FR3131443A1 - Solar panel comprising in particular a plurality of zones of electronic components connected together by a plurality of electric cables. - Google Patents

Abstract

Solar panel comprising in particular a plurality of zones of electronic components connected together by a plurality of electrical cables The invention relates to a solar panel (10) comprising: - a base being in contact with an ambient medium and defining a front face and a rear (18); - a plurality of photovoltaic cells (14) arranged on the front face of the base; - a plurality of electronic component areas (20A,…, 20N) arranged on the rear face of the base and connected to each other by a plurality of electrical cables (22), each cable (22) comprising at least one stress area (40A,…,40D, 42A,…,42D, 44A, 44B, 46A, 46B) so that two adjacent cables have at least one pair of stress zones; the cables are arranged on the rear face of the base so that the shortest path passing through the ambient medium between each pair of stress zones is equal to at least approximately 20 mm. Figure for abstract: Fig. 2.

Description

Solar panel comprising in particular a plurality of zones of electronic components connected together by a plurality of electrical cables.

The present invention relates to a solar panel comprising in particular a plurality of zones of electronic components connected together by a plurality of electrical cables.

The invention finds particular application in the space field. Thus, the solar panel according to the invention is carried on board a spacecraft such as a satellite for example and constitutes a source of electrical power for such a craft.

Generally speaking, the satellite includes one or more solar panels, also called solar generators, which are used to power at least part of the satellite's electrical devices.

A solar panel generally has a base which defines a front face intended to be exposed to the Sun, called the sun face and a rear face opposite the front face also called the night face. The front face is equipped with photovoltaic cells which are exposed to the Sun and are capable of generating electrical energy.

The rear face includes areas of components, for example electronics, making it possible to recover the electrical energy generated by the cells and to route this energy to the satellite's electrical devices.

The electronic component areas of the solar panel are notably connected to each other by a plurality of electrical cables.

The cables are generally electrically isolated from each other by dielectric sheaths. They are also grouped into strands, or glued in a layer on the face of the panel with glue dots.

The routing of these cables on the rear side of the base is naturally done in a symmetrical and identical manner (we speak of uniqueness of wiring methodology).

According to this methodology, for example, the glue points which allow each of the cables to be glued to the rear face of the panel are aligned or sometimes confused between adjacent cables. The same goes for the points where the cables change direction, for example, which are also aligned between adjacent cables. Thus, the cables are mounted identically on the solar panel.

During the operational phase of flight, it sometimes happens that faults appear in one or more cables.

These defects originate in particular from constraints of a mechanical, thermal nature and/or from aging of the materials due to the space environment (radiative dose, UV from the sun, thermal cycling on the orbit) (possibly coupled together) which are exerted on the cables.

It was further noted that due to the uniqueness of the wiring methodology of the prior art, the stresses experienced by the panel were transferred in an identical manner to neighboring cables and therefore increased the probability of seeing the appearance of an identical fault on two adjacent cables, at the same location on these cables.

These defects weaken the cable sheaths in particular by revealing bare parts (cracks) which expose the metallic material core of the cables.

We can then understand that this considerably increases the risk of establishing a short circuit, also known as an electric arc, between different adjacent electrical cables. Such an electric arc can seriously damage or even destroy the solar panel.

The aim of the present invention is to provide a solar panel in which the risk of establishing an electric arc between different cables is considerably reduced.

To this end, the invention relates to a solar panel comprising:
- a base being in contact with an ambient environment and defining a front face and a rear face;
- a plurality of photovoltaic cells arranged on the front face of the base;
- a plurality of zones of electronic components arranged on the rear face of the base and connected together by a plurality of electrical cables, each cable comprising at least one stress zone in which stresses of a mechanical, thermal or electromagnetic nature are exerted on the cable, so that two adjacent cables have at least one pair of stress zones;
the cables are arranged on the rear face of the base so that the shortest path passing through the ambient environment between each pair of stress zones is equal to at least approximately 20 mm.

A stress zone can be a portion of cables on which stresses can be exerted.

A constraint zone can be a fixed point or fixed point of cabling, that is to say points of intervention by an operator on the cabling such as cable fixing points or cable direction change points. For example.

A stress zone can also be a connection portion between a cable and an electronic component for example.

By “shortest path” we mean the shortest distance passing through the ambient environment between each pair of constraint zones.

Thus, thanks to the panel according to the invention, the differentiation of the wiring methodology caused by the distance of the stress zones from each other by at least 20 mm makes it possible to create a difference in stresses applied to adjacent cables. This difference will make it possible to considerably reduce or even eliminate the risk of faults appearing in the same places on adjacent cables such as cracks and even more so electric arcs.

