Non-uniform air gap modeling and electromagnetic characteristics of a new six-phase doubly salient electro-magnetic generator

The voltage harmonics of the six-phase doubly salient electro-magnetic generator (DSEG) are large, and the electromagnetic isolation is poor due to the mutual inductance of the armature winding. An optimization scheme for the stator non-uniform air gap structure is proposed. By establishing a non-uniform air gap angle function model, the analytical expression of the induced electromotive force in the non-uniform air gap structure is derived. Using finite element and mathematical model to verify that the stator tip is changed from circular arc to linear structure can increase power and reduce voltage high harmonics, improve the power quality of the generator. Based on the equivalent magnetic circuit, the influence of the winding method of the excitation winding on the mutual inductance of the armature winding is studied. When the field winding is wound interval every two stator poles, the mutual inductance is small. The electromagnetic properties of the new six-phase electric excitation double salient pole are analyzed by two-dimensional finite element analysis. The rationality of the proposed motor structure is verified by experiments.

A novel doubly salient electro-magnetic generator with symmetrical phase magnetic circuits: Basic topology, analysis, and experimental verification

The field winding of conventional multiphase doubly salient electro-magnetic generator is wound across multiple stator poles. There is a problem that the flux paths of the respective phases are not completely symmetrical. A novel E-core stator was proposed, the basic topology of the multi-phase E-core doubly salient electro-magnetic generator (E-core DSEG) with symmetrical phase magnetic circuits is derived by using the electrical formulas. This establishes a theoretical basis for the design of multiphase E-core DSEG. Based on the finite element simulation software, the static characteristics of multi-phase E-core DSEG were analyzed, including magnetic field distribution no-load electromotive force, flux linkage, self-inductance of field winding, cogging torque and so on. Finally, a prototype of three phases 18/20-pole generator was made and tested. The rationality of theoretical analysis and generator topology was verified by simulation and experiment.

Investigation on Tripping in Magnetic Generator in Steam-Assisted Gravity Drainage Wells Based on Numerical Simulation

Magnetic Guidance Technology can meet the precise measurement requirements when drilling steam-assisted gravity drainage (SAGD) oil wells. Magnetic generator is a key part in the Magnetic Guidance Technology. When magnetic generator is tripped into horizontal well, pump pressure and passing capacity of the magnetic source generator in the curved section need to be analyzed. So, a mathematical model of tripping in the magnetic generator is established. If curvature radius, deviation angle, and friction factor are known, the forces acting on the magnetic generator in different positions could be calculated. The finite element (FE) results show that: (1) with depth increasing in the curved section, the equivalent stress on the magnetic generator increases in a fluctuating manner, the contact area, friction drag, and energy loss increase. (2) The greater the hole curvature, the greater tripping in force and the higher pump pressure are needed. The lower friction coefficient is favorable to tripping in the magnetic generator. (3) The friction between the magnetic generator and tubing wall in the horizontal section is much less than that in the curved section. Field applications have shown that the maximum downforce is close to the result of finite element analysis. The research results provide a reasonable reference basis for smooth running of magnetic source generators with different trajectory conditions.

PENGARUH DIMENSI MAGNET PERMANEN NdFeB DAN JARAK CELAH UDARA TERHADAP KINERJA GENERATOR MAGNET PERMANEN FLUKS AKSIAL SATU FASA

