Method for functional testing of a fiber optic temperature sensor for a high-voltage electric battery

Abstract

The invention relates to a method for functional control of a fiber optic temperature sensing device (20) of an electric high-voltage battery (10), wherein the high-voltage battery (10) has a battery body (12) formed by several battery cells (14) and which has a sensor surface (18), wherein the fiber optic temperature detection (20) comprises a fiber layer (22) with multiple measuring points (26) and a temperature determination module (28), which determines the measurement point temperatures for the measurement points (26) of the fiber layer (22) and from this determines a two-dimensional actual temperature pattern (M20; M20'), wherein a control module (30) is provided which is connected to the temperature sensing unit (20) via a data connection and which has an electronic pattern memory (32) with the target temperature pattern (M32; M32') and a pattern comparator (34) which checks the conformity of the actual temperature pattern (M20; M20') with the target temperature pattern (M32; M32'), including the following procedural steps: Applying the defined temperature pattern (M; M') to the sensor surface (18) of the battery body (12), and permanently applying the fiber layer (22) to the sensor outer surface (18), or vice versa, subsequently: Comparing the actual temperature pattern (M20; M20') recorded by the temperature measurement (20) at the measuring points (26) with the target temperature pattern (M32; M32').

Description

[0001] The invention relates to a method for functional testing of a fiber optic temperature sensor of an electric high-voltage battery during or after assembly of the high-voltage battery.

[0002] From DE 10 2011 002 841 A1, an electric high-voltage battery is known with a battery body formed by a plurality of battery cells, which are combined to form a battery body that is essentially prismatic in appearance. The battery body has a sensor surface, which is a side surface of the battery body and onto which a layer of fiber optics for temperature sensing is thermally conductively applied. The fiber layer has several fiber optic light guides, each with a plurality of individual measuring points, which are distributed largely uniformly over the sensor surface of the battery body. The temperature sensing system also includes a temperature determination module that determines the local temperature at the measuring points of the light guides for all measuring points by evaluating light signals introduced into the light guides.In this way, the local temperature can be determined with high accuracy at many points on the battery body using non-electrical sensors.

[0003] However, the quality and reliability of the temperature measurement depend to a large extent on the good and homogeneous thermal coupling across the entire surface between the fiber layer and the sensor surface of the battery cells, and on the quality or integrity of the mechanically sensitive optical fibers of the fiber layer.

[0004] In contrast, the object of the invention is to create a method for functional control of a fiber optic temperature measurement of an electric high-voltage battery.

[0005] This problem is solved by a method for functional control of a fiber optic temperature measurement of an electric high-voltage battery with the features of claim 1.

[0006] In this context, a high-voltage battery is defined as a battery with a nominal voltage exceeding 100 V. Damage or malfunction in such a battery can therefore lead to thermal chain reactions that must be detected as early as possible. This is made possible, in particular, by a sufficiently dense temperature monitoring system capable of detecting thermal anomalies at an early stage. Preferably, the high-voltage battery is a traction battery for an electric motor vehicle.

[0007] The high-voltage battery comprises a battery body formed by several battery cells. These battery cells can be, for example, stacked prismatic cells, cylindrical cells, or pouch cells. The battery cells are grouped together to form the battery body, which has a large sensor surface. This sensor surface is preferably composed of one surface area from each of the battery cells. The sensor surface, for example in the case of cylindrical cells, is not necessarily seamless or perfectly flat.

[0008] The fiber optic temperature measurement system comprises at least one fiber layer with multiple measuring points and a temperature determination module that optically determines the temperature of each measuring point within the fiber layer and uses this data to generate a two-dimensional actual temperature pattern. Within the fiber layer, one or more optical fibers can be arranged to create a multitude of measuring points, enabling comprehensive and sufficiently dense temperature monitoring of the entire surface of the fiber layer or the sensor surface of the battery body.

[0009] A heat pattern applicator is provided that applies a defined temperature pattern, according to a desired and stored target temperature pattern, directly or indirectly to the sensor surface. The heat pattern applicator is therefore a heat source that applies the defined temperature pattern either directly to the sensor surface of the battery body, where the fiber layer is not yet applied but is immediately applied in a thermally conductive manner.

[0010] Or the heat pattern applicator applies the defined temperature pattern directly to the fiber layer, which in turn has already been applied to the sensor surface in a thermally conductive manner over its entire surface, so that in this way the temperature pattern is only indirectly applied to the sensor surface via the fiber layer.

