Connection unit for a fuel cell module or an electrolysis module for electrical contacting of their cells

Abstract

Connection unit (20) for an energy conversion module (10) designed as a fuel cell module or electrolysis module, which has a plurality of chemical cells (12) arranged to form a stack (11) and an electronic module (14) for connecting the chemical cells (12) to a higher-level system, controlling the chemical cells (12) and / or acquiring measurement data from the chemical cells (12), wherein the connection unit (20) is designed to electrically connect contacts (13) provided on the chemical cells (12) to the electronic module (14), characterized in that the connection unit (20) has at least one cell contacting unit (23) for electrically contacting at least one contact (13) provided on the cells (12), a module contacting unit (24) for electrically contacting the electronic module (14) and a connector (21) electrically contacting these with one another, wherein the connector (21) has at least one flexible tolerance compensation section (22A, 22B) which is designed to allow and compensate for relative movements of the at least one cell contacting unit (23) to the module contacting unit (24) along at least one spatial axis (X, Y, Z) while maintaining the electrical contact.

Description

[0001] The invention relates to a connection unit for a fuel cell module or an electrolysis module, wherein the connection unit is designed to electrically connect electrical contacts provided on the chemical cells of such an energy conversion module to an electronic module of such an energy conversion module.

[0002] Furthermore, the invention relates to an energy conversion module which is a fuel cell module or an electrolysis module and which has a connection unit according to the invention.

[0003] Fuel cell modules and electrolysis modules are known from the prior art and both serve to convert energy based on the same electrochemistry. Electrical energy is generated or converted from hydrogen by a fuel cell or a fuel cell module comprising a plurality of fuel cells. Essentially by reversing the process, hydrogen can be generated or converted from electrical energy by an electrolysis cell or an electrolysis module comprising a plurality of electrolysis cells. Since both a fuel cell module and an electrolysis module serve to convert energy, the term "energy conversion module" is used as a generic term for fuel cell modules and electrolysis modules.

[0004] Accordingly, it should be fundamentally noted that energy conversion modules comprise a plurality of chemical cells arranged in a stack, whereby the cells are referred to as fuel cells in the context of fuel cell modules and as electrolysis cells in the context of electrolysis modules. Several stacks, which can also be referred to as stacks, can be provided per energy conversion module. Furthermore, such energy conversion modules usually have an electronic module, and preferably one electronic module per stack, which can perform various functions and, for this purpose, must be electrically connected to electrical contacts provided on the individual cells of the stack.

[0005] For example, a bipolar plate can be provided between every two cells in the stack, which can also be part of one of the cells itself. Preferably, an electrical contact is provided on each of these bipolar plates, so that a stack comprises a plurality of bipolar plates, each with a contact, which must be contacted.

[0006] So-called cell contacting units are used for this purpose, as known, for example, from the documents DE 10 2021 121 359 A1, DE 10 2021 129 432 A1, DE 10 2021 129 433 A1 and DE 10 2022 129 736 A1.

[0007] In the current state of the art, it is usually provided to connect the cell contact units, which can also be referred to as “CVP” (Cell Voltage Pickup), to the associated electronic module via rigid or flexible cables.

[0008] However, since the cables used for this purpose are comparatively expensive and heavy, this leads to high costs and a higher weight of the individual stacks or energy conversion modules.

[0009] Furthermore, when using rigid or flexible cables, a tolerance compensation between the position of the cells and the electronic module or a relative movement is possible, but this tolerance compensation or the compensation of the relative movement is indeterminate, so that it is not possible to predetermine at which point in the cable a change in the cable route leads to a tolerance compensation.

[0010] The invention is therefore based on the object of overcoming the aforementioned disadvantages and of providing a connection unit for fuel cell modules and electrolysis modules referred to as energy conversion modules or also such energy conversion modules, in which a defined tolerance compensation of the electrical connection of the contacts provided on the cells to the associated electronic module is possible while at the same time providing a lighter, more cost-effective and reliable connection.

[0011] This problem is solved by the combination of features according to claim 1.

