Method of energy transmission using coherent electromagnetic radiation

The invention relates to a method and an Apparatus for power transmission by means of coherent electromagnetic radiation using a Transmitter and a receiver

Methods and devices of this type, without the direct mechanical and / or electrical contact work, are already known and are virtually exclusively for power transmission over short Distances and for small amounts of energy use.

The object of the invention is a method of type described above so that it on easily create a wireless power transmission to automatic supply of a distant mobile Unit with energy even over long distances permits and the same time simple, safe and is flexible. In addition to the Invention, an apparatus for carrying out a such a method are provided.

The invention solves the first task by at Such a method provides that a Transmitter unit a directed, controlled laser beam sent to the receiver and from this part of the incident radiation back to the transmitter unit and that is reflected from the reflected beam Information for an alignment of the transmitting unit derived and an alignment with a for the transmitting unit connected control unit are received. In order to solve the other Task provided device, the transmitter unit a control unit and actuators drivable mirror for deflecting the beam on and the receiving unit has a one annularly surrounding photocell array Retroreflector on.

In an advantageous embodiment of the invention is on Receiver an automatic alignment unit provided to the power receiving field optimally on the align incoming energy beam.

By in an advantageous development of the invention, provided for modulation of the laser beam is the Movement of the receiver and the beam is analyzed tracked on the transmitter device. The inventively provided regulation adopted on a Measuring the intensity of the reflected radiation based, thus enabling the consequences of the beam at a movement of the receiver in both the horizontal and in the vertical direction.

Below, the invention is based on the Drawing exemplary embodiments illustrated are explained. Show it<dl tsize="7" compact="compact"><dt>Fig. 1</dt><dd>the construction of a transmission unit,</dd><dt>FIG. 2</dt><dd>a detail of the arrangement according to FIG. 1,</dd><dt>Fig. 3</dt><dd>a schematic representation of a Receiver in front view,</dd><dt>Fig. 4</dt><dd>a rear view of the receiver according to FIG. 3,</dd><dt>Fig. 5</dt><dd>a schematic representation of a Adjustment mechanism of the arrangement according FIGS. 3 and 4,</dd><dt>Fig. 6</dt><dd>a schematic representation of the Procedure for finding a reflector,</dd><dt>Fig. 7</dt><dd>a schematic representation of the process for detecting the reflector ring,</dd><dt>Fig. 8</dt><dd>a schematic representation of a method for tracking of the laser beam,</dd><dt>Fig. 9:</dt><dd>a schematic representation of a further Nachführmethode,</dd><dt>Fig. 10</dt><dd>the occurrence of the fundamental and the first harmonic of the modulation frequency in dependence on the spatial upset</dd></dl>

is used in the apparatus shown in the figures a laser unit 1 as a power source. The beam This laser is a laser in the unit 1 integrated divergent optics widened before it in a Deflector enters. This consists of three rotatable members 9, 10a and 10b. The unit 9, to of the units 10a and 10b and the drive unit 3 are fixed, is on the drive unit 2 and the drive ring 6 is rotated around the axis a. The axis A is identical with the optical axis of the laser from the emitted light beam. In the unit 9 is under an angle of 45 ° to the axis a of the deflection mirror 4 fixed, of the laser beam in the direction b deflects, which thus is perpendicular to the axis a. The Axis B by rotating the unit 9 and the axis A can be selected in any direction, is the optical axis of the laser beam between the mirrors 4 and the axis of rotation units 10a and 10b when these by the drive unit 3 and the drive rings 7 and 8 are rotated relatively with respect to the unit. 9

The mirror 5 is in the unit 10a in the Basic position at an angle of 45 ° to the axis b arranged and directs the laser beam to the direction from under it leaves the transmitting unit. About two electromechanical control elements 11 and 12, For example, piezo actuators, the mirror 5 is to two axes perpendicular to the axis b tilted. These but tilting movement has a smaller parking area a shorter correction time as the rotation about the axes a and b. Thus, slow movements of the laser beam to large deflection angle by the rotation about the axes A and b realized; fast but small movements by the adjusting elements 11 and 12. The angle of rotation about the axes a and b can be 360 ​​° or larger. In synchronism with the unit 10a is also the unit 10 b is rotated about the axis b. b At the unit 10 is the Detector unit, for example consisting of a Parabolic mirror 28 and a radiation detector 29, for Receiving the light reflected back from the receiver Light installed. The synchronous rotation of units 10a and 10b ensures that the detector unit always aligned with the direction under which the Laser beam leaves the transmitting unit.

