JP2008092704A - Power feeding system between road vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power feeding system between road vehicles which can improve the transmission efficiency of energy, and can alleviate a load of a power receiving device caused by excessive power transmission. <P>SOLUTION: The power feeding system between the road vehicles comprises the power receiving device 20 which is mounted to the vehicle 50, and receives a microwave via a power receiving antenna 21, and a power transmission device 10 which is arranged at a road side, and transmits the microwave via a power transmission antenna 15. The system is also characterized in that a power transmission output of the power transmission device 10 is variable according a distance between the power receiving antenna 21 and the power transmission antenna 15, or according to the direction of the power transmission of the microwave which should be transmitted via the power transmission antenna 15. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention is a road-to-vehicle power supply system that includes a power receiving device that is mounted on a vehicle and receives microwaves via a power receiving antenna, and a power transmission device that is installed on the road side and transmits microwaves via a power transmitting antenna. About.

2. Description of the Related Art Conventionally, a power transmission device that is mounted on a vehicle and receives power supply by microwaves received via a power reception antenna, and a power transmission device that is installed on a road and that radiates microwaves from the road surface to the power reception antenna There is known a road-to-vehicle power supply system (see, for example, Patent Document 1). The power transmission device in this road-to-vehicle power supply system sets the irradiation region based on the reference position information received from the power reception device side and the laying region information of the power reception antenna, and irradiates the power transmission antenna in the set irradiation region with microwaves. The control means to be provided is provided.
JP 2006-166570 A

  However, in the above-described conventional technology, since the power transmission output when irradiating microwaves is not taken into consideration, for example, when the distance between the power receiving antenna mounted on the vehicle and the power transmitting antenna installed on the road is long If the power required by the vehicle is not sufficient, and if the distance between the power receiving antenna mounted on the vehicle and the power transmitting antenna installed on the road is short, more power is transmitted than necessary and the energy transmission efficiency May fall. Furthermore, when power exceeding the allowable power that can be received by the power receiving device is transmitted, there is a possibility that an abnormality may occur in the power receiving device.

  Therefore, an object of the present invention is to provide a road-to-vehicle power supply system capable of improving energy transmission efficiency and reducing the burden on a power receiving device due to overpower transmission.

In order to achieve the above object, a road-to-vehicle power supply system according to the present invention includes:
A power receiving device mounted on a vehicle and receiving microwaves via a power receiving antenna;
A road-to-vehicle power supply system having a power transmission device installed on the road side and transmitting microwaves via a power transmission antenna,
The power transmission output of the power transmission device is variable according to a distance between the power receiving antenna and the power transmission antenna or according to a power transmission direction of a microwave to be transmitted through the power transmission antenna. Thereby, since it can adjust to the power transmission output suitable for the said distance and the said power transmission direction, while being able to improve the transmission efficiency of the energy by a microwave, the power receiving device (especially built-in rectifier diode) by overpower transmission Can be reduced. For example, it is preferable to increase the power transmission output of the power transmission device as the distance is longer or as the angle between the direction in which the distance between the power receiving antenna and the power transmission antenna is the shortest and the power transmission direction is larger. .

  The road-to-vehicle power supply system according to the present invention described above further includes position information detection means for detecting the position information of the vehicle, and the distance is detected by the position information detection means. Is preferably derived on the basis of

  The road-to-vehicle power supply system according to the present invention described above further includes direction detection means for detecting the arrival direction of the signal by receiving the signal transmitted from the vehicle, and the power transmission direction is the direction. It is preferable to set based on the direction of arrival detected by the detecting means.

  ADVANTAGE OF THE INVENTION According to this invention, while improving the transmission efficiency of energy, the burden of the receiving device by overpower transmission can be reduced.

  The present invention provides a road-to-vehicle power supply system that applies non-contact power supply to a vehicle such as an electric vehicle traveling on a road from the road side by applying an energy transmission technique using electromagnetic waves such as microwaves. The energy transmission technology using electromagnetic waves is a technology for converting electric energy into radio wave energy of a predetermined frequency (for example, 2.45 GHz microwave) and transmitting the energy wirelessly. Energy transmission technology using electromagnetic waves is different from wired energy transmission technology, which has limitations in power transmission to traveling vehicles, in that power transmission to traveling vehicles is possible.

