FR2485263A1 - Compression loaded diode or thyristor stack chassis - has devices mounted between cooling pins with travel limit stops, and base spring loading to permit easy device replacement (BR 1.9.81) - Google Patents

Abstract

The chassis unit holds a stack of electrical devices under axially applied spring pressure. The stack is mounted between upper and lower end plates with central openings coaxial with the stack. A screw mounted, spring loaded base plate presses normally against the stack which butts against the upper end plate. The end plates are held together by Tension rods with a number of intermediate stops. The base plate screw may be adjusted sufficiently to allow the topmost device to clear the top plate under gravity, the intermediate stops limiting the travel and retaining the devices in the stack. The stops are located by insulating spacer sleeves. The devices are separated by cooling fins which extend out from the devices to the intermediate stops. The stops are equally spaced and when the base loading screw is loosened the devices are separated from the stack. The unit is tensioned by spring washers. It is suitable for thyristors and rectifiers and allows individual devices to be slid out and replaced without disassembling the complete unit in a high voltage, high current stack.

Description

 The invention relates to stacking modules for supporting and containing a plurality of electrical devices packed flat, in particular semiconductor devices such as thyristors or rectifiers, which must be maintained under a predetermined pressure to ensure a good thermal and electrical conduction.

 Typical stacking modules of the prior art are described in US Pat. Nos. 3,523,215 to J.J. Steinmeta et al. and No. 3,447,118 to H.E. Xerree. The stacking module of the aforementioned patents comprises upper and lower members connected by vertical tensioning members to maintain a stack of thyristors, each of these thyristors being interned between two cooling plates. An adjustable force is applied to the top of the stack through the center of the upper member, by means of adjustable load means comprising a bolt, and elastic structures.

 In stacking modules of the prior art comprising several cooling plates in a row, the successive cooling plates are used as connection elements for the power supply and also as thermal conductors. They are usually made of solid copper and are extremely heavy. Each semiconductor device is usually arranged on the upper surface of an adjacent cooling plate placed below, in good mechanical, thermal and electrical contact, and so must be the case with the adjacent upper cooling plate when it is mounted on top of the semiconductor device thus interposed between the two plates.

This constitutes a heavy stack of parts in which the cooling plates are connected by connectors to the supply conductor of the bridge of the semiconductor devices. It appears that a problem arises with stacked modules of the prior art when a semiconductor device has to be checked removed and / or replaced. Until now, to ensure this maintenance, the entire stacking module had to be disassembled so that the faulty semiconductor device can be identified and accessed.
An object of the present invention is to create a stacking module which makes it possible to remove and replace a semiconductor at a given time, without having to dismantle the assembly.
stacking block.

Another object of the invention is to allow
apply an adjustable force on a stacking module or
to release this force by disjoining the semi devices
conductors to such an extent that each of them can be
slipped out of the stack.

Another object of the invention is to relax
the adjustable force applied to the stack in such a way
that the disjunction of the semiconductor devices is effective
selectively killed So much so that a semiconductor device
particular can additionally slipped out of 11 stacking without releasing
unnecessarily all the others.

According to the present invention the objec
mentioned above are achieved collectively or individually
empty by means of means applying an adjustable force,
means likely to be used at the bottom
stack to lower or raise this stack in its
assembly frame with respect to the stop members which little
wind coincide with the respective cooling plates.

When the stack is lowered, and a stop member re
holds a cooling plate placed above, the dispo
adjacent electrical sitive remaining on the cooling plate
lower part is lowered and this device can be removed
of the interval thus created.

The invention also relates to a device for
loading the stack used to raise and lower
the entire stack during maintenance operations and
to apply a calibrated force to this stack during the
operation.

The stacking loading device
according to the invention, is self-centered and engages with
stacking at the bottom of it when a bolt screwed to the center of the lower member is moved up.

The stacking loading device
is a telescopic device comprising two mounted parts
with the interposition of elastic washers, these two parts
delimiting a certain interval between their two edges so as to provide a sight or so as to be able to be palpated by
simple touch to check if this interval is reduced.

by tightening the stacking load device due to the screwing of the bolt to a point where an exactly calibrated force is applied to the stacked components of the module which is, at this instant, operational.

