Electromagnetic Aircraft Launch System Research Articles

Effect of Occupational Extremely Low-Frequency Electromagnetic Field Exposure on the Thyroid Gland of Workers: A Prospective Study.

The aim of this study was to investigate the biological effects of occupational extremely low-frequency electromagnetic field (ELF-EMF) exposure on the thyroid gland. We conducted a prospective analysis of 85 workers (exposure group) exposed to an ELF-EMF (100 μT, 10-100 Hz) produced by the electromagnetic aircraft launch system and followed up on thyroid function indices, immunological indices, and color Doppler images for 3 years. Additionally, 116 healthy volunteers were randomly selected as controls (control group), the thyroid function of whom was compared to the exposure group. No significant difference was observed in thyroid function between the exposure and control groups. During the follow-up of the exposure group, the serum free triiodothyronine (FT3) level was found to slowly decrease and free thyroxine (FT4) level slowly increase with increasing exposure time. However, no significant difference was found in thyroid-stimulating hormone (TSH) over the three years, and no significant difference was observed in the FT3, FT4 and TSH levels between different exposure subgroups. Furthermore, no significant changes were observed in thyroid autoantibody levels and ultrasound images between subgroups or over time. Long-term exposure to ELF-EMF may promote thyroid secretion of T4 and inhibit deiodination of T4 to T3. ELF-EMF has no significant effect on thyroid immune function and morphology.

Design and Analysis of a High Efficient Multi-Segment Redundancy Linear Motor

Background: The electromagnetic aircraft launch system helps the carrier aircraft accelerate take-off on a short distance on the flight deck. Linear motors are required to have high efficiency and thrust / volume ratio, as the actuator of the EMALS. In addition, linear motors were required to have the fluctuation of the thrust is as small as possible to prevent impact and overstress on the airborne equipment. The thrust performance and thrust fluctuation suppression of linear motors are the current research hotspots in the field of EMALS. Objective: This paper proposes a multi-segment LPMSM to improve the efficiency of the system. Methods: We design a decentralized primary structure based on the Autonomous Decentralized System (ADS) concept. Only the coils near the moving secondary are motivated during the launch process. The others could be released from being driven after the secondary slide over; this control will save energy. Results: A multi-segment linear motor is proposed to improve the efficiency of the EMALS. This motor consists of two sections - the one with iron core for the low speed process and the one without iron core for the high speed process. Conclusion: The normal direction component of the air gap magnetic flux density is much larger than that of the longitudinal component, and their values are 80-90% and 10-20% respectively. For the normal direction component, it is mainly affected by the third, seventh, and ninth harmonics. The accelerating and energy test results show that, in the accelerating process, the efficiency of the linear motor can be more than 90%, and the acceleration is stable.

Conceptual Models of HTS Levitation and Linear Propulsion System

High-temperature superconductor (HTS) materials, including HTS wires and bulks, become available to apply in transportation applications such as various hybrid levitation and linear propulsion systems. In this paper, for the evacuated tube transportation and electromagnetic aircraft launch system applications, two different types of hybrid HTS levitation and linear propulsion systems have been designed and modeled, respectively. The levitation force and electromagnetic thrust performance of the systems have been studied by a numerical and finite element method. With the principal parameters' verification, this work forms a basis for the structural and electromagnetic design of a hybrid HTS levitation and linear propulsion systems for practical hyper flight applications.

The finite element analysis of the linear hybrid reluctance motor for the electromagnetic launch system

The Electromagnetic Aircraft Launch System (EMALS) is being developed utilizing electrical and electronic technologies. EMALS is emerging in order to replace the existing steam catapult on naval carriers. Recently, the double-sided linear launcher has drawn increasing attention of researchers. This paper presents the design and analysis of the Linear Hybrid Reluctance Motor (LHRM). This new motor is characterized by a stator, formed by a combination of independent magnetic structures. Each magnetic structure is composed of an electromagnet—the magnetic core with one or several coils wound around it and associated with a permanent magnet, disposed between their poles. The rotor has the same configuration of a switched reluctance motor (SRM) without any coil, magnets or squirrel cage. In order to improve the thrust of LHRM, the structural characteristics and magnetic field are analyzed. According to the initial design, the Finite Element Analysis (FEA) is presented to obtain the magnetic cogging force and thrust force. Moreover, the effects of the parameters on the thrust and thrust ripple waveforms are analyzed using FEA.