  FIG. 1 is a schematic diagram of a microwave energy transmission system. In the electromagnetic wave generator on the power transmission side, direct-current or alternating-current transmission power is converted into microwaves. As a means for converting DC power or AC power into microwaves, for example, there is a magnetron that is also used in a microwave oven. The microwave output from the magnetron is radiated from the power transmission antenna. The radiated power is received and rectified by a microwave power receiving rectifier element called a rectenna, and is taken out as DC power. The rectenna is a microwave power receiving rectifying element in which the power receiving antenna 21 and the rectifying circuit 22 are integrated. The rectifier circuit 22 is configured by connecting its input end to a ground line via one or more rectifier diodes 22a, and rectifies the microwaves input via the power receiving antenna 21.

  FIG. 2 is a schematic diagram of a road-to-vehicle power supply system that supplies power to a vehicle traveling on a road. In a power transmission road where microwaves are radiated via a power transmission antenna, the microwave generated by the microwave generation source is radiated toward the electric vehicle 50 traveling on the power transmission road. The radiated microwave is received by a rectenna mounted on the electric vehicle 50 and rectified to DC power. The DC power rectified by the rectenna is supplied to a drive source of the electric vehicle 50 such as a battery or a motor. Thus, the electric vehicle 50 can travel while suppressing battery consumption by external power feeding while traveling.

  FIG. 3 is a diagram showing a first embodiment of a road-to-vehicle power supply system according to the present invention. The road-to-vehicle power supply system of the first embodiment includes a power transmission device 10 installed on the road side and a power reception device 20 mounted on a vehicle 50. The power transmission device 10 includes an RF oscillation device 11, a divider 12, a phase shifter 13, an output variable amplifier 14, and a power transmission antenna 15. As shown in FIG. 1, the power receiving device 20 includes a power receiving antenna 21 and a rectifier circuit 22.

  The RF oscillation device 11 converts a direct current or an alternating current into a signal wave (RF output) having a frequency corresponding to a microwave, and outputs an RF output to the divider 12. Specific examples of the RF oscillation device 11 include a vacuum tube type oscillation device (for example, a magnetron) and a crystal oscillator.

  The divider 12 divides the RF output generated by the RF oscillation device 11 and outputs it to each of n (n is an integer of 2 or more) phase shifters 13. The n number of phase shifters 13 individually change the phase of the RF output from the divider 12 in accordance with the processing result of the calculation processing device 31 described later, and output it to the n number of output variable amplifiers 14. The n output variable amplifiers 14 change the microwave power transmission output according to the processing result of the calculation processing device 31 described later.

  The power transmission antenna 15 is an antenna that transmits the microwave with the power transmission output adjusted by the output variable amplifier 14 in the power transmission direction in which the microwave calculated by the calculation processing device 31 is to be transmitted. The power transmission antenna 15 that radiates microwaves for power supply to the vehicle 50 is preferably a planar antenna because it is embedded in each power supply section provided at predetermined intervals on the road on which the vehicle 50 travels. Examples of the planar antenna include a circular patch antenna, a slot antenna with a cavity, and a waveguide slot antenna. The power transmission antenna 15 includes a signal receiving antenna that receives a predetermined signal transmitted from the vehicle 50, details of which will be described later. Moreover, the power transmission apparatus 10, and the information detector 30 and the calculation processing apparatus 31, which will be described later, are installed for each power feeding section.

  The microwave radiated from the power transmission antenna 15 is received by the power reception antenna 21 of the power reception device 20 mounted on the vehicle 50. The power receiving device 20 receives the microwave radiated from the power transmitting antenna 15 by the power receiving antenna 21 and supplies power to a battery or the like mounted on the vehicle 50 via the rectifier circuit 22. The power receiving antenna 21 is desirably a planar antenna installed on the bottom surface of the vehicle 50 so that the microwave radiated from the road surface can be easily received. A specific example of the power receiving antenna 21 is a circular patch antenna because the power transmission / reception interval is narrow and the bottom surface of the vehicle is metal. FIG. 4 is a bottom view of the vehicle 50. A plurality of power receiving antennas 21 are arranged in an array on the bottom surface of the vehicle 50.