According to other advantageous aspects of the invention, the panel comprises one or more of the following characteristics, taken in isolation or in all technically possible combinations:

At least some of the cables are fixed to the rear face of the base in fixing points, each fixing point forming a stress zone.

The fixing points are arranged on the rear face of the base so as to guide the corresponding cables one parallel to the other at least on a rectilinear guide portion along a guide axis.

At least some of the fixing points form a group of fixing points, the fixing points of this group corresponding to different cables and being arranged in the rectilinear guide portion along an oblique axis forming an angle strictly less than 90° with the guide axis.

At least some of the fixing points form a group of fixing points, the fixing points of this group corresponding to different cables and being arranged in the rectilinear zigzag guide portion relative to a fixing axis forming a non- zero with the guide axis.

The panel further comprises at least one barrier made of dielectric material placed between two adjacent cables to extend the shortest path, by bypassing the barrier, between at least some of the stress zones of these cables.

The panel further comprises a plurality of barriers made of dielectric material in the form of a comb, each barrier being arranged between two adjacent cables to extend the shortest path, by bypassing the barrier, between at least some of the zones of constraints of these cables.

The height of the or each barrier is at least approximately 18 mm.

The panel is embarked in a spacecraft.

These characteristics and advantages of the invention will appear on reading the description which follows, given solely by way of non-limiting example, and made with reference to the appended drawings, in which:

There is a schematic view of a solar panel according to the invention facing the sun.

There represents a bottom view of the solar panel facing the night of the .

There shows a bottom view of the solar panel of the according to an alternative embodiment.

In the remainder of the description, when the term "approximately" is used in relation to a numerical value, it must be understood that the given numerical value is approximate with a margin of error which is determined by those skilled in the art in each case considered. For example, this margin of error is equal to +10% or -10% of the given value.

The solar panel 10 of the is carried on board a spacecraft such as a satellite.

However, it should be understood that the solar panel according to the invention can be embedded in any mobile device other than a satellite or, in general, can be used independently of any mobile device, for example in a fixed configuration on the earth's surface. or on another planet (lunar rover, Martian, interplanetary probe, etc.).

In reference to the , the solar panel 10 comprises a base 12 and a plurality of photovoltaic cells 14.

The base 12 is in contact with the ambient environment of the satellite which is then presented by a space environment devoid of atmosphere.

The base 12 is for example of substantially rectangular shape and defines a front face 16 facing the Sun and a rear face 18 opposite the front face 16.

The cells 14 are arranged homogeneously on the front face 16 of the base 12, for example in two rows, each row comprising four cells 14.

Cells 14 are known in themselves and make it possible in particular to generate electrical energy when they are illuminated by the Sun.

The rear face 18 is illustrated in more detail on the .

Thus, with reference to this figure, the rear face 18 comprises a plurality of component zones. These components make it possible to recover the electrical energy generated by the cells and to route this energy to the satellite's electrical devices. For example, the rear face 18 comprises a plurality of zones of electronic components 20A to 20N and a plurality of electrical cables 22 electrically connecting these zones of electronic components 20A to 20N.

The electronic components are known per se and in particular ensure the operation of the solar panel 10.

In the present discussion, each electronic component of component areas 20A to 20N is a diode.

In other examples, each electronic component can be chosen for example from the group including in particular

- transistors;

- capacitors;

- control circuit;

- connectors etc.

Can also be considered as a component, an assembly comprising holes through which the wiring passes to be connected to the solar cells on the front face or even the solar cells themselves. Indeed, the constraints are not exclusive to the rear face of the solar panel but can also be applied to the rear face, for example at the level of the cables which connect to the solar cells and which are therefore glued to the front face of the solar panel . Also, the risk of danger is predominant on the rear side but is not exclusive to this side.

The cables 22 connect these different zones of electronic components 20A to 20N according to their functionality and according to methods known per se.

Generally speaking, “cable” means any wire carrying current or electrical signals. Electric currents are for example used to power one or other of the electronic component zones 20A to 20N. According to the present invention, the cables are single or unitary wire cables.

The cables are also used to transport the current, called light current, generated by the solar cells exposed to sunlight which constitute the energy source of the spacecraft. This current is used to power the various equipment and/or charge the satellite's batteries, we speak of photovoltaic power.

Each cable 22 has a sheath making it possible to electrically isolate it from the other cables 22.

The cables 22 are fixed on the rear face 18 by individual fixing points using, for example, a suitable glue or a small fixing bracket or any device allowing the cable to be held close to the panel. For ease of reading, only a few fixing points 30A to 30D and 32A to 32D are shown on the .

The attachment points 30A to 30D and 32A to 32D are arranged so as to guide the corresponding cables 22 along the rear face 18 between different zones of electronic components 20A to 20N.

