DE102017205841A1 - Method for operating a solar energy device of a motor vehicle and motor vehicle - Google Patents

Abstract

Method for operating a solar energy device (7) of a motor vehicle (2) which comprises at least one solar cell (15) with a converter device (10) to which a control unit (11) is assigned for setting a maximum power point, the motor vehicle (2) at least an optical environment sensor, in particular a camera, wherein by evaluating image data of the optical motion sensor, the solar device in the future sweeping shadows (5, 5 ') are detected, the movement of the shadow (5, 5') relative to the motor vehicle (2) for calculating a predefined shading period for each solar cell (15) is calculated in advance and the control unit (11) is designed to lower the power point at the beginning of a predefined shading period.

Description

The invention relates to a method for operating a solar energy device of a motor vehicle, comprising at least one solar cell with a converter device, which is assigned a control unit for setting a maximum power point, wherein the motor vehicle comprises at least one optical environment sensor, in particular a camera. In addition, the invention relates to a motor vehicle.

In the prior art motor vehicles have been proposed, which can use a motor vehicle own solar energy device with usually several solar cells for the production of electrical energy. It has been proposed, for example, to arrange the solar energy device on the roof side of the motor vehicle ("solar roof"). Usually, a solar energy device thus comprises a plurality of individual solar cells for generating electric current. In this case, in a parallel circuit, an addition of currents occurs while the voltage remains lower, while adding the voltages in a series circuit.

Problems arise in such motor vehicles with solar energy devices, in particular, when shadowing of solar cells occur that reduce the performance of the solar energy device. When driving through a shadow, one or more solar cells of the solar energy device are covered, which may happen that they are non-conductive and in the worst case, for example in a series connection, the entire solar module is blocked. As a result, a break-in from full power, for example 300 W, to 0 W can take place within the shortest possible time.

In order always to achieve optimum, and thus maximum, performance, a so-called MPP control is known in the prior art. The abbreviation MPP stands for "Maximum Power Point", ie the maximum power point. The MPP control is a method in which the electrical load of a solar cell is adjusted so that the associated solar energy device, the largest possible power can be taken, the optimal operating point MPP is not constant, but among other things on the irradiance, the temperature the solar cell and the type of solar cell depends.

The setting of the optimum operating point and the ongoing tracking of the MPP is achieved by a control unit, for example an electronic circuit, which is assigned to a converter device of the solar cell. In general, it can be said that the largest possible power can be taken from a source when the internal resistance of the source, in this case the solar cell, is equal to an optimum value dependent on the external load resistance. Thus, in the converter device associated with the solar cell, the load resistance is influenced or tracked by the control unit in such a way that it produces the optimum relationship for the solar cell as precisely as possible and thus optimizes the power output under different operating conditions. There are various possibilities to implement the MPP control concretely, for example, iterative search methods and the like.

A problem with regard to the MPP control is that the current in the current-voltage curve or the power subsequently falls significantly below the MPP. This means for the shading of a solar cell that when a solar cell has just been heavily irradiated, usually a high voltage is applied, so that their sudden shading performance can actually drop to zero. In a series connection of solar cells, this is particularly problematic.

The known MPP regulations in the converter devices must again look for the optimal power point in such shading, which may take some time due to the strong differences in the irradiances. This is highly relevant in motorized vehicles in particular since frequently changing light / shadow can occur, for example, when the motor vehicle moves along a tree-lined road or frequent, high trucks on the oncoming lane lead to repetitive short-term shadows to which the MPP Regulation too slow follows. This can lead to a large reduction in the amount of energy consumed.

DE 10 2009 056 198 A1 relates to a method for operating a solar system arranged on a motor vehicle, which comprises a plurality of solar cells for generating electrical current. There it is proposed to electrically shadow solar cells individually or in groups for the duration of the shutdown, for which purpose bypass diodes can be used. In this way, however, a complete bridging / shading, so that even the residual light remaining in the shading can not even be used to generate electrical energy.

The invention is therefore based on the object to provide a higher energy yield permitting operating method for solar energy systems on motor vehicles in shading cases, especially in the case of fast and / or frequently changing irradiation intensities of individual solar cells.

