JP5487944B2 - Non-contact power feeding device - Google Patents

Description

  The present invention relates to a contactless power feeding device using a resonance method.

  As a non-contact (wireless) power transmission technique, a technique of transmitting power using resonance of an electromagnetic field is known (Non-Patent Document 1).

Karalis A. et al (Wireless Power Transfer via Strongly Coupled Magnetic Resonances) Science, vol. 317, no. 5834, pp. 83-86, 2007.

  However, the non-contact power feeding apparatus using the resonance method has a problem in that power transmission efficiency decreases when the distance between the power transmission resonance means and the power reception resonance means (hereinafter referred to as power transmission distance) becomes long.

  The problem to be solved by the present invention is to provide a non-contact power feeding device that can maintain power transmission efficiency even when the power transmission distance becomes long.

The present invention provides a relay resonance between a power transmission resonance unit and a power reception resonance unit at a power feeding position and set in a tire of a vehicle wheel at the same resonance frequency as the power transmission resonance unit and the power reception resonance unit. By providing means, the above-mentioned problem is solved.

  According to the present invention, power is supplied from the power transmission resonance means to the relay resonance means by magnetic coupling between the power transmission resonance means and the relay resonance means, and the magnetic resonance between the relay resonance means and the power reception resonance means is achieved. Power is supplied from the relay resonance means to the power reception resonance means by the coupling. Thereby, power transmission efficiency can be maintained even if the power transmission distance is increased.

1 is an overall configuration diagram showing a power feeding system to an electric vehicle to which an embodiment of the present invention is applied. 3 is a graph showing a relationship of coupling degree κ with respect to transmission distance Z. It is a graph which shows the relationship of the coupling | bonding degree (kappa) with respect to the shift | offset | difference X on an XY plane. It is the top view and front view which show the state which the power transmission coil 1 and the receiving coil 2 of FIG. 1 shifted | deviated within the XY plane. It is a graph which shows the relationship of the power transmission efficiency with respect to the power transmission distance Z or the gap | deviation X. It is a block diagram which shows the example of arrangement | positioning of the power transmission coil 1, the receiving coil 2, and the relay coil 3 which are shown in FIG. 4 is a graph showing a relationship between an angle θ formed by a coil central axis of the relay coil 3 and a coil central axis of the power transmission coil 1 and power transmission efficiency. It is sectional drawing of the tire which shows the example of arrangement | positioning of the relay coil of FIG. FIG. 6 is a front view illustrating another arrangement example of the power transmission coil 1, the power reception coil 2, and the relay coil 3. It is a front view which shows the further example of arrangement | positioning of the power transmission coil 1, the receiving coil 2, and the relay coil 3. FIG. It is a front view which shows the further example of arrangement | positioning of the power transmission coil 1, the receiving coil 2, and the relay coil 3. FIG. It is a front view which shows the further example of arrangement | positioning of the power transmission coil 1, the receiving coil 2, and the relay coil 3. FIG.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an overall configuration diagram showing a power supply system to an electric vehicle to which an embodiment of the present invention is applied, and is an example embodied in a power supply system for supplying electric power to a drive motor M of an electric vehicle V. is there.

  The power supply device 10 of this example includes a high-frequency AC power source 6, a primary coil 4, a power transmission coil 1, a power reception coil 2, a secondary coil 5, a rectifier 7, and a power storage device 8. Of the power feeding device 10, the power receiving coil 2, the secondary coil 5, the rectifier 7, and the power storage device 8 are provided in the electric vehicle V, and the high-frequency AC power source 6, the primary coil 4, and the power transmission coil 1 are provided. It is provided outside the vehicle (hereinafter also referred to as a power feeding place).

  A drive motor M is connected to the drive system (power train) of the electric vehicle V, and the drive motor M receives electric power from the power storage device 8 to generate a vehicle drive force. The generated drive force is The electric vehicle V travels by outputting to the wheels via the drive system. Although not shown, when an AC motor is used as the drive motor M, a power converter such as an inverter is provided between the power storage device 8 and the drive motor M.

