JP2013013274A - Power supply system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply system capable of suppressing deterioration of transmission efficiency due to displacement between a power supply side coil and a power incoming side coil, and supplying power from a power supply part to a power incoming part with high efficiency.SOLUTION: Variable inductance L1 which varies impedance of a power supply part 3 is connected in parallel to a power supply side helical coil 33. A CPU 9 detects displacement d between central axes of the power supply side helical coil 33 and power incoming side helical coil 51 by using a position sensor 10, adjusts the variable inductance L1 according to the displacement d, and adjusts the impedance of the power supply part 3.

Description

  The present invention relates to a power feeding system, and more particularly to a power feeding system that supplies power from a power feeding side coil to a power receiving side coil in a contactless manner.

  As the power feeding system described above, for example, the one shown in FIG. 5 is known (for example, Non-Patent Documents 1 and 2). As shown in the figure, the power feeding system 1 includes a power feeding unit 3 as a power feeding unit and a power receiving unit 5 as a power receiving unit. The power feeding unit 3 is arranged to be separated from the power feeding side loop antenna 32 to which power is supplied so as to face the power feeding side loop antenna 32 in the central axis direction, and is electromagnetically coupled to the power feeding side loop antenna 32. And a power supply side helical coil 33 as a power supply side coil. When power is supplied to the power supply side loop antenna 32, the power is sent to the power supply side helical coil 33 by electromagnetic induction.

  The power receiving unit 5 includes a power receiving side helical coil 51 serving as a power receiving side coil that electromagnetically resonates when the power receiving unit 5 is disposed so as to face the power feeding side helical coil 33 in the direction of the central axis thereof, and the power receiving side helical coil. And a power receiving side loop antenna 52 that is disposed so as to be opposed to the power receiving side helical coil 51 and is electromagnetically coupled to the power receiving side helical coil 51. When electric power is sent to the power supply side helical coil 33, the electric power is wirelessly sent to the power reception side helical coil 51 by magnetic field resonance.

  Further, when power is sent to the power receiving side helical coil 51, the power is sent to the power receiving side loop antenna 52 by electromagnetic induction and supplied to a load such as a battery connected to the power receiving side loop antenna 52. According to the power supply system 1 described above, electric power can be supplied from the power supply side to the power reception side in a non-contact manner by electromagnetic resonance between the power supply side helical coil 33 and the power reception side helical coil 51.

  Then, by providing the power receiving unit 5 described above in the automobile 4 and providing the power supply unit 3 in the road 2 or the like, it is possible to supply power to the battery mounted on the vehicle 4 wirelessly using the power supply system 1 described above. It is considered. In the power supply system 1 described above, it is difficult to stop the automobile 4 so that the central axis Z1 of the power supply side helical coil 33 and the central axis Z2 of the power reception side helical coil 51 are coaxial. As shown in FIG. 4, there may be a positional deviation d between the central axes Z1 and Z2.

In the power feeding system 1 shown in FIG. 5 described above, the present inventors have a positional deviation d = 0.375D (D = diameter of the power-receiving-side helical coil 51) when the positional deviation d = 0 of the central axes Z1, Z2. In each case, the transmission efficiency S21 ² of the power receiving side loop antenna 52 near the frequency f0 was simulated. A result is shown by the chain line of FIG.

As shown in the figure, the transmission efficiency S21 ² at the frequency f0 is about 97% when the positional deviation d is 0, but decreases to about 87% when the positional deviation d is 0.375D. There was a problem that it would.

A. Kurs, A. Karalis, R. Moffatt, J. D. Joannopoulos, P. Fisher, M. Soljacic, "Wireless power transfer via strongly coupled magnetic resonances", Science, Vol. 317, pp. 83-86, July 6, 2007 M.Soljacic, A.Karalis, J.Joannopoulos, A.Kurs, R.Moffatt, P.fisgeR, "Development of technology to transmit power wirelessly, lighting 60W bulb in experiment", Nikkei Electronics, 3Dec.2007

  Therefore, the present invention provides a power feeding system that can suppress a reduction in transmission efficiency due to the positional deviation d between the power feeding side coil and the power receiving side coil and can supply power from the power feeding means to the power receiving means with high efficiency. This is the issue.

