Abstract
The present invention relates to a method for operating an inductive transmission apparatus comprising a transmitting coil and a receiving coil, wherein the receiving coil is arranged in a vehicle and the transmitting coil is arranged in a fixed location, wherein the following steps are carried out: emission of a magnetic field by the transmitting coil; movement of the vehicle in the direction of a parking position, wherein the receiving coil at least partially overlaps the transmitting coil in the parking position; measurement of a magnetic flux linkage of the receiving coil; reduction in a speed of the vehicle when a first threshold value for the magnetic flux linkage through the receiving coil is exceeded; detection of undershooting of a second threshold value; detection of a point without effective magnetic flux linkage through the receiving coil.
Claims
1. A method for operating an inductive transmission apparatus (10) including a transmission coil (11) and a reception coil (12), wherein the reception coil (12) is arranged in a vehicle (13) and the transmission coil (11) is arranged at a fixed location, the method comprising: transmitting a magnetic field (15) by means of the transmission coil (11); moving the vehicle (13) in the direction of a parking position (16), wherein the reception coil (12) covers at least part of the transmission coil (11) in the parking position (16); measuring a magnetic flux passing through the reception coil (12); reducing a velocity of the vehicle (13) when a first threshold value (S1) for the magnetic flux passing through the reception coil (12) is exceeded; detecting when a second threshold value (S2) is undershot; and detecting a point (P1) without effective magnetic flux passing through the reception coil (12).
2. The method as claimed in claim 1, wherein the transmission coil (11) is arranged in the floor (14), in a wall (27) or in a ceiling (28).
3. The method as claimed in claim 1, wherein the vehicle (13) is moved in the direction of travel by a distance (17) from the point (P1) without effective magnetic flux passing through to the point (P3) at which the transmission coil (11) and the reception coil (12) are optimally oriented with respect to one another, and the vehicle (13) is stopped when a parking position (16) at the point (P3) at which at least part of the reception coil (12) is covered by the transmission coil (11) is reached.
4. The method as claimed in claim 1, wherein the vehicle (13) is moved in the direction of travel and at the same time the distance covered is measured and a second point (P2) without effective magnetic flux passing through the reception coil (12) is detected during the movement of the vehicle (13) and the vehicle (13) is stopped when the second point (P2) without effective magnetic flux passing through the reception coil (12) is reached and a distance (18) covered between point (P1) and point (P2) is ascertained, and the distance (19) to be covered contrary to the direction of travel up to the parking position (16) is calculated by halving the distance (18) and the vehicle (13) is moved contrary to the direction of travel by the distance (19) from the second point (P2) without effective magnetic flux passing through to the parking position (16) in which at least part of the reception coil (12) is covered by the transmission coil (11) at the fixed location.
5. The method as claimed in claim 1 for detecting the point (P1) without effective magnetic flux passing through the reception coil (12), wherein the undershooting of a second threshold value (S2) for the magnetic flux passing through the reception coil (12) is detected, the change of arithmetic sign of the gradient of the magnetic flux passing through the reception coil (12) is detected and the exceeding of a third threshold value (S3) for the magnetic flux passing through the reception coil (12) is detected.
6. The method as claimed in claim 4 for detecting the point (P2) without effective magnetic flux passing through the reception coil (12), wherein the undershooting of the third threshold value (S3) of the magnetic flux passing through the reception coil (12) is detected, the change of arithmetic sign of the gradient of the magnetic flux passing through the reception coil (12) is detected and the exceeding of the second threshold value (S2) of the magnetic flux passing through the reception coil (12) is detected.
7. The method as claimed in claim 4, wherein the interval (31) between the point (P1) and the point (P2) of the transmission coil (11) is queried from a database (30), the ascertained distance (18) is compared with the interval (31) ascertained from the database (30) and a difference (32) is ascertained, and the parking process is repeated if a fourth threshold value (S4) is exceeded by the magnitude of the difference (32).
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Further features and advantages of the present invention will become evident to a person skilled in the art from the description that follows of exemplary embodiments, which are not intended to be interpreted as restricting the invention, however, with reference to the accompanying drawings.