To achieve this object, the invention provides, in a method of the type mentioned above, that the solar device will be detected by evaluating image data of the ambient optical sensor in the future, the movement of the shadow is precalculated relative to the motor vehicle for determining a predefined shading period for each solar cell and the control unit is designed to lower the power point at the beginning of a predefined shading period.

In other words, an optical environment sensor system, for example a front camera, of the motor vehicle is used to specify when the shading will occur in the future in order to already predictively achieve a maximum power point (MPP) adjustment. In other words, the predictive information, hence the shading period, is used to extend the MPP control strategy of the solar energy device, and thus the operation of the control unit of the converter device, into a predictive MPP control strategy which no longer only optimizes the currently optimal performance as an optimization criterion. but maximizing the amount of energy over a period of time over which additional information is available. Thus, taking into account the information that one or more shadows will shortly reduce the performance of the solar energy device, it can be ensured that the solar energy device or the at least one solar cell immediately moves to an adapted power point which determines the recording power for the detected shadow (reduced irradiance ) and, after passing through the shadow in an advantageous embodiment of the present invention, immediately jump back to the optimum power point without any shadow effect. This provides a much faster adjustment to changes in irradiance due to shadows. Power failures can be avoided and the solar system used is used better and more economically. In particular, by adjusting the maximum power point at the beginning and at the end of a shading period, a faster finding of the actual new maximum power point within the scope of the usual control is possible, since a better starting point is given. This results in a significant increase in the total energy output of the solar energy system on roads with shading.

In particular, image processing algorithms can be applied to the image data to detect shadows. It should also be noted at this point that embodiments are also conceivable in which a converter device and thus a control unit is assigned to a plurality of solar cells, in particular parallel-connected. Such an arrangement of parallel-connected solar cells can also be referred to as a solar module.

In this case, and in particular also during the tracking of a shadow, already known image processing algorithms and / or post-processing algorithms can be used fundamentally in the prior art. If, therefore, a shadow is detected in the image data, it can also be tracked by means of suitable tracking algorithms, so that movement information regarding the shadow can already result therefrom. For prediction of the movement of the shadow, additionally or alternatively, the known and / or predicted and / or predicted movement of the motor vehicle can be taken into account as movement information. It is of course assumed that the position of the solar cells on the motor vehicle is known, so that it can be taken into account accordingly if a shading period is to be predicted.

As already mentioned, known image processing algorithms and / or tracking algorithms and / or further evaluation algorithms can be used in the context of the present invention, adapted to shadows or static objects. In particular, a shadow, when viewed as an object, can be regarded as a kind of collision object for predicting shadowing, as is known, for example, from corresponding collision-calculating security systems. Accordingly, collision algorithms known in the context of the collision calculation can also be included in the prediction. After the shadow course on the motor vehicle also depends on the geometry of the motor vehicle, it is otherwise expedient if a 3D model of the motor vehicle is also present and used.

Three-dimensional image data can be used as the image data, for example image data taken with a 3D camera as the ambient optical sensor, so that the removal of a shadow can be determined directly from the image data, thus three-dimensional position information relating to the shadow can be derived. However, the image data can also be at least partially two-dimensional, wherein, for example, an image sequence (optical flow) and / or additional information can be evaluated with regard to a shadow in order to determine three-dimensional position information. Additional information can be, for example, the orientation of the optical environment sensor and / or an assumption of a flat roadway and / or a height profile include digital map data. Corresponding possibilities for deriving three-dimensional position information from image data have already been described in the prior art.

It is preferred if at least one camera directed onto the apron of the motor vehicle is used as the optical environment sensor. Motor vehicles move forward in most cases, so that shadows in the run-up to the motor vehicle, which are traversed in the future, have the greatest relevance. Such shadows can be detected with a camera (front camera) directed towards the apron of the motor vehicle. Appropriately, of course, other cameras may be, for example, directed to the rear space of the motor vehicle camera whose information can be used when the motor vehicle reverses. It is also conceivable to realize a 360 ° coverage of the environment via cameras as optical environment sensors.

