Sensing device, power reception device, power transmission device, non-contact power transmission system, and sensing method

• US 9,057,753 B2
• Filed: 08/31/2012
• Issued: 06/16/2015
• Est. Priority Date: 09/09/2011
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Nakano, Hiroaki, Murakami, Tomomichi, Kozakai, Osamu, Fujimaki, Kenichi
• Primary Examiner(s): Nguyen, Tung X
• Assistant Examiner(s): RIOS RUSSO, RAUL J
• Application Number:
  US13/600,741
• Publication Number:
  US 20130063160A1
• Time in Patent Office: 1,019 Days
• Field of Search: 324 7611- 7683, 324/649, 324/653, 324/66, 324/67, 324/71.1, 324/663
• US Class Current: 1/1
• CPC Class Codes: G01R 27/28 Measuring attenuation, gain, phase shift or derived characteristics of electric four pole networks, i.e. two-port networks; Measuring transient response in line transmission systems H04B3/46
• CPC Class Codes: G01R 31/346 Testing of armature or field windings
• CPC Class Codes: G01R 31/42 AC power supplies
• CPC Class Codes: G01R 31/72 Testing of electric windings testing of transformers G01R31/62
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/60 responsive to the presence of foreign objects, e.g. detection of living beings

Abstract

There is provided a sensing device including a circuit including at least a coil electromagnetically coupled to an outside; a temperature detection unit for detecting a temperature of the coil; a sensing unit for measuring a Q value of the circuit; and a correction unit for correcting the Q value measured by the sensing unit based on temperature information detected by the temperature detection unit.

Claims

1. A sensing device comprising:

a circuit including a coil that can be electromagnetically coupled to another coil outside of the circuit and a capacitor coupled in series with the coil;

a temperature measuring unit that measures a temperature of the coil;

a sensing unit that measures a measured Q value of the circuit across the capacitor;

a correction unit that generates a temperature-corrected measured Q value using the temperature measured by the temperature measuring unit; and

a determination unit that compares the temperature-corrected measured Q value with a threshold Q value and determines the presence or absence of a metallic foreign material sufficiently proximate the sensing unit,

wherein,

the threshold Q value is either (a) a predetermined Q value corresponding to a Q value for the circuit when the metallic foreign material is not sufficiently proximate the sensing unit to affect the measured Q value or (b) a temperature-corrected predetermined Q value corresponding to the Q value for the circuit when the metallic foreign material is not sufficiently proximate the sensing unit to affect the measured Q value as corrected for coil temperature.

2. The sensing device of claim 1, the determination unit determines that the metallic foreign material is sufficiently proximate the sensing unit when the temperature-corrected measured Q value exceeds the threshold Q value.

3. The sensing device of claim 1, where the determination unit determines that the metallic foreign material is sufficiently proximate the sensing unit when the temperature-corrected measured Q value exceeds the temperature-corrected predetermined Q value.

4. The sensing device of claim 1, wherein the corrected measured Q value is subject to a relationship:

temperature-corrected measured Q Value=(Q value at steady temperature)×

{1−

(measured temperature−

steady temperature)×

(metal temperature coefficient)},

where,

steady temperature means a predetermined temperature, and

metal temperature coefficient is a temperature coefficient for a metal of which the coil is made.

5. The sensing device of claim 1, wherein the corrected threshold value is subject to a relationship:

temperature-corrected predetermined Q value=(predetermined Q value at steady temperature)×

{1−

(measured temperature−

steady temperature)×

(metal temperature coefficient)},

where,

steady temperature means a predetermined temperature, and

metal temperature coefficient is a temperature coefficient for a metal of which the coil is made.

6. The sensing device of claim 1, wherein corrected efficiency between the coils after generation of the temperature-corrected Q value is subject to a relationship:

corrected efficiency between coils=(corrected primary-side Q Value×

corrected secondary-side Q value×

k)2/{1+√

(1+corrected primary-side Q value×

corrected secondary-side Q value×

k)}2,

where,

k denotes a coupling coefficient,

the corrected primary side Q value is the Q value for the primary coil as corrected for coil temperature thereof, and

the corrected secondary side Q value is the Q value of the secondary coil as corrected for coil temperature thereof.

7. The sensing device of claim 1, wherein, given a coupling coefficient between the primary and secondary coils that is sufficiently small, the efficiency of the coils after the correction for coil temperatures is approximately subject to a relationship as follows:

corrected efficiency between the coils=value of efficiency between the coils at steady temperature−

{0.2×

√

(temperature at primary coil×

temperature measured at Secondary coil)−

steady temperature},

where, steady temperature is a predetermined temperature.

8. The sensing device of claim 1, further comprising a memory for storing the threshold Q value, wherein the determination unit reads the threshold Q value stored in the memory, and then compares the threshold Q value to the corrected measured Q value.

