Iron Loss Reduction Research Articles

Relationship Between Temperature Control and Iron Loss Reduction by Secondary Current Heating Method

Relationship Between Temperature Control and Iron Loss Reduction by Secondary Current Heating Method

Comparison and analysis of properties of V-type HV-LSPMSM with non-magnetic and magnetic-wedges

In order to improve the magnetic density distribution and torque ripple waveform of the motor and enhance its efficiency, the effect of slot wedge on motor performance is discussed in this paper. Taking 6 kV, 710 kW high-voltage line-start PMSM (HV-LSPMSM) as an example, the mathematical model is established, the influence mechanism of slot wedge on air gap density, loss, efficiency and torque ripple of motor is analyzed. The HV-LSPMSM prototype was manufactured, the deviations of several important motor parameters are less than 5% by comparing the test data and the finite element analysis (FEA) results, thus, the accuracy and reliability of the modified finite element model (FEM) are verified, it provides an experimental basis for further research on the effect of relative permeability variation on motor performance. The effects of nonmagnetic-wedges and magnetic-wedges on the motor’s performance are systematically compared. The research results show that compared with the non-magnetic wedges, the magnetic wedges are used to make the magnetic density more uniform, the eddy current loss with magnetic wedge (μ = 5) is reduced by 7.292 kW, and the motor efficiency is improved. The torque ripple rate with magnetic wedge (μ = 3) is reduced by 3.35%, and the torque waveform is significantly improved. And It is found that magnetic wedge (μ > 3) slowed down the iron loss reduction rate. The research provides an important theoretical and experimental basis for the design of HV-LSPMSM and the application of magnetic-wedge in motor.

Excellent magnetic properties obtained in planar flow casting Fe-6.5 %Si steel via low strain cold-rolling and annealing

Planar flow casting (PFC) has been applied to prepare Fe-6.5wt. %Si ultra-thin ribbons with a strong 〈001〉 fiber texture. However, critical issues such as fine grain size and large surface roughness are vital to overcome. In this study, low strain cold-rolling and subsequent annealing are applied to planar flow casting Fe-6.5 %Si ribbons. Cold-rolling reduces surface roughness and introduces heterogeneous deformation in the ribbons. Recrystallization occurs preferentially in high deformed areas during annealing. Recrystallizing grains grow significantly by consuming neighboring deformed grains with fine size and 〈001〉 orientation, leading to greatly reduced iron loss. Thus, the ribbon annealed at 1000 ℃ exhibits the best combination of magnetic properties with B8 of 1.29 T and P2/5000 of 6.95 W/kg. The kinetics of recrystallization and grain growth are described along with the calculations of activation energies, which suggests the cold-rolled ribbon has a faster growth rate than the undeformed one. Two mechanisms, namely strain-induced boundary migration (SIBM) and thermo-induced boundary migration (TIBM), are used to explain the grain growth. SIBM is dominant at low temperatures while TIBM is dominant at high temperatures. This work presents a strategy to tailor the microstructures and properties of PFC-prepared alloys with fine grain.

Щодо взаємодії і захоплення металевих крапель доменним шлаком

The mechanism of capture of metal drops by the slag melt was investigated using blast furnace slag as an example. The role of the viscosity of the blast furnace slag in reducing iron loss at the output from the blast furnace is shown. Reducing the viscosity of slags contributes to the rapid settling of small drops of cast iron in the slag volume. It is noted that the CaO/SiO2 ratio is an important parameter that changes the viscosity of blast furnace slag. To ensure the minimum viscosity of blast furnace slag, it is necessary to establish the optimal chemical composition of the slag, in particular the CaO/SiO2 ratio. A study of the temperature dependence of the viscosity of blast furnace slag melts was carried out using the method of estimating the content of the solid phase in the melt during its cooling. Calculations of the volume fraction of the solid phase for blast furnace slags were performed. An increase in the CaO/SiO2 ratio in slags leads to an increase in their crystallization ability. The microstructure and chemical composition of individual phases of a blast furnace slag sample were studied using scanning electron microscopy (SEM). It was established that the experimental slag contained at least three phases. The main (matrix) phase was an amorphous phase, which contained mainly SiO2 and Al2O3. The volume of the matrix phase contained interspersions of the crystalline phase of different sizes, which mainly included CaO and SiO2. In the volume of the crystalline phase, a metallic phase was found, which consisted mainly of Fe and Mn and had a regular rounded shape. The mechanism of capture of a metal droplet by slag is described. The metal drop serves as a frame (center) for the nucleation of the crystalline phase in the slag volume, as its surface energy decreases at the "metal drop - slag" interface. An increase in the mass of the crystalline phase around the metal drop leads to an increase in its lifting force and capture of the metal drop. Keywords: blast furnace slag, viscosity, metal loss, crystallization, scanning electron microscopy.