In an advantageous development of the invention, it can be provided that, for the detection of shadows in the image data, a classification algorithm of artificial intelligence is used, which was trained with training image data annotated with respect to shadows. Such an algorithm evaluates, for example, contrast differences due to the different illumination in the image data. However, such differences in contrast can also occur for other reasons, so that it is expedient to use artificial intelligence, in particular in the form of machine learning, in order to be able to classify objects visible in the image data as shadows. Training data of the and / or a comparable optical environment sensor are expediently used which, for example, by a person, contain annotations about where a shadow can be seen in an image. Accordingly, the artificial intelligence classification algorithm may be trained using the training data so that its parameters are adjusted to allow highly reliable detection of shadows in the image data.

A preferred embodiment provides that prior to the calculation of the shading period, a relevance criterion is evaluated for each detected shadow, which checks whether the shadow will cover the motor vehicle and / or the solar energy device, the shading periods only being determined for relevant shadows. The relevance criterion thus makes possible a type of preliminary check or rough estimate, which makes it possible to exclude shadows from more precise calculations / predictions, which do not affect the motor vehicle or, more specifically, the solar energy device at all. Specifically, it may be provided, for example, that in order to evaluate the relevance criterion, a trajectory of the shadow is spatially extrapolated in a reference system moved with the motor vehicle. For example, it is then possible to check whether the trajectory passes over a relevance region which is formed at least by the solar energy device. In particular, when future movement changes, in particular of the motor vehicle, are to be taken into account for shading periods, instead of overlapping the trajectory with the motor vehicle and / or the solar energy device, overlapping the trajectory with a tolerance range extending around the motor vehicle and / or the solar energy device be checked as a relevance area. The tolerance range is suitable to choose; in terms of a rough check the tolerance range can be defined for example by all possible changes in the movement of the motor vehicle. In particular, performance data of the motor vehicle can also be included here.

It is also particularly advantageous if a sun position information, in particular derived from the date and time, and / or a geodetic position of the motor vehicle and / or a geodetic orientation of the motor vehicle are taken into account for determining the shading period. In this way, it is thus possible, for example, to calculate the shadow origin direction, so that different heights of the shadow location can also be taken into account in the detection and prediction of the deactivation of the at least one solar cell.

In a particularly preferred embodiment, it is provided that an intensity of the shading is also determined from the image data for each shadow, the lowered power point being determined as a function of the intensity. It is also quite conceivable to consider relative intensities, for example for solar illumination, so that, for example, a contrast difference of the image data inside and outside the shadow, ideally on the same background, can be taken into account. If the shadow intensity, in particular relative to the otherwise given irradiance, is known, the predictive reduction of the feed-in power can be made even more accurate and adapted, so that an even faster adaptation to the new shading situation becomes possible.

As already indicated, it is preferred that at the end of the predicted shading period, in particular with the addition of a tolerance time, the power point is increased again. After the extent of the shadow can be determined, the length of the Shading period, ie the end of the shading time, predictable to the full power of the solar cell is made again, so that here is a power loss is minimized and a quick finding of the optimal, ie maximum power point is favored.

In an extension of the method according to the invention can be provided that in a planned parking of the motor vehicle and a number of possible parking spaces and / or parking alignments for the motor vehicle parking spaces and / or Abstellausrichtungen depending on one, in particular taking into account a sun position information, in particular derived from date and time, and / or a geodetic position of the motor vehicle, predicted shadows are evaluated for detected shadows and / or shadow-casting objects around the motor vehicle, wherein the selection of a parking space and / or a Abstellausrichtung depending on the evaluation. The basic procedure described here can thus also support the choice of a free parking space and / or a parking orientation. If several parking spaces and / or several parking orientations are available for selection, the shadow profile of the surroundings can be calculated from the information on the current position of the sun, the time of day, the geodetic position, in particular the GPS position, and the orientation (vehicle direction and inclination) of the motor vehicle. This can be a recommendation for a specific parking space and / or a certain Abstellausrichtung be given with the highest possible solar energy yield.

In addition to the method, the present invention also relates to a motor vehicle, comprising a solar energy device comprising at least one solar cell with a transducer device, which is assigned a control unit for setting a maximum power point, at least one optical environment sensor, in particular a camera, and a controller comprising the control unit for carrying out a method of the type according to the invention. All statements relating to the method according to the invention can be analogously transferred to the motor vehicle according to the invention, with which therefore also the already mentioned advantages can be obtained.