[0012] According to the invention, a connection unit for an energy conversion module, i.e. a fuel cell module or an electrolysis module, is therefore proposed, wherein such an energy conversion module has a plurality of chemical cells arranged to form a stack and an electronics module which serves to connect the chemical cells to a higher-level system, to control the chemical cells and / or to record measurement data from the chemical cells. As already explained, the chemical cells in the context of a fuel cell module are fuel cells and the stack is therefore a fuel cell stack. Analogously, the chemical cells in the context of an electrolysis module are electrolysis cells and the stack is therefore an electrolysis stack. In this case, for example, a contact, again designed as a contact tab or contact tongue, is provided on bipolar plates of the stack or cells, which contact is in contact with the cells orthe bipolar plates or be integrally formed by them and must be connected to the electronics unit. An energy conversion module can also comprise exactly one stack and exactly one electronics module, or a plurality of stacks and at least one electronics module, with preferably exactly one electronics module being assigned to each stack.

[0013] Although exactly one contact is preferably provided per bipolar plate or per cell, two contacts per bipolar plate or per cell can alternatively be provided.

[0014] Contacts can also be designed not only as contact lugs or contact tongues, but also as contact pockets or contact openings, for example.

[0015] According to the invention, the connection unit is designed to electrically connect the contacts provided on the chemical cells to the electronic module. For this purpose, the connection unit has at least one cell contacting unit for electrically contacting the at least one contact, a module contacting unit for electrically contacting the electronic module, and a connector that electrically contacts these two units. The cell contacting unit, which can also be referred to herein as a CVP, can be simply understood as a plug-in connector that can be plugged onto the contacts provided on the cells or plugged into the contacts.

[0016] According to the invention, the connector has at least one flexible tolerance compensation section, which is designed to allow and compensate for relative movements of the at least one cell contact unit and the module contact unit relative to one another along at least one spatial axis while maintaining electrical contact. For clarification, three mutually orthogonal spatial axes are assumed, wherein the tolerance compensation section enables the relative movement of the at least one cell contact unit and the module contact unit along at least one of the spatial axes, but preferably along at least or exactly two of the spatial axes.

[0017] The flexible tolerance compensation section preferably forms only a partial area of ​​the connector, so that the entire connector cannot be understood as a tolerance compensation section.

[0018] In addition, the flexible tolerance compensation section is preferably designed to change its spatial arrangement or its course in a predetermined manner and preferably in a predetermined direction in the event of a relative movement compensated by it.

[0019] In this case, the flexible tolerance compensation section can be deformed elastically and / or plastically, but with essentially no change in its electrical properties and, in particular, without damage.

[0020] A particularly advantageous development provides that the connector is formed, at least in sections, by a flexible printed circuit board, the conductor tracks of which are designed to electrically connect the at least one cell contacting unit and the module contacting unit. Preferably, at least one of the tolerance compensation sections and preferably all tolerance compensation sections are formed by a flexible printed circuit board.

[0021] Although the connector is preferably formed entirely by a flexible circuit board, it can be formed in sections by a rigid circuit board or other rigid components, with the sections formed by flexible circuit boards extending from this. For example, the collecting section mentioned below can be formed by a rigid circuit board, with the tolerance compensation sections formed by flexible circuit boards extending away from this and contacting the rigid circuit board. This can, in turn, be realized using one of the connection techniques mentioned below.

[0022] Regardless of whether the connector is formed entirely by a flexible circuit board or partially by flexible and rigid circuit boards, it can also be provided that additional electronic components are arranged and electrically contacted on the connector. For example, electronic components such as resistors, capacitors, or ICs can be provided on the collecting section of the connector already mentioned and explained below. These components are designed to evaluate, amplify, or prepare for further processing the electrical signals exchanged between the electronic module and the contacts provided on the cells.

[0023] Further preferably, the connector has an S-shaped or Z-shaped profile in the tolerance compensation sections, so that the at least one tolerance compensation section can be formed by an S-shaped or a Z-shaped profile of the connector.

[0024] For the sake of clarity, such a profile is stamped onto the connector at least in the area of ​​the at least one tolerance compensation section, so that the profile is maintained even without forces applied from the outside to the connector or the tolerance compensation sections.