The structure of such fine actuator on the basis of a piezoelectric crystal actuator is shown schematically in detail shown in Fig. 2. As can be seen, each of the Levels 4 or 5 to a point A pivotally supported. In this illustration, for convenience only a piezoelectric crystal 9 shown. The piezoelectric crystal is arranged between two lever arms 13,14 in which the a lever arm 13 deflects the mirror directly, while with the other lever 14 via an adjusting device 15 adjusted and preloaded the entire piezoelectric element can be. The entire suspension for both Piezo crystals for a mirror is in a private low distortion housing 16 accommodated.

The mobile receiver, for example, a one Space vehicle or, as in the case of the described herein Embodiment on a reconnaissance vehicle 17 is arranged, is located in an arbitrary Distance from the transmitter, but in its direct Field of view. This receiver has, as from the Figures 3 and 4 it can be seen a rotating and adjustable attachment 18, the reception of the laser beam serves. The beam receiver 18 is composed of a Solar array 19 and a surrounding, the Laser beam back to the transmitter reflective surface 20 built up. The solar cells convert the incident light of the laser beam into electricity, the is used for the power supply of the receiver. Due to the beam profile always hits a part of the Laser beam on the surrounding reflector ring 20, so that is not on the solar cells 19 of the this striking part of the light to the transmission unit back is reflected. The size of the laser beam is so chosen to be smaller than the diameter of the Solar cell 19 is to ensure that the Major portion of the available light energy is used for the conversion into electrical energy and only a very small portion is reflected.

Furthermore, in the described herein Embodiment, and as shown in Figures 4 and 5 shown in the beam receiver 18 a Aligning integrated, which ensures that the Beam receiver with its two transverse axes always normal is to the incident beam. Heart of this Alignment is in behind a small hole 21 Center of the solar cells 19 arranged Unidirectional sensor 22 in detail in Fig. 5 is shown and made at the ends of jet pipes 23 arranged photodiodes 24 is. By means of this Sensor 22 can be measured at any time, whether the Article 18 nor perpendicular to its two axes Beam is. Once in a downstream Evaluation unit 25 detected a deviation, is of an integrated in these Control electronics to motors 26 and Driving members 27 of the top 18 in his Orientation readjusted.

The recipient of the reflected component of the Light is in the transmitter unit over a Parabolic mirror 28 and collected on a central sensor 29 and specific filter in a Information signal with respect to the position of the beam converted on the solar surface of the receiver. This Signal is input to a control unit 30 of the transmitter used the optimum orientation of the mirror 4 and 5 to adjust and readjust.

The control computer 30 then controls on the basis of collected reflection signal in a cascaded Control both the motors 2 and 3 for the Coarse movement as well as the piezoelectric crystals and 9,10 11,12 for fine motor movements of both mirrors 4 and 5 to their respective pivot point A and adjusted to Thus, according to the overall system.

In addition to transmitting and receiving units still belongs a control program that the entire procedural Of the automatic power transmission of a Transmitting unit to a mobile receiver unit includes, for apparatus. This control program consists essentially of two parts: a Search algorithm of the search and retrieval Receiver unit in a wide range allows and a tracking, which ensures that a Receiver unit found over longer periods accurately tracked and thus constant with energy can be supplied.

In search mode are initially the motor-gear units uses the transmitting unit to a attenuated laser beam to the target area over a large area of scanning line by line for a return reflection. Becomes such reflection is detected, then in a submode the immediate vicinity of the last reflecting position accurately scanned and this independently of the center circle R_m the reflector ring 20 is determined. Here, the Beam on the fine-tuning by the Piezo crystals 9,10 and 11,12 positions. This occurs in a two-stage approach in that in a first step, a search pattern in the form of a 3 times 3 matrix is ​​measured while the brightest determined position and elected as the new starting point is, as is illustrated in Fig. 6. This Process is repeated several times. In a subsequent second step is then the shape of the Ring, and thus the central position of the solar panels 19 detected. This algorithm is based on Fig. 7 illustrated. From the starting point, several Search steps, exemplarily shown here 3 steps carried out in a similar direction in which for each step the reflection signal strength is measured. The step direction with the strongest Signal value is set as new main analysis direction assumed, and the process repeated until the Contour of the ring reflector is fully recorded. On the An individual basis, can now with a Gravity calculation of the area spanned the The center of this area can be determined and the Transmit beam so precisely on the solar cells 19 in the be out mid-ring 20th This method is oriented such that for searching and detecting the Solar cells not receiving unit necessarily already be aligned perpendicular to the beam direction must, but also skew detected safely and be measured.

