Power transmitting device and non-contact power feeding system

• US 10,778,046 B2
• Filed: 06/08/2016
• Issued: 09/15/2020
• Est. Priority Date: 06/25/2015
• Status: Active Grant

• Current Assignee: ROHM Co., Ltd.
• Original Assignee: ROHM Co., Ltd.
• Inventors: Ikefuji, Yoshihiro, Okui, Akihiro
• Primary Examiner(s): Barnie, Rexford N
• Assistant Examiner(s): Tran, Thai H
• Application Number:
  US15/736,425
• Publication Number:
  US 20180183277A1
• Time in Patent Office: 1,560 Days
• Field of Search: 307104, 320108
• 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
• CPC Class Codes: H04B 5/26 using coils
• CPC Class Codes: H04B 5/79 for data transfer in combination with power transfer

Abstract

In this non-contact power feeding system that is capable of transmitting power from a power transmitting device (1) to a power receiving device (2) by a magnetic field resonance scheme, the power transmitting device (1) is provided with first to n-th resonant circuits (TT[1]-TT[n]) which are provided with coils (T_L) that are different in size, respectively, and which have a resonant frequency set to a prescribed reference frequency. Prior to power transmission, test magnetic fields are generated in sequence in the first to n-th resonant circuits to detect the amplitude of current flowing through the coils of respective resonant circuits, and the presence/absence of a foreign object is determined on the basis of the obtained first to n-th amplitude detected values, to control execution of the power transmission.

Claims

1. A power transmitting device capable of transmitting power to a power receiving device by a magnetic field resonance scheme, comprising:

first to n-th resonant circuits having different sizes of coils and resonant frequencies set to a prescribed reference frequency;

a power transmission circuit arranged to selectively supply an AC signal to one of the first to n-th resonant circuits;

a detection circuit arranged to detect amplitude of current flowing in the coil of the resonant circuit supplied with the AC signal; and

a control circuit arranged to control the power transmission circuit, wherein n is an integer equal to or greater than 2,

the control circuit sequentially supplies the AC signal to the first to n-th resonant circuits so as to obtain first to n-th amplitude detected values corresponding to the first to n-th resonant circuits from the detection circuit prior to the power transmission, and performs execution control of the power transmission based on the first to n-th amplitude detected values,

in each of the first to n-th resonant circuits, a switch is provided in series with the coil,

the first to n-th amplitude detected values are obtained in first to n-th connection states, respectively,

in an i-th connection state, the power transmission circuit is connected only to an i-th resonant circuit out of the first to n-th resonant circuits and only the switch in the i-th resonant circuit out of the first to n-th resonant circuits is turned on, and

i is an integer equal to or greater than 1, but equal to or less than n,

wherein the control circuit determines presence or absence of a foreign object that is different from the power receiving device and includes another resonant circuit having a resonant frequency set to the reference frequency, based on the first to n-th amplitude detected values, and enables execution of the power transmission when determining that the foreign object does not exist, while it disables the execution of the power transmission when determining that the foreign object exists, and

wherein the other resonant circuit is different from any of the first to n-th resonant circuits.

2. The power transmitting device according to claim 1, wherein the control circuit determines whether to enable or disable execution of the power transmission by comparing each of the first to n-th amplitude detected values with a predetermined reference value.

3. The power transmitting device according to claim 1, wherein the control circuit determines whether to enable or disable execution of the power transmission by comparing a minimum value of the first to n-th amplitude detected values with a predetermined reference value.

4. The power transmitting device according to claim 1, wherein

the power transmission is performed using the power transmission circuit and the first resonant circuit, and

magnetic field intensities of magnetic fields generated by the coils of the resonant circuits when the AC signal is supplied to the resonant circuits prior to the power transmission is smaller than magnetic field intensity of a magnetic field generated by the coil of the first resonant circuit when the power transmission is performed.

5. The power transmitting device according to claim 1, wherein

the power receiving device includes a power reception resonant circuit having a resonant frequency set to the reference frequency so as to be capable of receiving power with the power reception resonant circuit, and

when the first to n-th amplitude detected values are obtained, the resonant frequency of the power reception resonant circuit is changed from the reference frequency, or a coil of the power reception resonant circuit is short-circuited in the power receiving device, according to a signal of communication from the power transmitting device.