[0018] In the drawings:
[0019] FIG. 1: shows a schematic depiction of the method according to the invention,
[0020] FIG. 2: shows a schematic depiction of the method according to the invention,
[0021] FIG. 3: shows a schematic depiction of the method according to the invention,
[0022] FIG. 4: shows a schematic depiction of an electrically driven vehicle having an inductive transmission system, consisting of a transmission coil and a reception coil,
[0023] FIG. 5: shows a schematic depiction of the field of a transmission coil and the velocity of the vehicle until it is at a standstill in the parking position when a point without effective magnetic flux passing through the reception coil is used,
[0024] FIG. 6: shows a schematic depiction of the field of a transmission coil and the velocity of the vehicle until it is at a standstill in the parking position when two points without effective magnetic flux passing through the reception coil are used.
DETAILED DESCRIPTION
[0025] All the figures are merely schematic depictions of the method according to the invention or of an exemplary embodiment of a vehicle equipped according to the invention. In particular intervals and magnitude relationships are not reproduced to scale in the figures. Corresponding elements are provided with the same reference numerals in the various figures.
[0026] FIG. 1 shows a schematic depiction of the method according to the invention. In the first step 100, a magnetic field 15 is transmitted by the transmission coil 11. In the second step 200, the vehicle 13 moves in the direction of the parking position 16. In the third step 300, the magnetic flux passing through the reception coil 12 is measured. The vehicle 13 moves on unchanged in this step 300. In the fourth step 400, the exceeding of the first threshold value S1 of the magnetic flux passing through the reception coil is detected. In this step 400, the velocity of travel of the vehicle 13 is reduced to the extent that the vehicle 13 can be stopped when the point P3 is reached. In the fifth step 500, the undershooting of the second threshold value S2 of the magnetic flux passing through the reception coil 12 is detected. The vehicle 13 moves on unchanged in this step 500. In the sixth step 600, the point P1 without effective magnetic flux passing through is detected.
[0027] FIG. 2 shows a schematic depiction of the method according to the invention, which follows the method shown in FIG. 1. In the first step 610, the vehicle 13 moves on unchanged, while for example wheel sensors are used to record the distance 17 covered between the points P1 and P3. In the second step 620, the distance measurement is used to detect when the distance 17 between the points P1 and P3 has been covered completely, and the vehicle 13 is stopped in its parking position 16 at the point P3 with the maximum effective magnetic flux passing through. The vehicle 13 has then reached the point P3 with the maximum effective flux passing through the reception coil 12 in a correct orientation and can be charged with an optimum coupling factor and hence high efficiency. This likewise applies to bidirectional use of the inductive transmission device for charging the vehicle battery and for feeding back electric power from the vehicle battery to the supply grid. Performing this method requires knowledge of the distance 17 between the points P1 and P3. This information may be present in the vehicle 13 or can be communicated to the vehicle 13 by the transmission coil 11 by means of a suitable communication device.
[0028] FIG. 3 shows a schematic depiction of the method according to the invention, which follows the method shown in FIG. 1. In the first step 710, the vehicle 13 moves on unchanged, while for example wheel sensors are used to record the distance 18 covered between the points P1 and P2. In the second step 720, the exceeding of the third threshold value S3 of the magnetic flux passing through the reception coil 12 is detected. The vehicle 13 moves on unchanged in this step 720. In the third step 730, the undershooting of the third threshold value S3 of the magnetic flux passing through the reception coil 12 is detected. The vehicle 13 is slowed down from the detection of the third threshold value S3 in this step 730. In the fourth step 740, a second point P2 without magnetic flux passing through the reception coil 12 is detected. The vehicle is stopped. The distance 18 between the points P1 and P2, which is ascertained between the first point P1 without magnetic flux passing through the reception coil 12 and the second point P2 without magnetic flux passing through the reception coil 12, is halved and the distance 19 between the points P2 and P3 is ascertained. In the fifth step 750, the vehicle 13 reverses contrary to the direction of travel by this distance 19 between the points P2 and P3 and is stopped at the point P3 with the maximum effective magnetic flux passing through. This means that the vehicle 13 has reached the point P3 with the maximum effective flux passing through the reception coil 12 in the correct orientation and can be charged with an optimum coupling factor and hence high efficiency. This method is particularly suitable if there is no information available about the distance 17 between the points P1 and P3. This method can be used by the vehicle 13 itself to ascertain this distance 17 between the points P1 and P3 by driving over the transmission coil 11 completely. Furthermore, by driving over the transmission coil 11 completely when the distance 18 between the points P1 and P2 is known, the vehicle 13 can ascertain the lateral offset between the transmission coil 11 and the reception coil 12. If the distance measurement of the distance 18 between the points P1 and P2 by the vehicle 13 results in a value whose absolute value of the difference from the communicated or known value of the distance 18 exceeds a threshold value S4, the lateral offset between the transmission coil 11 and the reception coil 12 is too great and a new parking process for the vehicle 13 at the inductive charging station 10 can be initiated.
