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2006 (English)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis

Abstract [en] : Outdoor applications of electronics modules expose the systems to harsh environmental conditions. When very high performance is required, it may be necessary to actively stabilize the temperature in the module. This thesis presents a systematic approach to the problem of designing a temperature stabilized environment for medium size electronics modules. The target system is the front-end electronics for the antennas in the EISCAT_3D incoherent scatter radar system. This will be placed in northern Scandinavia, with estimated outdoor temperature span from -40C to 40C. Very high demands on precision and timing will most likely require a temperature stable environment. The present state in high performance thermal management of electronics focuses on single circuit design. Thus the need of designing a temperature stable module which could hold the entire front- end electronics was recognized. The electronics have an estimated constant power dissipation of about 10 W. The temperature stabilization system consists of a 250x250x100 mm large aluminium box insulated on the outside. Two Peltier modules are used for active cooling and heating. Inside the box a 10 mm thick aluminium heat spreader is attached to the Peltier modules. The heat spreader is used both as a mount for the most temperature critical components, as well as a means to distribute heating and cooling inside the box. Also the aluminium casing itself is used to distribute heat energy evenly. The current through the Peltier modules is controlled using a PID controller acting on a linearly controlled H-bridge. The system was initially evaluated using FEM simulations. The simulations verified the design approach and gave a clear picture of the heat distribution in the box over the range of target temperatures. Measurements were made on the prototype system using a climate chamber in which the prototype box was exposed to temperatures from 40C down to -40C over a time period of 5.5 hours. Inside the box two power resistors were used to generate the estimated power dissipation of 10 W. The measurements show that the center of the heat spreader is kept at 20C with minor deviations of +-0.02C. The air inside the box measured 45 mm above the aluminium heat spreader shows temperature variations of +-5C. Both simulations and measurements clearly show the feasibility of the proposed design, with temperatures kept to close tolerances. Critical parts can be attached to the aluminium heat spreader while less critical can be positioned above. The use of a completely enclosed box without rotating parts should provide long life expectations.

Place, publisher, year, edition, pages: 2006.

Keyword [en] : Technology, Temperature stabilization, Peltier module, EISCAT_3D, thermal management

Keyword [sv] : Teknik

Identifiers: URN: urn:nbn:se:ltu:diva-43957ISRN: LTU-EX--06/273--SELocal ID: 1c3fe13d-060f-42da-bd84-2fb7b63af81fOAI: oai:DiVA.org:ltu-43957DiVA: diva2:1017231

Subject / course: Student thesis, at least 30 credits

Educational program: Electrical Engineering, master's level

Examiners : Johansson, Jonny

Note: Validerat; 20101217 (root)Available from: 2016-10-04 Created: 2016-10-04Bibliographically approved

Author: Gabert, Anders

Source: http://ltu.diva-portal.org/

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