Effect of initial grain size on microstructure, texture and magnetic properties of non-oriented electrical steel

The effect of initial grain size prior to cold rolling on the microstructure, texture evolution, and magnetic properties of Fe-3.5 wt% Si non-oriented electrical steel (NOES) was investigated through the introduction of normalization. There were massive intragranular shear bands in {111}<110> and {111}<112> deformed grains in the cold-rolled sheet with large initial grain size, providing nucleation sites for new recrystallized grains with Goss ({110}<001>), λ-fiber, γ-fiber, and {113}<631> components. Subsequent annealing resulted in weaker γ-fiber ({111}<110>−{111}<112>), stronger α*-fiber concentrated at {113}<631>, along with Goss and λ-fiber ({100}<001>−{100}<012>) textures. In addition, appropriate final annealing temperature effectively reduced iron loss. The simultaneous optimization of texture and grain size by normalization and annealing treatments led to improved magnetic properties, with the superior magnetic induction (B50 = 1.719) T, and the lowest core loss (P15/50 = 2.69 W/kg, P10/400 = 16.337 W/kg).

Rotor Reconstruction to Reduce Iron Losses in Partitioned Stator Flux-Modulation Machine

Rotor Reconstruction to Reduce Iron Losses in Partitioned Stator Flux-Modulation Machine

Designing size-controlled air cavities to reduce iron losses of 3D printed ferromagnetic parts: Modelling and experimental results

We studied the effect of cavity insertion to reduce iron losses into Fe-2.6wt.%Si ferromagnetic components fabricated by Laser Powder Bed Fusion (L-PBF) 3D printing process. Finite Element Method (FEM) simulation was used to understand the impact of various cavity configurations on eddy current losses and to identify design guidelines. Results highlight the dependence of losses on eddy current path length, which can be expressed by simple geometrical design parameters. Finally, L-PBF samples were magnetically characterized up to 500 Hz. A good correspondence between experimental data and modelling results is observed. A torus designed with six external cavities allowed the reduction of the losses by 60 % compared to a bulk specimen (0.5 T; 500 Hz).

Reduction of Iron Loss on Motor Stator Cores by Means of Secondary Current Heating Method

Reduction of Iron Loss on Motor Stator Cores by Means of Secondary Current Heating Method

Feature Analysis on B–H Curves of Dust Cores Under the Application of DC Bias Field

To realize high efficiency power converters, it is very important to reduce loss of passive magnetic components of transformers and inductors in high frequency region. Iron loss behavior under a DC bias field is crucially important to characterize inductor performance, but it has not been well analyzed. In this study, the iron loss behavior of a Sendust dust core has been analyzed in relation to the change in <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B-H</i> curve shape using principal component analysis (PCA). The iron loss monotonically decreases with increasing the DC bias field accompanying the reduction of permeability and slight asymmetric change in <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B-H</i> curve shape. PCA can extract featured quantities of these change in <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B-H</i> curve shape. Consequently, it is revealed that the curvature of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B-H</i> curve changes its polarity with increasing the DC bias field, and this behavior has a strong relationship with the reduction of iron loss.

A Novel Consequent-Pole Contra-Rotating Machine With Zero-Sequence Current Excitation

A novel hybrid excitation consequent-pole contra-rotating machine with zero-sequence current excitation is presented in this paper. The stator windings carry both the DC field winding current and the AC armature current, making the machine more compact. Further, the flux can be weakened or enhanced without the risk of demagnetization by controlling the zero-sequence current excitation in the integrated winding. Finally, the segmented stator can effectively reduce iron loss and simplify the manufacture processing.

Process Development of Screen-Printed Magnetic Sheets for Electric Machines via Statistical Design of Experiments

Electrical machines play a major role in achieving a more sustainable economy by driving the further electrification of industry and transportation. To enhance the electric motor productivity during production and the efficiency during operation, it is essential to maximize the material yield rate during the production of stator and rotor sheet stacks and reduce iron losses during operation. Screen-printing technology can help to achieve these goals by producing thin magnetic sheet laminations in near-net-shape geometry, resulting in minimum material waste during production. Moreover, reducing the sheet thickness decreases the eddy current losses and avoids mechanical stress during manufacturing, leading to improved motor efficiency. Additionally, screen printing facilitates the production of multi-material components and variable alloy compositions. This study aims to identify the relevant factors and printing parameters so that screen-printed magnetic sheets can achieve product specifications. A method involving the statistical design of experiments is performed in several iterations to investigate the target parameters of the print cycle time, green part weight, shape integrity and layer thickness, and to analyze the main interdependencies. The results of this study provide valuable insights into optimizing the screen-printing process for soft magnetic sheets, enabling the production of efficient electric motors while reducing material scrap.

