This article presents an up-to-date magnetic material investigation and overview on soft magnetic materials used in rotating electrical machines. The focus is on small-to-medium-sized high-performance and high-efficiency permanent-magnet and induction motors for different application scenarios. The investigated materials include fully processed silicon-iron (SiFe), nickel-iron (NiFe), and cobalt-iron (CoFe) lamination steels as well as soft magnetic composites (SMCs) and amorphous magnetic materials. This article focuses on the magnetic properties and iron losses as well as the manufacturing influence and required thermal treatments during the manufacturing process. A new loss-to-flux-density factor is introduced to compare the magnetization curve and the iron losses of different materials within the same diagram. This article provides a review and comparison of magnetic substances for use in high-performance machines.

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Magnetic Materials Used in Electrical Machines: A Comparison and Selection Guide for Early Machine Design

This paper employs grain-oriented electrical steel (GOES) in an axial-flux switched reluctance motor (AFSRM) to improve its torque characteristic, taking advantages of the material's excellent magnetic properties in the rolling direction. Based on the study on the parameter and switching characteristics of an AFSRM, GOES can be divided into pieces and arranged in the rotor and stator teeth so that the magnetic flux mainly travels along the rolling direction of the material. AFSRMs with different lamination shapes and deviation angles between the magnetic flux and rolling direction of the GOES have been studied to further improve the output performance; the maximum electromagnetic torque of the proposed design shows a 20.5% increase in comparison with that of the conventional nonoriented electrical steel motors under identical conditions. The rotor retaining ring is composed of epoxy resin lamination to constrain the rotor teeth modules. Thermal and stress analyses under fault conditions are analyzed to verify the reliability of the retaining ring. Furthermore, an AFSRM prototype is built and experiments are conducted to validate the calculated data.

Optimal Design of an Axial-Flux Switched Reluctance Motor With Grain-Oriented Electrical Steel

This paper presents a non invasive method for estimating the energy efficiency of induction motors used in industrial applications. This method is innovative because it is only based on the measurement of the external field emitted by the motor. The paper describes the sensors used, how they should be placed around the machine in order to decouple the external field components generated by both the air gap flux and the winding end-windings. The study emphasizes the influence of the eddy currents flowing in the yoke frame on the sensor position. A method to estimate the torque from the external field use is proposed. The measurements are transmitted by a wireless module (Zig-Bee) and they are centralized and stored on a PC computer.

https://www.mdpi.com/1424-8220/10/8/7874/pdf

Non Invasive Sensors for Monitoring the Efficiency of AC Electrical Rotating Machines

The selection of the appropriate core magnetic material for an electrical machine is one of the main design decisions that will significantly influence the power density and efficiency of the machine. The selection of the material is function of the torque/speed requirements and structure of the machine itself. Recent research have investigated different material options for electrical machine design and the basis of this paper is to provide a review and comparison of the research outcomes. The review is presented under three sections, viz. application of soft magnetic alloys, soft magnetic composites and amorphous magnetic materials. Based on the research outcomes, the most suitable applications for these different material categories have been identified. Future research directions of electrical machine design that may benefit the efficiency and power density are identified and associated research challenges are highlighted. The core loss parameters of state-of-the-art material in literature are compared and discussed.

Magnetic materials for electrical machine design and future research directions: A review

This paper deals with design and construction of a surface-mounted Permanent Magnet Synchronous Motor to be used in elevator hoisting machine. Direct-drive solution in combination with a motor with Grain Oriented electrical steel have been proposed in order to optimize the space utilization. Manufacturing solutions adopted for the segmental core arrangement and the motor design procedure based on a combined finite elements and analytical models are discussed. A 4 kW prototype has been realized and tested. The experimental results confirm the design specifications.

http://ieeexplore.ieee.org/iel5/6330482/6349821/06350037.pdf

Design of a Permanent Magnet Synchronous Motor with Grain Oriented electrical steel for Direct-drive elevators

This paper deals with the test results of an experimental prototype for a new electric motor magnetic circuit structure. Such configuration uses shifted non-segmented grain oriented steel laminations. The paper presents the magnetic circuit design, the experimental procedure and the results which point out the different advantages of this particular shifted structure.

S. Lopez

Papers

Grain Oriented Steel Assembly Characterization for the Development of High Efficiency AC Rotating Electrical Machines

Characterization of Electrical Steel Disc Stacks for the Development of New Circular Magnetic Circuits