JP2012039815A - Wireless power supply method and wireless power supply system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resonance type wireless power supply method.SOLUTION: In the wireless power supply method, a power transmission part comprises: a plurality of AC power supplies that output AC currents having different frequencies; means that frequency-multiplexes the AC currents output from the plurality of AC power supplies; a first excitation element that applies the frequency-multiplexed AC currents; and a first resonance element that is coupled to the first excitation element by electromagnetic induction, and a power reception part comprises: a second resonance element that is coupled to the first resonance element by a magnetic field resonance; a second excitation element that is coupled to the second resonance element by the electromagnetic induction; and means that rectifies and outputs the AC current inducted by the second excitation element. The frequency of the AC power supply and a resonance frequency of the second resonance element are set to have a frequency that is equivalent to a frequency in which a transmission efficiency is increased with respect to a frequency characteristic of the first resonance element in the power transmission part. The second resonance elements in the plurality of power reception parts are coupled to the first resonance elements in the power transmission part by the magnetic field resonance. The AC currents that are frequency-multiplexed at the power transmission part are supplied to the reception parts via the second resonance elements with respectively corresponding resonance frequencies.

Description

  The present invention relates to a resonance type wireless power feeding method and a wireless power feeding system.

  As a conventional wireless power feeding method, a method using electromagnetic induction is known, and it has been put to practical use with an electric shaver, an electric toothbrush, or the like as a home appliance (Non-Patent Document 1). However, since the coupling by electromagnetic induction strongly depends on the electromagnetic field strength and the number of magnetic flux linkages, it is necessary to bring the power transmission unit and the power reception unit close to each other and fix their positions so that there is no axis shift. For this reason, the distance between the power transmission unit and the power reception unit is limited, and simultaneous power feeding to a plurality of power reception units is considered difficult.

  Andre Kurs et al. Have proposed a wireless power feeding method in which resonant elements are arranged in a power transmitting unit and a power receiving unit, and the resonant elements are coupled by magnetic field resonance (Non-Patent Document 2). According to this method, high power transmission efficiency can be obtained even at some distance, and there is a feature that there is little influence due to the shaft.

FIG. 6 shows a configuration example of a conventional wireless power feeding system using magnetic field resonance.
In FIG. 6, in the power transmission unit 100, an alternating current output from the alternating current power supply 101 is applied to the excitation coil 102 at a predetermined resonance frequency. The excitation coil 102 is close to the resonance coil 103 and excites the resonance coil 103 by electromagnetic induction. The resonance coil 103 of the power transmission unit 100 is coupled to the resonance coil 201 of the power reception unit 200 by magnetic field resonance, and the electric power that excites the resonance coil 103 also excites the resonance coil 201. Such coupling by magnetic field resonance is characterized in that high coupling efficiency can be obtained by the Q value of the resonance coil, so that high transmission efficiency can be obtained even when the distance between the power transmission unit and the power reception unit is separated compared to electromagnetic induction. .

  The resonance coil 201 is coupled to the excitation coil 202 by electromagnetic induction, and the electric power excited by the resonance coil 201 is applied to the excitation coil 202. The electric power induced by the excitation coil 202 is converted into direct current power by the rectifier circuit 203 and supplied to the power source of the charger and the circuit.

H. Abe, et al. “A noncontact charger using resonant converter with parallel capacitor of the secondary coil,” IEEE Trans. On Industry Applications, Vol.36, No.2, pp.444-451, March 2000. Andre Kurs, et al. “Wireless Power Transfer via Strongly Coupled Magnetic Resonances”, Science, Vol.317, pp.83-85, 2007.

  By the way, in the conventional wireless power feeding method, the power transmitting unit and the power receiving unit transmit power one to one at a single resonance frequency. For this reason, when there are multiple power receiving units, set different resonance frequencies for each power receiving unit, and switch the power receiving units by matching the power transmission frequency of the power transmitting unit with the resonance frequency of each power receiving unit in a time division manner. However, it was common to transmit power. Therefore, it is difficult to select and supply power to a plurality of power receiving units at the same time.

  An object of the present invention is to provide a wireless power transmission method and a wireless power feeding system that can arbitrarily select a plurality of power receiving units and simultaneously feed power.

  According to a first aspect of the present invention, there is provided a wireless power feeding method in which a plurality of alternating current power supplies that output alternating currents having different frequencies to a power transmission unit, a means for frequency-multiplexing alternating currents output from the plurality of alternating current power supplies, A first excitation element for applying a current and a first resonance element coupled to the first excitation element by electromagnetic induction are coupled to each of the plurality of power reception units by magnetic resonance. A second resonance element; a second excitation element coupled to the second resonance element by electromagnetic induction; and means for rectifying and outputting an alternating current induced in the second excitation element. The frequency and the resonance frequency of the second resonance element are set to a frequency equivalent to a frequency at which transmission efficiency is higher than the frequency characteristic of the first resonance element of the power transmission unit, and the second resonance elements of the plurality of power reception units Is the first Bound by the element and the magnetic field resonance, characterized by feeding an alternating current frequency multiplexed to the power receiving portion through the second resonance element of the corresponding resonant frequency, respectively power transmission unit.