[0025] If the at least one tolerance compensation section is formed by a flexible printed circuit board, it also applies here that the S- or Z-shaped course is not realized by the flexible properties of the printed circuit board, but the flexible printed circuit board preferably already has the S- or Z-shaped course in its force-free basic position.

[0026] Furthermore, the connector preferably has a collecting section, a first tolerance compensation section extending from the collecting section to the module contacting unit and a plurality of second tolerance compensation sections which extend in particular parallel to one another and further in particular adjacent to one another from the collecting section to a respective cell contacting unit.

[0027] Although preferably a second tolerance compensation section extending to each cell contacting unit can be provided, alternatively two or more separate tolerance compensation sections can extend to a common cell contacting unit, so that additional decoupling is possible and, for example, a twist about an axis along which the second tolerance compensation sections extend can be compensated.

[0028] Based on this, it can be provided that the relative movements made possible by the second tolerance compensation sections are independent of one another.

[0029] Additionally or alternatively, the first tolerance compensation section is configured to enable a first relative movement along a first spatial axis, wherein the second tolerance compensation sections are each configured to enable a second relative movement along a second spatial axis orthogonal to the first spatial axis. Both can also enable a relative movement along a common third spatial axis, which is preferably orthogonal to the first and second spatial axes.

[0030] To enable a defined arrangement and simple fixation of the connector to the stack or to the cells, it is preferably provided that the connector has a carrier for connection to the stack, which preferably accommodates the collecting section of the connector and, for example, holds it in a single plane. For this purpose, corresponding connecting means can be provided on the connector and the carrier. For example, the carrier can have locking lugs on or behind which the connector can snap into place.

[0031] Such a carrier preferably has at least one first bearing body for fastening to the stack, serving as a fixed bearing, and a second bearing body for engaging, serving as a loose bearing, in a counter-body provided on the stack. The bearing bodies can preferably be arranged at opposite ends of the carrier relative to a longitudinal direction of the stack. Such a fixed-loose bearing configuration allows the individual cells of the stack to move relative to one another in the longitudinal direction of the stack, with the loose bearing compensating for the movement on the carrier and consequently on the connector.

[0032] The fixed bearing can be designed as a fixation and its first bearing body can therefore be designed, for example, as a locking mechanism, but also as a screw connection.

[0033] The loose bearing preferably provides that the counter body on the stack determines a defined path of movement along which the second bearing body can move or shift.

[0034] A particularly advantageous development provides that the connector is connected to the at least one cell contact unit and / or to the module contact unit by a respective zero-insertion force connector. Such zero-insertion force connectors, also referred to as ZIF (Zero Insertion Force) connectors, can be implemented, for example, by two contact plates that can be fixed to one another, between which a designated contact section of the connector can be inserted.

[0035] The connector can be connected or contacted with both the at least one cell contacting unit and the module contacting unit via such a zero-force plug connection.

[0036] Instead of a zero-force plug connection, the connector or its individual contacts can be connected to the at least one cell contact unit and / or to the module contact unit using an alternative connection technology. Examples of such alternative connection technologies include ACF bonding, laser soldering, crimping, or conductive rubber bonding.

[0037] Preferably, the connector is connected to the at least one cell contacting unit by a respective zero-force plug connection and to the module contacting unit by one of the mentioned alternative connection techniques.

[0038] The module contact unit can be designed as a rigid or flexible circuit board on which the electronic module or individual components forming the electronic module can be arranged and contacted. If the electronic module is a simple interface module for connecting the chemical cells to a higher-level system, a plug connection forming the interface module can, for example, be soldered onto a circuit board forming the module contact unit.

[0039] Alternatively, however, the module contacting unit can also be formed integrally by an end-side contact section of the connector or the first tolerance compensation section of the connector extending from the collecting section to the module contacting unit, which can then be contacted with the electronic module and in particular a printed circuit board of the electronic module, for example by a zero-force connection or the alternative connection techniques mentioned.

[0040] The at least one cell contacting unit preferably has a connecting body for connection to the connector and contact elements that protrude from the connecting body in a plug-in direction and correspond to the contacts of the cells. The connecting body can be, for example, a printed circuit board or a housing that at least partially encloses a printed circuit board. The contact elements are further configured to enable relative movements with respect to the contacts of the cells transversely to the plug-in direction.