Thus, as can be seen on the , during this routing, at least some of the cables 22 are guided one parallel to the other at least on a rectilinear guide portion along a guide axis.

On the , two rectilinear guide portions 33a and 33b respectively following guide axes X1 and X2 are shown.

Furthermore, during routing, at least some of the cables 22 are guided so that their routing direction changes at direction change points. Four direction change points 34A, 34B and 36A, 36B are shown on the .

The cables 22 can be subjected to constraints of a mechanical or thermal nature for example.

Thus, each constraint is chosen from the group including:

- thermal expansion and cycling;

- mechanical stress, for example a bend exerted on a strand of cable;

- exposure to significant radiative doses,

- exposure to light (aging due to UV);

- electrostatic discharges and/or electric arcs, etc.

One or more of these constraints combined simultaneously alter(s) the properties of the sheaths over time and weaken them. This generally results in hardening of the sheath dielectric, resulting in a lack of flexibility and cracking. It can also be a disintegration of the material itself due to irradiation of the environment which alters the chemical bonds, and which dilutes or decomposes the insulating material.

Only a few stress zones 40A to 40D, 42A to 42D, 44A, 44B and 46A, 46B are represented on the .

These constraint zones correspond for example to the intervention points of an operator on the routing of cabling such as cable fixing points or points for changing direction of cables for example.

So, in the example of the , certain constraint zones 44A, 44B and 46A, 46B correspond to the points of change of the routing direction respectively in points 34A, 34B and 36A, 36B.

In the same way, certain stress zones 40A to 40D and 42A to 42D correspond respectively to the attachment points 30A to 30D and 32A to 32D.

According to the invention, the cables 22 are arranged on the rear face 18 of the base 12 so that the shortest path passing through the ambient environment between each pair of stress zones 40A to 40D, 42A to 42D, 44A, 44B and 46A, 46B corresponding respectively to the fixing points 30A to 30D and 32A to 32D and to the routing direction change points 34A, 34B and 36A, 36B is equal to at least approximately 20 mm.

In this presentation, two adjacent cables have at least one pair of stress zones.

So, in the example of the , the fixing points 30A to 30D are arranged along an oblique axis Y1 forming an angle strictly less than 90° with the guide axis X1 so that the distance along the oblique axis Y1 between each pair of fixing points 30A and 30B, 30B and 30C, and 30C and 30D, equal to at least approximately 20 mm.

In this case, the shortest path between each pair of stress zones 40A to 40D formed by these points 30A to 30D is equal to at least approximately 20 mm.

The fixing points 32A to 32D are arranged in a zigzag manner relative to a fixing axis Y2 forming a non-zero angle with the guide axis X2 so that the distance between each pair of fixing points 32A and 32B, 32B and 32C, 32C and 32D, 32A and 32C, and 32B and 32D is equal to at least approximately 20 mm.

In the example of the , the fixing axis Y2 is substantially perpendicular to the guide axis X2.

Thus, in this case, the shortest path between each pair of stress zones 42A to 42D formed by these attachment points 32A to 32D is equal to at least approximately 20 mm.

According to one embodiment of the invention, a barrier 50 made of dielectric material such as Kapton® is arranged between the points of change of direction 34A and 34B so that the distance between these two points by bypassing the barrier 50 is equal to at least approximately 20 mm.

Thus, the shortest path around the barrier 50 between the stress zones 44A and 44D formed by these change of direction points 34A and 34B is equal to at least approximately 20 mm.

The height of the barrier 50 is equal to at least approximately 18 mm.

According to the present invention, the direction change points 36A and 36B are spaced from each other by the distance equal to at least about 20 mm.

Thus, the shortest path between the fixed points 46A and 46D formed by these direction change points 36A to 36D is equal to at least approximately 20 mm.

In the case where the distance of at least approximately 20 mm cannot be applied between the fixed points 46A and 46D corresponding to the points of change of direction 36A to 36D, a barrier 50 made of dielectric material as previously described is arranged between these points .

Of course, other embodiments are also possible.

For example, a stress zone may be a portion of a cable on which stresses can be exerted. Thus, as illustrated by , a first portion 22' of a cable is at least 20 mm (C1) away from a first portion 22'' of an adjacent cable. The pair of stress zones is thus formed by the first portions of the two adjacent cables.

In the example illustrated in , a second portion 23' of a cable is spaced at least 20 mm (C2) from a second portion 23'' of the adjacent cable. The pair of stress zones is thus formed by the second portions of the two adjacent cables.

For example, as illustrated in , another constraint zone can be formed by a connection portion 54A between a cable 22 and a zone of electronic components. A pair of stress zones is thus formed by two connection portions 54A, 54B of two adjacent cables each comprising a connection portion between a cable and a zone of electronic components. The cables are arranged on the rear face of the base so that the shortest path passing through the ambient environment the two connection portions 54A and 54B is equal to at least 20mm.