  The signal transmitting antenna 25 is mounted on a front part and a rear part (for example, a windshield and a rear glass) of the vehicle 50, and transmits signal waves related to vehicle information such as position information, speed information, and energy information of the vehicle 50. Antenna. The position information of the vehicle 50 may be absolute position information or relative position information, and can be specified by an in-vehicle GPS device or specified by a travel distance from a predetermined reference point (for example, a reference position set in a power feeding section). It is possible. The speed information of the vehicle 50 can be acquired by a wheel speed sensor. The energy information of the vehicle 50 is information representing a storage state (for example, battery voltage or SOC (State of Charge)) of a battery mounted on the vehicle 50. The signal transmission antenna 25 transmits a signal wave related to vehicle information such as position information of the vehicle 50 to the road side at a predetermined cycle.

  The information detector 30 is installed on the road side and receives a signal wave related to vehicle information transmitted by the signal transmission antenna 25 via the power transmission antenna 15 and detects the vehicle information. The vehicle information detected by the information detector 30 is input to the calculation processing device 31.

  The calculation processing device 31 is a computer including a central processing unit, and is based on a signal wave related to vehicle information transmitted by the signal transmission antenna 25 (based on vehicle information detected by the information detector 30). The transmission distance between the power receiving antenna 21 on the vehicle 50 side and the power transmitting antenna 15 on the road side (distance between the antennas), the direction of arrival of the signal wave, the relative speed between the power receiving antenna 21 and the power transmitting antenna 15 (relative speed between the antennas), in-vehicle Energy information such as battery SOC is derived. Based on these derivation results, the calculation processing device 31 calculates the optimum power transmission direction (scanning angle) and power transmission output of the microwave to be transmitted to the power receiving antenna 21 of the vehicle 50 via the power transmission antenna 15. . The calculation processing device 31 outputs the calculated power transmission direction (scanning angle) and power transmission output to the phase shifter 13 and the output variable amplifier 14 as the processing result. As a result, the calculation processing device 31 controls the power transmission device 10 so that the power transmission direction of the microwaves radiated from the power transmission antenna 15 matches the direction of the power reception antenna 21 mounted on the vehicle 50. The power transmission device 10 is controlled so as to obtain a power transmission output capable of supplying necessary power to the vehicle 50 within a range not exceeding the power receiving capability.

  FIG. 5 is a diagram for explaining a microwave power transmission direction according to the first embodiment. The transmission direction of the microwave is determined by the scanning angle θ shown in FIG. The scanning angle θ shown in FIG. 5 is obtained when the direction in which the distance between the power transmitting antenna 15 installed on the road surface and the power receiving antenna 21 installed on the bottom surface of the vehicle 50 is the shortest is the reference direction. An angle formed with a power transmission direction in which microwaves are transmitted through the antenna 15. That is, when the vehicle 50 exists vertically above the power transmission antenna 15 installed on the road surface, the scanning angle θ is 0 °.

  In other words, the calculation processing device 31 increases the scanning angle θ as the vehicle 50 traveling on the power transmission road moves away from the installation point of the power transmission antenna 15, thereby moving the power transmission antenna 15 from the power transmission antenna 15 toward the power reception antenna 21. The power transmission direction of the emitted microwave is made to follow. For example, when the distance between the antennas is approximately zero, the calculation processing device 31 considers that the power receiving antenna 21 of the vehicle 50 exists directly above the power transmitting antenna 15 embedded in the road, and sets the scanning angle θ to 0 °. Set and control the phase shifter 13. For example, when the distance between the antennas is a predetermined value (for example, 30 m) greater than zero, the calculation processing device 31 sets the scanning angle θ to an angle corresponding to the predetermined value and sets the phase shifter 13. Control.