[0041] In order to enable such a relative movement of the cell contacting unit with respect to the stack or its cells or the contacts of the cells, the contact elements can be designed as loop contacts which widen transversely to the plugging direction towards their end facing away from the connecting body and form an eyelet-shaped spring section so that they can continue to rest resiliently against the contact with the spring section even in the event of a corresponding movement.

[0042] Alternatively, the contact elements can be configured as at least two, and in particular three, contact fingers each, which correspond to a contact tongue serving as a contact for a cell and are configured to rest against two opposite sides of the contact tongue and resiliently clamp them between them. If two or an even number of contact fingers are provided, they preferably lie opposite one another on the contact tongue. If three or an odd number of contact fingers are provided, they preferably lie alternately on the two opposite sides.

[0043] These functional principles can also be inverted, so that, for example, the contact elements are each a contact tongue which corresponds to at least two contact fingers serving as a contact of a cell and is designed to rest resiliently on the contact fingers on their two opposite sides.

[0044] The connection unit preferably has a plurality of cell contacting units, each of which is configured to electrically contact the contacts of precisely one cell or to contact the contacts of precisely one group of cells. It should be noted that the cells of a stack are preferably divided into several groups, and furthermore, each group of cells preferably has exactly one cell contacting unit for contacting its cells.

[0045] A further aspect of the invention relates to an energy conversion module, which is a fuel cell module or an electrolysis module. As already explained, such an energy conversion module comprises a plurality of chemical cells arranged in a stack and an electronics module for connecting the chemical cells to a higher-level system, for controlling the chemical cells, and / or for acquiring measurement data from the chemical cells. Furthermore, the energy conversion module according to the invention comprises a connection unit designed to electrically connect contacts provided on the chemical cells to the electronics module.Furthermore, such a connection unit, which is preferably a connection unit proposed according to the invention, comprises at least one cell contacting unit for electrically contacting the contacts provided on at least one cell, a module contacting unit for electrically contacting the electronic module, and a connector electrically connecting them to one another. The connector comprises at least one flexible tolerance compensation section, which is designed to allow and compensate for relative movements of the at least one cell contacting unit and the module contacting unit relative to one another along at least one spatial axis while maintaining electrical contact.

[0046] Although such an energy conversion module preferably has exactly one stack, it can alternatively also have several stacks, which can be connected in series or parallel to one another.

[0047] All of the above-mentioned features relating to the connection unit also apply to the energy conversion module with a connection unit proposed according to the invention.

[0048] The features disclosed above can be combined as desired, as long as this is technically possible and they do not contradict each other.

[0049] Other advantageous developments of the invention are characterized in the subclaims or are presented in more detail below together with the description of the preferred embodiment of the invention with reference to the figures. They show: Fig. 1 a connection unit with an associated electronic module; Fig. 2 a connector of a connection unit; Fig. 3 an energy conversion module; Fig. 4 a first variant of a cell contacting unit; Fig. 5 contact elements of the first variant of the cell contacting unit; Fig. 6 a second variant of a cell contacting unit; Fig. 7 contact elements of the second variant of the cell contacting unit; Fig. 8 a fixed-loose bearing configuration according to Fig. 3; Fig. 9 Loose bearings of the fixed-loose bearing configuration according to Fig. 8.

[0050] The figures are schematic examples. Like reference numerals in the figures indicate like functional and / or structural features.

[0051] In an energy conversion module 10 designed as a fuel cell module or as an electrolysis module, as in Fig. 3, a plurality of chemical cells 12 are arranged in a stack 14. For example, to monitor the individual cells 12, a voltage must be measured at them. For this purpose, contacts 13 in a fixed-loose-bearing configuration are provided on the cells 12, which must be connected accordingly to a unit for measuring data acquisition. As such a unit, the energy conversion module 10 has an electronics module 14, which can also fulfill additional or alternative functions. The electronics module 14 can thus be designed to connect the chemical cells 12 to a higher-level system, to control the chemical cells 12 and / or to measure data from the chemical cells 12, as well as to evaluate the measured data.