The embodiments described in Figures 2 and 3 can be combined.

Thus, for example, when the cables are guided on a rectilinear guide portion, it is possible to extend the shortest path between each stress zone of these cables by putting a barrier of dielectric material between each pair of these cables. The barriers thus form a comb.

It is also possible to combine different embodiments with each other according to all technically possible combinations.

We can then see that the present invention presents a certain number of advantages.

Furthermore, according to the invention, the different stress zones are spaced apart from each other so that when cable defects appear on the cables, these defects are not applied to the same locations on adjacent cables and are sufficiently spaced between them to avoid the appearance of a lasting electric arc.

Furthermore, it has been demonstrated that when the distance between these stress zones is equal to at least 20 mm, the risk of the appearance of an electric arc, particularly in a space environment devoid of atmosphere, is considerably reduced. Indeed, this distance between the constraint zones makes it possible to create a difference in cabling methodology (or mounting or assembly) which will allow the cables to react in different ways to all the spatial constraints applied to them.

This then makes it possible to find an optimal arrangement of the cables on the rear face of the panel, avoiding the establishment of electrical arcs and keeping the structure of the panel relatively compact.

Thus, for example, to extend the shortest path between different constraint zones during cable routing in a rectilinear guide portion, the constraint zones are misaligned or are arranged along an oblique axis relative to the axis of guidance.

According to another alternative embodiment, barriers made of dielectric material are inserted between the cables to extend the shortest path between the corresponding stress zones.

Thus, when a fault appears on a cable, this fault is sufficiently far from any area in which another fault is likely to appear. The risk of establishing an electric arc between these faults is thus considerably reduced.

Claims (9)

Solar panel (10) comprising:
- a base (12) being in contact with an ambient environment and defining a front face (16) and a rear face (18);
- a plurality of photovoltaic cells (14) arranged on the front face (16) of the base (12);
- a plurality of zones of electronic components (20A,…,20N) arranged on the rear face (18) of the base (12) and connected together by a plurality of electrical cables (22), each cable (22) comprising at least one stress zone (40A,…,40D, 42A,…,42D, 44A, 44B, 46A, 46B) in which stresses of a mechanical, thermal or electromagnetic nature are exerted on the cable, so that two adjacent cables have at least one pair of stress zones;
the panel (10) being characterized in that the cables (22) are arranged on the rear face (18) of the base (12) so that the shortest path passing through the ambient environment between each pair of stress zones (40A,…,40D, 42A,…,42D, 44A, 44B, 46A, 46B) is equal to at least approximately 20 mm. Panel (10) according to claim 1, characterized in that at least some of the cables (20) are fixed to the rear face (18) of the base (12) in fixing points (30A,…,30D, 32A,…,32D), each fixing point (30A,…,30D, 32A,…,32D) forming a stress zone (40A,…,40D, 42A,…,42D). Panel (10) according to claim 2, characterized in that the fixing points (30A,…,30D, 32A,…,32D) are arranged on the rear face (18) of the base (12) so as to guide the cables (22) corresponding one parallel to the other at least on a rectilinear guide portion (33a, 33b) along a guide axis (X1, X2). Panel (10) according to claim 3, characterized in that at least some of the fixing points (30A,…,30D, 32A,…,32D) form a group of fixing points, the fixing points of this group corresponding to different cables (22) and being arranged in the rectilinear guide portion (33a) along an oblique axis (Y1) forming an angle strictly less than 90° with the guide axis (X1). Panel (10) according to claim 3 or 4, characterized in that at least some of the fixing points (30A,…,30D, 32A,…,32D) form a group of fixing points, the fixing points of this group corresponding to different cables (22) and being arranged in the rectilinear guide portion (33b) in a zigzag manner relative to a fixing axis (Y2) forming a non-zero angle with the guide axis (X2). Panel (10) according to any one of the preceding claims, characterized in that it further comprises at least one barrier (50) of dielectric material placed between two adjacent cables (22) to extend the shortest path, by bypassing the the barrier (50), between at least some of the stress zones (44A, 44B) of these cables (22). Panel (10) according to any one of the preceding claims, characterized in that it further comprises a plurality of barriers (50) made of dielectric material in the form of a comb, each barrier being arranged between two cables ( 22) adjacent to extend the shortest path, by bypassing the barrier, between at least some of the stress zones of these cables. Panel (10) according to claim 6 or 7, characterized in that the height of the or each barrier (50) is at least approximately 18 mm. Panel (10) according to any one of the preceding claims, characterized in that it is embarked in a spacecraft.