  The power receiving coil (secondary self-resonant coil) 2 provided on the electric vehicle V side is composed of an LC resonant coil whose both ends are open (not connected), and is connected to the power transmitting coil (primary self-resonant coil) 1 of the power feeding device 10 and the magnetic field. It is magnetically coupled by resonance and is configured to receive power from the power transmission coil 1. That is, the power receiving coil 2 is based on various conditions such as the voltage of the power storage device 8, the power transmission distance between the power transmitting coil 1 and the power receiving coil 2, and the resonance frequency between the power transmitting coil 1 and the power receiving coil 2. The number of turns, the thickness, and the winding pitch of the coil are appropriately set so that the Q value indicating the resonance intensity with the power receiving coil 2 and the κ value indicating the degree of coupling thereof are increased. Let the resonance frequency of the power receiving coil 2 be f2.

  The secondary coil 5 is a one-turn coil connected at both ends, and is configured to be able to receive power from the power receiving coil 2 by electromagnetic induction, and is preferably provided coaxially with the power receiving coil 2. The secondary coil 5 is provided so as not to change the self-resonant frequency f2 of the power receiving coil 2. Then, the secondary coil 5 outputs the power received from the power receiving coil 5 to the rectifier 7.

  Rectifier 7 rectifies high-frequency AC power received from secondary coil 5 and outputs the rectified power to power storage device 8. Instead of the rectifier 7, an AC / DC converter that converts high-frequency AC power received from the secondary coil 5 into the voltage level of the power storage device 8 may be used.

  The power storage device 8 is a DC power source that can be charged and discharged, and is composed of, for example, a secondary battery such as lithium ion or nickel metal hydride. The voltage of power storage device 8 is, for example, about 200 to 500V. In addition to storing the electric power supplied from the rectifier 7, the power storage device 8 can also store the regenerative power generated by the driving motor M. The power storage device 8 supplies the stored electric power to the drive motor M. As the power storage device 8, a large capacity capacitor can be employed instead of or in combination with the secondary battery, and the electric power from the rectifier 7 and the driving motor M is temporarily stored and stored. Any power buffer that can supply power to the drive motor M may be used.

  On the other hand, the high-frequency AC power supply 6 provided at a power feeding place outside the vehicle includes, for example, a system power supply 6a (commercial infrastructure AC power supply owned by an electric power company) and a power converter 6b. The power converter 6b converts the power received from the AC power supply 6a into a high frequency power that can be transmitted from the power transmission coil 1 to the power reception coil 2 on the vehicle side by resonating the magnetic field, and the converted high frequency power is supplied to the primary coil 4. Supply.

  The primary coil 4 is configured to be able to transmit power to the power transmission coil 1 by electromagnetic induction, and is preferably arranged coaxially with the power transmission coil 1. The primary coil 4 is provided so as not to change the self-resonant frequency f1 of the power transmission coil 1. And the primary coil 4 outputs the electric power received from the power converter 6b to the power transmission coil 1.

  The power transmission coil 1 is disposed, for example, in the vicinity of the ground of a power feeding place. The power transmission coil 1 is composed of an LC resonance coil that is open (not connected) at both ends, and is magnetically coupled to the power reception coil 2 of the electric vehicle V by magnetic field resonance so that power can be transmitted to the power reception coil 2. ing. That is, the power transmission coil 1 is a voltage of the power storage device 8 that is charged by power transmitted from the power transmission coil 1, a power transmission distance between the power transmission coil 1 and the power reception coil 2, and a resonance frequency between the power transmission coil 1 and the power reception coil 2. Based on various conditions such as the above, the number of turns, the thickness, and the winding pitch of the coil are appropriately set so that the Q value and the coupling degree κ value are increased.

  The resonance frequency f1 of the power transmission coil 1 is set to a value equal to the resonance frequency f2 of the power reception coil 2 described above (f1 = f2). However, the power transmission coil 1 and the power reception coil 2 may have the resonance frequencies f1 and f2 set equal, and the coil shape and size such as the number of turns, thickness, and winding pitch of the coils need not be the same. Further, since the resonance frequencies f1 and f2 may be set equal, a capacitor may be externally attached to the power transmission coil 1 and / or the power reception coil 2.

