Why Use Aluminum Wire?

Focus:

Aluminum wire is produced by major wire companies yet is not commonly found in the transformers and inductors (transductors) of switching power converters. Nevertheless, aluminum (Al) wire has an advantage over copper wire at high frequencies because its conductivity is lower than copper, causing its skin depth to be greater at the same frequency. Its conductive area is greater and thus its resistance for the same length and cross-sectional area of wire is lower. When is it advantageous to use it? This article explores this question, discussing concepts such as skin effect depth, frequency-dependent resistance ratio, and proximity effect, and analyzing the impact of temperature, number of windings, and wire gauge on the resistance of aluminum versus copper wire in transductors. Equations are derived and plots of resistance ratios under various scenarios are shown. Author concludes that aluminum wire can have lower resistance than copper with multiple-layer windings, while also noting some practical pros and cons of using aluminum wire.

What you’ll learn:

• How to understand the potential advantages of using aluminum wire in power transformers and inductors
• How to determine when aluminum wire offers lower resistance than copper in power magnetics

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Author & Publication:

Dennis Feucht, Innovatia Laboratories, Cayo, Belize, How2Power Today, Jul 27 2011

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