[0011] In principle, the defined temperature pattern or the target temperature pattern can be homogeneous across the entire surface. However, it is particularly preferred that the defined temperature pattern or the target temperature pattern be inhomogeneous, for example, checkerboard-like with alternating warm and cold zones.

[0012] A control module is provided, connected to the temperature sensor via a data link, and includes an electronic pattern memory containing the target temperature pattern and a pattern comparator. The pattern comparator checks the conformity of the actual temperature pattern with the target temperature pattern. The control module then outputs a conformance value indicating the quantitative agreement between the actual and target temperature patterns.

[0013] The defined temperature pattern refers to the temperature pattern transmitted by the heat pattern applicator at the moment of application. The actual temperature pattern refers to the two-dimensional temperature pattern detected by the fiber optic temperature sensor at the time the temperature pattern of the fiber layer already applied to the sensor surface is acquired. The application of the defined temperature pattern by the heat pattern applicator can occur several seconds or minutes before the acquisition of the actual temperature pattern.

[0014] According to a first embodiment of the method according to the invention, the heat pattern applicator first applies the defined temperature pattern directly onto the sensor surface of the battery body. Subsequently, the fiber layer of the fiber optic temperature sensor is applied directly onto the heated sensor surface in a thermally conductive connection. The temperature sensor then detects the actual temperature pattern at the measuring points, and the control module compares the detected actual temperature pattern with the target temperature pattern. Finally, the control module outputs the compliance value.

[0015] In this way, various quality parameters of the high-voltage battery can be recorded, namely the accuracy of the desired position of the fiber layer on the sensor surface, the integrity of the mechanically sensitive fiber layer including its light guides, and the quality of the heat conduction between the sensor surface of the battery body and the fiber layer of the fiber optic temperature measurement.

[0016] Preferably, the process step of applying the defined temperature pattern takes place immediately before the permanent application of the fiber layer to the sensor surface. The faster the fiber layer is applied to the sensor surface of the battery body after the application of the defined temperature pattern, the more accurately the control module can assess and classify the conformity of the actual temperature pattern with the target temperature pattern.

[0017] Alternatively, according to a second embodiment, the fiber layer can first be thermally and permanently applied to the sensor surface. Only then is the defined temperature pattern applied directly to the fiber layer and thus indirectly to the sensor surface. Subsequently, the fiber optic temperature sensor determines the two-dimensional actual temperature pattern, and the control module compares the actual temperature pattern with the target temperature pattern, so that the control module finally outputs the compliance value.

[0018] Preferably, the defined temperature pattern applied to the sensor surface is inhomogeneous in terms of area and has, for example, warm zones and cold zones arranged in a checkerboard pattern.

[0019] Preferably, a heated stamp is provided as the heat pattern applicator, through which the defined temperature pattern is applied. In this way, the defined temperature pattern can be applied very quickly and homogeneously. Alternatively, the heat pattern applicator can be a point-acting heat probe, through which the defined temperature pattern is applied successively and point by point to the sensor surface or the fiber layer.

[0020] Two embodiments of the invention will be explained in more detail below with reference to the drawings. The drawings show: Fig. 1 a first process step of a first embodiment of the method for functional control of a fiber-optic temperature measurement of an electric high-voltage battery by a temperature determination module and a control module, Fig. 2 a second process step of the first embodiment of the method, with the battery body of the high-voltage battery of the Fig. 1 with a defined temperature pattern applied directly to a sensor surface of the battery body by a heat pattern applicator, Fig. 3 the process step of comparison by the control module according to the first embodiment, with a fiber layer of the temperature determination module applied to the battery body, and Fig. 4 the process step of comparison by the control module according to a second embodiment of the method.

[0021] In the Fig. Figures 1 to 4 show a housingless high-voltage battery 10, in its assembled state, which is in the Fig. 3 and Fig. Figure 4 shows a battery body 12 consisting essentially of a prismatic body, which is composed of a plurality of individual plate-shaped and stacked battery cells 14, and a fiber layer 22 of a fiber-optic temperature sensing system 20 applied to a sensor surface 18 of the battery body 12. The high-voltage battery 10 is, for example, a traction battery of a motor vehicle and has, for example, a nominal voltage of 400 V or 800 V.

[0022] The sensor surface 18 of the battery body 12 is formed by a stack side composed of the side walls of the battery cells 14, and is therefore not formed by a single battery cell 14 at an end face of the battery body 12. The sensor surface 18 lies in a vertical plane xz.