  Further, the calculation processing device 31 may determine the direction in which the microwaves should be transmitted via the power transmission antenna 15 by the retrodirective method. The retrodirective method is a phased array method for transmitting microwaves in the arrival direction of a pilot signal based on the Van Atta Array. In the Van Atta Array, the positions of the array antennas for pilot signal reception and microwave transmission are arranged one-dimensionally symmetrically, and the reception antennas and the transmission antennas at the symmetrical positions are connected at the same distance, thereby moving in the direction of the pilot signal. Microwave can be directed. Based on this, in the retrodirective method, the microwave is transmitted in the direction of the pilot signal by taking the phase conjugate of the received pilot signal. In the Van Atta Array, the microwave is sent back with the symmetry of the position, whereas the retrodirective uses the symmetry of the phase of the radio wave. For this reason, since the retrodirective obtains the antenna position information as the phase information of the received pilot signal, microwaves can be transmitted in the direction of arrival of the pilot signal regardless of the shape of the antenna. That is, the signal wave related to the vehicle information transmitted by the signal transmission antenna 25 may be regarded as the pilot signal.

  Further, the calculation processing device 31 estimates the arrival direction of the signal wave related to the vehicle information transmitted by the signal transmission antenna 25 based on the reception level indicating the reception sensitivity of the reception wave received by the power transmission antenna 15, You may determine the direction which should transmit a microwave via the power transmission antenna 15. FIG. The calculation processing device 31 detects the reception level when the signal wave related to the vehicle information transmitted by the signal transmission antenna 25 is received via the power transmission antenna 15. The calculation processing device 31 has the maximum reception level of the received wave when the directivity of the power transmission antenna 15 is switched to one direction among the reception levels of the received wave when the directivity of the power transmission antenna 15 is switched to each direction. In some cases, it is estimated that there is a vehicle 50 equipped with the signal transmission antenna 25 that transmits a signal related to vehicle information in one direction. The calculation processing device 31 sets the scanning angle θ corresponding to the estimated direction of the vehicle 50 (the direction of the power receiving antenna 21), and controls the phase shifter 12.

  On the other hand, the calculation processing device 31 calculates the microwave power transmission output, for example, based on the distance between the antennas of the power transmission antenna 15 and the power reception antenna 21. Since the influence of atmospheric attenuation increases as the distance between antennas increases, the calculation processing device 31 increases the power transmission output as the distance between antennas increases based on a map value that defines the relationship between the distance between antennas and the power transmission output. Calculate as follows. The calculation processing device 31 controls the output variable amplifier 14 so that the calculated power transmission output is obtained.

  Further, the calculation processing device 31 determines the transmission power of the microwave according to the arrival direction of the signal wave related to the vehicle information transmitted by the signal transmission antenna 25 (that is, the direction in which the microwave should be transmitted). Also good. Since the microwave energy loss differs depending on the microwave transmission direction (especially, the loss due to the mutual interference of the phased array method is large), the processing unit uses the scanning angle θ that determines the microwave transmission direction and the microwave transmission. Based on the map value that defines the relationship with power, the power transmission output is calculated to increase as the scanning angle θ increases. The calculation processing device 31 controls the output variable amplifier 14 so that the calculated power transmission output is obtained.

  The calculation processing device 31 also determines energy transmission output of the microwave in consideration of energy information such as the SOC of the in-vehicle battery derived based on the vehicle information detected by the information detector 30. The calculation processing device 31 adjusts the power transmission output of the microwave according to the power storage state of the in-vehicle battery. For example, when the power storage state of the on-vehicle battery is fully charged, the power transmission output is set to zero. It is also possible to stop power transmission.

  FIG. 6 is a diagram showing a second embodiment of the road-to-vehicle power supply system according to the present invention. In the configuration of the second embodiment, parts having the same or similar functions as those of the first embodiment are given the same reference numerals as those of the first embodiment, and the description thereof is omitted or simplified. The road-to-vehicle power supply system of the second embodiment also includes a power transmission device 10 installed on the road side and a power reception device 20 mounted on the vehicle 50. The power transmission device 10 in the second embodiment includes an RF oscillation device 11, a motor 16, and a parabolic antenna 17. The power receiving device 20 in the second embodiment includes a power receiving antenna 21 and a rectifier circuit 22 as shown in FIG.