  The invention according to claim 1 for solving the above-described problem is a power supply means provided with a power supply side coil to which power is supplied, and receives power from the power supply side coil by electromagnetic resonance with the power supply side coil. A power receiving system provided with a power receiving side coil, wherein the impedance of at least one of the power feeding means and the power receiving means provided in at least one of the power feeding means and the power receiving means is variable. A matching unit, position detecting means for detecting a relative position between the power feeding side coil and the power receiving side coil, and adjusting the matching unit according to the position detected by the position detecting means, And an impedance adjusting unit that adjusts an impedance of at least one of the power feeding unit and the power receiving unit. It resides in the stem.

  The invention according to claim 2 is characterized in that the position detecting means detects a positional deviation d between the central axis of the power supply side coil and the central axis of the power reception side coil as a relative position. The power supply system.

  As described above, according to the first aspect of the present invention, the impedance adjusting unit adjusts the matching unit according to the relative position between the power feeding side coil and the power receiving side coil detected by the position detecting unit, and the matching unit The impedance of at least one of the power feeding means and the power receiving means provided with is adjusted, so that a decrease in transmission efficiency due to the positional deviation d between the power feeding side coil and the power receiving side coil is suppressed, and high efficiency is achieved from the power feeding means to the power receiving means. Can supply power.

  According to the second aspect of the present invention, the position detecting means detects the positional deviation d between the central axis of the power feeding side coil and the central axis of the power receiving side coil as a relative position, and therefore is caused by the positional deviation d of the central axis. A reduction in transmission efficiency can be suppressed, and power can be supplied from the power supply unit to the power reception unit with high efficiency.

It is a figure which shows the electric power feeding system of this invention. It is a perspective view of the electric power feeding side loop antenna, electric power feeding side helical coil, electric power receiving side helical coil, and electric power receiving side loop antenna which comprise the electric power feeding system shown in FIG. In a power feeding system in which the number of turns of the power supply side and power reception side helical coils is 2, when there is alignment when the positional deviation d = 0 of the central axis of the power supply side and power reception side helical coils, there is alignment when the positional deviation d = 0.375D When the positional deviation d = 0.375D and there is no matching, the transmission efficiency S21 ² near each frequency f0 is a graph. In a power supply system in which the number of turns of the helical coil on the power supply side and the power reception side is 1, when there is a match at the positional deviation d = 0 of the central axis of the power supply side and the power reception side helical coil, When the positional deviation d = 0.375D and there is no matching, the transmission efficiency S21 ² near each frequency f0 is a graph. It is a figure which shows the conventional electric power feeding system.

  The power supply system of the present invention will be described below with reference to FIGS. FIG. 1 is a diagram showing a power supply system of the present invention. FIG. 2 is a perspective view of a power feeding side loop antenna, a power feeding side helical coil, a power receiving side helical coil, and a power receiving side loop antenna constituting the power feeding system shown in FIG. As shown in the figure, the power supply system 1 includes a power supply unit 3 as a power supply unit provided on a road 2 and the like, and a power reception unit 5 as a power reception unit provided in an abdomen of an automobile 4 or the like. ing.

  The power feeding unit 3 includes a DC / AC converter 31 that converts DC power supplied from the DC power source 6 into AC power, and a power-feed-side loop antenna 32 that is supplied with AC power converted by the DC / AC converter 31. And a feed-side helical coil 33 that is spaced apart from the feed-side loop antenna 32 in the central axis direction and electromagnetically coupled to the feed-side loop antenna 32, and is connected in parallel to the feed-side helical coil 33. A capacitor C1 and a variable inductor L1 as a matching unit are provided.

  The feeding-side loop antenna 32 is provided in a circular loop shape, and the central axis thereof is arranged along the direction from the road 2 toward the abdomen of the automobile 4, that is, the vertical direction. A DC / AC converter 31 is connected to both ends of the feeding-side loop antenna 32, and AC power converted by the DC / AC converter 31 as described above is supplied.

  The power supply side helical coil 33 is constituted by winding a winding in a helical shape, for example. In the present embodiment, the power supply side helical coil 33 is provided with two turns. The power supply side helical coil 33 is disposed coaxially with the power supply side loop antenna 32 on the side of the power supply side loop antenna 32 on the vehicle 4 side. The power feeding side loop antenna 32 and the power feeding side helical coil 33 are within the range where they can be electromagnetically coupled to each other, that is, when AC power is supplied to the power feeding side loop antenna 32 and AC current flows, electromagnetic induction is generated in the power feeding side helical coil 33. They are provided apart from each other within a range where they occur.

  The capacitor C1 is provided to adjust the resonance frequency. The variable inductance L1 is a coil whose inductance changes according to an adjustment signal output from the CPU 9 described later.