[0029] FIG. 4 shows a schematic depiction of a vehicle 13 having an inductive charging device 10. The vehicle is standing on a floor area 14. This floor area 14 has a recessed inductive transmission coil 11 for charging the electrical energy store of the vehicle 13. In a further embodiment, the transmission coil 11 may have been placed onto the floor area 14. The underside of the vehicle 13 has the reception coil 12 fitted, which, during a charging process, needs to be positioned in the parking position 16 with as correct an orientation as possible above the transmission coil 11 in order to achieve an optimum coupling factor and hence a good system efficiency for the inductive charging apparatus 10. The vehicle 13 and hence the reception coil 12 can be oriented above the transmission coil 11 by the driver without further tools. The vehicle 13 is oriented in the transverse direction usually by the driver. Together with a transverse tolerance for the reception coil 12 above the transmission coil 11 that is expanded by design, this is sufficiently accurate. The longitudinal orientation of the reception coil 12 above the transmission coil 11 is more difficult to implement solely by means of the wits and skills of the driver and cannot normally be carried out with sufficient accuracy by the driver without further tools. Further embodiments are obtained by means of the arrangement of the transmission coil 11 on or in a wall 27 or on or in a ceiling 28 and the corresponding arrangement of the reception coil 12 of the vehicle 13.
[0030] FIG. 5 shows a schematic depiction of the field of a transmission coil 11 and the velocity of the vehicle 13 up until it is at a standstill when a point P1 without effective magnetic flux passing through the reception coil 12 is detected. In this depiction, the vehicle 13 approaches the transmission coil 11 from the left. When the exceeding of the first threshold value S1 is detected, the velocity of travel of the vehicle 13 is reduced. Following detection of the undershooting of the second threshold value S2 and detection of the point P1 without effective magnetic flux passing through the reception coil 12, the distance measurement of the distance 17 between the points P1 and P3 is started from the point P1 without effective magnetic flux passing through the reception coil 12. Following complete coverage of the distance 17 between the points P1 and P3, the vehicle 13 is stopped in its parking position 16 at the point P3 with the maximum effective magnetic flux passing through the reception coil 12 and is parked for the charging process.
[0031] FIG. 6 shows a schematic depiction of the field of a transmission coil 11 and the velocity of the vehicle 13 up until it is at a standstill when a point P1 without effective magnetic flux passing through the reception coil 12 is detected. In this depiction, the vehicle 13 approaches the transmission coil 11 from the left. When the exceeding of the first threshold value S1 is detected, the velocity of travel of the vehicle 13 is reduced. From when the point P1 without effective magnetic flux passing through the reception coil 12 is detected, the distance measurement of the distance 18 between the points P1 and P2 is started. When the second point P2 without effective magnetic flux passing through the reception coil 12 is detected, the vehicle is stopped and the measured distance 18 is halved by computer. The vehicle 13 reverses contrary to the direction of travel by the distance 19 thus ascertained between the points P2 and P3 by the distance 19 between the points P2 and P3 and is stopped at the point P3 with the maximum effective magnetic flux passing through the reception coil 12 and is parked for the charging process. This means that the vehicle 13 has reached the point P3 with the maximum effective magnetic flux passing through the reception coil 12 in the correct orientation and can be charged with an optimum coupling factor and hence high efficiency. If the value for the distance 18 between the points P1 and P2 is known, a comparison between the measured value of the distance 18 between the points P1 and P2 and the value of the distance 18 that is known from a database 31 can be performed. If the difference between the measured distance 18 and the distance 18 known from a database 31 is greater than a fourth threshold value S4, the vehicle 13 has been positioned above the transmission coil 11 with too great a lateral offset and a new parking process for the vehicle 13 at the inductive transmission apparatus consisting of a transmission coil and a reception coil can be initiated.