  The principle of power transmission by the resonance method will be described. In the resonance method, two LC resonance coils having the same natural frequency resonate via a magnetic field, in the same manner as two tuning forks resonate. Power is transmitted wirelessly to the coil.

  That is, when high-frequency AC power is input to the primary coil 4 by the high-frequency AC power source 6, a magnetic field is generated in the primary coil 4, and high-frequency AC power is generated in the power transmission coil 1 by electromagnetic induction. The power transmission coil 1 functions as an LC resonator based on the inductance of the coil itself and the stray capacitance between the conductors, and is magnetically coupled to the power reception coil 2 having the same resonance frequency as that of the power transmission coil 1 by magnetic field resonance. Electric power is transmitted to the coil 2. Then, high-frequency AC power due to electromagnetic induction is generated in the secondary coil 5 by the magnetic field generated in the power receiving coil 2 by receiving power from the power transmitting coil 1, and the DC power is supplied to the power storage device 8 after being rectified to DC power by the rectifier 7. Is done.

  Now, in the power transmission system based on the resonance method, it is known that the degree of coupling κ varies depending on the positional relationship between the power transmission coil 1 and the power reception coil 2, thereby varying the power transmission efficiency. FIG. 2A is a graph showing the relationship of the degree of coupling κ with respect to the transmission distance Z between the power transmission coil 1 and the power reception coil 2, and FIG. It is a graph which shows the relationship of (kappa). 2A is defined as a linear distance between the tip of the power transmission coil 1 and the tip of the power receiving coil 2 in the Z-axis direction. 2B is defined as the distance on the XY plane between the coil central axis of the power transmission coil 1 and the coil central axis of the power receiving coil 2 as shown in FIG. 2C.

  As shown in FIG. 2A, the coupling degree κ between the power transmission coil 1 and the power receiving coil 2 gradually decreases as the power transmission distance Z increases, and the coupling between the power transmission coil 1 and the power receiving coil 2 when the deviation X increases as shown in FIG. 2B. The degree κ gradually decreases. As a result, as shown by a dotted line in FIG. 3D, the transmission efficiency of the power transmitted from the power transmission coil 1 to the power reception coil 2 decreases as the power transmission distance Z or the deviation X increases.

  Although there is no particular limitation, considering the case where the electric vehicle V is parked at the power supply location and the power storage device 8 is charged, the transmission distance Z differs depending on the layout of the power receiving coil 2 installed on the vehicle side and the height of the electric vehicle V. There are things to do. For example, it is desirable that the power receiving coil 2 be disposed as low as possible in the vehicle, such as the floor portion of the vehicle. However, depending on the layout of the electric vehicle V, the power receiving coil 2 may be located away from the road surface such as in a trunk room or an engine room. There may also be circumstances that must be arranged. Due to these circumstances, the power transmission distance Z at the power feeding location may become long.

  In addition, the displacement X between the power transmission coil 1 and the power reception coil 2 may not be accurately parked at the power feeding location due to the driver's driving skill, etc., which may cause the displacement X to be long even if the power transmission distance Z is short. is there. When the power transmission distance Z or the deviation X is increased, the power supply efficiency is lowered, so that the charging time at the power supply place is increased. And in order to shorten charging time, it is necessary to raise the electric power of the high frequency alternating current power supply 6. FIG.

  The power feeding apparatus 10 of this example includes the relay coil 3 in order to maintain the charging time without increasing the power of the high-frequency AC power source 6 even if the power transmission distance Z or the deviation X is somewhat increased. The relay coil 3 may be provided on either the vehicle side or the vehicle exterior side (the ground surface, road surface, wall surface, etc.), but in the example shown in FIG. 1, the relay coil 3 is built in each of the front wheels and the rear wheels. An arrangement example of the relay coil 3 of this example is shown in FIG.

