Electrical transmission or interconnection systems – Vehicle mounted systems
Reexamination Certificate
1999-07-01
2001-12-11
Paladini, Albert W. (Department: 2841)
Electrical transmission or interconnection systems
Vehicle mounted systems
C062S259200, C123S041120
Reexamination Certificate
active
06329723
ABSTRACT:
FIELD OF TECHNOLOGY
The invention relates to the field of cooling technology of power electronic circuits. It is based on a coolant temperature control for regulating the coolant temperature of a power converter of an electrically driven vehicle, in particular an electric locomotive, according to the preamble of the first claim.
STATE OF THE ART
High performance traction power converters are constantly subject to fluctuations of the ambient temperature. These fluctuations are decisively influenced by the seasonal cycle and the daily cycle. Furthermore, coolant temperature fluctuations caused by the greatly varying power converter power loss during load cycles (standstill, start, driving, breaking) occur. The coolant of the power converter (for example oil or water with glycol) is dependent on the ambient temperature because of a coolant air recooler. The coolant temperature, and thus the temperature of the connected components, in particular of the semi-conductor power circuits, is kept as low as possible, and the power converter power loss is removed into the environment. During times of standstill and light load operation of the vehicle, the coolant is cooled relatively quickly to the ambient temperature. During high load operation, the coolant heats to about 10 to 20K over ambient temperature.
According to the state of the art, the coolant temperature therefore follows the ambient temperature, except for the temperature differentials caused by the load cycle. The ambient temperature fluctuations and overlapping load cycle temperature fluctuations, which may be rather significant, are therefore all transferred directly to the components connected to the cooling cycle. This results in a drastic temperature alternation stress which greatly reduces the component lifetime. Semiconductor modules with integrated cooler and soldering joints between semiconductors, insulating layer, and cooler are especially subjected to severe stress by this. Given the high number of cycles—a specified life of 30 years for a locomotive results in 30 annual cycles, about 11,000 daily cycles, and about 500,000 load cycles—this may result in lifetime problems.
DESCRIPTION OF THE INVENTION
It is therefore the objective of the invention to describe a coolant temperature control for regulating the coolant temperature of a power converter of an electrically driven vehicle, where said control makes it possible for the components of the power converter to be subject to less distinct load alternations, so that the entire vehicle will have a longer lifetime.
That is, at the core of the invention is the fact that the coolant temperature control regulates the coolant temperature to a set value that is independent from the current ambient temperature. In particular, it makes it possible to use an expected daily maximum, a daily average, or an optimized set value progression as a set value. Over a period of a year, the set value may follow the annual progression.
The advantages of the invention are in particular that the fluctuations of the ambient temperature are no longer directly transferred to the components in the cooling cycle, and that the coolant fluctuations caused by the greatly varying power losses during load cycles can be kept negligibly small. The extreme temperature fluctuations to which the components had been exposed can be avoided. The temperature alternation profile is significantly ameliorated by the invention, and the components achieve a life that is higher by factors between 2 and 10.
Other advantageous embodiments result from the respective dependent claims.
REFERENCES:
patent: 4415847 (1983-11-01), Galloway
patent: 4962734 (1990-10-01), Jorgensen
patent: 5531285 (1996-07-01), Green
patent: 5937664 (1999-08-01), Matsuno et al.
patent: 0 821 468A2 (1998-01-01), None
patent: 1-222652A (1989-09-01), None
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German Patent Office Search Report dated Feb. 15, 1999.
Gottschalk, G., u.a.: Variobahn die Stadtbahn der Zukunft. In: ABB Technik Apr. 1944, S.31 (p. 31).
Burns Doane Swecker & Mathis L.L.P.
Daimler-Chrysler AG
Paladini Albert W.
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