Magnetics Business & Technology - Fall 2013 - (Page 8)

CASE STUDY Nanocrystalline Materials for the Next Generation of Noise Suppression Solutions By Roman Klinger and Dr. Johannes Beichler • Vacuumschmelze In recent years, innovative soft magnetic materials have moved to the forefront of electrical engineering and electronics and led to the development of many advanced components. Today, Vacuumschmelze (VAC) produces an array of high-quality soft magnetic alloys and advanced alloy products for a wide range of applications, including installation technology (e.g. electronic electricity meters) and renewable energies (solar, wind) to modern consumer products (computers, flat screen TVs). Although VAC’s contributions are usually concealed within the finished product, they fulfill important functions such as device and personal protection, billing processes accurate to the last cent, low-loss energy transmission and the interference-free operation of electronic devices. Toroidal tape-wound cores made from the nanocrystalline alloy Vitroperm have a proven track record in common-mode chokes (CMCs) for the interference suppression for electronic devices. The properties of Vitroperm CMCs enable high attenuation at lowfrequency ranges and improved high-frequency (HF) attenuation. Vitroperm has already established itself in a wide range of applications as a universal solution for EMC problems through its use of low-cost alloy constituents (Fe-based) and modern largescale production lines. Key applications for nanocrystalline CMCs are switched-mode power supplies, uninterruptable power supplies, welding equipment, photo-voltaic solar inverters, wind generators, electric and hybrid cars and frequency converters. Nanocrystalline Vitroperm alloys are based on Fe, Si and B with Nb and Cu additions. Using rapid solidification technology, thin tapes or ribbons approximately 20 µm thick are produced from these alloys in a single process step. Figure 3. Rapid solidification technology is used to produce amorphous alloy tapes. Figure 1. Broadband Attenuation Compared to chokes made with ferrite cores, the broadband interference suppression, coupled with improved thermal properties, delivers significant advantages in filter design and enables the production of highly reliable EMI filters. In certain conditions, intelligent filter configuration enables single-stage filters to be used instead of two-stage filters, hence reducing the number of passive components, system costs and component dimensions. Figure 2. Nanocrystalline CMCs enable a reduction of filter stages. 8 Magnetics Business & Technology • Fall 2013 Special winding machines are used to produce tape-wound cores from these ribbons, with external diameters ranging from 2 mm to 600 mm. The cores then undergo a heat treatment at 500°C to 600°C while still in an amorphous state, to form the nanocrystalline microstructure. This process results in a two-phase structure in which fine crystalline grains (average grain size 10 to 40 nm) are embedded in an amorphous residual phase. This characteristic structure maximises the permeability µ and minimizes the coercivity Hc. In addition, the low tape thickness and relatively high electrical resistivity of 1.1 to 1.2 µΩm ensures minimal eddy current losses and outstanding frequency response for the core. As a high-tech nanocrystalline soft magnetic alloy, Vitroperm combines these properties with a saturation flux density of 1.2 T and favorable thermal characteristics. It thus represents a universal solution to EMC problems which, in many aspects, is superior to conventional ferrites and amorphous materials. Vitroperm vs. Ferrite The properties of Vitroperm differ widely from those of conventional ferrites. This must be considered in filter design if optimum solutions are to be achieved. In low-frequency ranges the permeability of Vitroperm 500F is higher than that of ferrite. Nanocrystalline materials show a less marked reduction of www.MagneticsMagazine.com http://www.MagneticsMagazine.com

Table of Contents for the Digital Edition of Magnetics Business & Technology - Fall 2013

Editor's Choice
Nanocrystalline Materials for the Next Generation of Noise Suppression Solutions
Magnetic Continuously Variable Transmission
Magnets • Materials • Measurement
Simulation Accuracy Helps Pioneering Superconducting Generator Developments
Application • Component Developments
Research & Development
Industry News
Marketplace/Advertising Index
Spontaneous Thoughts: NdFeB: The First 30 Years and the Next 30 Years

Magnetics Business & Technology - Fall 2013