Magnetic materials influence with their magnetic properties the performance and efficiency of electrical machines strongly. Design and construction of those electrical machines are influenced and optimized by choosing the material which fits best.
To do this up to now only the standard measuring techniques described in international standards are mainly available. Existing set-ups provide results only for sinusoidal field magnetization. Due to the growing demand of completely new designs for electrical systems to fulfil the future requirements in efficiency and carbon neutral demands these standard measurements are not able to deliver the data needed. Therefore, it is necessary to develop and manufacture a high performance magnetic materials characterization setup to measure the magnetic properties (mainly: losses, permeability, remanence, saturation, coercive field, etc.) with the necessary flexibility to accommodate aerospace motor requirements.
The equipment characterised magnetic materials in terms of B-H characteristics and losses of the soft and hard materials being used within the electrical machines developed for the future needs, to handle soft and hard magnetic materials used for high performance electrical machines.
For the optimisation of high-performance aerospace applications the setup has to generate, beside the standard measurements on hard and soft magnetic materials the following test results:
- Magnetic properties at high excitation frequencies;
- Magnetic properties at pulse width excitation;
- Magnetic properties at wave form excitation with higher harmonic content;
- Magnetic properties at free wave form excitation;
- Characterisation of the magnetic properties under rotational flux vector conditions;
- Characterisation of the magnetic material using finished product shape (nonstandard sample shape).
The purpose of this project was to develop a test setup able to characterise magnetic materials when excited with pulsating or rotational fields at high frequency and high flux density under various mechanical conditions. This development will help the European aeronautic partners to have better knowledge on the design criteria of aerospace electrical machines and have a reliable test method to guarantee that the materials will behave as expected in the application at hand.
The main objectives of the project, defined as work packages, were to review, design and manufacture test-setup prototypes with the final aim of developing a test systems for both soft and hard magnetic materials, controlled by a central measurement unit.
Following proper system calibration and results verification the commissioned setup met the required specification by fulfilling the five main measurement sequences mentioned below:
- Measurement of 1D iron losses using both sinusoidal and non-sinusoidal flux excitation in soft magnetic materials subjected to simultaneous strain (compressive or tensile) and temperature variations:
- High frequency sinusoidal up to 20 kHz; Amplifier bandwidth up to 100 kHz for PWM
- Up to 500 MPa in tension
- From -40°C to 300°C
- Measurement of magnetostriction under 1D excitation, stress and ambient temperature
- Measurement of 1D iron losses for annular samples compressed radially and axially
- Measurement of 2D iron losses at rotational power loss tester using both sinusoidal and non-sinusoidal flux excitation in soft magnetic materials
- Measurement of iron losses in hard magnetic materials exposed to high frequency counter fields and subjected to compressive strain and temperature variation
- Full characterisation of hard magnetic materials using a hysterograph