  In addition, the second resonance elements of the plurality of power reception units are arranged in series with respect to the first resonance element of the power transmission unit, and resonance coils connected to each other in front and back are coupled by magnetic field resonance to supply power. May be.

  The power receiving unit includes means for adjusting the impedance of the second resonance element, and the second resonance element of the power reception unit has the same frequency resonance frequency as that of the frequency-multiplexed alternating current. The frequency may be selected and received by adjusting the impedance.

  The first resonance element of the power transmission unit and the second resonance element of the plurality of power reception units may be coupled by electric field resonance.

  According to a second aspect of the present invention, a wireless power feeding system includes: a plurality of AC power supplies that output alternating currents having different frequencies to a power transmission unit; a unit that frequency-multiplexes alternating currents output from the plurality of AC power supplies; And a first resonance element coupled to the first excitation element by electromagnetic induction, and each of the plurality of power reception units is coupled to the first resonance element by magnetic field resonance. 2 resonance elements, a second excitation element coupled to the second resonance element by electromagnetic induction, and means for rectifying and outputting an alternating current induced in the second excitation element, the frequency of the AC power supply And the resonance frequency of the second resonance element is set to a frequency equivalent to a frequency at which transmission efficiency is higher than the frequency characteristic of the first resonance element of the power transmission unit, and the second resonance elements of the plurality of power reception units are First of the power transmission unit Bound by the element and the magnetic field resonance ringing, power transmitting portion in a configuration for feeding the frequency multiplexed alternating current to the power receiving portion through the second resonance element of the corresponding resonant frequency, respectively.

  In addition, the second resonance elements of the plurality of power reception units are arranged in series with respect to the first resonance element of the power transmission unit, and resonance coils connected to each other are coupled by magnetic field resonance to supply power. Also good.

  The power receiving unit includes means for adjusting the impedance of the second resonance element, and the second resonance element of the power reception unit has the same frequency resonance frequency as that of the frequency-multiplexed alternating current. It is good also as a structure which adjusts an impedance and receives a frequency selection electric power.

  The first resonance element of the power transmission unit and the second resonance element of the plurality of power reception units may be coupled by electric field resonance.

  In the power transmission unit, the resonance element is configured such that each frequency of the plurality of AC power supplies is set to a resonance frequency different from each other, and each resonance frequency of the plurality of power reception units is any resonance frequency set in the power transmission unit. By adjusting the reactance value, it is possible to supply power to a plurality of power receiving units simultaneously and selectively with frequency.

It is a figure which shows the system configuration example of Example 1 of this invention. It is a figure which shows the power transmission efficiency characteristic in case the receiving part is 3 by the structure of Example 1. FIG. It is a figure which shows the system configuration example of Example 2 of this invention. It is a figure which shows the power transmission efficiency characteristic in case the receiving part is 4 with the structure of Example 2. FIG. It is a figure which shows the structural example of the resonance element using the coupling | bonding by an electric field resonance. It is a figure which shows the structural example of the wireless power feeding system by the conventional magnetic field resonance.

  FIG. 1 shows a system configuration example according to the first embodiment of the present invention. Here, an example is shown in which power is transmitted from a power transmission unit to a plurality of n power reception units in a 1: n ratio.

  In FIG. 1, the power transmission unit 10 includes a plurality of AC power supplies 11 (1) to 11 (n). The frequencies f1 to fn of the AC power supplies are different from each other, and each output is input to the multiplexing device 12 and frequency-multiplexed. The frequencies f1 to fn are set so as to have the same value as the resonance frequency for each power receiving unit described later. The multiplexing device 12 outputs the frequency-multiplexed alternating current to the excitation coil 13. The excitation coil 13 and the resonance coil 14 are coupled by electromagnetic induction, and the electric power induced in the excitation coil 13 excites the resonance coil 14. The resonance coil 14 is coupled to the resonance coils 21 (1) to 21 (n) of the power reception units 20 (1) to 20 (n) by magnetic field resonance, and the power transmission unit 10 and the power reception unit 20 (1) due to its high coupling efficiency. Even though ˜20 (n) is some distance away, power is transmitted with low loss.