9. The sensing device of claim 1, further comprising a control unit for stopping electromagnetic coupling between the coil and the outside when the temperature of the coil measured by the temperature measuring unit exceeds a predetermined value.

10. The sensing device of claim 1, wherein:

the temperature measuring unit uses a thermistor, and

the sensing unit acquires a voltage value corresponding to the temperature of the coil from the temperature measuring unit and measures the temperature of the coil using the voltage value.

11. A power reception device comprising:

a circuit including a coil that electromagnetically receives power from outside the circuit and a capacitor coupled in series with the coil;

a temperature measuring unit that measures a temperature of the coil;

a sensing unit that measures a measured Q value of the circuit;

a correction unit that generates a temperature-corrected measured Q value using the temperature measured by the temperature measuring unit; and

a determination unit that compares the temperature-corrected measured Q value with a threshold Q value and determines the presence or absence of a metallic foreign material sufficiently proximate the sensing unit,

wherein,

the threshold Q value is either (a) a predetermined Q value corresponding to a Q value for the circuit when the metallic foreign material is not sufficiently proximate the sensing unit to affect the measured Q value or (b) a temperature-corrected predetermined Q value corresponding to the Q value for the circuit when the metallic foreign material is not sufficiently proximate the sensing unit to affect the measured Q value as corrected for coil temperature.

12. A power transmission device comprising:

a circuit including a coil that electromagnetically transmits power to an outside of the circuit and a capacitor coupled in series with the coil;

a temperature measuring unit that measures a temperature of the coil;

a sensing unit that measures a measured Q value of the circuit across the capacitor;

a correction unit that generates a temperature-corrected measured Q value using the temperature measured by the temperature measuring unit; and

a determination unit that compares the temperature-corrected measured Q value with a threshold Q value and determines the presence or absence of a metallic foreign material sufficiently proximate the unit,

wherein,

the threshold Q value is either (a) a predetermined Q value corresponding to a Q value for the circuit when the metallic foreign material is not sufficiently proximate the unit to affect the measured Q value or (b) a temperature-corrected predetermined Q value corresponding to the Q value for the circuit when the metallic foreign material is not sufficiently proximate the sensing unit to affect the measured Q value as corrected for coil temperature.

13. A non-contact power transmission system comprising (a) a power transmission device for wirelessly transmitting power;

and (b) a power reception device for receiving the power from the power transmission device, one of the power transmission device or the power reception device including;

a circuit with a coil electromagnetically coupled to another coil in the other of the power reception device or the power transmission device and a capacitor coupled in series with the coil;

a temperature measuring unit that measures a temperature of the coil;

a sensing unit that measures a measured Q value of the circuit across the capacitor;

a correction unit that generates a temperature-corrected measured Q value using the temperature measured by the temperature measuring unit; and

a determination unit that compares the temperature-corrected measured Q value with a threshold Q value and determines the presence or absence of a metallic foreign material sufficiently proximate the sensing unit,

wherein,

the threshold Q value is either (a) a predetermined Q value corresponding to a Q value for the circuit when the metallic foreign material is not sufficiently proximate the sensing unit to affect the measured Q value or (b) a temperature-corrected predetermined Q value corresponding to the Q value for the circuit when the metallic foreign material is not sufficiently proximate the sensing unit to affect the measured Q value as corrected for coil temperature.

14. A sensing method comprising:

providing a circuit including (a) a coil that can be electromagnetically coupled to an outside of the circuit and a capacitor coupled in series with the coil, (b) a temperature measuring unit that can measure a temperature of the coil, (c) a sensing unit that can measure a measured Q value of the circuit across the capacitor, (d) a correction unit that can generate a temperature-corrected measured Q value using the temperature measured by the temperature measuring unit, and (e) a determination unit that can compare the temperature-corrected measured Q value with a threshold Q value and determine the presence of a metallic foreign material sufficiently proximate the sensing unit, the method comprising the steps of;

measuring the temperature of the coil with the temperature measuring unit;

measuring the measured Q value of the circuit with the sensing unit;

generating the temperature-corrected Q value for the circuit with the correction unit;

comparing the temperature-corrected Q value and the threshold Q value with the determination unit; and

determining with the determination unit the presence of the metallic foreign material when it is sufficiently proximate the sensing unit when the temperature-corrected Q value exceeds the threshold Q value,

wherein,

the threshold Q value is either (a) a predetermined Q value corresponding to a Q value for the circuit when the metallic foreign material is not sufficiently proximate the sensing unit to affect the measured Q value or (b) a temperature-corrected predetermined Q value corresponding to the Q value for the circuit when the metallic foreign material is not sufficiently proximate the sensing unit to affect the measured Q value as corrected for coil temperature.

15. The method of claim 14, wherein the determination unit determines that the metallic foreign material is sufficiently proximate the sensing unit when the temperature-corrected measured Q value exceeds the temperature-corrected predetermined Q value.