High-Efficiency Control Strategy of an Air-Core Pulsed Alternator Pair

As an attractive power supply for high energy level pulsed power applications, such as long range electromagnetic railgun, electromagnetic aircraft launch system, and high-energy laser, multiple pulsed alternators can not only meet the high energy level requirement of the load, but also lower the requirements of the power electronics in the system. Utilizing multiple pulsed alternators work together also makes the control strategy of the system more flexible. In order to improve the efficiency of the whole system, a novel control strategy of an air-core pulsed alternator pair is proposed in this paper. Like a single pulsed alternator, the whole work process of the pulsed alternator pair can also be divided into three subprocesses: the self-excitation process, the discharge process, and the energy reclamation process. In the self-excitation and energy reclamation processes, the armature windings of the pulsed alternator pair are connected in series, and the filed windings are connected in parallel. In order to illustrate the advantages of this control strategy, a comprehensive discussion of different connection topologies of the alternator pair has been made in this paper. A mathematical model based on the equivalent circuit of the air-core pulsed alternator considering the harmonic components was also established in this paper, which could help calculating the system efficiency more accurately. The results and conclusions of the analyses and simulations can offer guidance for the air-core pulsed alternator pair system design and optimization.

Design and Simulation of a Moving-magnet-type Linear Synchronous Motor for Electromagnetic Launch System

The Electromagnetic Aircraft Launch System (EMALS) offers significant benefits to the aircraft, ship, personnel, and operational capabilities. EMALS has such advantages as high thrust, good controllability, reusable, etc., as a launching motor, a double-side plate Permanent Magnet Linear Synchronous Motor (PMLSM) can provide high instantaneous thrust. This paper presents the design and analysis of the moving-magnet-type permanent magnet linear synchronous motor (PMLSM). A detailed analytical modeling based on Maxwell’s equations is presented for analysis and design of PMLSM with Halbach array. In order to improve the thrust characteristics of PMLSM, the structural characteristics and magnetic field are analyzed. The results show an enhancement in the motor performance. Finally, we have used 2-D nonlinear time-stepping transient finite element method to demonstrate validity of the analytical analysis and parametric search is used for multi-objective optimization of PMLSM. Using Finite Element Analysis (FEA), the effects of the parameters on the thrust and thrust ripple waveforms are analyzed.

History and the Status of Electric Ship Propulsion, Integrated Power Systems, and Future Trends in the U.S. Navy

While electric propulsion for warships has existed for nearly a century, it has only been since the end of the Cold War that modern integrated power systems have been developed and implemented on U.S. Navy warships. The principal enablers have been the products of research and development for rotating machines (generators and propulsion motors), power electronics (power conversion and motor drives), energy storage, and controls. The U.S. Navy has implemented this advanced technology incrementally. Notably, DDG 1000 with its integrated propulsion system and CVN 78 with its electromagnetic aircraft launch system will soon join the fleet and mark another important advance to the electric warship. In the future, the integration of electric weapons such as railguns, high power radars, and lasers will result in the final achievement of the electric warship.

A Variable Pole Pitch Linear Induction Motor for Electromagnetic Aircraft Launch System

A variable pole pitch linear induction motor (VPPLIM) is proposed as a new member of the family of electromagnetic aircraft launch system (EMALS). With proper designing of the variation of the pole pitch, the VPPLIM could accelerate the aircraft almost uniformly at the condition of the usual ac supply, avoiding the use of large-scale power electronic converters. Special considerations in the design of VPPLIM, such as the structure topology, the variation of the pole pitch, and the winding arrangement are discussed in detail in this paper. The acceleration performance of the VPPLIM fed by a constant-voltage constant-frequency supply is analyzed by means of the quasi-steady-state 2-D magnetic field model and the difference model of mover's dynamics. A two-stage method is proposed to simulate the acceleration performance of the VPPLIM based on a 2-D thrust table of the motor achieved by the finite-element method. The calculated features of the prototype VPPLIM consist well with those expected for EMALS.

