Efficiency monitor for inductive power transmission

Patent metadata

Field	Value
Publication number	US-10020680-B2
Application number	US-201414909285-A
Country	US
Kind code	B2
Filing date	Jul 30, 2014
Priority date	Jul 30, 2013
Publication date	Jul 10, 2018
Grant date	Jul 10, 2018

Abstract

An inductive power transmitter for inductive power transmission to an inductive power receiver is provided, comprising a primary coil, capable of being inductively coupled to a secondary coil in the inductive power receiver, a power supply and an associate driver configured to provide a varying electrical potential from the power supply to the primary coil, a monitoring system configured to measure electrical flow parameters of the primary coil, and a controller configured to detect, based on the electrical flow parameters measured by the monitoring system, an error condition indicative of a foreign object introduced between the primary coil and the secondary coil, and to facilitate, when the error condition is detected, interrupting the electrical potential to the primary coil.

First claim

The invention claimed is:

1. A wireless power transmitter for wireless power transmission to a wireless power receiver, the wireless power transmitter comprising:
a primary coil, capable of being inductively coupled to a secondary coil in said wireless power receiver;
a power supply and an associate driver configured to provide a varying electrical potential from said power supply to said primary coil;
a monitoring system configured to measure electrical flow parameters of the primary coil;
a controller configured to detect, based on said electrical flow parameters measured by said monitoring system, an error condition indicative of a foreign object introduced between said primary coil and said secondary coil by calculating one or more reference parameters and comparing said electrical flow parameters to said reference parameters, and to facilitate, when said error condition is detected, interrupting said electrical potential to said primary coil; and
a signal conditioner comprising a frequency changer configured to increase the frequency of an output signal of the monitoring system.

2. The wireless power transmitter according to claim 1 , wherein said monitoring system comprises: a voltage monitor configured to measure the voltage across said primary coil; and a current monitor configured to measure the current across the primary coil.

3. The wireless power transmitter according to claim 1 further comprising a circuit breaker configured to interrupt said electrical potential to said primary coil, said controller being configured to direct operation of the circuit breaker, thereby facilitating the interruption.

4. The wireless power transmitter according to claim 1 , wherein said controller comprises a comparator configured to facilitate the comparing.

5. The wireless power transmitter according to claim 1 further comprising a memory module, said reference parameters being stored in said memory module.

6. The wireless power transmitter according to claim 5 , wherein said memory module comprises non-volatile memory.

7. The wireless power transmitter according to claim 1 , further comprising a signal conditioner comprising a frequency changer configured to increase the frequency of an output signal of the monitoring system.

8. The wireless power transmitter according to claim 1 , wherein said signal conditioner further comprises a filter configured to reduce noise of said output signal.

9. A method for detecting a foreign object between a wireless power transmitter and a wireless power receiver, the method comprising:
providing said wireless power transmitter, said wireless power transmitter being configured for wireless power transmission to a wireless power receiver and comprising a primary coil capable of being inductively coupled to a secondary coil in said wireless power receiver;
measuring electrical flow parameters of the primary coil;
detecting, based on the measured electrical flow parameters, an error condition indicative of a foreign object introduced between said primary coil and said secondary coil by calculating one or more reference parameters and comparing said electrical flow parameters to said reference parameters; and
calculating said reference parameters based on the frequency of the varying electrical and at least one measured electrical flow parameter.

10. The method according to claim 9 , further comprising interrupting said electrical potential to said primary coil when said error condition is detected.

11. The method according to claim 9 , further comprising a submethod of performing a startup foreign object test, the submethod comprising:
decreasing the frequency of said varying electrical potential through a plurality of frequencies from a first frequency to a second frequency;
determining a threshold value for each of one or more of said electrical flow parameters for at least some of said plurality of frequencies, said threshold values corresponding to non-error conditions and constituting one of said reference parameters;
monitoring said electrical flow parameters; and
detecting said error condition if one or more of said electrical flow parameters exceeds said threshold value.

12. The method according to claim 11 , wherein said electrical flow parameters comprise the voltage and current across the primary coil.

13. The method according to claim 11 , wherein said decreasing, monitoring, and detecting of said startup foreign object test are performed when charging is initiated.

14. The method according to claim 9 , further comprising a submethod of performing a transmission foreign object test, the submethod comprising:
determining a relationship between two or more of said electrical flow parameters;
determining a threshold value for said relationship, said threshold value corresponding to a non-error condition and constituting said reference parameters;
monitoring said electrical flow parameters;
calculating a measured relationship of the measured electrical flow parameters; and
detecting said error condition if said measured relationship is beyond said threshold value.

15. The method according to claim 14 , wherein said relationship is based on at least the voltage and current across the primary coil.

16. The method according to claim 15 , wherein said relationship is further based on the frequency of said varying electrical potential.

17. The method according to claim 9 , further comprising a submethod of performing an idle foreign object test, the submethod comprising:
determining a reference signal decay time of a ping signal transmitted when an error condition does not exist;
transmitting a test ping signal;
measuring the signal decay time of said test ping signal and comparing it to said reference calibration decay time; and
detecting said error condition if the signal decay time is below said reference decay time beyond a predetermined threshold.

18. The method according to claim 17 , wherein said idle foreign object test is performed when the wireless power transmitter is not transmitting power to a wireless power receiver.

19. The method according to claim 9 , further comprising increasing the frequency of an output signal of the monitoring system.

Assignees

• Powermat Tech Ltd

Inventors

• Raveh Guy
• Rofe Arik
• Greenwald Oola
• Ben Shalom Amir
• Mach Elieser
• Gluzman Ilya
• Mushkovich Oz

Classifications

• H02J7/65 Primary

  against overtemperature · CPC title

• H02J50/80

  involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices · CPC title

• H02J50/60

  responsive to the presence of foreign objects, e.g. detection of living beings · CPC title

• H02J7/025

  Electricity · mapped topic

• H02J17/00

  Electricity · mapped topic