For reliable tracking of the transmission beam on the found and measured receiving unit alternatively four different basic algorithms provided that will be described in more detail below should.

In the first method, also known as "random walk" is designated, the position of the laser beam is of the start position by a small step in a changed any direction and by means of Receiver back reflected light determines whether this Step improvement or deterioration showed. In case of deterioration is the Start position return is made; with an improvement is the new position as a new starting position maintained. Thereafter, the procedure with a new will continued step in any direction. The Decision whether a position change to a Improvement or a deterioration has led, can For example, on the overall intensity of the back reflected light are determined, the closer the Position of the laser beam at the center of the solar cell 21, the less light is incident on the reflector ring 20 and is reflected, or it may, for example, by the "modulation method" that is, by the Detection at twice the frequency to be determined, as described later as a separate method is.

In the second, the "main process" designated procedure is the current position the laser beam to be the center. are now at least three vectors of the same length, but different directions selected. The directions are preferably selected so that they axially symmetrically for horizontal and vertical axes are as shown in Fig. 8 is illustrated for 4 vectors. Than it will be positioned the beam in any direction and the vector Signal strength at each endpoint determined. After each Position was measured once, be a Gravity calculation the vectors with their Signal strength weighted each other. As a result, yields a new vector, the strongest in the direction Shows intensity and the amount of which a measure of the Offset distance is. is the basis of this vector the new center determined. The process can be still improve by after each measurement already a correction step of new and old Vectors is determined. This optimization increases on the one hand, the responsiveness of the system to other changes in direction are smooth designed, as is easily corrected after each measurement and not only after a full cycle.

In the third, the so-called "circle method", is the second in the beam direction mirror 5 in horizontal direction, a modulation frequency f and in the vertical direction, a modulation of the same Frequency but phase shifted by 90 degrees, embossed. Thereby, the mirror 5 performs circular movements by and the laser beam is in this way about the center modulated. By measuring the reference voltage to the Piezoelectric crystals, it is possible to determine, in angle at which the mirror 5 is straight. Now will exactly one circle through long measured continuously. The reflection signal then describes to the direction a sinusoidal contour as in FIG. 9 illustrated. The greater the amplitude, the more Next there is the beam of the center away on the reflection film. By a comparison with the Reference signal, it is possible, the individual phases assign directions and it is in the direction weakest intensity controls to the center of the to be solar panels.

In the fourth, the so-called "modulation method" is the position x of the laser beam about its Center position x_M in function of time t with a modulation frequency f in accordance with x = x_M + x₀ sin (2 nf t) modulated. Since, as shown in Fig. 10, always Part of the laser beam on the reflecting ring 20 applies, the back-reflected light with the modulated frequency f and their higher harmonics be. 11 shows the back-reflected Light intensity as a function of the position of the Laser beam onto the receiver. Is x_M exactly the in Center of the photocell 19 and x₀ smaller than the radius photocell, so take portions of the Laser beam in a vibration through both right and left on the reflector ring 20. The back-reflected light is at twice the frequency 2 f modulated. The more x_M from the center of the photocell is removed, the lower the component in 2f because on one side is the reflector ring 20 always less taken. Is x_M exactly on the edge of Photocell 20, so, in a vibration process in half the time the photo cell 19 and in the other half the time of the reflector ring 20 swept; the back-reflected is now only with the frequency f modulated and has virtually no components in the Frequency f 2. If the laser beam on the Center radius of the reflector ring 20 (r_M in Figure 6) have slipped, as occurs in the back-reflected light again a strong component at the frequency f 2 on; this component is, however, relative to the position "x_M in "Out of phase with the center of the photocell by 180 °, as the light beam at the reversal points of the oscillation encounters low reflective structures.

Thus, from the size and the phase of the component derive at frequency f 2, as well the position of the laser beam x_M with the center of the photocell 20 matches. For a control loop, for example, a lock-in amplifier or a Fourier analysis be used.

The modulation method is not limited to a dimension limited. The mirror 5, for example, in horizontal and in vertical direction with two different frequencies f₁ and f₂ modulates will. Preferably, both frequencies are significantly not rational differently and in a selected relationship to each other, to the Frequency analysis of the reflected light back exactly to be able to recognize in what way the position of the Laser beam deviates from the center of the solar cell.

In this way, in each of the above Method described optimal alignment of the achieved arrangement also maximizing Energy transfer guaranteed.