Optimal Design of EMALS Based on a Double-Sided Tubular Linear Induction Motor

A novel evolutionary algorithm is used for the optimization of the thrust force of the stages of an electromagnetic aircraft launch system, based on a double-sided tubular linear induction motor. A semianalytical model allows for a fast and accurate prediction of all the electromagnetic quantities in the device, including the thrust force, the back electromotive force, the distribution of the induced current density, and the average magnetic flux density in the teeth. Using the semianalytical formulation, the characterization of the machine is greatly facilitated, so allowing a fast evaluation of the cost function and of the design constraints.

The Double-Sided Tubular Linear Induction Motor and Its Possible Use in the Electromagnetic Aircraft Launch System

In this paper, a double-sided stator tubular linear induction machine is presented, and its performance is discussed for possible use as a catapult in the electromagnetic acceleration of aircraft. Based on the use of the Fourier transform in the direction of the motion, a semianalytical model that is able to take into account the end effects due to the finite length of the stators is derived. The effectiveness of the model has been proven by comparison with a numerical analysis based on the finite-element method. The reported results obtained using the two methods show excellent agreement that makes the proposed model a valuable tool for a preliminary design of the device.

고출력 에너지 사용 체계 플랫폼 실현을 위한 해군함정의 통합 동력 시스템 발전 경향 분석

본 논문은 고도로 발전된 군사과학 기술의 영향과 급변하는 해양전장환경의 디지털화, 함정생존 성 극대화를 위한 고출력 센서체계 등 고출력 에너지 사용 체계 플랫폼 실현을 위한 해군함정의 통합 동력 시스템 발전 경향을 분석하는데 초점을 두었다. 함정에서 전자기를 이용하는 항공기 출격 시스템, 200NM(370km) 이상 원거리에서 정밀타격이 가능한 전자기 포 등 고출력 에너지를 사용하는 각종 무기 체계가 탑재되기 위해서는 추진동력을 포함한 함정에 공급되는 모든 동력이 단일화 되어야하는 통합 동력 시스템으로 변화하는 것이 가장 이상적이다. 선진국을 중심으로 통합 동력 시스템을 실현하기 위해서 기계식 추진시스템에서 하이브리드 및 완전전기추진시스템으로 변화하고 있는 추세이며 이러한 노력은 연료사용의 절감, 함정 탑재 장비의 고출력화, 함정 총 수명주기 비용 절감 등을 포함하고 있다.

Next-Generation Power and Energy: Maybe Not So Next Generation1

Through many a technical society paper and/or presentation, such as this, future high-power mission loads such as Electromagnetic Aircraft Launch System, Electromagnetic Rail Gun, and Free Electron Laser that will provide capabilities far greater than can be achieved by existing platforms, have been presented. With these high-power and energy mission loads comes the need for next-generation integrated power systems possessing higher voltage distribution systems (AC or DC), compact/ power-dense conversion modules, high-speed power-dense power generation modules, energy storage modules, and appropriate supervisory and machinery controls to provide and partition the available power and energy to the right load, with the right power and at the right time. This remains the vision for the after all-electric warship (AEW). However, Now and Next Navy platforms have challenges and needs that ongoing investments and advanced developments in power and energy technologies can help to meet. Such challenges include reduced dependency on foreign-supplied fossil fuel, increasing demand for installed ship power, controlling ship procurement and life-cycle costs. This paper will present planned and ongoing efforts that can be aligned to meet these nearer term ship challenges, and at the same time, with an eye on the future power and energy requirements when they materialize, be refocused to enable and support the high-power and energy demands of the AEW.

Transient Electromechanical Modeling for Short Secondary Linear Induction Machines

Linear induction motors are under development for a variety of demanding applications including aircraft launchers and magnetically levitating trains. These applications require machines that can produce large forces, operate at high speeds, and can be controlled precisely to meet performance requirements. The design and implementation of these systems require fast and accurate techniques for performing system simulation and control system design. We present techniques for modeling and controlling linear induction machines based on a direct and quadrature (DQ) representation of the system dynamics. Simulation results using the DQ representation of the machine dynamics are presented and compared to test data from a Subscale Integration Test Bed developed for the U.S. Navy's Electromagnetic Aircraft Launch System program.