Laser punching of soft magnetic Fe-based amorphous ribbons

Soft-magnetic Fe-based amorphous materials are indispensable in electronic components. However, traditional processing methods (mechanical punching or wire cutting) degrade the amorphous structure, introduce stress, and are inefficient. To overcome these limitations, we introduce a precision processing technique for the Fe-based amorphous ribbons, namely laser punching. We compare two laser types: the picosecond pulse ultraviolet (PS-UV) laser, representing “cold” lasers, and the continuous-wave infrared (CW-IR) laser, epitomizing “hot” lasers. Our results demonstrate that the PS-UV laser can produce intricate geometries with minimal thermal or stress-induced effects. In contrast, the CW-IR laser induces nano-crystallization and crinkling due to heavy thermal effect. As an example, we successfully craft an amorphous motor stator using the PS-UV laser-processed ribbons, which exhibits considerably reduced iron losses compared to that fabricated with CW-IR laser. The reduction in iron loss and enhanced efficiency underscores the potential of PS-UV laser punching as a promising method for manufacturing amorphous motors.

Loss analysis of magnetization annealed amorphous alloy replacement stator teeth

With the development of electric motors, high speed and high efficiency have become the new development trend. Therefore, reducing the iron loss of motors has become the focus of academia and industry. Amorphous alloys are gradually being used in high speed motors by virtue of their low loss characteristics at high frequencies. Amorphous alloys generate large internal stresses during the manufacturing process, and annealing is usually required to eliminate the effect of internal stresses on magnetism. Amorphous transformer cores are usually annealed by applying a magnetic field in the direction of the magnetic circuit to improve the magnetic domain state, increase the saturation density in that direction, and reduce iron loss. Since the magnetic field of the motor stator teeth is pulsating, and amorphous annealed under longitudinal magnetic field (AALM) has the most performance along the direction of the annealed magnetic field. Therefore, in this paper, the magnetic properties of AALM, annealed amorphous (AA), and unannealed amorphous (UA) are tested to prove the advantages of the material, and then AALM is spliced as the tooth of the motor. The advantages of this material in the motor species are further demonstrated by designing a comparative simulation scheme in the longitudinal direction (same material with different structure) and in the transverse direction (same structure with different material).

A Study on Optimal Design Process of Dual Rotor Axial-Flux Permanent Magnet Synchronous Motors

The core design elements of the motor for the co-robot joint are miniaturization and high torque. In this paper, a dual rotor axial-flux permanent magnet (DRAFPM) motor is proposed to improve the performance of robot joints. DRAFPM motors have the advantage of reducing iron loss and minimizing volume because they can remove stator yoke. When designing a motor with the same volume, it can be designed to increase the height of the fixed ruler by the thickness of the yoke of the fixed ruler and increase the number of turns. In the case of existing axial-flux permanent magnet (AFPM) motors, the shape of the three-dimensional structure is limited by radial laminating of stator. Therefore, considering the production of 3D printing, the shape of stator shoe is designed. The optimal design problem of DRAFPM motor consists of real and integer design variables. In addition, due to the structural characteristics of DRAFPM motors, 3D finite element analysis (FEA) is required, so it takes a long time to interpret. Therefore, this paper proposes an efficient optimal design process to optimize the remaining real design variables after prioritizing the integer design variables. The proposed optimization process is applied to the DRAFPM motor for robot joints, and the optimal design plan satisfying the design function is derived from various design variables to prove the validity of the optimization process.

A Study on the Design Method for Improving the Efficiency of Spoke-Type PMSM

Considerable progress has been achieved in motor design and control and related material technologies. Motor driving systems are increasingly being incorporated in various applications, such as transportation machines, including hybrid/electric vehicles, and industrial machines, including robot, crane, rolling mill machine, and home appliances. However, various motors used in such applications consume the majority of electric energy generation. Increasing electric energy generation through the expansion of a power generation system is time-consuming and requires considerable money and time. Therefore, a high-efficiency motor should be designed. Domestic and foreign standard agencies are implementing policies and standards to grade energy efficiency based on the electric energy used by motors. A study was conducted on improving motor efficiency for home appliances. When designing a high-efficiency motor for home appliances, a design plan that maximizes the magnetic flux density of the air gap and reduces various losses was first considered. In this study, a spoke-type structure was proposed to maximize the effective magnetic flux density in the air gap for achieving high-efficiency motors. The space available for fitting motors inside applications is reducing. For miniaturization and improving the efficiency of the motor considering space constraints, the application of the overhang (O/H) and spoke-type structures was considered. In addition to the O/H structure, electrical steel sheet SRA was investigated for reducing iron loss. The effect of the spoke-type structure with O/H applied for high efficiency was verified through 3-D finite element analysis and experimental results after motor manufacturing.