  The power receiving unit 5 is disposed so as to face the power receiving side helical coil 51 in electromagnetic resonance with the power receiving side helical coil 33 and to face the power receiving side helical coil 51 in the central axis direction. A coupled power receiving side loop antenna 52, an AC / DC converter 53 that converts AC power received by the power receiving side loop antenna 52 into DC power, and a capacitor C2 connected in parallel to the power receiving side helical 51 are provided. ing.

  A load 7 such as an in-vehicle battery is connected to the power receiving side loop antenna 52 via an AC / DC converter 53. Further, the power receiving side loop antenna 52 is provided in a circular loop shape, and is arranged so that its central axis is along the direction from the abdomen of the automobile 4 toward the road 2, that is, the vertical direction. Further, in the present embodiment, as shown in FIG. 2, the power receiving side loop antenna 52 is provided with the same diameter as the power feeding side loop antenna 32 described above, but the present invention is not limited to this. For example, the diameter of the power receiving side loop antenna 52 may be smaller than the diameter of the power feeding side loop antenna 32 described above.

  The power receiving side helical coil 51 is configured, for example, by winding a winding in a circular helical coil shape. In the present embodiment, the power-receiving-side helical coil 51 is provided with two turns as in the case of the power-feeding-side helical coil 33. Moreover, although the said receiving side helical coil 51 is provided in the same diameter as the electric power feeding side helical coil 33 mentioned above, this invention is not limited to this, For example, the diameter of the receiving side helical coil 51 is the above-mentioned. The diameter of the feeding-side helical coil 33 may be smaller.

  The power receiving side helical coil 51 is arranged on the road 2 side of the power receiving side loop antenna 52 and coaxially with the power receiving side loop antenna 52. As a result, the power receiving side loop antenna 52 and the power receiving side helical coil 51 are within a range where they are electromagnetically coupled to each other, that is, within a range where an induction current is generated in the power receiving side loop antenna 52 when an alternating current flows through the power receiving side helical coil 51. Are spaced apart from each other. The capacitor C2 is provided to adjust the resonance frequency, like the capacitor C1. The capacitors C1 and C2 have capacities adjusted in advance so that the resonance frequency of the power supply side helical coil 33 and the power reception side helical coil 51 is a desired frequency f0 (for example, 10 MHz).

  According to the power feeding system 1 described above, the power receiving unit 5 of the automobile 4 approaches the power feeding unit 3 provided on the road 2, and the power feeding side helical coil 33 and the power receiving side helical coil 51 are opposed to each other with a space therebetween in the central axis direction. In this case, the power supply side helical coil 33 and the power reception side helical coil 51 can electromagnetically resonate to supply power from the power supply unit 3 to the power reception unit 5 in a non-contact manner.

  More specifically, when AC power is supplied to the power feeding side loop antenna 32, the power is sent to the power feeding side helical coil 33 by electromagnetic induction. That is, power is supplied to the power supply side helical coil 33 via the power supply side loop antenna 32. When electric power is sent to the power supply side helical coil 33, the electric power is wirelessly sent to the power reception side helical coil 51 by magnetic field resonance. Further, when power is sent to the power receiving side helical coil 51, the power is sent to the power receiving side loop antenna 52 by electromagnetic induction, and the load 7 connected to the power receiving side loop antenna 52 is passed through the AC / DC converter 53. Supplied.

  Further, as shown in FIG. 1, the power supply system 1 described above includes a switch 8 provided between the DC power supply 6 and the DC / AC converter 31, a CPU 9 that controls the entire power supply unit 3, and a power supply. A position sensor 10 for detecting a relative position of the side helical coil 33 and the power receiving side helical coil 51.

  The CPU 9 is connected to the switch 8 and a receiver 10b described later. The position sensor 10 is mounted on the automobile 4 and is disposed in the vicinity of the power receiving side helical coil 51, and the receiver 10b is disposed on the road 2 side and is disposed in the vicinity of the power feeding side helical coil 33. It is equipped with. The transmitter 10 a is disposed in the abdomen of the automobile 4 so as to be disposed in the vicinity of the power receiving side helical coil 51. The transmitter 10a is composed of, for example, a light emitting element that emits spot light and a control circuit that controls light emission of these light emitting elements, and periodically irradiates the spot light downward vertically. Yes.