Finite difference study of unconventional structures of permanent-magnet linear machines for electromagnetic aircraft launch system

This paper deals with the design of an electromagnetic aircraft launch system (EMALS). The system studied is based on a linear permanent-magnet (PM) machine. For the same thermal, geometric, and feeding specifications, original configurations of linear machines have been studied and compared to more classical ones in terms of performance. The work shows that originals structures which use Halbach array configuration in association with unconventional winding strategy can produce very interesting solutions with which to build an EMALS synchronous PM machine.

Flywheel charging module for energy storage used in electromagnetic aircraft launch system

Optimal energy systems is currently designing and manufacturing flywheel based energy storage systems that are being used to provide pulses of energy for charging high voltage capacitors in a mobile military system. These systems receive their energy from low voltage vehicle bus power (<480 VDC) and provide output power at over 10,000 VDC without the need for DC-DC voltage conversion electronics. This energy conversion is accomplished through the use of OES patented ultra high-speed flywheel power module (FPoM) technology. In this paper, adaptation of the OES FPoM technology to energy storage for electromagnetic aircraft launch system (EMALS) applications is described. Physical system design parameters are summarized for the FPoM. Transient PSPICE electrical and MSC/Nastran FEA thermal analyses characterize operation and response in a conceptual EMALS energy storage environment.

Design of a Linear Bulk Superconductor Magnet Synchronous Motor for Electromagnetic Aircraft Launch Systems

High-temperature superconducting (HTS) material in bulk form is used to design a linear synchronous motor for an electromagnetic aircraft launch system. The motor is designed without an iron core. Stator coils are placed in the air while the permanent magnets used in conventional design of linear permanent magnet synchronous motors are replaced by the HTS bulk magnets. The physical, operational, and equivalent circuit parameters of the linear motor with HTS bulk magnets are compared with those of a linear permanent magnet synchronous motor and linear induction motor designed for the same application. Results show that utilizing superconducting magnets is only superior at temperatures below 40 K.

Electromagnetic aircraft launch system development considerations

The US Navy is developing an electromagnetic aircraft launch system for its next generation of aircraft carriers. Its approach to the program is predicated on the state of the technology and expertise of the participants. A revised business model is discussed.

The Benefits of Electromagnetically Launching Aircraft

ABSTRACT The Electromagnetic Aircraft Launch System (EMALS) is being developed, utilizing electrical and electronic technologies, to replace the existing steam catapult on naval carriers. The EMALS offers significant benefits to the aircraft, ship, personnel, and operational capabilities. These benefits combine to provide enhanced warfighting capabilities at a reduced cost.

Figuring Flow

NASA and the US Navy are exploring magnetic fields in search of quicker, smoother, and cheaper launches. A Navy program based in Lakehurst, NJ, wants to learn if magnetic propulsion is the answer. It awarded two contracts in December for what it calls the electromagnetic aircraft launch system. One award went to Northrop Grumman of Sunnyvale, California, and the other to General Atomics in San Diego. NASA is in the second year of a three-year program to investigate magnetic launch technology. The systems under study by NASA combine linear induction, to accelerate the vehicle to launch speed, with magnetic levitation, using opposing magnetic fields to suspend the vehicle above its track. The Navy’s catapult program does not require magnetic levitation. The US Maglev Technology Assessment, written jointly by the Corps of Engineers and the Department of Transportation, points out that since ‘magnetic drag is small at high speeds, only aerodynamic drag consumes appreciable energy.

Induction for the Birds

NASA and the US Navy are exploring magnetic fields in search of quicker, smoother, and cheaper launches. A Navy program based in Lakehurst, NJ, wants to learn if magnetic propulsion is the answer. It awarded two contracts in December for what it calls the electromagnetic aircraft launch system. One award went to Northrop Grumman of Sunnyvale, California, and the other to General Atomics in San Diego. NASA is in the second year of a three-year program to investigate magnetic launch technology. The systems under study by NASA combine linear induction, to accelerate the vehicle to launch speed, with magnetic levitation, using opposing magnetic fields to suspend the vehicle above its track. The Navy’s catapult program does not require magnetic levitation. The US Maglev Technology Assessment, written jointly by the Corps of Engineers and the Department of Transportation, points out that since ‘magnetic drag is small at high speeds, only aerodynamic drag consumes appreciable energy.