The invention will be described in more detail with reference to an exemplary embodiment shown in the accompanying drawings, in which t
- Figure 1 schematically shows the stacking module according to the present invention in two different positions to the left i the stacking is completely lifted so as to apply the adjustable force components filled; on the right the section is partially lowered in order to provide access to the fourth of the seven electrical devices shown in this example.

the fit1 2 shows the stop devices according to the invention positioned with respect to the interval between two consecutive upper and lower cooling plates of the stack of FIG. 1,
FIG. 5 shows the electrical circuit of an AC / DC power supply using a stack of electrical components such as that shown in FIG. 1,
FIG. 4 shows in more detail the cooling plates and their relation to the axis of the vertical tension members of the stacking module carrying the stop members of FIGS. 1 and 2,
FIG. 5 is a top plan view of a cooling plate,
- the SA fi6e is a section of a cooling plate, its ends, the electrical device and the vertical member associated to show their relationship with the upper and lower stop devices
FIG. 6B is a section through a vertical member for tensioning the module according to a plane lying above a cooling plate
- Figure 7 shows in side view the bolt and the stacking loading device according to the invention when engaged llun with each other.

FIG. 8A is a section through the device for loading the stack,
- Figures 8B and 8C are respectively top and bottom views of the stacking loading device.

Referring to FIG. 1s, a stacking module for the flat packaging of semiconductor devices, diagrammatically represented, comprises 1 A stack of six electrical devices ED1 to ED6, cha
none of these devices being interposed between two plates
cooling adjacent RS1 to HS7 2.- A support for this stack comprising upper members
and lower UM, LM respectively at the upper part
and at the bottom of the stack, and worm organs
EN ticals rigidly connected to the cor ends
of the upper and lower organs.

3.- A telescopic device for loading the stack
SJ, 3LT to apply an adjustable force F, axially
relative to this stacking and, upwards from the
below the stack, against the upper body UM, 4.- STP1 to S2PS stop devices mounted on the bodies
of voltage TM and arranged at different levels in the
delimited intervals between cooling plates
successive to retain the cooling plate above
when, as the right side of the fi
gure 1, the stack has been lowered by the delivery device
in charge of stacking enough for a plate of
upper cooling on an organ engaged
stop placed below it,
This arrangement allows: a) to apply an adjustable force to the stacking between the organs
nes upper and lower so as to obtain contact
thermal and electrical required between electrical devices
triques and the cooling plates, while the
stacking module is kept tight but not excessively
sive which would result in damage to one of the dis
positive-electric.

h) release the pressure and lower the stack along
the longitudinal axis Xi, h of its support thus allowing
the stack to open successively from a rear member
stop at the next, freeing up any electrical device that
must be entered or changed at any selected level w
depending on the degree of withdrawal of the charging device
stacking or lowering this stacking.

Figure 1 shows the stacking module according to the present invention in two positions. On the left, the piling was lifted by an ELT bolt rotatably mounted in an opening along the median axis X1, X2, x of the device. The end
Ion TSLT applies a force F along the axis and against the weight of the stack by means of a loading device
SL which engages with the bottom of the stack. For simplicity, the stack loading device
SL is assumed to engage the lower part of the lower HS7 cooling plate. As will be explained below, the stacking device SL is a telescopic device comprising an elastic washer (not shown) which can be compressed by turning the bolt BLT further upwards until that the upper cooling plate HS1 which rises with the stack, begins to engage with the upper member. When this is done, the telescopic device (as explained below) causes the edge Ei of an internal sail member of the telescopic device and of the edge EX of the outer wall of the loading device SL until these two edges are aligned. In construction, when this occurs, the elastic washer contained in the loading device, develops both with respect to the ELT bolt and with respect to stacking, the effort required for efficient operation and str of stacking when supplied with current and voltage. A visible coloration or a marking on the side of the projecting internal member, provides a sight which guides the operator adjusting the pressure with the BLT bolt. In the absence of any mark, the operator can also realize simply by touching them, If the two edges E1 and E2 are aligned which is another means of checking that the force applied to the stacking by means of the device SL for stacking loading by the bolt BLT is exactly correct.

