Design and Analysis Considering Magnet Usage of Permanent Magnet Synchronous Generator Using Analytical Method

In this study, the characteristic analysis of a permanent magnet synchronous generator was performed using the analytical method, and the validity of the analytical method was compared with that of the finite element method (FEM). For the initial design, the rotor size was selected using the torque per rotor volume method, and the stator size was selected according to the saturation of the stator iron core. In addition, fast Fourier transform analysis was performed to determine the appropriate magnet thickness point, and it was confirmed that the open circuit and armature reaction magnetic flux densities were consistent with the FEM analysis results. Based on the analytical method, the generator circuit constants (phase resistance, back EMF, and inductance) were derived to construct an equivalent circuit. By applying the equivalent circuit method to the derived circuit constants, the accuracy of the equivalent circuit method was confirmed by comparing the FEM and experimental results.

The Three-dimensional Collapse of a Rapidly Rotating 16 M ⊙ Star

I report on the three-dimensional (3D) hydrodynamic evolution of a rapidly rotating 16 M ⊙ star to iron core collapse. For the first time, I follow the 3D evolution of the angular momentum (AM) distribution in the iron core and convective shell burning regions for the final 10 minutes up to and including gravitational instability and core collapse. In 3D, convective regions show efficient AM transport that leads to an AM profile that differs in shape and magnitude from MESA within a few shell convective turnover timescales. For different progenitor models, such as those with tightly coupled Si/O convective shells, efficient AM transport in 3D simulations could lead to a significantly different AM distribution in the stellar interior affecting estimates of the natal neutron star or black hole spin. The results suggest that 3D AM transport in convective and rotating shell burning regions are critical components in models of massive stars and could qualitatively alter the explosion outcome and inferred compact remnant properties.

Design of a High Efficiency High Step-Up/Step-Down Bidirectional Isolated DC–DC Converter

This paper presents a novel bidirectional DC–DC converter, equipped with a three-winding coupled inductor, that can be applied to high-voltage, bidirectional DC–DC energy conversion and meet battery charging and discharging requirements. The architecture consists of a semi-Z-source converter and a forward–flyback converter featuring a three-winding coupled inductor with an iron core. This proposed topology retains the current continuity characteristics of the low-voltage side, all switches possess the zero-voltage switching feature, and the switches on the low-voltage side in the step-down mode have a synchronous rectification function. A 500-W bidirectional converter is implemented to examine the practicality and feasibility of the proposed topology. The relatively streamlined design of the converter can greatly reduce production costs. In the step-up and step-down modes, the maximum energy conversion efficiencies are 95.74% and 96.13%, respectively.

Design and Thermal Modeling of Modular Hybrid Excited Double-Sided Linear Flux Switching Machine

This paper presents a Hybrid Excited Double-Sided Linear Flux Switching Machine (HEDSLFSM) with a crooked tooth modular stator. Generally, the conventional stators are made of a full-length iron core, increasing manufacturing costs and iron losses. Higher iron losses result in lower efficiency and lower overall performance. A U-shaped modular stator with a crooked tooth is used to lower iron consumption and increase the machine’s efficiency. Ferrite magnets are used to replace rare earth magnets, which also reduces the machine cost. Two DC excitation windings are used above and below the ferrite magnet to reduce the PM volume. 2D electromagnetic performance analysis is done to observe the key performance indices. Geometric optimization is used to optimize the Split Ratio (S.R), DC winding slot area (DCw), and AC winding slot area (ACw). Stator Tooth Width (STW), space between the modules (S.S.), and crooked angle (α) are optimized through JMAG in-built Genetic Algorithm (G.A.) optimization. High thrust force density and modular stator make it a good candidate for long-stroke applications like railway transits. The thermal analysis of the machine is performed by FEA analysis and then validated by 2D LPMC (Lumped Parametric Magnetic Equivalent Circuit) model. Both analyses are compared, and an error percentage of less than 4% is achieved.