[0052] Accordingly, the electronic module 14 must be electrically connected to the contacts 13 of the cells 12, for which purpose in the prior art mostly rigid or alternatively substantially completely flexible connectors are selected.

[0053] In the production of energy conversion modules 10, it has been shown that individual, small manufacturing tolerances of the cells can add up during the arrangement into a stack, such that the usual rigid connectors and in some cases also the flexible connectors can no longer contact all contacts as intended.

[0054] In addition, it has been shown that during practical use of the energy conversion modules 10, a relative movement of the components of the energy conversion module 10 can occur due to the chemical effects that occur, due to material aging, but also due to an external force, as a result of which a permanent and secure electrical connection of the electronic module 14 with the contacts 13 can often not be guaranteed with the connectors known in the prior art.

[0055] The connection unit 20 according to the invention enables such a relative movement and thus also tolerance compensation.

[0056] In Fig. 1 shows, by way of example, a connection unit 20 which has a plurality of cell contacting units 23 and electrically connects these to an electronic module 14, which itself is not part of the actual connection unit 20. Rather, the connection unit 20 has a module contacting unit 24, which in this case is formed by a rigid printed circuit board to which the electronic module 14 is contacted.

[0057] Alternatively, and as for example in Fig. 2, the module contacting unit 24 can also be formed by a contact section which can be connected and electrically contacted with a printed circuit board belonging to the electronic module 14, for example by means of a zero contact connection or by other connection techniques.

[0058] Furthermore, according to the invention, the connection unit 20 has a connector 21 which enables tolerance and movement compensation. For this purpose, the connector 21 has at least one and, according to the variants shown in the figures, several tolerance compensation sections 22A, 22B which are designed to allow and compensate for relative movements of the cell contacting units 23, i.e. the cells 12 or their contacts 13 with which the cell contacting units 23 are contacted, to the module contacting unit 24, i.e. the electronic module 14 with which the module contacting unit 24 is contacted, along at least one of three spatial axes X, Y, Z while maintaining the electrical contact.

[0059] For this purpose, the connector 21 is formed by a flexible printed circuit board which has a collecting section 22C and a plurality of first tolerance compensation sections 22A extending from the collecting section 22C to a respective cell contacting unit 23, as well as a second tolerance compensation section 22B extending from the collecting section 22C to the module contacting unit 24.

[0060] The tolerance compensation sections 22A, 22B each have an S-shaped or Z-shaped profile, so that movement in two spatial directions can be compensated. Because the second tolerance compensation sections 22B extend parallel to one another and orthogonally to the first tolerance compensation section 22A, they enable or compensate for relative movement along the Y-spatial axis and the X-spatial axis, whereas the first tolerance compensation section 22A enables or compensates for relative movement along the Z-spatial axis and the Y-spatial axis, so that relative movements and tolerance compensation are realized along all mutually orthogonal spatial axes X, Y, Z.

[0061] Since the connector 21 is essentially realized by a flexible printed circuit board, additional electronic components 32 can be contacted with it and preferably provided in the region of the collecting section 22C.

[0062] In Fig. 2, the connector 21 is shown insulated and without the cell contact units 23, whereby in the Fig. 2, the module contacting unit 24 is formed by an end-side contact section on which electrical contacts are provided for contacting the module contacting unit 24.

[0063] For all figures shown, the connector 21 has zero-force connectors 27, as shown by way of example in Fig. 4, with the individual cell contacting units 23, but additionally or alternatively with the module contacting unit 24 or also directly with the electronic module 14, which significantly simplifies assembly.

[0064] As already explained, in Fig. 3 shows an energy conversion module 10 with its chemical cells 12 arranged in a stack 11. Although the energy conversion module 10 is specifically a fuel cell module and serves to convert hydrogen into electrical energy, or an electrolysis module and serves to convert electrical energy into hydrogen, it can be left open whether in Fig. 3 shows a fuel cell module or an electrolysis module.

[0065] Rather, with regard to the Fig. 3, it is essential that the energy conversion module 10 comprises a connection unit 20 according to the invention, which electrically contacts the contacts 13 provided on the cells 12 with the electronic module 14 and thereby allows and compensates for relative movements between the components.