  The receiver 10 b is disposed on the road 2 so as to be disposed in the vicinity of the power supply side helical coil 33. The receiver 10b is composed of a light receiving element on which a light receiving surface for receiving spot light is formed and a detection circuit for outputting a position signal corresponding to the position on the light receiving surface irradiated with the spot light. A position signal from the detection circuit is output to the CPU 9.

  The CPU 9 detects the relative position between the power supply side helical coil 33 and the power reception side helical coil 51 based on the position signal from the receiver 10b. Specifically, the CPU 9 detects a positional deviation d (FIG. 5) between the central axis Z1 (FIG. 2) of the power supply side helical coil 33 and the central axis Z2 (FIG. 2) of the power reception side helical coil 51 as a relative position. . In this embodiment, an example in which an optical sensor is used as the position sensor 10 as described above will be described. However, the present invention is not limited to this, and other ultrasonic sensors, wireless sensors, and the like are also known. The position sensor 10 may be used. Further, as is apparent from the above, the position sensor 10 and the CPU 9 constitute position detecting means in the claims.

Next, the principle of the present invention will be described before the operation of the power feeding system 1 is described. First, the inventors adjust the impedance of the variable inductance L1 to adjust the impedance of the power feeding unit 5 so as to obtain the highest efficiency in the case of the positional deviation d = 0, and adjust the impedance of the power feeding unit 5 near the frequency f0. 52 transmission efficiency S21 ² was simulated. The results are shown by the chain line in FIG. As shown in the figure, when the positional deviation d = 0, a transmission efficiency S21 ² of 97% can be realized.

Next, the inventors simulated the transmission efficiency S21 ² of the power receiving side loop antenna 52 in the vicinity of the frequency f0 with the positional deviation d = 0.375D (D = the diameter of the power receiving side helical coil 51). A result is shown with the dashed-dotted line of FIG. Note that the inductance of the variable inductance L1 at this time is the same as the value adjusted when the positional deviation d = 0. As shown in the figure, when the positional deviation d occurs, the transmission efficiency S21 ² decreases to about 87%.

The reason why the transmission efficiency S21 ² is reduced in this way is that when the positional deviation d = 0, even if the impedances of the power feeding unit 3 and the power receiving unit 5 are matched, if the positional deviation d occurs, impedance matching is performed. This is probably because the power transmitted from the power feeding unit 3 is reflected by the power receiving unit 5. Therefore, the inventors adjust the inductance of the variable inductance L1 again in the case of the positional deviation d = 0.375D, adjust the impedance of the power feeding unit 3, and transmit the power receiving side loop antenna 52 near the frequency f0. Efficiency S21 ² was simulated. The result is shown by the solid line in FIG. As shown in the figure, when the impedance is adjusted, the transmission efficiency S21 ² is improved to about 93%.

Therefore, the relationship between the positional deviation d and the inductance of the variable inductance L1 that provides the best transmission efficiency S21 ² is obtained by simulation or experiment, and a table representing the obtained relationship is stored in advance in a memory (not shown). Then, the CPU 9 obtains an inductance corresponding to the positional deviation d detected by the position signal from the receiver 10b from a table stored in the memory, and outputs an adjustment signal for obtaining the obtained inductance to the variable inductance L1. To do.

  Next, a detailed operation of the power supply system 1 described in the above outline will be described. First, the CPU 9 takes in the position signal of the receiver 10b and determines whether spot light is received. If the spot light is received, it is determined that the vehicle 2 is nearby, and the CPU 9 next obtains the positional deviation d between the central axes Z1 and Z2 based on the position signal from the receiver 10b.

  Thereafter, the CPU 9 functions as an impedance adjusting means, obtains an inductance corresponding to the obtained positional deviation d from a table or the like stored in the memory, and outputs an adjustment signal for obtaining the obtained inductance to the variable inductance L1. Next, the CPU 9 turns on the switch 8 to supply the AC power of the power feeding side loop antenna 32. As a result, power is transmitted wirelessly from the power feeding unit 3 to the power receiving unit 5 while maintaining high efficiency.

  Thereafter, the CPU 9 captures the position signal of the receiver 10b again, and when the spot light is no longer received, the CPU 9 determines that the automobile 2 has left, turns off the switch 8, and supplies the AC power supplied to the feeding-side loop antenna 32. Cut off.

