Challenges and Opportunities of an Inline PM Rotor Production Control by Magnetic Field Measurement
by David Schwarzer of M-Pulse GmbH

1. System description: - Introduction of sensor type - Explanation of the measurement process - Identification of quality values that can be extracted from the measurement signal - Possible integration methods into a series production line - Influences to the cycle time 2. Close look to the measured field distribution - Challenges due to an open magnetic field measurement - Influences of the mechanical alignment to the measurement accuracy 3. Measuring ability and traceability - Calibration process - Angle and amplitude master - System repeatability 4. Conclusions - Added value of such a system

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Hirst's Pulse Field Magnetometry and Open to Closed Measurement Technologies
by John Dudding, Robin Cornelius, & James Clewett of Hirst Magnetics

Hirst’s history of practical, innovative magnetising and material parameter testing techniques is coupled to its long term aim of reinterpreting the open magnetic circuit measurements of magnet materials. Hirst’s 25 year development of Pulse Field Magnetometry (PFMs) led to the writing of IEC Technical Report TR62331 and is currently leading the international team working on the new International Standard IEC 60404 part 18 detailing the PFM technique. Hirst has overcome many of the perceived limitations of the PFM technique but the ultimate goal has always been to use the PFM technique to provide accurate, repeatable and fast Permeameter, (BH Tracer,) closed circuit like results for engineering and quality control. As well as a brief overview of its magnetising technologies which have also made progress, Hirst will describe the workings of PFMs, the limitations of the Permeameters and also its new PFM process*, enabling Open to Closed (O2C**) measurements of rare earth permanent magnet material and finished magnets in industrial shapes. This process enables, fast, repeatable measurements, between +210 °C and -40 °C with an accuracy currently under a confirmation review in an active joint project with the National Physical Laboratory (NPL) Open to Closed measurement is expected to open a new era in the magnetic measurement of magnetic materials at a time when efficiency is powering our Green Technology revolution. Shaped pre magnetised components will at last have a pre-assembly and pre magnetisation QA capability. *Patent applied for. ** Registered Trade Mark

The Pulsed Field Hysteresis Meter: What More Can You Get?
by Luc Van Bockstal of Metis Instruments

The HyMPulse, a prominent pulsed field magnetometer, is being used for quality control of magnetic properties. Its accurate and repeatable measurements are the basis for worldwide acceptance of the HyMPulse system. The capability to measure a variety of sample shapes and sizes is an added bonus. In the HyMPulse, a simple Helmholtz coil is used as a basis for the measurement of the magnetic response of the sample. Some straightforward steps are taken to make this Helmholtz coil suitable for use in a pulsed field. The instrument not only offers the classical BH curves, but can also be used to analyze other properties: examples will be shown of initial saturation, demagnetization of partially saturated samples, and losses due to eddy currents.

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Post Assembly Magnetisation of PM Rotors
by Chris Riley of Bunting Magnetics

Including Static and Rotating systems, focusing on the benefits of Halbach design within these systems. The presentation will look at the different saturation levels within a magnet array and how we are able to generate bespoke magnet data for these regions, utilizing this to generate a real-world model of the system. In addition to design considerations for engineers to facilitate post assembly magnetising we will look at the downstream advantages of this process including the obvious reduction in Health and Safety risk as well as the time saved in assembly, the ease of operations like machining, grinding and balancing and the utilization of any banding materials to their fullest potential without a limit on magnet killing temperature effects.

Electromagnetic Forming with High Transient Fields
by Jonas Walter of Magnet-Physik

Using fast rising transient currents to contactlessly form conductive materials

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Metrology of Soft Magnetic Materials at Operational Conditions
by Daniel Brunt of NPL

With the drive towards electrification of vehicles a greater understanding of a material’s properties under operational conditions is needed to build more efficient machines. I present the work NPL has been doing to perform magnetic characterisation at operation conditions with a focus on electrical steels and soft magnetic materials. I will also highlight future work to better understand the magnetisation processes within electrical steels while under these conditions.

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A Geometry-Independent Moment Correction Method for the MPMS3 SQUID-Based Magnetometer
by Randy Dumas of Quantum Design, Inc.

The modern superconducting quantum interference device (SQUID) magnetometer is incredibly sensitive, with the ability to resolve magnetic moments ~1E-8 emu. More specifically, the MPMS3 SQUID-based magnetometer from Quantum Design utilizes two complimentary techniques to measure the DC magnetic moment of a sample. The DC-scan mode uses a traditional linear extraction technique, whereas the SQUID-VSM mode oscillates the sample with a small amplitude, both within a 2nd order gradiometer. While the ultimate measurement sensitivity is determined primarily by the SQUID detection circuitry, the measurement accuracy is strongly affected by the size, shape, and centering of the sample. If the experimental sample differs in size and/or shape from the calibration sample additional scale factors need to be applied to improve measurement accuracy. Most significantly, a radial offset of the sample within the gradiometer not only adversely affects the accuracy most, but is also difficult to measure and therefore account for in the calculation of any post-measurement corrective scale factors. In this talk I will show that the measured moments extracted from the DC-scan and SQUID-VSM modes are not only related to one another, but that this relation is surprisingly independent of sample size, shape, and radial offset. By exploiting this trend, a geometry-independent correction factor can be calculated by simply measuring a sample, which may have an arbitrary shape, size, and radial offset, using both DC-scan and SQUID-VSM modes, thus greatly improving measurement accuracy utilizing a simple post-processing algorithm.

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The Role of Steel Cores in the Magnetisation Field Requirement for In-Situ Magnetisation of Permanent Magnets
by Govind Bisht of Laboratorio Elettrofisico

IEC technical report (IEC TR 62517) explains how magnetization process is closely related to the coercivity mechanisms, specifically in the case of nucleation type RE-Fe-B, sintered ferrites and SmCo5 magnets. Open circuit magnetization of magnets can be vastly different from in-situ magnetization of magnets in a rotor assembly because of the presence of steel in rotor and magnetizer fixture, as the stray fields effect in the two cases can be quite different. The focus of this presentation is to show how magnetization requirement for saturating certain permanent magnets in-situ is different from the open circuit and what are the factors that affect the magnetization process.

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Measurement Technologies for Evaluation of Magnetic Properties of Stator Cores
by Lukasz Mierczak of Brockhaus Measurements

In the design process of electric motors and generators the power losses of stator cores are calculated based on the material supplier’s data from standard magnetic measurements performed under sinusoidal magnetization. This type of data does not include the additional loss from non-sinusoidal multi-harmonic motor excitation nor the detrimental effects of residual stress remaining in the motor laminations after manufacturing processes, such as punching, welding, housing shrink fitting and winding. Moreover, in production a considerable attention is given to the measurements of mechanical dimensions of stator cores, whereas verification of their magnetic properties is typically neglected, which can lead to inconsistent efficiency of assembled motors. Therefore, to enable a comprehensive characterization of stators, Brockhaus Measurements developed a range of in-line and off-line measurement technologies for testing of their magnetic properties under different excitation conditions. Experimental data obtained with Brockhaus systems which emphasized the requirement for advanced characterization of stator cores at various design and production stages will be presented.

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