On the right of Figure i, the stacking module is shown in its lowered position. The bolt BLT has been shown lowered to such an extent that the cooling plates EE1 to RS4 are held back by the respective stop members SUP1 to STP5. The lowering of the stack by the setting device 81 loading of the stack is not sufficient, however, in the situation represented in FIG. I, for the cooling plates HS and RS6 to be retained by the stop members STP5 and STP6 respectively
Consequently, only the electrical devices Bli to ET4 remaining on the adjacent cooling plate placed below (HS2 to HS5) are separated from the upper cooling plate (EX1 to HS4). Such a separation is sufficient for the operator to be able to remove any of these devices. In fact, when the lowering is limited to the separation between BD1 and B81 the electrical device ED1 is the first and also the only one, which can be replaced, checked or for any other reason removed. Continued lowering of the stack by means of the BLT mold and the positive arrangement 81 interposed for loading the stack, will release ED2, ED3 in turn and thus until the last electrical device which is BD6 when the cooling plate engages with STP6 stop member and is retained by it. In other words, thanks to the bolt is the stack loading device 81 can move in both directions of the distance between ES6 and STP6 on the left of Figure 1.

With reference to FIG. 2, the stop members STP1 to STP6 are shown in relation to the adjacent upper and lower cooling plates at different levels in the interval L1 separating two successive cooling plates. For each stop member, there is gradually approaching to the lower cooling plate and then moving away from the upper cooling plate in the order of succession of these stop members. Each stopper has an upper surface which is intended to engage the upper cooling plate when it is at a level which is a multiple of
L / 5. If it is assumed that each stop member has a defined height h for between housed within the interval L1, the STP stop members are respectively positioned at the levels
(Lh) / 5, 2 (Lh) / 5, 3 (Lh) / 5, 4 (Lh) / 5 and (Ih) from the upper cooling plate. This is only a preferred embodiment in the case where 6 electrical devices are associated in interposition with 7 cooling plates. There are other possibilities of choosing the levels of the STP stop members to selectively release an ED electrical device to a given moment, by gradually lowering the stack with the central bolt BLT and the device 81 which is associated therewith for loading the stack, mounted on the lower member LM of the stack module. In other words, Figures 1 and 2 are given by way of illustration and example only.

Referring to FIG. 3, the electrical supply apparatus is schematically represented there. A three-phase alternating current (PH1, PH2, PH3) of 1500 amps, 700 Volts is converted into a direct current of 800 Volts (L conductors
L2). The apparatus comprises two stacking modules of six thyristors in a bridge (ED1 to ED6 on the left of FIG. 3 and ED1 'to ED6' on the right), each of these thyristors being interposed between two cooling plates (shown diagrammatically according to HS1 to HS6 on the stacking module on the left and sel on HS1 'to HS6' on the stacking module on the right). The electrical device may as well be a diode earlier than a thyristor. As for the stacking module of FIG. 1 2, the electrical components SOli maintained inside a chassis comprising upper and lower members such as UM and LM and tension members such as TM in FIG. 1, which for reasons of clarity, are not shown in FIG. 3 for both of the stacking modules A device 81 for loading the stack is shown, applying a force 2 to the lower part stacking in the left stacking module. A similar stacking loading device S1 is also associated with the straight stacking module
The fact that the device for loading the stack, its bolt BLT (not shown) and the lower member IM are at ground potential, while the last cooling plate ES7, in the example shown , is around 700 Volts above ground potential, the SL charging device is applied against the underside of the cooling plate RS7 by means of an insulating block INS2 which is dimensioned so as to present along its periphery a sufficient length for the bypass voltage. Typically, INS2 is a square 25.4 mm thick and 101t6 mm side. For the same reason, the upper cooling plate HS1 similarly engages the upper member UM (not shown) by the 'through an insulating block INS1 because the organ UM is at ground potential. the blocks ISS1 and INS2 are typically made of a plastic material capable of withstanding the forces applied to the stack under its own weight as well as due to the clamping forces.

The same construction applies to the right stacking module of FIG. 3. More generally, the right stacking module is the image in a mirror as regards its construction and its electrical connections of the left stacking module which comes between described.

 Referring to Figure 11, the stacking module of Figure i or Figure 3, is shown in more detail. Typically, the RS cooling plates are made of a solid copper core of cylindrical shape 76.2 mm high and 76.2 mm in diameter, having 8 terminations laterally and on opposite sides 38.1 mm in length and also made of a solid thickness of copper. These terminations are welded or brazed to the surface of the cylindrical core at regularly distributed levels.

The cylindrical core in solid culmee of each cooling plate has an upper- and lower base which come into contact with an adjacent thyristor or an adjacent ED diode which are inserted, pressed by tightening the stacking module thanks to the setting device. in charge of stacking Si. This is only given as an example.

