Electric power transmission device and electric power transmission method

• US 20060239043A1
• Filed: 04/22/2005
• Published: 10/26/2006
• Est. Priority Date: 04/22/2005
• Status: Active Grant

• Current Assignee: Yonezawa Electric Wire Company Limited (Fujikura Limited), Konomu Takaishi
• Original Assignee: Konomu Takaishi
• Inventors: Ohbo, Noboru
• Granted Patent: US 7,310,245 B2
• Time in Patent Office: Days
• US Class Current: 363/25
• CPC Class Codes: H02M 1/0058 by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current flow is zero using an auxiliary actively switched resonant commutation circuit connected to an intermediate DC voltage or between two push-pull branches of an inverter bridge H02M7/4811; in resonant inverters H02M7/4815; in inverters operating from a resonant DC source H02M7/4826
• CPC Class Codes: H02M 3/3376 with automatic control of output voltage or current
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

In an electric power transmission device in which a primary side power transmission coil (L1) and a secondary side power receiving coil (L2) are magnetically coupled, and electric power is transmitted from the primary side power transmission coil (L1) to the secondary side power receiving coil (L2) via a non-contact and out of touch, a capacitor (C1) is connected to the primary side power transmission coil (L1) in series, a voltage to be supplied to the primary side power transmission coil (L1) is converted into AC voltage and stepped up, and a series resonance circuit (7) including a mutual inductance (M) by the secondary side power receiving coil (L2) is formed; wherein a resonance point of the series resonance circuit (7) including the mutual inductance (M) by the secondary side power receiving coil (L2) is set to a frequency higher than a resonance point of a primary side series resonance circuit (6) which is composed of the primary side power transmission coil (L1) and the capacitor (C1), whereby a high electric power transmission efficiency of practical level can be obtained and thus reduction in size and weight and electric power saving can be easily realized with the high electric power transmission efficiency.

Claims

1. An electric power transmission device for magnetically coupling a primary side power transmission coil to a secondary side power receiving coil and for transmitting electric power from said primary side power transmission coil to said secondary side power receiving coil via a non-contact and out of touch, said electric power transmission device comprising:

a capacitor connected in series to said primary side power transmission coil, for converting a voltage which is to be supplied to said primary side power transmission coil into an AC voltage and being stepped up, and for configuring a series resonance circuit which includes a mutual inductance by said secondary side power receiving coil,

wherein a resonance point of said series resonance circuit which includes said mutual inductance by said secondary side power receiving coil is set to a frequency higher than a resonance point of a primary side series resonance circuit which is composed of said primary side power transmission coil and said capacitor.

2. The electric power transmission device according to claim 1, wherein said capacitor is arranged on said primary side power transmission coil in series, the number of said capacitor being one.

3. The electric power transmission device according to claim 2, wherein said capacitor is arranged on said primary side power transmission coil in series, the number of said capacitor being two that sandwiches said primary side power transmission coil therebetween.

4. The electric power transmission device according to claim 1, wherein said primary side power transmission coil and said secondary side power receiving coil are formed by a planate air-core coil.

5. The electric power transmission device according to claim 1, wherein said primary side power transmission coil and said secondary side power receiving coil are formed by a planate air-core coil which is configured by a spirally wound litz wire with the number of winds of 10 or more and 50 or less on a plane surface.

6. The electric power transmission device according to claim 1, further comprising:

phase detection means for detecting a phase of a voltage of said primary side power transmission coil; and

control means for outputting a control signal to control the amount of electric power that is supplied to said primary side power transmission coil based on an output of said phase detection means,

wherein said control means determines as no load when delaying in phase of a voltage of said primary side power transmission coil compared to a voltage to be supplied to said primary side power transmission coil, and determines as a foreign material load when advancing, at this time a first control signal for intermittently supplying electric power to said primary side power transmission coil at predetermined intervals during predetermined time only is outputted; and

determines as a normal load when being in the same phase, and a second control signal for continuously supplying electric power to said primary side power transmission coil is outputted.

7. The electric power transmission device according to claim 6, further comprising:

amplitude detection means for detecting amplitude as well as said phase detection means for detecting a phase of a voltage of said primary side power transmission coil,

wherein said control means determines as a foreign material load when a phase of a voltage of said primary side power transmission coil advances compared to a voltage to be supplied to said primary side power transmission coil and said amplitude is more than a predetermined reference value.

8. The electric power transmission device according to claim 7, wherein said phase detection means and said amplitude detection means input a voltage of said primary side power transmission coil from said primary side power transmission coil side of said capacitor.

9. The electric power transmission device according to claim 7, wherein said phase detection means and said amplitude detection means input a voltage of said primary side power transmission coil from an opposite side to said primary side power transmission coil of said capacitor via another capacitor.

10. The electric power transmission device according to claim 7, further comprising:

secondary side ID output means for being connected to said secondary side power receiving coil and for varying a load with respect to electric power based on a predetermined specific secondary side ID signal,

wherein information transmission is performed to a primary side power receiving coil from said secondary side power receiving coil by load modulation, and

said control means confirms a normal load based on information transmitted to said primary side power receiving coil.

11. The electric power transmission device according to claim 1, further comprising:

rectification means for rectifying an output voltage of said secondary side power receiving coil; and

smoothing means for smoothing a rectification output from said rectification means.

12. An electric power transmission method for magnetically coupling a primary side power transmission coil to a secondary side power receiving coil and for transmitting electric power from said primary side power transmission coil to said secondary side power receiving coil via a non-contact and out of touch,

wherein a capacitor is connected to said primary side power transmission coil in series, the number of said capacitor being one or two that sandwiches said primary side power transmission coil therebetween, a voltage which is to be supplied to said primary side power transmission coil is converted into a AC voltage and stepped up, and a series resonance circuit which includes a mutual inductance by said secondary side power receiving coil is formed,

said series resonance circuit which includes said mutual inductance by said secondary side power receiving coil is resonated by said primary side power transmission coil, said secondary side power receiving coil, and said capacitor at a frequency higher than a resonance frequency of a primary side series resonance circuit which is composed of said primary side power transmission coil and said capacitor, and

electric power is transmitted from said primary side power transmission coil to said secondary side power receiving coil.