Patent Application
20090108441
This present application relates generally to systems for providing compression to semiconductor stacks. More specifically, but not by way of limitation, the present application relates to a rigid frame clamping system for compressing a semiconductor stack.
Semiconductors have many commercial applications, including use in power converters and industrial drives. A common semiconductor system is an integrated gate commutated thyristor (“IGCT”) semiconductor (which will be used herein as an exemplary system, though the invention is so limited). IGCT semiconductors are layered devices, which generally include semiconductors stacked in series (i.e., a semiconductor stack). In operation, IGCT semiconductors require a compressive clamping force, which may be approximately 36 to 44 kN, to press the stack together so that good conductivity is achieved throughout the layers. For the semiconductor stack to operate properly, the compressive force must be applied in a precise amount and location through the stacked semiconductors.
Commercially available clamps are available for clam ping semiconductor stacks. In general, such semiconductor clamps rely upon compressing the semiconductor stack by tightening nuts on a plurality of threaded rods mounted between two endplates. Specifically, the semiconductor stack is placed between the two endplates, the nuts are tightened, which draws the endplates closer together and compresses the semiconductor stack.
However, the threaded rod/nut configuration is fraught with inefficiencies. First, the compression force is not delivered in a precise manner to the stacked units. The tightening of a plurality of rods means that the compression is done in an unbalanced manner. Second, the threaded rod/nut configuration makes access and repair to the semiconductor stack difficult. To remove the stacked devices, the entire clamp assembly must be substantially disassembled, which negatively affects repair time, cost, and the required training for the service technicians. Third, the protruding rods of the rod/nut configuration impose a greater length requirement on the clamp assembly. Accordingly, space adjacent to the stack assembly must be allocated to accommodate the extension of the threaded rods.
Fourth, available clamp assemblies provide limited possibilities for component registration. As used herein, component registration refers to the mounting of semiconductor components to the clamping system such that proper alignment for compression is achieved. As one of ordinary skill in the art will appreciate, for proper operation, the IGCT semiconductors of a system must be precisely aligned along the compression axis, i.e., the axis along which compression is performed. The accompanying components, such as the water-cooled heat sinks, also must be precisely located in relation to the semiconductor, in order to adequately cool the devices. For these reasons, component registration is a significant concern, yet commercially available clamps require additional parts to be added to the clamping system for proper component registration to be achieved. Fifth, current clamps do not allow for water delivery manifolds to be directly mounted to the threaded rods of the clamp assembly.
Sixth, in operation, IGCT semiconductor systems are mounted within an enclosure via the frame of the clamp. Currently available clamps do not allow for direct mounting to the enclosure. Conventional clumps, because one of the clamping end plates must be free to move in relation to the other end plate, lack a convenient rigid structure with which to mount the system. As such, an additional component must be incorporated into the clamping device to mount the semiconductor stack within the enclosure.
Seventh, presently available clamps are only adaptable to a single semiconductor stack within one clamp, due to the plurality of the clamping rods and registration concerns. If additional stacks are desired within a single semiconductor application, an auxiliary clamp structure must be added to the assembly.
All of these factors contribute to additional cost and complexity of employing conventional clamps for use in semiconductor stacks. Thus, there is a need for an improved semiconductor clamp.
The present application thus may describe a system for clamping a plurality of semiconductors that includes: 1) a first endplate and a second endplate that are substantially parallel and oppose each other across a predetermined distance, the predetermined distance being fixed by one or more tension members; and 2) means for providing a compressive force from one of the endplates. The plurality of semiconductors may be a plurality of integrated gate commutated thyristor semiconductors.
The means for providing a compressive force may be attached to the first endplate and compress inward toward the second endplate. In some embodiments, the means for providing a compressive force may be a screw jack. The screw jack may include a threaded cylinder that moves through a threaded opening in the first endplate upon being rotated. The screw jack may be rotated via a screw jack head at a first end of the screw jack. The first end of the screw jack may protrude out of an outer surface of the first end plate. A second end of the screw jack may be a ball bearing.
In some embodiments, the one or more tension members may be rigid rods that connect to an inner face of each of the endplates, the one or more tension members being substantially perpendicular to each of the endplates. In some embodiments, the one or more tension members may be four tension members. The tension members may be located in predetermined locations based upon registering the semiconductors and/or other semiconductor system components along a compression axis. The system may further include registration brackets attached to the semiconductors and/or other semiconductor system components. The registration brackets may engage the one or more of the tension members such that the semiconductors and/or other semiconductor system components are fixed in the compression axis and while being able to slide along the length of the one or more tension members.
The system may further include a spring washer attached to one of the endplates. The spring washer may include a ball bearing. The compression of the spring washer may indicate the clamping force applied to the plurality of semiconductors. The system further may include fixed registration brackets that allow for fixed registration of semiconductor system components to the tension members such that, when the fixed registration bracket is engaged, the semiconductor system component does not slide along the length of the tension members. The system further may include mounting apertures in at least one of the endplates. The mounting apertures may include an opening through the endplate through which the system may be directly mounted to an enclosure.
The present application further may describe a system for clamping a plurality of semiconductors that includes: 1) a first endplate and a second endplate that are substantially parallel and oppose each other across a predetermine distance (the predetermined distance being fixed by one or more tension members that extend between the first endplate and the second endplate); and 2) a screw jack that includes a threaded cylinder that moves through a threaded opening in the first endplate upon being rotated such that the threaded cylinder moves toward the second endplate if rotated one direction and away from the second endplate if rotated the opposite direction. In some embodiments, the system further may include a spring washer attached to the second endplate such that the compression of the spring washer indicates the clamping force applied to the plurality of semiconductors. The screw jack may be rotated via a screw jack head at a first end of the screw jack, the first end of the screw jack protruding out of an outer surface of the first end plate. A second end of the screw jack may include a ball bearing that is configured to engage one of the plurality of semiconductors. The system further may include registration brackets attached to the semiconductors and/or other semiconductor system components, the registration brackets engaging one or more of the tension members such that the semiconductors and/or other semiconductor system components are fixed in the compression axis while being able to slide along the length of the one or more tension members.
