POWER TRANSMISSION SYSTEM

• US 20140368056A1
• Filed: 08/28/2014
• Published: 12/18/2014
• Est. Priority Date: 03/06/2012
• Status: Active Grant

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Murata Manufacturing Co Limited
• Inventors: HOSOTANI, Tatsuya
• Granted Patent: US 9,478,992 B2
• Time in Patent Office: Days
• US Class Current: 307/104
• CPC Class Codes: H01F 27/28 Coils; Windings; Conductive connections
• 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 7/0063 with circuits adapted for supplying loads from the battery
• CPC Class Codes: H02J 7/00711 with introduction of pulses during the charging process
• CPC Class Codes: H04B 5/24 Inductive coupling
• CPC Class Codes: H04B 5/79 for data transfer in combination with power transfer

Abstract

A power transmitting unit-side resonance circuit including a resonance capacitor connected in series to a power transmitting coil and a power receiving unit-side resonance circuit including a resonance capacitor connected in series to a power receiving coil are caused to resonate with each other so that each resonance circuit resonates. With this, power is transmitted between the power transmitting coil and the power receiving unit making use of magnetic field resonance coupling and electric field resonance coupling. By making use of resonance, only effective power is transmitted from the power transmitting unit side to the power receiving unit side, while reactive power that is reflected is reserved as resonance energy in each resonance circuit.

Claims

1. A power transmission system comprising:

a power transmitting unit having a power transmitting coil; and

a power receiving unit having a power receiving coil,

the power transmitting unit including;

a power transmitting unit-side resonance capacitor configuring a power transmitting unit-side resonance circuit along with the power transmitting coil; and

a power transmitting unit-side alternating current generation circuit electrically connected with the power transmitting coil, including a switching circuit configured of a parallel connection circuit in which a switching element, a diode, and a capacitor are connected in parallel, and an inductor having a value of inductance making it possible to form a current source, from an inputted direct-current voltage, taken as a direct current in comparison with an alternating current that is flowed in the power transmitting coil, so as to generate the alternating current to be flowed in the power transmitting coil,

the power receiving unit including;

a power receiving unit-side resonance capacitor configuring a power receiving unit-side resonance circuit along with the power receiving coil; and

a power receiving unit-side rectification circuit connected with the power receiving coil and rectifying an alternating current generated on the power receiving coil,

an electromagnetic field resonance coupling circuit configured with mutual inductance and mutual capacitance being equivalently formed between the power transmitting coil and the power receiving coil so that the power transmitting unit-side resonance circuit and the power receiving unit-side resonance circuit resonate with each other to transmit power from the power transmitting unit to the power receiving unit,

energy that is reflected without being transmitted from the power transmitting unit being taken as reactive power and reserved as resonance energy in the power transmitting unit-side resonance circuit, and

of the energy received by the power receiving unit, energy that is reflected without being supplied to output is taken as reactive power and reserved as resonance energy in the power receiving unit-side resonance circuit.

4. The power transmission system according to claim 1,

wherein the power receiving unit includes an information transmitting circuit configured to detect output information of the power receiving unit-side rectification circuit and transmit the output information having been detected to the power transmitting unit side, and

the power transmitting unit includes an output information receiving circuit configured to receive the output information and a transmission power control circuit configured to control the transmission power through controlling the power transmitting unit-side alternating current generation circuit in accordance with the output information.

5. The power transmission system according to claim 4,

wherein the information transmitting circuit is a circuit that transmits the output information by wireless communication, and

the output information receiving circuit is a circuit that receives the output information by wireless communication.

6. The power transmission system according to claim 4,

wherein the information transmitting circuit is a circuit that converts an electric signal to an optical signal so as to transmit the output information, and

the output information receiving circuit is a circuit that converts an optical signal to an electric signal so as to receive the output information.

7. The power transmission system according to claim 1,

wherein the power transmitting unit-side alternating current generation circuit is configured to control transmission power using frequency control PFM (pulse frequency modulation) in which a switching frequency for turning on/off a switching circuit is changed.

8. The power transmission system according to claim 1,

wherein the power transmitting unit-side alternating current generation circuit is configured to control transmission power using PWM (pulse width modulation) in which a time ratio is controlled by turning on/off a switching circuit at a fixed switching frequency.

9. The power transmission system according to claim 1,

wherein the power receiving unit-side rectification circuit is a synchronous rectification circuit including a switching element.

10. The power transmission system according to claim 9,

wherein the power receiving unit includes an operation frequency control circuit for controlling an operation frequency of the synchronous rectification circuit, and is configured to control reception power with the operation frequency.

11. The power transmission system according to claim 1,

wherein the power receiving unit includes a control circuit for controlling a circuit of the power receiving unit side, and the control circuit is configured to operate using power that the power receiving unit has received.

12. The power transmission system according to claim 1,

wherein, when power is transmitted from an output section of the power receiving unit-side rectification circuit, the power receiving unit-side rectification circuit acts as the power transmitting unit-side alternating current generation circuit while the power transmitting unit-side alternating current generation circuit acts as the power receiving unit-side rectification circuit, thereby making it possible to transmit power bi-directionally.