[0066] For this purpose, the connection unit 20 has a carrier 25 on which the connector 21 and in particular the collecting section 22C of the connector 21 is fixed. The carrier 25 has a first bearing body 26A serving as a fixed bearing, with which the carrier 25 is fixed to the stack 11 on a side of the stack 11 facing away from the electronic module 14.

[0067] Furthermore, the carrier 25 has a second bearing body 26B, which engages with a corresponding counterbody 16 provided on the stack 11 and designed as a guide. If a relative movement or tolerance compensation occurs along the Z spatial axis, the second bearing body 26B is guided as a loose bearing in the counterbody 16, so that the connection unit compensates for this.

[0068] In Fig. 4 is a first variant of a cell contacting unit 23 and in Fig. 5 shows a contact element of such a cell contacting unit 23 designed as a contact finger 29.

[0069] The same applies to Fig. 6 that a second variant of a cell contacting unit 23 as well as in Fig. 7 shows a contact element of such a cell contacting unit 23 designed as a loop contact 30.

[0070] In each case, the cell contacting units 23 are also designed to allow tolerance compensation and relative movement.

[0071] The first variant according to Fig. 4 provides that contact elements 28 extend in the plugging direction S from a connecting body 28, which are designed as contact fingers 29.

[0072] The contact fingers 29 alternately engage a respective contact 13 designed as a contact tongue, so that the contact tongue or contact 13 is resiliently held between the contact fingers 29. This allows a displacement of the contact elements 29 transversely to the plug-in direction S on the contacts 13 and thus a tolerance compensation and a relative movement, wherein the displacement is limited by a housing surrounding the contact fingers 29 in the circumferential direction around the plug-in direction S.

[0073] According to the Fig. 6 and Fig. In the variant shown in Figure 7, loop contacts 30 extend in the plugging direction S from the connecting body 28, which loop contacts 30 increasingly widen in the stretching direction S and form an eyelet-shaped spring section 31 in an end section spaced from the connecting body 28, with which they bear against the contact 13, establishing an electrical connection. This in turn creates a displaceability transverse to the plugging direction S, which enables tolerance compensation and permits relative movement, which is also spring-reset by the loop contacts 30.

[0074] In the Fig. 8 and Fig. 9 is the Fig. 3 already explained fixed-loose bearing configuration is shown again in detail, whereby the already explained applies analogously.

[0075] Accordingly, the connection unit 20 is designed to enable tolerance compensation along the Z spatial axis, wherein the support 25 of the connection unit 20 has, for this purpose, a first bearing body 26A serving as a fixed bearing on a side facing away from the electronics module 14. This fixed bearing can be implemented, for example, as a latching or screw connection.

[0076] On the side facing the electronic module 14, the carrier 25 further comprises a second bearing body 26B, as shown by way of example in Fig. 9. The second bearing body 26B is designed in the present case as a cylinder or pin extending in the X-spatial axis, which corresponds to the counter body 16 provided on the stack 11, wherein the counter body 16 is designed as a double-sided guide for the bearing body 26B and the latter is guided accordingly along the Z-spatial axis.

[0077] In the event of an extension or displacement, the second bearing body 26B can move along the Z spatial axis guided by the counter body 16, so that relative movements or tolerance compensation along the Z spatial axis are possible. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This 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

[0000] DE 10 2021 121 359 A1

[0006] DE 10 2021 129 432 A1

[0006] DE 10 2021 129 433 A1

[0006] DE 10 2022 129 736 A1

[0006]

