DETECTION APPARATUS, POWER RECEIVING APPARATUS, NON-CONTACT POWER TRANSMISSION SYSTEM AND DETECTION METHOD

• US 20130162054A1
• Filed: 11/29/2012
• Published: 06/27/2013
• Est. Priority Date: 12/21/2011
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Komiyama, Shinji
• Granted Patent: US 9,482,702 B2
• Time in Patent Office: Days
• US Class Current: 307/149
• CPC Class Codes: G01R 15/18 using inductive devices, e.g. transformers
• CPC Class Codes: G01R 21/006 Measuring power factor
• CPC Class Codes: G01V 3/10 using induction coils
• 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
• CPC Class Codes: H02J 50/80 involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices

Abstract

Disclosed herein is a detection apparatus including: a resonant circuit provided with a Q-factor measurement coil and one or more capacitors to serve as a circuit for receiving pulses; a response-waveform detecting section configured to detect the waveform of a response output by the resonant circuit in response to the pulses; and a Q-factor measuring section configured to measure a Q factor of the resonant circuit from the response waveform detected by the response-waveform detecting section. It is possible to increase the precision of detection of a metallic foreign substance existing between a power transmitting side and a power receiving side.

Claims

1. A detection apparatus comprising:

a resonant circuit provided with a Q-factor measurement coil and one or more capacitors to serve as a circuit for receiving pulses;

a response-waveform detecting section configured to detect the waveform of a response output by said resonant circuit in response to said pulses; and

a Q-factor measuring section configured to measure a Q factor of said resonant circuit from said response waveform detected by said response-waveform detecting section.

2. The detection apparatus according to claim 1, wherein said response waveform detected by said response-waveform detecting section is a time-domain response waveform.

3. The detection apparatus according to claim 2, wherein said Q-factor measuring section measures said Q factor of said resonant circuit from a first amplitude obtained from said time-domain response waveform at a first time and a second amplitude obtained from said time-domain response waveform at a second time lagging behind said first time by a time period determined in advance.

4. The detection apparatus according to claim 3, wherein, when the resonance frequency of said resonant circuit is denoted by f, said first amplitude obtained from said time-domain response waveform at said first time t₁ is denoted by V₁, and said second amplitude obtained from said time-domain response waveform at said second time t₂ is denoted by V₂, said Q-factor measuring section measures said Q factor in accordance with the following equation:

Q=π

f·

(t₂−

t₁)/ln(V₁/V₂)

5. The detection apparatus according to claim 4, wherein said Q-factor measuring section measures said Q factor when said second amplitude obtained from said time-domain response waveform is in a predetermined amplitude range not including said first amplitude.

6. The detection apparatus according to claim 5, wherein said predetermined amplitude range set for said second amplitude obtained from said time-domain response waveform is a range of 40% to 25% of said first amplitude obtained from said time-domain response waveform.

7. The detection apparatus according to claim 4, wherein, if said second amplitude obtained from said time-domain response waveform has not entered a predetermined amplitude range not including said first amplitude within a predetermined time period, said Q-factor measuring section measures said Q factor by detecting said second amplitude at a point of time after the lapse of said predetermined time period.

8. The detection apparatus according to claim 2, wherein, when the number of vibrations occurring within a predetermined time period of said time-domain response waveform is denoted by “

vibration-count,”

an amplitude obtained at the start of said predetermined time period is denoted by V₁, and an amplitude obtained at the end of said predetermined time period is denoted by V₂, said Q-factor measuring section measures said Q factor in accordance with the following equation;

Q=π

·

vibration-count/ln(V₁/V₂)

9. The detection apparatus according to claim 1, further comprising

a determination section configured to determine a state of electromagnetic coupling between said Q-factor measurement coil and an external apparatus by comparing said Q factor measured by said Q-factor measuring section with a predetermined reference value.

10. The detection apparatus according to claim 9, wherein said state of electromagnetic coupling between said Q-factor measurement coil and said external apparatus implies existence/non-existence of a circuit including any coil or a conductor between said Q-factor measurement coil and said external apparatus.

11. The detection apparatus according to claim 10, further comprising

a control section configured to execute control to stop output of a power transmission signal from said external apparatus in case it is determined that a circuit including any coil or a conductor exists between said Q-factor measurement coil and said external apparatus.

12. The detection apparatus according to claim 1, wherein said response waveform detected by said response-waveform detecting section is a frequency-domain response waveform.

13. The detection apparatus according to claim 12, wherein said Q-factor measuring section measures said Q factor from a bandwidth between two frequencies at each of which the amplitude of said frequency-domain response waveform is 1/√

2 times an amplitude at a resonance frequency of a series resonant circuit, said series resonant circuit including one or more said capacitors and said Q-factor measurement coil.

14. The detection apparatus according to claim 12, wherein said Q-factor measuring section measures said Q factor from a bandwidth between two frequencies at each of which the amplitude of said frequency-domain response waveform is √

2 times an amplitude at a resonance frequency of a parallel resonant circuit, said parallel resonant circuit including one or more said capacitors and said Q-factor measurement coil.

15. The detection apparatus according to claim 1, wherein said pulses applied to said resonant circuit are a single pulse.

16. The detection apparatus according to claim 1, further comprising

a pulse generator configured to generate said pulses and apply said pulses to said resonant circuit.

17. A power receiving apparatus comprising:

a power receiving coil electromagnetically coupled to an external apparatus;

a power receiving section configured to receive electric power from said external apparatus through said power receiving coil;

a resonant circuit provided with a Q-factor measurement coil and one or more capacitors to serve as a circuit for receiving pulses;

a response-waveform detecting section configured to detect the waveform of a response output by said resonant circuit in response to said pulses; and

a Q-factor measuring section configured to measure a Q factor of said resonant circuit from said response waveform detected by said response-waveform detecting section.

18. A non-contact power transmission system comprising:

a power transmitting apparatus configured to transmit electric power by adoption of a non-contact transmission technique; and

a power receiving apparatus configured to receive said electric power from said power transmitting apparatus,

wherein said power receiving apparatus includes

a power receiving coil electromagnetically coupled to a power transmitting coil of said power transmitting apparatus,

a power receiving section configured to receive electric power from said power transmitting apparatus through said power receiving coil,

a resonant circuit provided with a Q-factor measurement coil and one or more capacitors to serve as a circuit for receiving pulses,

a response-waveform detecting section configured to detect the waveform of a response output by said resonant circuit in response to said pulses, and

a Q-factor measuring section configured to measure a Q factor of said resonant circuit from said response waveform detected by said response-waveform detecting section.

19. A detection method comprising:

applying pulses to a resonant circuit provided with a Q-factor measurement coil and one or more capacitors;

driving a response-waveform detecting section to detect the waveform of a response output by said resonant circuit in response to said pulses; and

driving a Q-factor measuring section to measure a Q factor of said resonant circuit from said response waveform detected by said response-waveform detecting section.