• 1 einen Ablaufplan eines Ausführungsbeispiels des erfindungsgemäßen Verfahrens,
• 2 beispielhafte Bilddaten einer Frontkamera,
• 3 eine Skizze zur Relevanz und Prädiktion von Schatten, und
• 4 ein erfindungsgemäßes Kraftfahrzeug.

Further advantages and details of the present invention will become apparent from the embodiments described below and with reference to the drawing. Showing:

• 1 a flowchart of an embodiment of the method according to the invention,
• 2 exemplary image data of a front camera,
• 3 a sketch on the relevance and prediction of shadows, and
• 4 an inventive motor vehicle.

The embodiment of the method according to the invention shown below relates to an advantageous modification of the MPP control of a solar energy device of a motor vehicle, in particular during a journey, wherein a predictive component is added by the prediction of shadowing of the usual MPP control. By way of example, the motor vehicle should have a plurality of solar cells, of which in each case a fixed number is connected in parallel to a solar module, wherein each solar module, ie the corresponding solar cells, a transducer device, as basically known, is assigned. The converter device includes a control unit which carries out the MPP control and thus also realizes a part of the method according to the invention. For the prediction of shadowing, use is made of the fact that the motor vehicle has at least one optical environment sensor, in this case at least one front camera.

Accordingly, in a step S1, image data is recorded with this front camera. These image data are evaluated in a step S2 with respect to shadows visible therein. For the detection of shadows, a classification algorithm of artificial intelligence defined by machine learning is used. Once detected shadows are tracked in subsequent images of the image data by means of a suitable tracking algorithm, so that a trajectory of the switching can be obtained. Information on the three-dimensional position of detected shadows is obtained directly from the image data in a 3D camera and can otherwise be determined by methods of optical flow and / or on the basis of additional information, as is known in principle.

2 shows an example of such an image 1 a front camera. Evidently the motor vehicle is driving 2 doing it on a street 3 at the edge of which are trees 4 are located. The shadow of the trees 4 is as a shadow 5 clearly visible on the road.

The solar energy device of the motor vehicle 2 is provided on its roof. Drives the motor vehicle 3 through the shadow 5 , At least a portion of the solar cells are covered for a period of time, so that there is less irradiance, which can lead to a loss of power due to the previously strong irradiance and the set maximum power point. In order to predict such shading periods, a further analysis of the shadows detected in the image data now takes place.

Thus, in a step S3, a relevance criterion is first checked for the detected shadows. It's about whether a detected shadow 5 the car 2 or its solar energy device concerns at all, so that if necessary shadows can be rejected as irrelevant and prove no further computational resources. This is with the help of 3 explained in more detail. In the present exemplary embodiment, the current trajectory of a detected shadow in one of the motor vehicle 2 Fixed coordinate system extrapolated as indicated by the arrow 6 is hinted at. Exemplary is another shadow 5 ' shown next to the road 3 was detected, cf. this also the arrow 6 ' , It is now considered a relevance area 8th a tolerance range around the motor vehicle 2 or the solar energy device 7 defines that considers that still movement changes of the motor vehicle can occur, which can go into the actual prediction. In the present example, the predicted trajectory of the shadow crosses 5 the motor vehicle so that it is recognized as relevant. For the shadow 5 ' this is not true; he will not be analyzed further.

In a step S4, cf. in turn 1 , then becomes a predictive shading period by relevant shadows 5 calculated. Here are the relevant shadows 5 considered as objects, similar to a collision computation, where motion information of the shadow 5 , Movement information of the motor vehicle 2 and further information will be considered. In particular, the further information also includes the geodetic position (GPS position) of the motor vehicle 2 , the sun's position and slope information of the road 3 , so that respective trajectories can be predicted and also different heights of the solar energy device 7 and the shadow location can be taken into account in detection. This exact consideration, which also considers speeds for determining the shading period, is indicated by the dashed arrow 9 in 3 indicated. The solar energy facility becomes apparent 7 ' through the shadow 5 be swept, whereby for each solar cell or at least for each solar module, a beginning and an end of the predicted shading period can be determined. By observing the relative intensity in the image data, the intensity of the shading is determined.

