Efficiency monitor for inductive power transmission

• US 8,965,720 B2
• Filed: 12/06/2013
• Issued: 02/24/2015
• 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): TSAI, CAROL S W
• Application Number:
  US14/098,880
• Publication Number:
  US 20140097677A1
• Time in Patent Office: 445 Days
• Field of Search: 702/62, 307/104, 307/11, 320/108, 363/21.02, 363/157, 315/224, 340/657, 340/854.8
• US Class Current: 702/62
• 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

An efficiency monitor for monitoring the efficiency of power transmission by an inductive power outlet. The efficiency monitor includes an input power monitor, for measuring the input power delivered to the primary coil, and an output power monitor, for measuring the output power received by the secondary coil. The input and output powers are used by a processor to determine an index of power-loss. A circuit breaker may be used to disconnect the inductive power outlet in case of excessive power loss.

Claims

1. A system for transmitting power inductively to at least one electric load via an inductive energy coupling, said inductive energy coupling comprising a primary coil and a secondary coil connected to said electric load, said system comprising:

a multi-coil power transmission surface comprising an array of said primary coils each connected to a driver wired to a power source, and

a signal transfer system comprising at least one transmission circuit connected in parallel with the electric load and operable to transmit control signals; and

at least one reception circuit associated with said multi-coil power transfer surface and operable to detect said control signals;

wherein;

said signal transfer system is operable to monitor strength of said control signals and thereby identify the primary coil closest to the location of the secondary coil; and

said driver is operable to operate the primary coil closest to the secondary coil.

2. The system of claim 1 wherein each primary coil may be independently connected to the power source via a driver.

3. The system of claim 1 wherein each primary coil is operable at a plurality of power levels and the driver is configured to:

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

to provide the coupled primary coil with a higher power.

4. The system of claim 1 wherein said driver is configured to operate the primary coils sequentially, and the reception circuit is configured to detect second harmonic signals in the power supplied to at least one primary coil, indicating that the primary coil is coupled to a secondary coil.

5. The system of claim 1, wherein said transmission circuit comprises a switch for intermittently connecting an ancillary load to the secondary coil and said reception circuit comprises a current monitor for monitoring a primary current drawn by said primary coil.

6. The system of claim 1 wherein the transmission circuit comprises a frequency divider.

7. The system of claim 1, wherein:

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

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

8. The 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.

9. The 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 coil;

location of the secondary 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 coil;

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

10. A method for selecting, from an array of primary coils, the primary coil closest to the location of a secondary coil connected to an electric load, the method comprising:

providing a driver connected to said array of primary coils;

providing at least one transmission circuit associated with said secondary coil and connected in parallel to the electric load;

providing at least one reception circuit associated with said array of primary coils;

said at least one transmission circuit transmitting control signals;

said at least one reception circuit receiving said control signals via at least one primary coil;

monitoring strength of said control signals received via each primary coil; and

said driver driving the primary coil receiving the strongest control signal.

11. The method of claim 10, wherein said transmission circuit comprises an ancillary load connectable to the secondary coil in parallel to said electrical load, and a switching unit.

12. The method of claim 11, wherein transmitting said control signals comprises said switching unit connecting said ancillary load to said secondary coil at a determined rate.

13. The method of claim 10 wherein said reception circuit comprises a power monitor for monitoring power provided to the primary coil.

14. The method of claim 13, wherein receiving said control signals comprises said power monitor monitoring primary current drawn by the primary coil.

15. The method of claim 10, wherein further comprising said reception circuit detecting second harmonic signals.