Claims

[1] Connection unit (20) for an energy conversion module (10) designed as a fuel cell module or electrolysis module, which has a plurality of chemical cells (12) arranged to form a stack (11) and an electronic module (14) for connecting the chemical cells (12) to a higher-level system, controlling the chemical cells (12) and / or acquiring measurement data from the chemical cells (12), wherein the connection unit (20) is designed to electrically connect contacts (13) provided on the chemical cells (12) to the electronic module (14), characterized by , that the connection unit (20) has at least one cell contacting unit (23) for electrically contacting at least one contact (13) provided on the cells (12), a module contacting unit (24) for electrically contacting the electronic module (14) and a connector (21) electrically contacting these with one another, wherein the connector (21) has at least one flexible tolerance compensation section (22A, 22B) which is designed to allow and compensate for relative movements of the at least one cell contacting unit (23) to the module contacting unit (24) along at least one spatial axis (X, Y, Z) while maintaining the electrical contact. [2] Connection unit according to claim 1, wherein the connector (21) is formed at least in sections by a flexible printed circuit board, the conductor tracks of which are designed to electrically connect the at least one cell contacting unit (23) and the module contacting unit (24) to one another. [3] Connection unit according to claim 1 or 2, wherein the at least one tolerance compensation section (22A, 22B) is formed by an S-shaped or a Z-shaped course of the connector (21). [4] Connection unit according to one of the preceding claims, wherein the connector (21) has a collecting section (22C), a first tolerance compensation section (22A) extending from the collecting section (22C) to the module contacting unit (24) and a plurality of second tolerance compensation sections (22B) which extend from the collecting section (22C) to a respective cell contacting unit (23). [5] Connection unit according to the preceding claim, wherein the relative movements enabled by the second tolerance compensation sections (22B) are independent of each other and / or wherein the first tolerance compensation section (22A) is designed to enable a first relative movement along a first spatial axis, and the second tolerance compensation sections (22B) are each designed to enable a second relative movement along a second spatial axis orthogonal to the first spatial axis. [6] Connection unit according to one of the preceding claims, wherein the connector (21) has a carrier (25) for connection to the stack (11), which has at least a first bearing body (26A) for fastening to the stack (11) serving as a fixed bearing and a second bearing body (26B) for engaging, serving as a loose bearing, in a counter-body (16) provided on the stack (11). [7] Connection unit according to one of the preceding claims, wherein the connector (21) is connected to the at least one cell contacting unit (23) and / or to the module contacting unit (24) by a zero-force plug connection (27). [8] Connection unit according to one of the preceding claims, wherein the at least one cell contacting unit (23) has a connecting body (28) for connection to the connector (21) and contact elements (29, 30) protruding from the connecting body (28) in a plugging direction (S) and corresponding to the contacts (13) of the cells (12), wherein the contact elements (29, 30) are designed to enable relative movements with respect to the contacts (13) of the cells (12) transversely to the plugging direction (S). [9] Connection unit according to the preceding claim, wherein the contact elements are designed as loop contacts (30) which widen transversely to the plug-in direction (S) towards their end facing away from the connecting body (28) and form an eyelet-shaped spring section (31), or wherein the contact elements are each at least two contact fingers (29) which correspond to a contact tongue serving as a contact (13) of a cell (12) and are designed to bear against two opposite sides of the contact tongue and to clamp them resiliently between them, or wherein the contact elements are each a contact tongue which corresponds to at least two contact fingers serving as a contact of a cell (12) and are designed to rest resiliently on the contact fingers on their two opposite sides. [10] Connection unit according to one of the preceding claims, comprising a plurality of cell contacting units (23), each of which is designed to electrically contact the contacts (13) of exactly one cell (12) or to contact the contacts (13) of exactly one group of cells (12). [11] Energy conversion module (10), which is a fuel cell module or an electrolysis module, with a plurality of chemical cells (12) arranged to form a stack (11) and an electronic module (14) for connecting the chemical cells (12) to a higher-level system, controlling the chemical cells (12) and / or acquiring measurement data from the chemical cells (12), and with a connection unit (20) which is designed to electrically connect contacts (13) provided on the chemical cells (12) to the electronic module (14), characterized by , that the connection unit (20) comprises at least one cell contacting unit (23) for electrically contacting the contacts (13) provided on at least one cell (12), a module contacting unit (24) for electrically contacting the electronic module (14) and a connector (21) electrically connecting them to one another, wherein the connector (21) has at least one flexible tolerance compensation section (22A, 22B) which is designed to allow and compensate for relative movements of the at least one cell contacting unit (23) and the module contacting unit (24) to one another along at least one spatial axis (X, Y, Z) while maintaining the electrical contact.

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