Energy efficient inductive power transmission system and method

• US 8,981,598 B2
• Filed: 08/09/2011
• Issued: 03/17/2015
• 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, Leibovitz, Alfred, Ashery, Moti
• Primary Examiner(s): CAVALLARI, DANIEL J
• Application Number:
  US13/205,672
• Publication Number:
  US 20120193993A1
• Time in Patent Office: 1,316 Days
• Field of Search: 307/104
• US Class Current: 307/104
• CPC Class Codes: H01F 2038/143 for signals
• 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 50/12 of the resonant type
• CPC Class Codes: H02J 50/40 using two or more transmitting or receiving devices H02J50/50 takes precedence
• 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 7/00045 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 7/0029 with safety or protection devices or circuits
• CPC Class Codes: H02J 7/0047 with monitoring or indicating devices or circuits
• 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: H04B 5/79 for data transfer in combination with power transfer
• 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 inductive power transfer system and method for transferring power to an electrical device wirelessly. The system includes an inductive power outlet and an inductive power receiver. During operation, instruction signals are sent from the inductive power outlet to the inductive power receiver. When no instruction signals are transferred, the system is configured to deactivate such that power is drawn by the system only during operation.

Claims

1. An inductive power outlet for transmitting power to at least one inductive power receiver, said inductive power outlet comprising:

at least one primary inductor wired to a power supply, said primary inductor for forming an inductive couple with at least one secondary inductive coil associated with said inductive power receiver; and

at least one driver configured to provide an oscillating voltage across said primary inductor;

wherein said inductive power outlet further comprises

a trigger sensor configured to detect a release signal indicating proximity of a inductive power receiver; and

a signal detector operable to detect instruction signals from said inductive power receiver concurrently with power transfer;

and wherein

said release signal triggers said inductive power outlet to generate an activation signal detectable by said inductive power receiver;

said signal detector is operable to detect an identification signal sent by said inductive power receiver to said inductive power outlet and to start said inductive power outlet driving said primary inductor such that said inductive power receiver draws power therefrom for a limited time duration and to stop driving said oscillating voltage if no instruction signal is received during said time duration.

2. The inductive power outlet of claim 1, said instruction signal comprises pulses in primary voltage or primary current having a characteristic frequency, wherein said inductive power outlet further comprises:

at least one pulse detector configured to detect said pulses; and

at least one processor operable to determine said characteristic frequency of said pulses.

3. The inductive power outlet of claim 1 wherein said driver is operable to perform at least one function selected from a group consisting of:

selecting a first operating power if said signal detector detects a first identification signal;

selecting a second operating power if said signal detector detects a second identification signal;

increasing operating power by an increment if said signal detector detects a power increase signal;

decreasing operating power by an increment if said signal detector detects a power decrease signal;

continuing to provide said oscillating voltage across said primary inductor at same power if said signal detector detects a perpetuation signal; and

ceasing to provide said oscillating voltage across said primary inductor if said signal detector detects a termination signal.

4. The inductive power outlet of claim 1 wherein said activation signal comprises an induced voltage across said secondary inductive coil.

5. The inductive power outlet of claim 1 wherein said driver is operable to adjusting operating power level by adjusting at least one of operating frequency, duty cycle and amplitude of operating voltage.

6. An inductive power receiver for receiving power from at least one inductive power outlet, said inductive power receiver comprising:

at least one secondary inductor for forming an inductive couple with at least one primary inductive coil;

at least one signal transmission circuit; and

an output regulator operable to monitor power output from said secondary inductive coil;

wherein;

said output regulator is further operable to detect an activation signal sent by said inductive power outlet; and

said signal transmission circuit is configured to generate at least one identification signal in response to said activation signal, said identification signal being detectable by a signal detector associated with said inductive power outlet thereby triggering

said inductive power outlet to drive an oscillating voltage across said primary inductive coil for a limited time duration; and

said signal transmission circuit is further operable to send at least one instruction signal to said inductive power outlet concurrently with power transfer during each said time duration.

7. The inductive power receiver of claim 6, said transmission circuit comprising at least one electrical element selectively connectable to said secondary inductor by a switching unit, wherein said switching unit is configured to connect said electrical element to said secondary inductor with a characteristic frequency.

