Researchers at NASA are exploring the use of soft magnetic materials in electrified aircraft systems to increase vehicle performance and efficiency. These materials allow systems to operate at higher frequencies and temperatures with minimal power loss and waste heat.
Quick Facts
NASA Glenn is home to the largest U.S.-owned caster machine that allows researchers to create ribbons in large sizes and quantities for prototype component development and demonstration.
Soft magnetics materials are lightweight and ideal for larger electrified aircraft power electronics components.
Overview
Future electrified aircraft will require megawatt-scale propulsion systems that are lightweight, fault-tolerant, and reliable. Currently, engineers are limited to off-the-shelf components that are too heavy for many practical aviation uses. These technologies often exhibit excessively high losses at the desired conversion frequencies, which creates significant power loss and large amounts of waste heat.
NASA’s materials research is helping solve these challenges by increasing the efficiency and specific power of a wide range of energy generation and conversion components for aircraft and other applications. A key focus of this research is advancing soft magnetic materials development, which enable vehicle electrification by operating at higher frequencies and temperatures with low power loss.
How Magnetic Materials Work
There are two types of magnetic materials: hard and soft. The differences lie in how these materials respond to an externally applied magnetic field.
Hard magnets, similar to those used on home refrigerators, are difficult to magnetize. But once magnetized, the change is permanent as they tend to retain their magnetism for decades and are not easily demagnetized by external factors.
On the other hand, soft magnets are easily magnetized and demagnetized and are used to fabricate smaller, more lightweight power electronic components, like motor laminations, transformers, filter circuits (inductors), and electric machines (motors and generators).
Enabling Future Electrified Aircraft
By developing low-loss soft magnetic materials and components, NASA engineers are able to design smaller, more lightweight power-conversion components for aircraft power electronics that are capable of running at the much higher frequencies required for large, electrified aircraft designs.
NASA engineers are demonstrating this innovation by developing nanocomposite soft magnetic materials. One advantage of these alloys is they are capable of operating at higher power densities, frequencies, and temperatures than conventional materials while maintaining lower losses. They can also deflect magnetic flux, making them ideal for electromagnetic interference (EMI) shields.
The Generalized Intelligent Motor Controller (GIMC), a NASA-developed power converter, is an example of this technology designed for use in future electrified aircraft projects. An early version of the GIMC system used a commercially available inductor, which was bulky and required a separate circuit board and cooling system (a heat sink) to deal with the excessive heat.
Engineers at NASA’s Glenn Research Center in Cleveland proposed a “bead” inductor made from conformable soft magnetic materials, and the resulting inductor was smaller, produced 20 times less waste heat, and made the system lighter by eliminating the need for a dedicated circuit board and cooling system.
NASA is also exploring the development, manufacturing, and characterization of a promising new class of amorphous-nanocrystalline composite alloys.
A large-scale soft magnetic material spin casting unit originally developed under U.S. Army support has been transitioned to NASA and upgraded to increase yield and ribbon quality. This is one of the few facilities in the United States capable of producing magnetic material ribbons wide enough for the development of low power loss and high operational frequency components and devices.
A wide range of magnetic material characterization equipment is available, including a custom core loss measurement system, as well as a device for measuring magnetic field domains in materials.
Capabilities at NASA Glenn
In support of these efforts, the Materials and Structures team at NASA Glenn focuses on fundamental alloy research and development, casting/fabrication scale-up, computer-based modeling, and high-power component testing.
After casting, the materials can be further processed in a number of ways to produce tailored magnetic properties, such as permeability, in order to meet the unique demands of any specific application. In addition, Glenn has filed a patent on a particular alloy that not only maintains the desirable loss properties but also doubles the operating temperature of this class of material.
The rapid solidification technique used at Glenn is seen as the preferred method as it locks in the amorphous structure (a non-repeating structure like glass), gives the material a very unique magnetic property, and allows for very thin ribbons to be produced, which are ideal for aviation applications.
To achieve this, the Glenn team built up a series of capabilities not readily available in the public sector. The centerpiece of the magnetics laboratory processing facilities is the 5-kilogram capacity planar flow caster – the largest U.S.-owned caster for research purposes – designed to produce about one mile of 25-50-millimeter-wide soft magnetic, amorphous ribbon. The ability to create ribbons this size and in large quantities allows NASA engineers to build prototype components for testing and demonstration.
In addition to the large caster, a 60-gram caster, capable of producing approximately 25-millimeter-wide ribbon, is also available for alloy development trials or for production of smaller-scale components such as those found on circuit boards. This casting is performed in an environmental chamber, which is critical when casting alloys that are sensitive to oxygen.
In developing these unique alloys, researchers are working hard to get them out of the lab and into real-world components. The lab also hosts a wide range of magnetic material characterization equipment that includes an alternating current (AC) permeameter, a vibrating sample magnetometer, a permanent magnet hysteresigraph, and a Magneto Optical Kerr Effect (MOKE) microscope.
Applications Outside of Aviation
In addition to advancing the future of aviation, these technologies can be developed to benefit systems on the ground as well.
Electric cars can benefit from magnetics research due to the need for smaller, lower-loss electrical circuits with lower amounts of waste heat.
Solar energy systems can leverage these magnetic technologies to more easily integrate into the national power grid system with little to no electrical variations or disruptions. Low-loss soft magnetic materials can also significantly increase efficiency of our national power infrastructure in developing future renewable energy sources.
Resources
Publications
Explore and download a collection of publications to learn more about soft magnetic material development at NASA.
Aircraft Concepts
Learn more about NASA’s conceptual aircraft design studies for future electrified aircraft.
EAP Labs and Testbeds
Learn about NASA’s labs and testbeds enabling advanced electrified aircraft propulsion research.
Technology
Discover the innovative systems and technologies that enable safe and efficient electrified propulsion.
