Wireless power supply system and power receiver

• US 10,418,858 B2
• Filed: 12/13/2017
• Issued: 09/17/2019
• Est. Priority Date: 08/28/2015
• Status: Active Grant

• Current Assignee: IHI Corporation
• Original Assignee: IHI Corporation
• Inventors: Murayama, Takahiko, Araki, Jun, Nakamura, Toshio
• Primary Examiner(s): Fureman, Jared
• Assistant Examiner(s): Bukhari, Aqeel H
• Application Number:
  US15/840,885
• Publication Number:
  US 20180109149A1
• Time in Patent Office: 643 Days
• Field of Search: None
• CPC Class Codes: B60L 53/122 Circuits or methods for driving the primary coil, e.g. supplying electric power to the coil
• CPC Class Codes: B60L 53/126 Methods for pairing a vehicle and a charging station, e.g. establishing a one-to-one relation between a wireless power transmitter and a wireless power receiver
• 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 50/80 involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices
• CPC Class Codes: H02J 50/90 involving detection or optimisation of position, e.g. alignment
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 90/12 Electric charging stations
• CPC Class Codes: Y02T 90/14 Plug-in electric vehicles

Abstract

A wireless power supply system includes a power transmitter having a power-transmitting coil to which AC power of a frequency is input from a power source; and a power receiver having a power-receiving coil magnetically coupled to the power-transmitting coil at a coupling coefficient, and a first power-receiving-side series element coupled in series to the power-receiving coil and having imaginary impedance, in which the frequency, the coupling coefficient and the imaginary impedance are determined on the basis of satisfying a predetermined relationship.

Claims

1. A wireless power supply system comprising:

a power transmitter; and

a power receiver,

the power transmitter comprising a power-transmitting coil to which AC power of a frequency is input from a power source, and

the power receiver comprising;

a power-receiving coil magnetically coupled to the power-transmitting coil at a coupling coefficient; and

a first power-receiving-side series element coupled in series to the power-receiving coil and having imaginary impedance jZ_S2i,

wherein the frequency, the coupling coefficient and the imaginary impedance are determined on the basis of satisfying the following formula,

2. The wireless power supply system according to claim 1, wherein the coefficient K_I is a value larger than 0 and smaller than 1, or a value larger than 1.

3. The wireless power supply system according to claim 2, wherein:

the power transmitter further comprises;

a power-transmission-side parallel element coupled in parallel to the power-transmitting coil and having imaginary impedance jZ_P1i; and

a first power-transmission-side series element coupled in series to the power-transmitting coil at a position closer to the power-transmitting coil than the power-transmission-side parallel element and having imaginary impedance jZ_S1i-2;

the power receiver further comprises a power-receiving-side parallel element coupled in parallel to the power-receiving coil at a position closer to the power-receiving coil than the first power-receiving-side series element and having imaginary impedance jZ_P2i;

the imaginary impedance of the first power-transmission-side series element satisfies the following formula; and

Z_S1i-2=−

ω

L₁(1−

K_I²) 

 

Formula (2)

the imaginary impedances of the power-transmission-side parallel element and the power-receiving-side parallel element satisfy the following formula.

4. The wireless power supply system according to claim 3, wherein:

a variable range of the frequency is determined;

a fluctuation range of the coupling coefficient is determined; and

the imaginary impedances of the first power-receiving-side series element and the power-receiving-side parallel element are determined so as to satisfy Formula (1), when the frequency is an upper limit or a lower limit of the variable range and the coupling coefficient is an upper limit or a lower limit of the fluctuation range.

5. The wireless power supply system according to claim 4, wherein the imaginary impedances of the first power-receiving-side series element and the power-receiving-side parallel element are determined so that a phase difference between an electromotive force induced in the power-receiving coil by magnetic coupling of the power-transmitting coil to the power-receiving coil and the current of the power receiving coil is 0°

.

6. The wireless power supply system according to claim 4, wherein:

a load whose impedance fluctuates is coupled to the power receiver; and

the imaginary impedances of the first power-receiving-side series element and the power-receiving-side parallel element are determined so as to satisfy Formula (1) irrespective of the impedance of the load, when the frequency is the upper limit or the lower limit of the variable range and the coupling coefficient is the lower limit of the fluctuation range.

7. The wireless power supply system according to claim 3, wherein the first power-receiving-side series element is an inductor, and the power-receiving-side parallel element is a capacitor.

8. The wireless power supply system according to claim 3, wherein the first power-receiving-side series element and the power-receiving-side parallel element are capacitors.