13. The power transmission system according to claim 1,

wherein a resonance capacitor is provided in parallel with respect to the power transmitting coil or the power receiving coil.

14. The power transmission system according to claim 13,

wherein the resonance capacitor is configured with stray capacitance that is made to become equivalent capacitance by electric field resonance formed between the power transmitting coil and the power receiving coil.

15. The power transmission system according to claim 13,

wherein the resonance capacitor is configured with equivalent mutual capacitance formed between the power transmitting coil and the power receiving coil.

16. The power transmission system according to claim 1,

wherein the power transmitting coil and the power receiving coil are air-core inductors.

17. The power transmission system according to claim 1,

wherein the mutual inductance is equivalent magnetization inductance generated by magnetic field resonance coupling which is formed between the power transmitting coil and the power receiving coil.

18. The power transmission system according to claim 1,

wherein, of inductance components of the power transmitting coil or the power receiving coil, leakage inductance that is not related to resonance coupling is used as an inductor which configures the power transmitting unit-side resonance circuit or the power receiving unit-side resonance circuit.

19. The power transmission system according to any claim 1,

wherein the power transmitting unit-side alternating current generation circuit includes a plurality of the power transmitting coils and a plurality of the switching circuits, the power transmitting coils and the switching circuits are configured to be electrically connected with each other, and the plurality of switching circuits sequentially perform switching operation in a periodic manner.

20. The power transmission system according to claim 1,

wherein the power transmitting unit-side alternating current generation circuit includes the plurality of switching circuits, the plurality of switching circuits are configured to be electrically connected with the power transmitting coils, and the plurality of switching circuits sequentially perform the switching operation in a periodic manner.

2. A power transmission system comprising:

a power transmitting unit having a power transmitting coil; and

a power receiving unit having a power receiving coil,

the power transmitting unit including;

a power transmitting unit-side resonance capacitor configuring a power transmitting unit-side resonance circuit along with the power transmitting coil; and

a power transmitting unit-side alternating current generation circuit electrically connected with the power transmitting coil, including a switching circuit configured of a parallel connection circuit in which a switching element, a diode, and a capacitor are connected in parallel, and an inductor having a value of inductance making it possible to form a current source, from an inputted direct-current voltage, taken as a direct current in comparison with an alternating current that is flowed in the power transmitting coil, so as to generate the alternating current to be flowed in the power transmitting coil,

the power receiving unit including;

a power receiving unit-side resonance capacitor that configures a power receiving unit-side resonance circuit along with the power receiving coil; and

a power receiving unit-side rectification circuit connected with the power receiving coil and rectifying an alternating current generated on the power receiving coil,

a magnetic field resonance coupling circuit configured with mutual inductance being equivalently formed between the power transmitting coil and the power receiving coil so that the power transmitting unit-side resonance circuit and the power receiving unit-side resonance circuit resonate with each other to transmit power from the power transmitting unit to the power receiving unit,

energy that is reflected without being transmitted from the power transmitting unit being taken as reactive power and reserved as resonance energy in the power transmitting unit-side resonance circuit, and

of the energy received by the power receiving unit, energy that is reflected without being supplied to output is taken as reactive power and reserved as resonance energy in the power receiving unit-side resonance circuit.

3. A power transmission system comprising:

a power transmitting unit having a power transmitting coil; and

a power receiving unit having a power receiving coil,

the power transmitting unit;

a power transmitting unit-side resonance inductor configuring a power transmitting unit-side resonance circuit along with a power transmitting unit-side resonance capacitor; and

a power transmitting unit-side alternating current generation circuit electrically connected with the power transmitting coil, including a switching circuit configured of a parallel connection circuit in which a switching element, a diode, and a capacitor are connected in parallel, and an inductor having a value of inductance making it possible to form a current source, from an inputted direct-current voltage, taken as a direct current in comparison with an alternating current that is flowed in the power transmitting coil, so as to generate the alternating current to be flowed in the power transmitting coil,

the power receiving unit including;

a power receiving unit-side resonance inductor configuring a power receiving unit-side resonance circuit along with a power receiving unit-side capacitor; and

a power receiving unit-side rectification circuit connected with the power receiving coil and rectifying an alternating current generated on the power receiving coil,

an electric field resonance coupling circuit configured with mutual capacitance being equivalently formed between the power transmitting coil and the power receiving coil so that the power transmitting unit-side resonance circuit and the power receiving unit-side resonance circuit resonate with each other to transmit power from the power transmitting unit to the power receiving unit,

energy that is reflected without being transmitted from the power transmitting unit being taken as reactive power and reserved as resonance energy in the power transmitting unit-side resonance circuit, and

of the energy received by the power receiving unit, energy that is reflected without being supplied to output is taken as reactive power and reserved as resonance energy in the power receiving unit-side resonance circuit.