  The RF oscillation device 11 converts a direct current or an alternating current into a signal wave (RF output) having a frequency corresponding to a microwave, and outputs an RF output to the parabolic antenna 17. The RF oscillation device 11 varies the microwave power transmission output according to the processing result of the calculation processing device 31.

  The parabolic antenna 17 changes the transmission direction of the microwave by changing the direction of the parabolic antenna 17 itself by the rotation of the motor 16. The parabolic antenna 17 is an antenna that transmits a microwave with a power transmission output adjusted by the RF oscillation device 11 in a power transmission direction in which the microwave calculated by the calculation processing device 31 is to be transmitted. The parabolic antenna 17 that radiates microwaves for power supply to the vehicle 50 is provided for each power supply section provided at predetermined intervals on the road on which the vehicle 50 travels.

  The microwave radiated from the parabolic antenna 17 is received by the power receiving antenna 21 of the power receiving device 20 mounted on the vehicle 50. The power receiving antenna 21 is installed in the vehicle 50 in a direction that facilitates reception of the microwave radiated from the parabolic antenna 17. For example, the power receiving antenna 21 is mounted at a position where microwaves from the side of the vehicle 50 can be easily received.

  The information detector 32 is installed on the road side, receives a signal wave related to vehicle information transmitted by the signal transmission antenna 25, and detects the vehicle information. The vehicle information detected by the information detector 32 is input to the calculation processing device 31.

  As described above, the calculation processing device 31 is a computer including a central processing unit, and is based on a signal wave relating to vehicle information transmitted by the signal transmission antenna 25 (a vehicle detected by the information detector 32). Based on the information), the distance between the antennas, the arrival direction of the signal wave, the relative speed between the antennas, the energy information, etc. are derived. Based on these derivation results, the calculation processing device 31 calculates the optimum power transmission direction (scanning angle) and power transmission output of the microwave to be transmitted toward the power receiving antenna 21 of the vehicle 50 via the parabolic antenna 17. . The calculation processing device 31 outputs the calculated power transmission direction (scanning angle) and power transmission output to the RF transmission device 11 and the motor 16 as the processing result.

  FIG. 7 is a diagram for explaining a microwave power transmission direction according to the second embodiment. FIG. 7 is a view of the vehicle 50 traveling in the power feeding section of the road as viewed from above. The transmission direction of the microwave is determined by the scanning angle θ shown in FIG. When the scanning angle θ shown in FIG. 7 is a reference direction in which the distance between the parabolic antenna 17 installed adjacent to the road and the power receiving antenna 21 installed on the bottom and side surfaces of the vehicle 50 is the shortest, The angle between the reference direction and the power transmission direction in which microwaves are transmitted through the power transmission antenna 15 is referred to. That is, when the direction of the parabolic antenna 17 itself installed adjacent to the road is perpendicular to the road, the scanning angle θ is 0 °.

  For example, when the distance between the antennas is substantially zero, the calculation processing device 31 assumes that the power receiving antenna 21 of the vehicle 50 exists right next to the parabolic antenna 17 installed adjacent to the road, and sets the scanning angle θ to 0 °. And the motor 16 is controlled. For example, when the distance between the antennas is a predetermined value (for example, 30 m) greater than zero, the calculation processing device 31 sets the scanning angle θ to an angle corresponding to the predetermined value and controls the motor 16. .

  Further, the calculation processing device 31 may detect the position of the vehicle 50 with two cameras, and may control the motor 16 so that the direction of the parabolic antenna 17 itself is directed in that direction. Further, the calculation processing device 31 may determine the direction of the parabolic antenna 17 itself based on the retrodirective method or the like, as in the first embodiment. The calculation processing device 31 calculates the microwave power transmission output based on the distance between the vehicle 50 and the installation location of the parabolic antenna 17, energy information, and the like, as in the first embodiment.