Effects of slab reheating temperature and hot rolling process on microstructure, texture and magnetic properties of 0.4% Si non-oriented electrical steel

The effect of different slab reheating temperatures (1150 °C and 1000 °C), thicknesses of hot rolled sheet (2.8 mm, 2.3 mm and 2.0 mm) and coiling temperatures (630 °C and 750 °C) on microstructure, texture and magnetic properties of 0.4 wt% Si non-oriented electrical steel was comparatively studied in detail. This work focused on the effect of ultra-low temperature slab reheating and ultra-thin gauge hot rolling on magnetic properties. It was found that with the thinning of hot-rolled sheet thickness, the final grain size increased and iron loss decreased regardless of slab reheating temperature and coiling temperature. Lowering slab reheating temperature or increasing coiling temperature could further reduce iron loss. However, their effect on magnetic induction was relatively complex. When coiling at low temperature of 630 °C after hot rolling, decreasing thickness of hot rolled sheet did not always improve magnetic induction, but also depended on the reheating temperature. Because the low coiling temperature could not eliminate severely deformed grains in hot rolled sheets, which obviously deteriorated magnetic induction. To eliminate the deformed grains, coiling temperature was increased from 630 °C to 750 °C, and the microstructures were fully equiaxed grains. Both thinning hot-rolled sheet thickness and lowering slab reheating temperature promoted the development of shear bands during cold rolling, thus resulting in weakening γ-fiber (<111>//ND) texture and strengthening λ-fiber (<100 >//ND) in final sheets. As a result, the magnetic induction was significantly increased. Furthermore, the recrystallization behavior of different cold rolled microstructures during annealing was investigated using a quasi-in-situ electron backscattered diffraction (EBSD) technique.

Reduction of Iron Loss on Grain-oriented Electrical Steel Sheet Using Vector Magnetic Characteristic Control Technology

Reduction of Iron Loss on Grain-oriented Electrical Steel Sheet Using Vector Magnetic Characteristic Control Technology

Effect of hot band annealing prior to cold rolling on the mechanical toughness and magnetic properties of non-oriented electrical steel

In this work, the effect of hot band annealing on subsequent microstructure, toughness and final magnetic properties of non-oriented electrical steel was investigated. It was found that the hot band annealing temperature plays an important role in the microstructure, toughness, texture and final magnetic properties. After hot band annealing, the grain size of hot-rolled and final annealed steels were increased, which made contribution to the reduction of iron loss. Besides that, hot band annealing could enhance the favorable θ-fiber texture and weaken the unfavorable γ-fiber texture of the final annealed steel. The magnetic induction B5000 of final annealed steel increased with the increasing of hot band annealing temperature within the testing range. In addition, the coarsening grain size caused by high hot band annealing temperature leaded to a sharp decrease in toughness of the hot-rolled steel. An increase in test temperature would improve the impact toughness of hot-rolled steel after hot band annealing. When the test temperature rose to 100 °C, ductile fracture occurred in all the hot-rolled steels under the hot band annealing condition of 850–950 °C.

Improvement in soft magnetic properties of thin bilayer ribbons using magnetoelastic effect

We have prepared Fe-Ni-system bilayer ribbons with different magnetostriction (compositions) and investigated the improvement of soft magnetic properties using the magnetoelastic effect. A toroidal core with D = 10 mm was made from the Fe6Ni94/Fe56Ni44 bilayer ribbon, and the B-H loop of the core was measured. The shape of the hysteresis loop dramatically changed depending on the inner layer (inner magnetic phase). This result indicates that the direction of the anisotropy induced by bending stress was changed depending on the inner layer. The slope of the B-H loop and coercivity reduced when the Fe56Ni44 layer was on the inner side. From the experimental results, we found that domain rotation was dominant for the magnetization process. Consequently, the increase in the coercivity over frequency could be suppressed by controlling the magnetization process. From these results, we found that a thin bilayer ribbon with positive and negative magnetostriction constant is an attractive material for reducing iron losses under high frequency.

Additively Manufactured Transverse Flux Machine Components with Integrated Slits for Loss Reduction

Laser powder bed fusion (L-PBF) was used to produce stator half-shells of a transverse flux machine from pure iron (99.9% Fe). In order to reduce iron losses in the bulk components, radially extending slits with a nominal width of 150 and 300 µm, respectively, were integrated during manufacturing. The components were subjected to a suitable heat treatment. In addition to a microscopic examination of the slit quality, the iron losses were also measured using both a commercial and a self-developed measurement setup. The investigations showed the iron losses can be reduced by up to 49% due to the integrated slits and the heat treatment.