  FIG. 3 is a front view illustrating an arrangement example of the relay coil 3 when the coil central axis of the power transmission coil 1 in FIG. 1 and the coil central axis of the power receiving coil 2 coincide with each other. The relay coil 3 is composed of an LC resonance coil whose both ends are open (not connected) like the power transmission coil 1 and the power reception coil 2, and the resonance frequency f3 is the resonance frequency f1 of the power transmission coil 1 and the resonance frequency of the power reception coil 2. It is set to a value equal to f2 (f3 = f1 = f2). However, the relay coil 3 has only to set the resonance frequencies f1, f2, and f3 equal in relation to the power transmission coil 1 and the power reception coil 2, and has the same coil shape and size such as the number of turns, thickness, and winding pitch of the coil. There is no need to make it. Alternatively, since the resonance frequencies f1, f2, and f3 may be set to be equal, a capacitor may be externally attached to the power transmission coil 1, the power reception coil 2, and / or the relay coil 3. Further, it is not necessary to provide the relay coil 3 with the primary coil 4 and the secondary coil 5 for transmitting and receiving electric power by electromagnetic induction.

  As shown in FIG. 3, when the distance between the tip of the power transmission coil 1 and the tip of the power reception coil 2 is Z (corresponding to the power transmission distance Z described above), the relay coil 3 of this example is the tip of the power transmission coil 1. And within a radius Z and preferably within a radius Z from the tip of the power receiving coil 2. In this case, it is desirable that at least the tip of the relay coil 3 is disposed within the range. In addition, it is desirable to set the arrangement direction of the relay coil 3 so that the angle θ formed by the coil central axis of the relay coil 3 and the coil central axis of the power transmission coil 1 is an angle other than 90 degrees. The angle θ is more preferably close to 0 degrees.

  FIG. 4 is a graph showing the result of confirming the relationship between the angle θ formed by the coil central axis of the relay coil 3 and the coil central axis of the power transmission coil 1 and the power transmission efficiency. In the same figure, the power transmission efficiency is shown for each of the resonance frequencies fn1 to fn4 of the relay coil 3 and the power transmission coil 1, but the coil central axis of the relay coil 3 and the coil central axis of the power transmission coil 1 are formed regardless of the resonance frequency. It has been confirmed that the power transmission efficiency is lower when the angle θ is close to 90 degrees than when the angle θ is close to 0 degrees. It can also be understood that the higher the resonance frequency is set like fn1 and fn2 in the figure, the higher the transmission efficiency can be maintained by simply setting the angle θ to an angle other than 90 degrees.

  Returning to FIGS. 1 and 3, the solid line arrows in FIG. 1 indicate the effective magnetic flux that is transmitted to the power receiving coil 2 by the magnetic flux generated in the power transmission coil 1, and the dotted arrow indicates that the magnetic flux generated in the power transmission coil is not transmitted to the power receiving coil 2. The leakage magnetic flux which leaks is shown. When the power transmission distance Z between the power transmission coil 1 and the power reception coil 2 is increased, it is assumed that the effective magnetic flux decreases and the leakage magnetic flux increases, resulting in a decrease in power transmission efficiency. However, when the relay coil 3 is arranged between the power transmission coil 1 and the power reception coil 2 as in this example, the relay coil 3 mainly receives the leakage magnetic flux out of the magnetic flux generated in the power transmission coil 1, and this is shown in FIG. It is added to the power receiving coil 2 as indicated by the arrow of the one-dot chain line. Thereby, as shown by the solid line in FIG. 2D, when the transmission distance Z is the same, the transmission efficiency is improved, and even if the transmission distance Z is increased, a decrease in the transmission efficiency can be suppressed. In other words, the transmission distance can be increased if the transmission efficiency is the same.

  In addition, the relay coil 3 shown in FIG. 1 is schematically shown, and in fact, as shown in FIG. 5, it is inclined so that the central axis of the coil does not become horizontal in the hollow portions of the front tire and the rear tire T. Is provided. Further, the relay coil 3 does not have to be provided on all of the front tires and the rear tires T, and may be provided on any one of the tires T. Furthermore, the installation location of the relay coil 3 is not limited to the hollow portion of the tire T, and may be in the range between the power transmission coil 1 and the power reception coil 2 described in FIG. Therefore, depending on the case, it can also arrange | position on the road surface side instead of the vehicle side.