9. The wireless power supply system according to claim 2, wherein:

the power transmitter further comprises;

a power-transmission-side parallel element coupled in parallel to the power-transmitting coil and having imaginary impedance jZ_P1i; and

a first power-transmission-side series element coupled in series to the power-transmitting coil at a position closer to the power-transmitting coil than the power-transmission-side parallel element and having imaginary impedance jZ_S1i-2;

the power receiver further comprises;

a power-receiving-side parallel element coupled in parallel to the power-receiving coil at a position closer to the power-receiving coil than the first power-receiving-side series element and having imaginary impedance jZ_P2i; and

a second power-receiving-side series element coupled in series to the power-receiving coil at a position closer to the power-receiving coil than the power-receiving-side parallel element and having imaginary impedance jZ_S2i-2;

the imaginary impedances of the first power-transmission-side series element and the second power-receiving-side series element satisfy the following formula; and

10. The wireless power supply system according to claim 9, wherein:

a variable range of the frequency is determined;

a fluctuation range of the coupling coefficient is determined; and

the imaginary impedances of the first power-receiving-side series element, the second power-receiving-side series element and the power-receiving-side parallel element are determined so as to satisfy Formula (1), when the frequency is an upper limit or a lower limit of the variable range and the coupling coefficient is an upper limit or a lower limit of the fluctuation range.

11. The wireless power supply system according to claim 10, wherein:

a load whose impedance fluctuates is coupled to the power receiver; and

the imaginary impedances of the first power-receiving-side series element, the second power-receiving-side series element and the power-receiving-side parallel element are determined so as to satisfy Formula (1) irrespective of the impedance of the load, when the frequency is the upper limit or the lower limit of the variable range and the coupling coefficient is the lower limit of the fluctuation range.

12. The wireless power supply system according to claim 10, wherein the imaginary impedances of the first power-receiving-side series element, the second power-receiving-side series element and the power-receiving-side parallel element are determined so that a phase difference between an electromotive force induced in the power-receiving coil by magnetic coupling of the power-transmitting coil to the power-receiving coil and the current of the power receiving coil is 0°

.

13. The wireless power supply system according to claim 9, wherein the first power-receiving-side series element is an inductor, and the second power-receiving-side series element and the power-receiving-side parallel element are capacitors.

14. The wireless power supply system according to claim 9, wherein the first power-receiving-side series element, the second power-receiving-side series element and the power-receiving-side parallel element are capacitors.

15. The wireless power supply system according to claim 1, wherein:

the power transmitter further comprises a power-transmission-side series element coupled in series to the power-transmitting coil and having imaginary impedance jZ_s1i; and

the imaginary impedances of the power-transmission-side series element and the first power-receiving-side series element satisfy the following formula.

16. The wireless power supply system according to claim 3, wherein:

the power transmitter further comprises a power-transmission-side series element coupled in series to the power-transmitting coil at a position closer to the power source than the power-transmission-side parallel element and having imaginary impedance jZ_S1i; and

the imaginary impedances of the power-transmission-side series element and the first power-receiving-side series element satisfy the following formula.

17. The wireless power supply system according to claim 9, wherein:

the power transmitter further comprises a second power-transmission-side series element coupled in series to the power-transmitting coil at a position closer to the power source than the power-transmission-side parallel element and having imaginary impedance jZ_S1i; and

the imaginary impedances of the second power-transmission-side series element and the first power-receiving-side series element satisfy the following formula.

18. The wireless power supply system according to claim 2, wherein:

a fluctuation range of the coupling coefficient is determined; and

the coefficient K_I satisfies 0<

K_I<

1.

19. The wireless power supply system according to claim 1, wherein:

a fluctuation range of the coupling coefficient is determined; and

when the self-inductances of the power-transmitting coil and the power-receiving coil change on the basis of change in the coupling coefficient, the self-inductances of the power-transmitting coil and the power-receiving coil take values within a changing range of the self-inductances depending on change in the coupling coefficient within the fluctuation range.

20. A power receiver that receives electric power wirelessly from a power transmitter comprising a power-transmitting coil to which AC power of a frequency is input from a power source, the power receiver comprising:

a power-receiving coil magnetically coupled to the power-transmitting coil at a coupling coefficient; and

a first power-receiving-side series element coupled in series to the power-receiving coil and having imaginary impedance jZ_S2i,

wherein the frequency, the coupling coefficient and the imaginary impedance are determined on the basis of satisfying the following formula,