Date of Graduation

5-2021

Document Type

Thesis

Degree Name

Bachelor of Science in Electrical Engineering

Degree Level

Undergraduate

Department

Electrical Engineering

Advisor/Mentor

Balda, Juan

Committee Member/Reader

Balda, Juan

Committee Member/Second Reader

Ware, Morgan

Abstract

This thesis is focused on the evaluation of the thermal conductivity of certain potting materials, in particular Aluminum Nitride (AlN), thermal putty, and silicone oil using the “hot-wire” method in order to allow volume reductions of inductors, and thus, increase the power density of converters. The main objective of this thesis is then to study the behavior of these specific materials intended for high-density power converters by mixing them with different proportions and placing the resulting compounds into a can for calculating their thermal conductivities, in order to evaluate the effects on the power density of inductor-based converters. One objective in calculating the thermal conductivity is to determine the duration of the various experiments since they are time-consuming. To this end, two rounds of experiments are performed up to 15 and 30 minutes, respectively, since there was a clear idea for the time needed for the various mixtures to reach steady-state temperatures. The “hot-wire” method is normally used to measure the thermal conductivity of a material. For this thesis work, the “hot-wire” method equipment needed for the experiments is adapted to the equipment available in the Engineering Research Center (ENRC) at the University of Arkansas. Errors occurring during the experiments could have many reasons; for example, external factors that affect external temperature readings (for example, individual performing tests in the same lab room and adding heat to the ambient, the thermocouple not being firmly placed on the resistor inside the can, errors in weighing the materials on the digital scale, etc). The analysis of the results for the 15- minute experiments has errors due to negative value results, so this time was not suitable for calculating the thermal conductivities. The experiments conducted to 30 minutes produced good results. Thus, the influence of time is important to get very good results. However, the experiments performed up to 30 minutes demonstrated a reduction in both maximum temperature ii rise and the time to reach a stable temperature which gives improvements in efficiency and performance in the system. Further experiment analysis of some other materials like silicone epoxy should be conducted to analyze the thermal conductivity behavior and determine if other materials can enable faster heat removal.

Keywords

thermal conductivity, potting materials, volume reduction of inductors, EVs

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