load and wherein the control signal determines the duty cycle of a varying voltage signal provided to the primary inductor.

9. The electrical device of claim 8, the primary inductive coil being connected to a reception circuit configured to detect an ancillary current.