For each solar module, it is then checked in step S5 whether, in particular using a tolerance time, the beginning of a shading period, as predicted, has been reached. If this is the case, the maximum power point, ie the operating point, is lowered in the control unit as a function of the intensity of the shading, so that no excessive power dip occurs and the new maximum power point can be found faster in the sense of the usual MPP control, cf. , Step S6. In step S7, it is monitored whether the end of a predefined shading period exists, that is to say that in a step S8 an increase of the maximum power point, in particular to the original value, can take place.

Such a prediction of shadow movement can also be expediently used when determining a most favorable parking space and / or a most favorable parking orientation with regard to the energy yield.

4 finally shows a schematic diagram of a motor vehicle according to the invention 2 , The solar energy facility 7 is arranged on the roof side and has several solar modules 14 with parallel solar cells 15 on.

Every solar module 8th is a converter device 10 with appropriate control unit 11 which is to find the optimum operating point as maximum power point (MPP). The control units 11 use shadowing periods, that of an image processing unit 12 are delivered, the image data of the front camera 13 evaluates as an optical environment sensor. The control units 11 and the image processing unit 12 thus form a control device which carries out the inventive method.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102009056198 A1 [0008]

Claims (10)

Method for operating a solar energy device (7) of a motor vehicle (2) comprising at least one solar cell (15) with a converter device (10), to which a control unit (11) is assigned for setting a maximum power point, the motor vehicle (2) at least an optical environment sensor, in particular a camera, comprises, characterized in that by evaluating image data of the optical motion sensor, the solar device in the future sweeping shadows (5, 5 ') are detected, wherein the movement of the shadow (5, 5') relative to the motor vehicle (2) for calculating a predicted shading period for each solar cell (15) is calculated in advance and the control unit (11) is designed to lower the power point at the beginning of a predefined shading period. Method according to Claim 1 , characterized in that at least one camera (13) directed towards the apron of the motor vehicle (2) is used as the optical environment sensor. Method according to Claim 1 or 2 , characterized in that for the detection of shadows (5, 5 ') in the image data an artificial intelligence classification algorithm is used which has been trained with training image data annotated with respect to shadows (5, 5'). Method according to one of the preceding claims, characterized in that prior to the calculation of the shading period for each detected shadow (5, 5 ') a relevance criterion is evaluated, which checks whether the shadow (5, 5') the motor vehicle (2) and / or the solar energy device (7) will sweep, with the determination of the shading periods only for relevant shadows (5, 5 '). Method according to Claim 4 , characterized in that for the evaluation of the relevance criterion, a trajectory of the shadow (5, 5 ') is spatially extrapolated in a reference frame moving with the motor vehicle (2). Method according to one of the preceding claims, characterized in that for determining the Abschattungszeitraum further Sonnenstandsinformation, in particular derived from date and time, and / or a geodetic position of the motor vehicle (2) and / or a geodetic orientation of the motor vehicle (2) are considered , Method according to one of the preceding claims, characterized in that an intensity of the shading is determined from the image data for each shadow (5, 5 '), the lowered power point being determined as a function of the intensity. Method according to one of the preceding claims, characterized in that at the end of the predicted shading period, in particular with the addition of a tolerance time, the power point is increased again. Method according to one of the preceding claims, characterized in that in a planned parking of the motor vehicle (2) and a number of possible parking spaces and / or Abstellausrichtungen for the motor vehicle (2) the parking spaces and / or Abstellausrichtungen depending on one, in particular taking into account Sun position information, in particular derived from the date and time, and / or a geodetic position of the motor vehicle (2), predicted shadow profile for detected shadows (5, 5 ') and / or shadow-casting objects in the environment of the motor vehicle (2) are evaluated, the selection a parking space and / or a Abstellausrichtung depending on the evaluation. Motor vehicle (2), comprising a solar energy device (7) comprising at least one solar cell (15) with a converter device (10), which is assigned a control unit (11) for setting a maximum power point, at least one ambient optical sensor, in particular a camera, and a control device comprising the control unit (11) for carrying out a method according to one of the preceding claims.

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