In the example shown and with the devices currently available on the market, the thyristors used are typically 31.75 mm high. With such a configuration, the entire stack represents a combination of 7 cooling plates at 9.07 kg each, and 6 electrical devices at 0.9 kg each for a total of 63.5 kg to be kept in the support constituted by the horizontal members UM and LM as well as by the verti caus members M. This weight of 63.5 kg must also be lifted by the BIT bolt and the SL device for loading the stacking towards the member upper UM and it must be lowered from this high level over the entire travel distance (Ih in Figure 2). The stacking load device is a telescopic device capable of moving this weight against the end of the BIT bolt. The tension members TM are made of grade 5 SAE steel connected to the upper and lower members DM, LM by high-strength bolts and nuts as shown in Figure 1.

 As shown in FIG. 5, the terminations of the cooling plates HS of FIG. 4 have a recess RC in the form of a semi-circle at their ends on the two sides of the central core. This recess is provided to provide the vertical members TM with appropriate insulation, while providing between the cooling plates, a sufficient surface with which the adjacent stop member STP can come into engagement when the stack is lowered as shown. for five stop devices on the right side of figure 1.

FIG. 6A shows the mechanical and electrical relationships between a vertical member TM made of steel and at ground potential and the recess RC of the termination of a cooling plate HS.

 Typically, the vertical member TM identical in this case to those of FIGS. 1, 3 and 4, has a diameter of 12.7 mm.

An insulating sleeve ILS, with a thickness of 3.2 mm has been threaded around the organ TN which extends over the entire distance between the upper and lower organs UM, EM. Arrest organs
STPs typically have a height of 9.5 mm and an outside diameter of 6.3 mm. It remains on an ISP insulating sleeve playing the role of spacing between these stop members. The length of the ISP sleeve varies in accordance with the interval provided between the stop members as shown in FIG. 2. FIG. 6B shows in section, a vertical tension member TN of FIG. 6A according to a passing horizontal plane between the cooling plates oath in the absence of any electrical device between them
The ISP insulating sleeve has sufficient mechanical strength to support the upper cooling plate when the latter is applied by its own weight to the adjacent stop member STP. The ISP insulating sleeve also has a thickness of 3.2 mm and at least a diameter of 15.9 mm so as to house inside the vertical member {and its insulating sleeve 181.

 Figure 4 also shows the device SL for stacking loading. The stacking loading device consists of two parts arranged telescopically against a common internal elastic washer. These two parts have visible edges E1 for the external part and E2 for the upper part. A dark surface with a side wall of the projection extending beyond the edge provides a SIT sight. It is assumed that the BIT bolt has not already advanced towards the stacking and the upper member UN to the point where it compresses the elastic washer inside the loading device and brings the telescopic device up to a point where E1 and E2 merge, that is to say align.

 The BIT bolt is applied against the stacking load device by means of a ball bearing BLL which is engaged by a conical surface WD against the end of the BIT bolt. The BIT bolt has a fine thread engaged in a thread complementary to the central opening OP provided in the lower member NM and in the axis of the loading device Si, of the insulator INS2 and of the assembly of stacking.

From the position; t indicated in Figure 6 where the bolt has lifted the stack until it comes slightly into engagement with the upper member UX via its upper insulator INS1 (and this without applying a greater pressure on the internal elastic washer of the device (if stacking is loaded) the bolt
BIT can be unscrewed down until a position $ t 1 or initial position, is reached, as indicated in dashes, position for which all the stop devices of figure 1 have in fact released all the devices electric ZD1 to ED6. Alternatively, from position # 2, the BIT bolt can be screwed up so that by means of the BLL ball and the stacking load device the internal elastic washer is compressed and develops an effort which is distributed between all the components of the stack. The elastic washer is calibrated inside the stacking loading device, so that, although the telescopic device closes under the force exerted by the BIL ball bearing, the desired force is obtained when the edge E1 is aligned with edge E2.In other words, the SIT sight must have disappeared or else simply by touch, the two edges must be in the same plane
Referring to FIGS. 7, 8A, 8B and 8C, the device SL for loading the stack will now be described in detail as regards its relationship with the bolt ELT. Figure 7 is a vertical view of the stacking loading device with the BIT bolt applied to its base. The stacking loading SL device of Figure 7 appears in section in Figure 88o. in charge of stacking is essentially made up of two parts BMOS and CE. telescopically mounted one inside the other with a BS spring between them. The first of these parts is a basic BM member, the second part is a centering cup member. These two parts are on the opposite sides of three Belleville Bs springs resting one on the other with dsz opposite angles going from one to the next. The centering cup member includes a cup
CP in which a BLL ball is supported. This ball bearing transmits the force from the conical end WD of the BIT bolt to the centering cup. The centering cup, in turn, transmits this force via the Belleville spring to the basic member BM which normally comes into contact with the pilings, typically with the lower insulator IN of FIG. 4. A washer of upper retainer and a lower retainer washer (URW, LRW) are fixed by SCU screws on the opposite sides of the CCM centering cup member.