  As described with reference to FIG. 4, the power transmission efficiency increases as the angle θ between the coil central axis of the relay coil 3 and the coil central axis of the power transmission coil approaches 0 degrees. Therefore, it is desirable to arrange the coil central axes to coincide or be parallel between the power transmission coil 1 and the power reception coil 2. 6A to 6C show other arrangement examples of the power transmission coil 1, the power reception coil 2, and the relay coil 3. FIG.

  FIG. 6A is an example in which the coil central axis of the power transmission coil 1, the coil central axis of the power receiving coil 2, and the coil central axis of the relay coil 3 are aligned with each other. 6B is an example in which the coil central axis of the power transmission coil 1, the coil central axis of the power receiving coil 2, and the coil central axis of the relay coil 3 are arranged in parallel. In either case, the relay coil 3 receives the effective magnetic flux of the magnetic flux generated in the power transmission coil 1 and passes it to the power receiving coil 2, and the leakage magnetic flux of the magnetic flux generated in the power transmission coil 1 is relayed to the relay coil 3. Is added to the power receiving coil 2. Therefore, as shown in FIGS. 1 and 3, the power transmission efficiency can be further maintained higher than the case where the relay coil 3 is disposed at an inclination.

  FIG. 6C is an example in which a plurality of relay coils 3 are arranged by combining the example shown in FIG. 3 and the example shown in FIG. 6A or 6B. According to this example, the relay coils 3a and 3a receive mainly the leakage magnetic flux of the magnetic flux generated in the power transmission coil 1, and add it to the relay coil 3b (or the power reception coil 2). At the same time, the relay coil 3 b receives the effective magnetic flux of the magnetic flux generated in the power transmission coil 1, and passes this and the added magnetic flux from the relay coils 3 a and 3 a to the power receiving coil 2. Therefore, even if the power transmission distance Z between the power transmission coil 1 and the power reception coil 2 is set to be long, a decrease in power transmission efficiency can be suppressed by appropriately arranging these relay coils 3a and 3b according to the layout.

  As described with reference to FIG. 4, when the coil center axis of the LC resonance coil is orthogonal, the power transmission efficiency is extremely reduced. That is, the effective magnetic flux generated in the power transmission coil 1 is hardly transmitted to the power receiving coil 2 and only the leakage magnetic flux is transmitted. If the transmission distance is long, the leakage flux may not be transmitted. Therefore, it is desirable that the coil central axes of the power transmission coil 1 and the power reception coil 2 are parallel or close to each other. However, the coil central axes of the power transmission coil 1 and the power reception coil 2 may have to be orthogonal depending on the layout of the vehicle side and the power feeding location. FIG. 6D shows an arrangement example using the relay coil 3 of this example in such a case.

  As shown in FIG. 6D, the coil central axis of the power transmission coil 1 and the coil central axis of the power receiving coil 2 are set to be orthogonal or close to each other. The relay coil 3 in this example is disposed between the power transmission coil 1 and the power reception coil 2, and is set at an inclination angle such that the coil central axis of the relay coil 3 is not orthogonal to the coil central axis of the power transmission coil 1. According to this example, the relay coil 3 receives the effective magnetic flux of the magnetic flux generated in the power transmission coil 1 and transfers it to the power receiving coil 2. At the same time, the leakage magnetic flux of the magnetic flux generated in the power transmission coil 1 is also relayed. The coil 3 receives it and adds it to the power receiving coil 2. Therefore, even when the coil central axes of the power transmission coil 1 and the power receiving coil 2 are set to be orthogonal or close to each other, power transmission can be performed or reduction in power transmission efficiency can be suppressed. it can.