Mechanism of Blunt Punching Tools’ Influence on Deformation and Residual Stress Distribution

Punching is the main manufacturing process with high efficiency and machining accuracy used to produce the iron cores of motors. However, it usually introduces residual stress at the cutting edge and affects the magnetic properties of the iron core. Further studies show that the tensile residual stress (TRS) has a negligible effect on the magnetic properties, compared with the compressive stress. The blunt punch tools cause local TRS and the formation of local large plastic deformation (PD) at the cutting edge as the cost. The PD has a more serious effect on the magnetic properties of materials than TRS. Therefore, this study mainly focused on local deformation distribution and the associated microstructure evolution using EBSD (Electron Backscatter Diffraction) and finite element analysis; and the formation mechanism of tensile residual stress during the punching process at the cutting edge of a non-oriented silicon steel after punching with blunt tools, by using nanoindentation and a numerical simulation. The experimental results showed the existence of a specific bending area, a highly deformed area and a large burr at the cutting edge. These direct observations were confirmed with those obtained by the simulation model. Furthermore, the tensile residual stress on the surface was verified through nanoindentation tests and by a numerical simulation. The results indicate also that the formation of a tensile residual stress zone depends especially on the bending area formed during punching with blunt tools.

Research on Electromagnetic Force of Hybrid Electromagnetic Levitation Needle Driving System

Hybrid electromagnetic levitation drive system is the core of the needle drive structure, and its performance directly determines the size of the needle drive force. According to the initial design results, the simulation model of the needle drive is established in the electromagnetic field simulation software Maxwell, and the influence of the structural parameters of the hybrid electromagnetic drive system:, the material of the iron core, the number of coil turns on its static characteristics is analyzed. The simulation results show that at the same height, when the isolation ring material is aluminum, the time for the permanent magnet needle to rise to the highest position is the shortest.

Supernova Preshock Neutronization Burst as a Probe of Nonstandard Neutrino Interactions

A core-collapse supernova (CCSN) provides a unique astrophysical site for studying neutrino–matter interactions. Prior to the shock-breakout neutrino burst during the collapse of the iron core, a preshock ν e burst arises from the electron capture of nuclei and it is sensitive to the low-energy coherent elastic neutrino–nucleus scattering (CEνNS) which dominates the neutrino opacity. Since the CEνNS depends strongly on nonstandard neutrino interactions (NSIs), which are completely beyond the standard model and yet to be determined, the detection of the preshock burst thus provides a clean way to extract the NSI information. Within the spherically symmetric general-relativistic hydrodynamic simulation for the CCSN, we investigate the NSI effects on the preshock burst. We find that the NSI can maximally enhance the peak luminosity of the preshock burst almost by a factor of three, reaching a value comparable to that of the shock-breakout burst. Future detection of the preshock burst will have critical implications on astrophysics, neutrino physics, and physics beyond the standard model.

DVR Transient Analysis with Saturated Iron-Core Superconducting Fault Current Limiter

The saturated iron-core super conducting fault current limiter exceeds all other fault current limiters in terms of technical performance. Based on the real structure, magnetic structures have been proposed. Simulated current limiting inductance was calculated using the Newton iteration method and the fundamental magnetization curve. Sagging and soaring current levels occurred frequently during the faulting process. Short circuits and voltage fluctuations are two of the most typical grid-related issues.. The use of the SISFCL and DVR in this project resulted in a reduction in the amount of fault current and voltage variation. With the help of Matlab/Simulink and theoretical insights from previous research, we were able to construct an electromagnetic transient simulation model. The transient behavior of these devices during simulation tests demonstrates the accuracy and validity of the suggested strategy. Keywords: Analysis of transient electromagnetic waves in a saturated iron core using a Newton iteration method. Fault current limiter (SISFCL), dynamic voltage restorer (DVR), pulse width modulation (PWM)