  According to the power feeding system 1 described above, the variable inductance L1 according to the positional deviation d between the central axis Z1 of the power supply side helical coil 33 and the central axis Z2 of the power reception side helical coil 51 detected by the CPU 9 using the position sensor 10. Is adjusted to adjust the impedance of the power feeding unit 3 provided with the variable inductance L1, so that a decrease in transmission efficiency due to the positional deviation d between the power feeding side helical coil 33 and the power receiving side helical coil 51 is suppressed. Power can be supplied from the unit 3 to the power receiving unit 5 with high efficiency.

  According to the power supply system 1 described above, the CPU 9 uses the position sensor 10 to detect the positional deviation d between the central axis Z1 of the power supply side helical coil 33 and the central axis Z2 of the power reception side helical coil 51 as a relative position. Further, it is possible to suppress a decrease in transmission efficiency due to the positional deviation d between the central axes Z1 and Z2, and to supply power from the power feeding unit 3 to the power receiving unit 5 with high efficiency.

In the above-described embodiment, the two power supply side and power reception side helical coils 33 and 51 have been described. However, the present invention is not limited to this. The number of turns of the power supply side and power reception side helical coils 33 and 51 may be one or three or more. In order to verify that the above-described effect can be obtained even with other numbers of turns, the inventors of the power supply system 1 in which the number of turns of the power supply side and power reception side helical coils 33 and 51 is 1, and the alignment is zero when the displacement is d = 0. In some cases, the transmission efficiency S21 ² near each frequency f0 was simulated when there was a match with a positional deviation d = 0.375D and when there was no matching with a positional deviation d = 0.375D. The results are shown in FIG.

As shown in the figure, when the positional deviation d = 0, the transmission efficiency S21 ² was 95%. On the other hand, if there is no matching when the positional deviation d = 0.375D, the transmission efficiency S21 ² is reduced to 73%. It was found that the transmission efficiency S21 ² can be improved to 85% when matching is achieved using the variable inductance L1.

  In the above-described embodiment, the variable inductance L1 that is a matching unit is provided only in the power feeding unit 3, but the present invention is not limited to this. For example, a matching unit may be provided only in the power receiving unit 5, or a matching unit may be provided in both the power feeding unit 3 and the power receiving unit 5.

  In the above-described embodiment, the variable inductance L1 is used as the matching device, but the present invention is not limited to this. As the matching device, a known device such as a capacitor or a combination of a capacitor and an inductance may be used.

  In the above-described embodiment, the variable inductance L1 as a matching unit is connected to the power supply side helical coil 33. However, the present invention is not limited to this. In the present invention, the impedance between the power feeding unit 3 and the power receiving unit 5 may be matched, and a matching unit may be provided in the power feeding side and power receiving side loop antennas 32 and 52, or the DC / AC converter 31 and AC / AC The DC converter 53 may be provided.

  In the above-described embodiment, it is desired to detect the positional deviation d and adjust the variable inductance L1 so as to prevent a reduction in transmission efficiency due to the positional deviation d, but the present invention is not limited to this. For example, the distance X (FIG. 3) between the feeding-side helical coil 33 and the receiving-side helical coil 51 in the central axis direction is detected, and the variable inductance L1 is adjusted so as to prevent a decrease in transmission efficiency due to fluctuations in the distance X. May be.

  Further, the above-described embodiments are merely representative forms of the present invention, and the present invention is not limited to the embodiments. That is, various modifications can be made without departing from the scope of the present invention.

1 Power Supply System 3 Power Supply Unit (Power Supply Means)
5 Power receiving unit (power receiving means)
9 CPU (impedance adjusting means, position detecting means)
10 Position sensor (position detection means)
33 Feeding side helical coil (feeding side coil)
51 Receiving side helical coil (Receiving side coil)
L1 Variable inductance (matching device)

Claims (2)

Power supply comprising: a power supply means provided with a power supply side coil to which power is supplied; and a power reception means provided with a power reception side coil that electromagnetically resonates with the power supply side coil to receive power from the power supply side coil. In the system,
A matching unit that is provided in at least one of the power supply unit and the power reception unit, and makes the impedance of at least one of the power supply unit and the power reception unit provided variable;
Position detecting means for detecting a relative position between the power feeding side coil and the power receiving side coil;
An impedance adjusting unit that adjusts the matching unit according to the position detected by the position detecting unit and adjusts the impedance of at least one of the power feeding unit and the power receiving unit provided with the matching unit;
A power supply system comprising: The power supply system according to claim 1, wherein the position detection unit detects a positional shift between a central axis of the power supply side coil and a central axis of the power reception side coil as a relative position.

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