8. The inductive power receiver of claim 6 wherein said time duration is between five milliseconds and ten milliseconds.

9. The inductive power receiver of claim 6 further wherein at least one instruction signal comprises a termination signal instructing said inductive power outlet to cease driving the primary inductive coil.

10. The inductive power receiver of claim 6 wherein said signal transmission circuit comprises a signal generator operable to generate at least one instruction signal having a characteristic frequency selected from at least one of a group consisting of:

250 hertz, 500 hertz, 1 kilohertz, 1.5 kilohertz, 5 kilohertz and 8 kilohertz.

11. The inductive power receiver of claim 6 wherein said output regulator is operable to monitor power output from said secondary inductor;

to compare said power output with at least one threshold value.

12. The inductive power receiver of claim 6 wherein said signal transmission circuit is further operable to generate at least one instruction signal selected from a group consisting of:

an initial pulse of approximately one kilohertz a power increase signal to instruct the inductive power outlet to increase operating power by an increment;

a power decrease signal to instruct the inductive power outlet to decrease operating power by an increment;

a perpetuation signal to instruct the inductive power outlet a pulse of approximately 500 hertz to instruct the inductive power outlet to continue driving the primary inductive coil at the same power; and

a termination signal to instruct the inductive power outlet to cease driving the primary inductive coil.

13. The inductive power outlet of claim 6 wherein said instruction signal comprises pulses in primary voltage or primary current having a characteristic frequency selected from at least one of a group consisting of:

250 hertz, 500 hertz, 1 kilohertz, 1.5 kilohertz, 5 kilohertz and 8 kilohertz.

14. A signal transmission circuit for controlling an inductive power receiver receiving power from at least one inductive power outlet, said inductive power receiver having at least one secondary inductor for forming an inductive couple with at least one primary inductive coil;

said signal transmission circuit configured to generate at least one control signal, said control signal being detectable by a signal detector associated with said inductive power outlet,

said signal transmission circuit comprising;

a rectifier wired to said secondary inductor;

an output regulator operable to monitor power output from said secondary inductive coil;

at least one switching unit configured to connect an electrical element to said secondary inductor; and

a signal generator;

wherein;

said output regulator is further operable to detect an activation signal sent by said inductive power outlet; and

said signal generator is configured to generate at least one identification signal in response to said activation signal, said identification signal being detectable by a signal detector associated with said inductive power outlet thereby triggering said inductive power outlet to drive an oscillating voltage across said primary inductive coil for a limited time duration; and

said signal transmission circuit is further operable to send at least one control signal to said inductive power outlet concurrently with power transfer during each said time duration.

15. The signal transmission circuit of claim 14 wherein said switching unit comprises a MOSFET configured to connect said electrical element to said secondary inductor with a characteristic frequency.

16. The signal transmission circuit of claim 14 wherein said time duration is between five milliseconds and ten milliseconds.

17. The signal transmission circuit of claim 14 further wherein at least one control signal comprises a termination signal instructing said inductive power outlet to cease driving the primary inductive coil.

18. The signal transmission circuit of claim 14 wherein said signal generator is operable to generate at least one control signal having a characteristic frequency selected from at least one of a group consisting of:

250 hertz, 500 hertz, 1 kilohertz, 1.5 kilohertz, 5 kilohertz and 8 kilohertz.

19. The signal transmission circuit of claim 14 wherein said output regulator is operable to monitor power output from said secondary inductor;

to compare said power output with at least one threshold value.

20. The signal transmission circuit of claim 14 further operable to generate at least one instruction signal selected from a group consisting of:

a power increase signal transmitted to said inductive power outlet when said output regulator detects a power output below a first threshold value thereby instructing the inductive power outlet to increase operating power by an increment;

a power decrease signal transmitted to said inductive power outlet when said output regulator detects a power output above a second threshold value thereby instructing the inductive power outlet to decrease operating power by an increment.

21. The signal transmission circuit of claim 14, further operable to send a perpetuation signal when said output regulator detects a power output within a permissible range of values thereby instructing the inductive power outlet to continue driving said primary inductive coil at the same power level.