The purpose of this research is to know the influence of NdFeB permanent magnet dimensions and the distance of air gap on performance of single phase axial flux permanent magnet generator. In this research using quantitative approach with experimental method. Research subjects used, namely permanent magnetic generator axial flux with two rotor samples that have different magnetic dimensions and conducted air gap variation. The research data was collected by testing without load and testing with electrical load, to know the performance values of the generator in the form of induction voltage and electric power. The results showed that the induction voltage and electric power were affected by the magnetic dimensions and the distance of the air gap. These results indicate that the rotor with a magnetic surface area of 0.0058 m2 and 0.0034 m2 produces an induced voltage of 91.7 and 27.1 V, as well as a power of 14 and 2.8 W. Whereas, for variations in the air gap with the rotor magnetic surface area 0.0058 m2 and varied 2; 3; 4; 5; and 6 mm produces an induced voltage of 91.7; 89.0; 86.5; 80.2; and 68.5 V, and power of 14; 12; 10.9; 10.5; and 8.8 W. Thus, the use of a magnet ic dimension that is larger and in accordance with the size of the coil, as well as the use of a small air gap distance will result in a better induction voltage value. Abstrak Tujuan dari penelitian ini adalah untuk mengetahui pengaruh dimensi magnet permanen NdFeB dan jarak celah udara terhadap kinerja generator magnet permanen fluks aksial satu fasa. Pada penelitian ini menggunakan pendekatan kuantitatif dengan metode eksperimen. Subjek penelitian yang digunakan, yaitu generator magnet permanen fluks aksial dengan dua sampel rotor yang memiliki dimensi magnet berbeda dan dilakukan variasi celah udara. Pengumpulan data penelitian dilakukan dengan pengujian tanpa beban dan pengujian dengan beban listrik, untuk mengetahui nilai-nilai kinerja generator berupa tegangan induksi dan daya listriknya. Hasil penelitian menunjukkan bahwa tegangan induksi dan daya listrik dipengaruh oleh dimensi magnet dan jarak celah udara. Hasil tersebut menunjukkan bahwa pada rotor dengan luas permukaan magnet 0,0058 m2 dan 0,0034 m2 menghasilkan tegangan induksi sebesar 91,7 dan 27,1 V, serta daya sebesar 14 dan 2,8 W. Sedangkan, pada variasi celah udara dengan rotor luas permukaan magnet 0,0058 m2 dan divariasi 2; 3; 4; 5; dan 6 mm menghasilkan tegangan induksi sebesar 91.7; 89.0; 86.5; 80.2; dan 68.5 V, serta daya sebe sar 14; 12; 10,9; 10,5; dan 8,8 W. Maka, penggunaan dimensi magnet yang lebih besar dan sesuai dengan ukuran kumparan, serta penggunaan jarak celah udara yang kecil akan menghasilkan nilai tegangan induksi yang lebih baik.

Rogue-wave-energy: wave-to-wire mathematical modelling

<p>A novel wave-energy device design [1,2] will be presented based on the following features: (i) an electro-magnetic generator based on cylindrical magnets moving through induction wires around a cylindrical tube, like in the IP wave-buoy, (ii) a convergence in a breakwater to amplify the incoming waves, like in the TapChan device, and (iii) a wave-activated buoy with magnets attached, like in the Berkeley wedge, constrained to move in a slight arc or in a rectilinear manner. Its workings will be demonstrated in a first, operating proof-of-principle. A monolithic mathematical model is established by coupling the three variational principles for the hydro-dynamic wave motion, using the potential-flow approximation, the constrained wave-activated buoy motion, and the electro-magnetic generator together into one grand variational principle. The resistive losses in the electrical circuit and the energy harvested in the (parallel LED) loads are subsequently added to the dynamics. After linearisation of the resulting full 3D nonlinear model around a state of rest and application of the shallow-water approximation, we discretize the linear dynamics in a compatible, i.e. geometrically consistent, manner using a finite-element approach in space and symplectic integrators in time. Preliminary numerical modelling and simple optimization will be shown and these are promising. Finally, further optimisation of the device for different geometries and for a given wave-climate as well as alternative designs will be discussed.<br><br></p><p><strong>References<br></strong>[1] O. Bokhove, A. Kalogirou, W. Zweers 2019: From bore-soliton-splash to a new wave-to-wire wave-energy model. Water Waves<strong> 1</strong>.<br>[2] O. Bokhove, A. Kalgirou, D. Henry, G. Thomas 2019: A novel rogue-wave-energy device with wave amplification and induction actuator. In: 13th European Wave and Tidal Energy Conference 2019, Napoli, Italy.</p>

Source of megaampere current with the rise time ∼100 ns on the basis of explosive magnetic generator

To achieve a thermonuclear ignition threshold in the scheme of indirect irradiation of Z‑pinch by X‑radiation, it is necessary to implode the liner by the current with the amplitude 65 МА for the time 100 ns. The currents with such parameters can be achieved with the use of super-power disk explosive magnetic generators and a two-stage current pulse sharpening system based on foil electrically exploded current opening switches in a form of a serpentine. The implementation of the explosive current source with a rise time of 100 ns is advisable to be carried out in stages by increasing the magnitude of current. The results of the first-stage experiments, in which the current with the amplitude of 5 MA was produced on the basis of the helical explosive magnetic generator in the load of 10 nH for the time of 110 ns, are presented.