  A variable capacitor 15 is loaded on the resonance coil 14 of the power transmission unit 10. The variable capacitors 22 (1) to 22 (n) are loaded on the resonance coils 21 (1) to 21 (n) of the power receiving units 20 (1) to 20 (n), respectively. Arbitrary resonance frequencies are set between the power transmission unit 10 and the power reception units 20 (1) to 20 (n) by adjusting the variable capacitors 15, 22 (1) to 22 (n), respectively. The

  In the resonance coils 21 (1) to 21 (n), power of the resonance frequency set for each of the power receiving units 20 (1) to 20 (n) is excited by magnetic field resonance via the resonance coil 14. Since the resonance coils 21 (1) to 21 (n) are coupled to the excitation coils 23 (1) to 23 (n) by electromagnetic induction, they are excited by the resonance coils 21 (1) to 21 (n). The electric power excites the excitation coils 23 (1) to 23 (n) and inputs them to the rectifier circuits 24 (1) to 24 (n). The rectifier circuits 24 (1) to 24 (n) convert alternating current components into direct current components and supply power to chargers and circuit power supplies.

  Here, FIG. 2 shows power transmission efficiency characteristics in the case of the configuration of the first embodiment and three receiving units. By setting the capacitance and inductance of each of the power receiving units 20 (1) to 20 (n) to be different from each other and adjusting the impedance while keeping the capacitance, inductance and impedance of the power transmitting unit 10 constant, each power receiving unit 20 ( 1) Resonance frequencies for 20 (n) are different values.

  The configuration of this embodiment is characterized in that power is transmitted in a frequency-multiplexed manner by setting a frequency corresponding to a plurality of resonance frequencies to each of the AC power supplies 11 (1) to 11 (n). That is, the maximum number of multiplexing is determined by the frequency characteristics of the resonance coil 14 (and the excitation coil 13) provided in the power transmission unit 10, and is equal to the number of frequency bands with high transmission efficiency. The frequency characteristics can be designed flexibly by combining the resonance coils.

  The effect of setting different resonance frequencies in each of the power receiving units 20 (1) to 20 (n) is that when power is transmitted to only a part of the power receiving units, the AC power supply 11 (1 By controlling the outputs of ˜11 (n), it is possible to realize the flexibility that power can be transmitted only to a desired power receiving unit. Further, by controlling the outputs of the AC power supplies 11 (1) to 11 (n), it is possible to individually control the power transmitted to the power receiving units 20 (1) to 20 (n).

  Thus, in the power transmission unit 10, the frequencies of the AC power supplies 11 (1) to 11 (n) are set to different resonance frequencies, and the resonance frequencies of the power reception units 20 (1) to 20 (n) are set to the power transmission units. By adjusting the reactance values of the resonance coils 14, 21 (1) to 21 (n) so that any one of the resonance frequencies set in the 10 AC power supplies 11 (1) to 11 (n) is obtained, a plurality of It is possible to supply power to the power receiving units 20 (1) to 20 (n) simultaneously and selectively with frequency.

  In the first embodiment, as a method of controlling the resonance frequency, a case where a variable capacitor is connected in parallel to the resonance coil is shown. However, when a variable capacitor is connected in series, or an inductance of the resonance coil is provided by an actuator or the like. There is no particular limitation as long as it is a method of changing the resonance frequency such as changing the resonance frequency.

FIG. 3 shows a system configuration example according to the second embodiment of the present invention.
In FIG. 3, the configuration and operation of the power transmission unit 10 and the plurality of power reception units 20 (1) to 20 (n) are almost the same as those in the first embodiment, and therefore only the differences will be described.

  The power receiving units 20 (1) to 20 (n) are arranged in series with respect to the power transmitting unit 10, and a resonance coil (first resonance coil of the power transmitting unit) and a magnetic field connected to the front and rear are connected. Bind by resonance. As in the case of the first embodiment, by adjusting the power receiving units 20 (1) to 20 (n), a plurality of resonance frequencies as shown in FIG. 4 can be obtained for all the power receiving units. As a result, the power excited by the power transmission unit 10 is transmitted in the order of the power reception units 20 (1), 20 (2),..., 20 (n) while maintaining the same frequency characteristics. Actually, power is transmitted through a resonance coil having the same frequency characteristic.

  In the power transmission unit 10, the frequency of the AC power supplies 11 (1) to 11 (n) is set to the resonance frequency (frequency with high transmission efficiency shown in FIG. 4), and the resonance of each power reception unit 20 (1) to 20 (n). Power is transmitted by adjusting the reactance value of the resonance coil so that the frequencies are the same. On the other hand, the excitation coils of the respective power receiving units 20 (1) to 20 (n) are adjusted so as to have a resonance frequency at which power is extracted by each power receiving unit. Each power receiving unit 20 (1) to 20 (n) is set to self while the power transmitted by the power transmitting unit 10 is relayed by the resonance coil of each power receiving unit 20 (1) to 20 (n). It is possible to extract power corresponding to the resonance frequency.