[0023] The fiber layer 22 is applied to the sensor surface 18. This layer consists of a carrier film 23 and an optical fiber 25 applied to the carrier film 23, which in the present embodiment is laid out in a meandering pattern on the carrier film 23. The optical fiber 25 has a plurality of spaced-apart temperature measuring points 26, which are formed by defined optical inhomogeneities in the optical fiber 25. The measuring points 26 are densely distributed over the entire surface of the carrier film 23, the geometry of which corresponds to the geometry of the sensor surface 18 of the battery body 12.

[0024] An electronic temperature determination module 28 is optically connected to the fiber layer 22 or the light guide 25 and determines the temperature of all measuring points 26 of the fiber layer 22. From this, the temperature determination module 28 generates a geometric actual temperature pattern M20; M20' for the entire fiber layer 22 or the entire sensor surface 18 of the battery body 12 at short time intervals of, for example, a maximum of a few seconds.

[0025] The in the Fig. 1, Fig. 3 and Fig. The arrangement shown in Figure 4 for functional control of the fiber-optic temperature sensing system 20 of the high-voltage electric battery 10 further comprises an electronic control module 30, which is connected to the temperature determination module 28 of the temperature sensing system 20 via a data connection. The control module 30 receives the actual temperature pattern M20; M20' quasi-continuously via this data connection. The control module 30 has an electronic pattern memory 32 in which a target temperature pattern M32; M32' is stored. Furthermore, the control module 30 has a pattern comparator 34, which comparatively determines the degree of agreement between the actual temperature pattern M20; M20' and the target temperature pattern M32; M32', and sends a corresponding agreement value U resulting from this comparison to a functional control controller 90.

[0026] The in the Fig. 1 and Fig. The arrangement shown in Figure 4 further comprises a heat pattern applicator 80; 80' by which a defined temperature pattern M; M' can be applied directly to the sensor surface 18, as shown in the first embodiment, or directly to the fiber layer 22 already applied to the sensor surface 18, as shown in Figure 4. Fig. Figure 4 shows the heat pattern applicator 80 of the first embodiment of the Fig. 1 to 3 is in this case designed as a heated stamp 60 which can be moved by a stamp drive 62 in transverse direction y onto the sensor surface 18 of the battery body 20.

[0027] During a functional test cycle, the heat pattern applicator 80 imprints a checkerboard pattern of warm and cold zones onto the sensor surface 18 of the battery body 12 as a defined temperature pattern M. The heated stamp 60 is then removed from the sensor surface 18. Immediately afterward, the fiber layer 22 is permanently applied to the sensor surface 18 with good thermal coupling. Subsequently, the control module 30 compares the actual temperature pattern M20, recorded by the temperature sensor 20 at the measuring points 26, with the target temperature pattern M32 and outputs a conformance value U to the functional test controller 90.

[0028] The target temperature pattern M32 correlates with the defined temperature pattern M, but is not completely identical to it, since the defined temperature pattern M changes in a specific and reproducible manner through cooling and the application of the fiber layer 22, provided that the fiber layer 22 is completely intact, the fiber layer 22 is geometrically offset on the sensor surface 18, and the heat transfer between the sensor surface 18 of the battery body 12 and the fiber layer 22 is homogeneous and defect-free across the entire surface.

[0029] If the actual temperature pattern M20 deviates significantly from the target temperature pattern M32, the type and magnitude of the deviation can indicate whether it is caused by a damaged fiber layer 22, a geometric misalignment of the entire fiber layer 22, or a faulty local heat transfer between the sensor surface 18 and the fiber layer 22. This allows for highly differentiated functional testing and fault analysis.

[0030] In the Fig. In the second embodiment shown in Figure 4, the heat pattern applicator 80' is designed as a point-acting heat probe 70, which can be moved in all three spatial directions x, y, z by a special drive 75. The heat pattern applicator 80' can apply various freely programmable, defined temperature patterns M' directly to the fiber layer 22.

[0031] In the second embodiment of the Fig. 4 Before the defined temperature pattern M' is applied, the fiber layer 22 of the temperature sensing device 20 is already applied to the sensor surface 18 of the battery body 12. The defined temperature pattern M' is therefore applied directly to the fiber layer 22 and thus indirectly to the sensor surface 18 by the heat pattern applicator 80'.

[0032] The evaluation by the control module 30 then takes place in the same way as in the first embodiment of the Fig. 1-3. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2011 002 841 A1

[0002]

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