  As described above, in the power supply device 10 of this example, the power from the AC power source 6 a is converted into the high frequency power by the power converter 6 b and is supplied to the power transmission coil 1 by the primary coil 4. The power transmission coil 1 and the power receiving coil 2 of the electric vehicle V are magnetically coupled by magnetic field resonance, and power is transmitted from the power transmitting coil 1 to the power receiving coil 2. At the same time, the power generated in the power transmission coil 1 by the relay coil 3 or the leakage power thereof can be delivered to or added to the power receiving coil 2. The electric power received by the power receiving coil 2 is rectified by the rectifier 7 and stored in the power storage device 8 of the electric vehicle V.

  Therefore, according to the power supply device 10 of this example, charging power can be transmitted wirelessly from the AC power supply 6a outside the vehicle to the electric vehicle V, and the power storage device 8 mounted on the vehicle can be charged. And even if the power transmission distance Z or gap | deviation X of the power transmission coil 1 and the receiving coil 2 becomes large, the fall of power transmission efficiency can be suppressed by the effect | action of the relay coil 3. FIG. In other words, the transmission distance can be set longer by providing the relay coil 3. Moreover, even if the parking position of the electric vehicle V is slightly shifted at the power feeding place, the displacement X on the XY plane fluctuates, or even if the power transmission distance Z varies depending on the vehicle specifications, the power transmission efficiency is maintained. As a result, the charging time can be shortened or maintained.

  The power transmission coil corresponds to power transmission resonance means according to the present invention, the power reception coil corresponds to power reception resonance means according to the present invention, the high-frequency AC power supply corresponds to the power supply according to the present invention, and the power feeding place is The power transmission distance Z corresponds to the predetermined distance according to the present invention, the relay coil corresponds to the relay resonance means according to the present invention, and the electric vehicle corresponds to the vehicle according to the present invention. The rectifier corresponds to the rectifying means according to the present invention, and the power storage device corresponds to the power storage means according to the present invention.

DESCRIPTION OF SYMBOLS 10 ... Feeding device 1 ... Power transmission coil 2 ... Power receiving coil 3, 3a, 3b ... Relay coil 4 ... Primary coil 5 ... Secondary coil 6 ... High frequency alternating current power supply 6a ... AC power supply 6b ... Power converter 7 ... Rectifier 8 ... Power storage device V ... Electric vehicle M ... Electric motor for driving

Claims (5)

Non-electric power is received from the power source by magnetic coupling due to magnetic field resonance with a power transmission resonance unit that is installed outside the vehicle and receives power from an AC power source and set to a predetermined resonance frequency. A contact power feeder,
The vehicle is provided with power receiving resonance means set to the same resonance frequency as the predetermined resonance frequency,
From the power supply by the magnetic coupling due to the resonance of the magnetic field between the power transmission resonance means and the power reception resonance means at the power feeding position where the power reception resonance means is located at a predetermined distance from the power transmission resonance means. In the non-contact power feeding device that supplies power to the power receiving resonance means via the power transmission resonance means,
In the power feeding position, within the predetermined distance from the power transmission resonance means and within the predetermined distance from the power reception resonance means, the same resonance as the predetermined resonance frequency is provided in the tire of the vehicle wheel. A non-contact power feeding apparatus comprising a relay resonance unit set to a frequency. The contactless power supply device according to claim 1 ,
Rectifying means for rectifying the power received by the power receiving resonance means;
The non-contact power feeding apparatus further comprising: a power storage unit that stores the power rectified by the rectification unit. In the non-contact electric power feeder of Claim 1 or 2 ,
A non-contact power feeding apparatus comprising a plurality of relay resonance means. In the non-contact electric power feeder as described in any one of Claims 1-3 ,
The power transmission resonance means includes a power transmission coil set to the predetermined resonance frequency, and a primary coil that supplies power from the power source by electromagnetic induction to the power transmission coil,
The power receiving resonance means includes a power receiving coil set to the predetermined resonance frequency, and a secondary coil that receives power from the power source by electromagnetic induction with respect to the power receiving coil,
The contactless power feeding device, wherein the relay resonance means includes a relay coil set to the predetermined resonance frequency. In the non-contact electric power feeder of Claim 4 ,
The non-contact power feeding device, wherein the relay coil is arranged such that an angle formed between a coil central axis of the power transmission coil and a coil central axis of the relay coil is an angle other than 90 degrees.

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