Refrigeration – Structural installation – With electrical component cooling
Reexamination Certificate
1999-09-30
2001-08-28
Doerrler, William (Department: 3744)
Refrigeration
Structural installation
With electrical component cooling
C062S119000, C165S104270, C165S104330
Reexamination Certificate
active
06279336
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an assembly for switching electrical power, wherein at least one semiconductor switch is arranged in a power electronics assembly.
BACKGROUND OF THE INVENTION
Such power electronics assemblies are employed e.g. in the form of half bridge arrangements for forming converters for the most different applications, e.g. for feeding polyphase machines, permanent magnet machines, and the like (see e.g. German Patent Publication DE-A-40 27 969).
However, there is the problem that the power density, i.e. the power output related to the volume of the assembly is relatively low with the conventional arrangements. Moreover, the weight of conventional arrangements is relatively high.
From U.S. Pat. No. 5,132,896 a converter arrangement is known which comprises plate-shaped feed lines with large surface areas in order to reduce the effect of distributed inductances of the conductors which are used for connecting the capacitors and the semiconductor switches. With this, large damping capacitors for the compensation of line inductances are avoided. Moreover, heat radiation can be improved by the large area configuration of the plate-shaped feed lines. Moreover, the plate-shaped feed lines are designed in such a manner that amperage and direction of the current flow through the plate-shaped feed lines minimize the effect of the distributed inductances.
The large area feed lines of this converter assembly, however, only serve to reduce interference inductances and are employed as feed lines to large electrolytic capacitors.
From European Patent Publication 586 793 B1 a half bridge arrangement is known which, in comparison, has a considerably better power density. Therein, the initially described semiconductor switch is arranged in a half bridge arrangement which is further developed in that the capacitor arrangement is formed by at least one junction capacitor at one printed circuit board carrying one or several of such semiconductor switches and/or by at least one paper capacitor formed as a hollow winding, with the semiconductor switches being arranged in the paper capacitor formed as a hollow winding and a fluid cooling being provided in the hollow winding. The contents of this publication are herewith expressly referred to.
Based on this, the invention relates to further developments of this known arrangement, which serve to further increase the power density, to widen the ranges of application of this arrangement, and to make manufacture and operation of this arrangement more economical, simple and safer.
SUMMARY OF THE INVENTION
According to an aspect of the invention, the semiconductor switch is arranged in a pressure-resistant vessel which is partially filled with an inert liquid in order to effect a fluid cooling of the semiconductor switch during operation and the interior of the vessel is coupled with a cooling circuit, with at least one vapour line leading from the vessel to a radiator, and at least one liquid line leading from the radiator to the vessel, with the liquid line being arranged at least sectionwise within the vapour line and being extended from a connection point at the vessel into the interior of the vessel to such a length that its free end opens below the liquid level of the cooling liquid.
In this manner the pressure-resistant vessel is to be provided with only one cutout or one opening for the connections with the cooling circuit. Moreover, the space requirement for the line to/from the radiator is reduced.
The arrangement is preferably further developed in such a manner that the vapour line at the radiator side opens at a manifold chamber, and the liquid line at the radiator side opens at a collecting chamber, with at least one cooling line being arranged between the manifold chamber and the radiator chamber, at the inner wall of which vapour from the vapour line condensates and flows as liquid into the collecting chamber.
The cooling lines can also be forced-cooled. This can be realized with the inventive arrangement being employed in a motor vehicle by means of the air stream and/or a blower. Alternatively, a liquid cooling can serve as a heat sink for the cooling lines.
In a preferred embodiment of the invention, a compensating tank is connected at the manifold chamber via a throttle section.
According to the invention the semiconductor switch is arranged in a pressure resistant essentially cylindrical vessel which is partially filled with an intert liquid; in order to effect a fluid cooling of the semiconductor switch during operation the cylindrical vessel comprises a flange which intersects its wall, which is adapted for receiving a connection of a radiator, with the connection being connected with the flange by means of screw connections and with spring elements being provided at each of the screw connections which resiliently bias the connection against the flange.
Due to the fact that the pressure in the vessel interior increases during operation of the arrangement with the heat loss of the semiconductor switches heating the inert liquid to its boiling point, safeguarding of the vessel against bursting must be provided by suitable measures. The usually employed burst disks are very expensive and require individual type tests.
Thus the invention provides an arrangement which can be assembled very easily. Because the connection for the radiator need not be welded to the vessel, but can be assembled, extensive welding operations are omitted. If the arrangement has previously been manufactured from aluminium, the expensive and virtually not feasible aluminium weld test is also omitted. In addition, the individual components can be tested before they are assembled. Furthermore, a surface treatment of the individual components can be carried out more easily. Another advantage is the considerably larger opening cross section in the case of an overpressure, compared to burst disks, because virtually the entire connection is lifted off the flange. In addition, the spring force of the spring arrangement seals the vessel again as soon as the pressure within the vassel drops below the predetermined value.
The spring elements are preferably formed by at least one cup spring or a cup spring pack. These springs are very favourably priced and their force/travel characteristic can be set very precisely.
In a preferred embodiment the screw connections are formed by threaded bolts the shaft area of which is surrounded by the spring elements.
According to the invention the spring elements are dimensioned and biased by screwing in the screw connections in such a manner that the connection clears the flange upon a predetermined fluid pressure prevailing within the vessel.
Preferably, a sealing element is arranged between the flange and the connection.
According to another aspect of the invention the semiconductor switch is arranged in a pressure-resistant vessel which is partially filled with an inert liquid and in order to effect a fluid cooling of the semiconductor switch during operation the interior of the vessel is coupled with a cooling circuit, with an outlet towards atmosphere being provided in the cooling circuit, which is closed by a filter arrangement which is permeable for air and impermeable for vapour from the inert liquid.
This arrangement enables the filling of the arrangement with inert liquid in a simple manner: Air which is trapped in the vessel during this operation and which would affect the function of a (condensation) radiator during operation will be expelled from the vessel during operation through the filter arrangement.
In a preferred embodiment the filter arrangement is formed by a molecular filter, preferably by a plastic foil.
In addition, a stabilizer is arranged at the side of the filter arrangement facing towards the vessel interior and/or at the side of same facing away from it.
In addition, a valve arrangement can be arranged at the side of the filter arrangement facing away from the vessel interior.
This allows to design the control lines shorter and thus less susceptible to interferenc
Grundl Andreas
Hoffmann Bernhard
Doerrler William
Grundl und Hoffmann GmbH Gesellschaft fur Elektrotechnische
Haverstock & Owens LLP
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