  Therefore, according to the above-described embodiment, the microwave power transmission output can be varied according to the distance between the antennas and the microwave power transmission direction, so that energy efficiency can be improved and power reception by overpower transmission can be achieved. The burden on the device 20 can be reduced and a failure of the power receiving device 20 can be avoided.

  In other words, even if the distance between the antenna that transmits microwaves and the vehicle 50 is long, the power required by the vehicle 50 is insufficient without adding a power transmission antenna on the road to prevent a decrease in transmission efficiency due to atmospheric attenuation. It is possible to prevent the transmission of excessive electric power to the vehicle 50 even when the distance between the antenna for transmitting the microwave and the vehicle 50 is short. In particular, the power receiving device 20 such as a rectenna has a maximum received power per size, and power exceeding this is not subjected to RF-DC conversion and becomes an internal resistance loss of the built-in rectifier diode 22a. It is necessary to prevent power transmission.

  In addition, according to the above-described embodiment, the power transmission output can be varied to the optimum value, so that the electric cost can be reduced as compared with the case where the power transmission output is constant.

  The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the present invention. Can be added.

  For example, although the embodiment of the present invention has been described with reference to a “vehicle” as a specific example of a mobile object that is an object of energy transmission, the mobile object targeted by the mobile energy transmission system according to the present invention is an airplane A ship, a robot, etc. may be sufficient.

  Further, although the embodiment of the present invention has been described with reference to “microwave” as a specific example of the electromagnetic wave for transmitting energy, the electromagnetic wave used for energy transmission by the energy transmission system for a mobile body according to the present invention is an efficiency or signal wave. In consideration of interference with the light, electromagnetic waves in other frequency bands such as light may be used.

  The means for detecting the position and speed of the vehicle 50 may be a laser distance meter installed on the road side. The means for detecting the position of the vehicle 50 may be a phototube sensor or a weight sensor.

It is a schematic diagram of a microwave energy transmission system. 1 is a schematic diagram of a road-to-vehicle power supply system that supplies power to a vehicle traveling on a road. 1 is a diagram showing a first embodiment of a road-to-vehicle power supply system according to the present invention. 4 is a bottom view of the vehicle 50. FIG. It is a figure for demonstrating the power transmission direction of the microwave in 1st Embodiment. It is a figure which shows 2nd Embodiment of the road-to-vehicle power supply system which concerns on this invention. It is a figure for demonstrating the power transmission direction of the microwave in 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Power transmission apparatus 11 RF oscillation apparatus 12 Divider 13 Phase shifter 14 Output variable amplifier 15 Power transmission antenna 16 Motor 17 Parabolic antenna 20 Power reception apparatus 21 Power reception antenna 22 Rectifier circuit 22a Rectifier diode 30, 32 Information detector 31 Calculation processing apparatus 50 Vehicle

Claims (4)

A power receiving device mounted on a vehicle and receiving microwaves via a power receiving antenna;
A road-to-vehicle power supply system having a power transmission device installed on the road side and transmitting microwaves via a power transmission antenna,
The power transmission output of the power transmission device is variable according to a distance between the power receiving antenna and the power transmission antenna, or according to a power transmission direction of a microwave to be transmitted through the power transmission antenna, Road-to-vehicle power supply system.   The power transmission output of the power transmission device is increased as the distance is longer or as the angle between the direction in which the distance between the power receiving antenna and the power transmission antenna is the shortest and the power transmission direction is larger. The road-to-vehicle power supply system according to claim 1. Comprising position information detecting means for detecting position information of the vehicle,
The road-to-vehicle power supply system according to claim 1 or 2, wherein the distance is derived based on the position information of the vehicle detected by the position information detection means. Direction detecting means for detecting the direction of arrival of the signal by receiving the signal transmitted from the vehicle;
The road-to-vehicle power supply system according to claim 1 or 2, wherein the power transmission direction is set based on an arrival direction detected by the direction detection means.

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