Preliminary analysis of eddy current and iron loss in magnetic gear in electric vehicle

The inclusion of a high energy density permanent magnet into magnetic gear improves the machine's torque density. However, it also contributes to eddy current loss, especially in a high-speed application such in electric vehicle. In this paper, the losses from eddy current and iron loss are investigated on concentric magnetic gear (CMG). Torque multiplier CMG is designed with 8/3 gear ratio for this study. Iron loss and eddy current loss are compared and discussed. Based on this study, eddy current loss contributes to almost 96% of the total loss. This finding is hoped to direct the researcher to focus more on reducing loss associated with eddy current loss.

A mixed multiscale FEM for the eddy current problem with T,Φ-Φ and vector hysteresis

Purpose This work introduces an efficient and accurate technique to solve the eddy current problem in laminated iron cores considering vector hysteresis. Design/methodology/approach The mixed multiscale finite element method based on the based on the T,Φ-Φ formulation, with the current vector potential T and the magnetic scalar potential Φ allows the laminated core to be modelled as a single homogeneous block. This means that the individual sheets do not have to be resolved, which saves a lot of computing time and reduces the demands on the computer system enormously. Findings As a representative numerical example, a single-phase transformer with 4, 20 and 184 sheets is simulated with great success. The eddy current losses of the simulation using the standard finite element method and the simulation using the mixed multiscale finite element method agree very well and the required simulation time is tremendously reduced. Originality/value The vector Preisach model is used to account for vector hysteresis and is integrated into the mixed multiscale finite element method for the first time.

A Novel Pulsed Eddy Current Criterion for Non-Ferromagnetic Metal Thickness Quantifications under Large Liftoff

The pulsed eddy current (PEC) inspection is considered a versatile non-destructive evaluation technique, and it is widely used in metal thickness quantifications for structural health monitoring and target recognition. However, for non-ferromagnetic conductors covered with non-uniform thick insulating layers, there are still deficiencies in the current schemes. The main purpose of this study is to find an effective feature, to measure wall thinning under the large lift-off variations, and further expand application of the PEC technology. Therefore, a novel method named the dynamic apparent time constant (D-ATC) is proposed based on the coil-coupling model. It associates the dynamic behavior of the induced eddy current with the geometric dimensions of the non-ferromagnetic metallic component by the time and amplitude features of the D-ATC curve. Numeral calculations and experiments show that the time signature is immune to large lift-off variations.

Ultra-Compact Eddy Current Transducer for Corrosion Defect Search in Steel Pipes

This research is devoted to the application of non-destructive testing methods for detecting defects of the internal structure of the material in steel pipelines. Despite the use of modern approaches to the design and manufacture of pipelines, which make it possible to lay a significant margin of safety in the created system, the task of developing new approaches to measuring the technical and operational characteristics and parameters of steel parts using software and hardware complexes for non-destructive testing does not lose its relevance. The paper presents the results of the development of defect detection system aimed at detecting damage of the structure of the material with a diameter of 0.2 mm and located at a depth of up to 2 mm. The proposed system is based on the physical principles of the influence of the existing defect on the value of the transformer voltage, which is induced in the measurement circuit of the sensor built on eddy current effects. The focus of the research is the relationship between the linear dimensions of the defect, its location and the generated voltage indications of the developed sensor. Also, within the framework of the study, the results of processing and analysis of the data collected by the defect detection system are presented, the result of which was the determination of the parameters of the detected defects.

Model of Magnetically Shielded Ferrite-Cored Eddy Current Sensor

Computationally fast electromagnetic models of eddy current sensors are required in model-based measurements, machine interpretation approaches or in the sensor design phase. If a sensor geometry allows it, the analytical approach to the modeling has significant advantages in comparison to numerical methods, most notably less demanding implementation and faster computation. In this paper, we studied an eddy current sensor consisting of a transmitter coil with a finitely long I ferrite core, which was screened with a finitely thick magnetic shield. The sensor was placed above a conductive and magnetic half-layer. We used vector magnetic potential formulation of the problem with a truncated region eigenfunction expansion, and obtained expressions for the transmitter coil impedance and magnetic potential in all subdomains. The modeling results are in excellent agreement with the results using the finite element method. The model was also compared with the impedance measurement in the frequency range from 5 kHz to 100 kHz and the agreement is within 3% for the resistance change due to the presence of the half-layer and 1% for the inductance change. The presented model can be used for measurement of properties of metallic objects, sensor lift-off or nonconductive coating thickness.