  In the first embodiment and the second embodiment, the case where the coupling between the resonance coils is magnetically resonated is shown, but the present invention can be applied to a configuration using coupling by electric field resonance.

  For example, as shown in FIG. 5, the power transmission unit and the power reception unit are configured by meander lines 30 and 31 connected to the power transmission port and the power reception port, and variable capacitors 32 and 33 and variable inductances 34 and 35 loaded respectively. Then, electric field resonance is performed on the coupling between the meander lines to improve power transmission efficiency. Also in this electric field coupling type power supply configuration, the resonance frequency can be adjusted by the variable capacitors 32 and 33 and the variable inductances 34 and 35.

DESCRIPTION OF SYMBOLS 10 Power transmission part 11 AC power supply 12 Multiplexer 13 Excitation coil 14 Resonance coil 15 Variable capacity 20 Power receiving part 21 Resonance coil 22 Variable capacity 23 Excitation coil 24 Rectifier circuit 30, 31 Meander line 32, 33 Variable capacity 34, 35 Variable inductance

Claims (8)

A plurality of AC power supplies that output alternating currents having different frequencies to the power transmission unit, a means for frequency-multiplexing the AC currents output from the plurality of AC power supplies, and a first excitation that applies the frequency-multiplexed AC currents An element, and a first resonance element coupled to the first excitation element by electromagnetic induction,
A second resonance element coupled to each of the plurality of power reception units by magnetic field resonance; a second excitation element coupled to the second resonance element by electromagnetic induction; and Means for rectifying and outputting an alternating current induced in the excitation element,
The frequency of the AC power supply and the resonance frequency of the second resonance element are set to a frequency equivalent to a frequency at which transmission efficiency is higher than a frequency characteristic of the first resonance element of the power transmission unit, The second resonance element of the power receiving unit is coupled to the first resonance element of the power transmission unit by magnetic field resonance, and the second resonance element having a resonance frequency corresponding to each of the alternating currents frequency-multiplexed by the power transmission unit is provided. A wireless power feeding method, wherein power is fed to the power receiving unit. The wireless power feeding method according to claim 1,
The second resonance elements of the plurality of power reception units are arranged in series with respect to the first resonance element of the power transmission unit, and resonance coils connected to each other are coupled to each other by magnetic field resonance to supply power. A wireless power feeding method characterized by the above. The wireless power feeding method according to claim 1 or 2,
The power reception unit includes means for adjusting the impedance of the second resonance element,
The wireless power feeding method, wherein the frequency selective power reception is performed by adjusting an impedance of the second resonance element of the power receiving unit so that an arbitrary frequency of the frequency-multiplexed alternating current and a magnetic field resonance frequency are the same. . The wireless power feeding method according to any one of claims 1 to 3,
The wireless power feeding method, wherein the first resonance element of the power transmission unit and the second resonance element of the plurality of power reception units are coupled by electric field resonance. A plurality of AC power supplies that output alternating currents having different frequencies to the power transmission unit, a means for frequency-multiplexing the AC currents output from the plurality of AC power supplies, and a first excitation that applies the frequency-multiplexed AC currents An element, and a first resonance element coupled to the first excitation element by electromagnetic induction,
A second resonance element coupled to each of the plurality of power reception units by magnetic field resonance; a second excitation element coupled to the second resonance element by electromagnetic induction; and Means for rectifying and outputting an alternating current induced in the excitation element,
The frequency of the AC power supply and the resonance frequency of the second resonance element are set to a frequency equivalent to a frequency at which transmission efficiency is higher than a frequency characteristic of the first resonance element of the power transmission unit, The second resonance element of the power receiving unit is coupled to the first resonance element of the power transmission unit by magnetic field resonance, and the second resonance element having a resonance frequency corresponding to each of the alternating currents frequency-multiplexed by the power transmission unit is provided. The wireless power feeding system is configured to feed power to the power receiving unit via the power receiving unit. The wireless power supply system according to claim 5, wherein
The second resonance elements of the plurality of power reception units are arranged in series with respect to the first resonance element of the power transmission unit, and resonance coils connected to each other are coupled to each other by magnetic field resonance to supply power. A wireless power supply system characterized by having a configuration. The wireless power supply system according to claim 5 or 6,
The power reception unit includes means for adjusting the impedance of the second resonance element,
The frequency selective power reception is performed by adjusting the impedance of the second resonance element of the power reception unit so that an arbitrary frequency of the frequency-multiplexed alternating current and the magnetic field resonance frequency are the same. Wireless power supply system. The wireless power feeding system according to any one of claims 5 to 7,
The wireless power feeding system, wherein the first resonance element of the power transmission unit and the second resonance element of the plurality of power reception units are coupled by electric field resonance.

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