The centering cup member has a central part
CEP extending inside the central space of the Balm spring lever to center it The upper retaining washer is fixed by a screw on the central part CEP in the center of it to retain from the top, basic unit in alignment with the Belleville spring and against it. the centering cup member CP comprises a circular flange FL extending -radially with the same diametrical dimension as the base member ZMo The flange FL projects by a cylindrical extension CE comprising an edge E .An outer wrap envy OS is brazed or welded around the base member BS to constitute an extension or a cylindrical envelope in the form of a skirt which has the same internal diameter as the external diameter of the base member DM and that the extension
cylindrical CE of the PL flange. This outer envelope
has an edge E2. A colored mark on the outside of the pro
long cylindrical CE provides an SIT sight as shown in Figures 1 and 4.The IRW lower retaining washer,
as shown in Figure 8C, has a central opening CO and is
fixed by three SCW screws to the lower part of the body to
CCM centering cup to hold the BLL ball in the
CP cup, while allowing the 311 ball to sail
ties down through the central opening CO.

Figures 8A, 83 and 8C are external views
of the stacking loading device. The fi
gure SÂ is a side view of the loading device
stacking with its BIT bolt. Figure 83 is a view of
Figure 8C is a bottom view of the stacking load device. Referring again to Figure
7, it can be seen that when the device for charging the em
pounding is pressed by its basic organ against the lower part
of the stack in the module assembly and that the stack
the age was lifted by the BIT bolt in position # 2 of the
Figure 5, further tightening of the BIT bolt will result in
compression of the Belleville BS spring. In this process, the
edge E1 of the cylindrical extension CE comes more and more
near the edge E2 of the outer envelope OS.

To illustrate the characteristic reaction of a
such stacking loading device the following table
vant indicates the deflections as a function of the load applied
quite by the bolt BIT t
BOARD
LOAD FLECHI S SEEENT (kgs) (mm)
1433 1.04
2,810 2.09
4140 3p13
5443

Claims (6)

a E V E N I CÂT ION s  1.- Chassis assembly to hold together under elastic pressure a stack of electrical components along an axis, assembly characterized in that it comprises: - upper and lower end members arranged trans versally to the stack at each end of it> cst lower organ and this upper organ comprising an owrel- central structure centered on the ase, - a base plate resiliently mounted in this opening central and normally engaged with the lower end  stack to elastically load this stack of  electrical posers - screwing means engaged with this fucking plate for apply via this base plate a  stack pressure in abutment against the upper end member laughing. mina1 higher. so that it comes into engagement and out of engagement with the organ ter extreme actions to move the Roumis stack to gravity wise being likely to be implemented between two posi upper and lower end organs, the means of sis-  upper and lower terminals to connect these - tension members mounted transversely to the members  are implemented. traversed by the base plate when the screwing means  electrical components in position as a function of distance on at least one of these tension members to retain the - a plurality of stop means mounted at different levels 2. An assembly according to claim 1 characterized in that it comprises electrically insulated spacer sleeves, mounted on the tension members to space and retain the means dtarr8t at predetermined levels.  3. An assembly according to claim 2, characterized in that the stack cooling plates comprising thernically and electrically conductive members, are respectively inserted between two electrical components oansdeutiSs, these conductive members comprising lateral parts extending so that the stop means are in their path when the stack is moved by the screwing means, thanks to which these parts of the conductive members come into engagement with a corresponding stop means when the stack is moved.  4. An assembly according to claim 3, characterized in that it comprises a first and a second insulation means respectively mounted between the upper and lower members and the corresponding end of the stack.  5. An assembly according to claim 2, characterized in that the spacing sleeves are uniformly spaced along at least one of the tension members thanks to which the implementation of the screwing means releases and tightens the components all together in the assembly.  6.- An assembly according to claim 2, characterized in that the spacing sleeves are distributed unevenly along at least one of the tension members, whereby the electrical components are separated from the stack under the action of gravity at selected levels when the screwing means lower the stack, and engage one on the other at selected levels when the screwing means raise the stack in the assembly.