6. The non-contact power feeding system according to claim 1, wherein

the power transmission is performed using the power transmission circuit and the first resonant circuit, and

magnetic field intensities of magnetic fields generated by the coils of the resonant circuits when the AC signal is supplied to the resonant circuits prior to the power transmission is smaller than magnetic field intensity of a magnetic field generated by the coil of the first resonant circuit when the power transmission is performed.

7. The power transmitting device according to claim 1, wherein

the first to n-th resonant circuits respectively have first to n-th coils, first to n-th capacitors, and first to n-th switches,

an i-th coil, an i-th capacitor, and an i-th switch are provided in the i-th resonant circuit, and

in the i-th resonant circuit, the i-th switch has two switches, a first one of which is provided between one terminal of the i-th coil and one terminal of the i-th capacitor, and a second one of which is provided between another terminal of the i-th coil and another terminal of the i-th capacitor.

8. A non-contact power feeding system capable of transmitting power from a power transmitting device to a power receiving device by a magnetic field resonance scheme, wherein

the power transmitting device includes first to n-th resonant circuits having different sizes of coils and resonant frequencies set to a prescribed reference frequency, a power transmission circuit arranged to selectively supply an AC signal to one of the first to n-th resonant circuits, a detection circuit arranged to detect amplitude of current flowing in the coil of the resonant circuit supplied with the AC signal, and a control circuit arranged to control the power transmission circuit, where n is an integer equal to or greater than 2,

the power receiving device includes a power reception resonant circuit including a power reception coil, and a resonant state changing circuit arranged to change a resonant frequency of the power reception resonant circuit from the reference frequency as a resonant frequency for the power reception, or to short-circuit the power reception coil, prior to power reception from the power transmitting device, and

the control circuit sequentially supply the AC signal to the first to n-th resonant circuits so as to obtain first to n-th amplitude detected values corresponding to the first to n-th resonant circuits from the detection circuit, prior to the power transmission, in the state where the resonant frequency of the power reception resonant circuit is changed or the power reception coil is short-circuited in the power receiving device, based on a signal of the communication from the power transmitting device, and performs execution control of the power transmission based on the first to n-th amplitude detected values,

in each of the first to n-th resonant circuits, a switch is provided in series with the coil,

the first to n-th amplitude detected values are obtained in first to n-th connection states, respectively,

in an i-th connection state, the power transmission circuit is connected only to an i-th resonant circuit out of the first to n-th resonant circuits and only the switch in the i-th resonant circuit out of the first to n-th resonant circuits is turned on, and

i is an integer equal to or greater than 1, but equal to or less than n;

wherein the control circuit determines presence or absence of a foreign object that is different from the power receiving device and includes another resonant circuit having a resonant frequency set to the reference frequency, based on the first to n-th amplitude detected values, and enables execution of the power transmission when determining that the foreign object does not exist, while it disables the execution of the power transmission when determining that the foreign object exists, and

wherein the other resonant circuit is different from any of the first to n-th resonant circuits.

9. The non-contact power feeding system according to claim 8, wherein the control circuit determines whether to enable or disable execution of the power transmission by comparing each of the first to n-th amplitude detected values with a predetermined reference value.

10. The non-contact power feeding system according to claim 8, wherein the control circuit determines whether to enable or disable execution of the power transmission by comparing a minimum value of the first to n-th amplitude detected values with a predetermined reference value.

11. The non-contact power feeding system according to claim 8, wherein

the first to n-th resonant circuits respectively have first to n-th coils, first to n-th capacitors, and first to n-th switches,

an i-th coil, an i-th capacitor, and an i-th switch are provided in the i-th resonant circuit, and

in the i-th resonant circuit, the i-th switch has two switches, a first one of which is provided between one terminal of the i-th coil and one terminal of the i-th capacitor, and a second one of which is provided between another terminal of the i-th coil and another terminal of the i-th capacitor.