These and other features of the present application will become apparent upon review of the following detailed description of the preferred embodiments when taken in conjunction with the drawings and the appended claims.
Referring now to the figures, where the various numbers represent like parts throughout the several views,
Each of the tension members 104 may be pinned to the endplate 102 by pins 106. Specifically, the end of the tension member 104 may insert into an opening in the endplate 102 and a pin 106 may be inserted through the edge of the endplate 104 such that the pin 106 passes through the tension member 104 and terminates in the endplate 102. Those of ordinary skill in the art will appreciate that other methods of connecting the tension member 104 to the endplate 102 also may be used.
The rigid frame 100 may be made of a rigid, non-conducting material, such as a fiberglass composite laminate, glastic engineering material, fully insulated metal or other similar material. The non-conducting quality of the material may electrically isolate all of the semiconductor components that come in contact with the rigid frame 100.
Each of the endplates 102 may include an opening through the approximate center of the endplate 102 that aligns with the central axis of the semiconductor stack. A screw jack opening 108 may be substantially circular in shape and, as discussed in more detail below, be used in conjunction with the installation of a screw jack (not shown in
Mounted within the screw jack opening 108 may be mechanical means for providing a compressive force into the rigid frame 100, which in some embodiments may include screw jack 204. The screw jack 204 may be a screw jack that extends inward into the rigid frame 100 (and out of the inner face of the endplate 102) upon the clockwise rotation of a screw jack head 206. The screw jack head 206 may be allen-wrench compatible, though other head configurations may be used. Those of ordinary skill in the art will appreciate that other mechanical means may be used beside the specified screw jack 204 to provide the described functionality. Similar to the bellville washer 202, at the end of the screw jack 204 that extends inward into the rigid frame 100 may be a screw jack ball bearing (not visible in
In operation, as shown in
The screw jack ball bearing may engage the IGCT semiconductors at one end of the stack at a preformed dimple. The washer ball bearing 203 may engage the IGCT semiconductor at the other end of the stack at a second preformed dimple. Thus engaged, the screw jack 206 may be rotated such that the screw jack 206 extends into the rigid frame 100. The distance between the endplates 102 remains fixed due to the tension members 104 such that the extension of the screw jack 206 compresses the IGCT semiconductor stack. Specifically, the extension of the screw jack 206 may place the tension member 104 in a state of tension, which may act to compress the IGCT semiconductor stack. The screw jack 206 is the only component that must be adjusted to apply an even compressive force to the semiconductor stack. As the IGCT semiconductor stack is compressed, the bellville washer 202 may be compressed. The compression of the bellville washer 202 will cause it to deflect inward. The extent of the deflection may be used to calibrate the amount of compressive force applied to the semiconductor stack. In this manner, a known compressive force may be evenly applied to the semiconductor stack at precise points.
As shown in the exemplary embodiments of
In similar fashion, the other components of the IGCT semiconductor system 300 may be registered onto the rigid frame 100. For example, as demonstrated in the other blown-up section of
Given the registration of the components as described above, installation of the component parts of the IGCT semiconductor system 300 in the rigid frame clamping systems 200 may be completed in an efficient manner. For example, to install the components, the pins 106 of one of the endplates 102 may be removed such that the endplate 102 is disconnected from the tension members 104. With the ends of the tension members 104 free at one end, the gate drive 304, for example, may be installed by sliding the gate drive registration brackets 402 onto the two relevant tension members 104. In some embodiments, the gate drive 304 may have two gate drive registration brackets 402 on each of its sides. Each of the relevant tension members 104 may be inserted into the slot of the gate drive registration bracket 402 and the gate drive 304 may slide down the tension members 104 into position. With the predetermined positioning of the tension members 104, the gate drives 304 may be supported, and fixed in the appropriate position along the compression axis, as shown.
To take another example, the heat sinks 306 (and related hardware) may be installed in much the same manner. In addition, if one of the heat sinks 306 is part of a pre-assembled unit of semiconductor components, which may include, for example, the gate drive 304, the IGCT semiconductor, and other components, the pre-assembled unit may be efficiently installed at once by engaging the brackets to the relevant tension members 104 and sliding the unit down the tension members 104 into position. In this manner, the components may be efficiently installed while fixing their position along the compression axis.
Access to components already installed in the IGCI semiconductor system 300 also is enhanced. The compression force of the rigid frame clamping system 200 may be released simply by turning the screw jack 206 in the counter-clockwise direction. Once the clamp released, the components may slide lengthwise along tension members to either be removed or spread out, which may allow for convenient removal, replacement or repair of any of the component parts.
Because the tension members 104 are rigid and do not change position in relation to the endplates 104 (as conventional clamps do), some of the components may be fixed to the tension members 104 (i.e., fixed in such a manner that the component is not allowed to slide along the length of the tension member 104). An example of a component that may be registered in this manner is the water delivery manifolds 308, which, as illustrated in
It should be apparent that the foregoing relates only to the described embodiments of the present application and that numerous changes and modifications may be made herein without departing from the spirit and scope of the application as defined by the following claims and the equivalents thereof.
