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The transverse flux permanent-magnet (PM) linear machine has attracted much attention in high-performance direct-drive applications because of its high torque density and efficiency. However, due to its inherent large open-circuit flux leakage, the prominent cogging force makes it difficult to obtain a high accuracy in position and speed control, which restricts its potential for precision industrial processing applications. To overcome this problem, a novel transverse flux linear machine is proposed in this paper. The key is by creatively combining a consequent-pole mover design and a stator-segment-interlacing configuration in such a way that a parallel and complementary transverse magnetic circuit is realized for the moving PMs, which can effectively minimize the open-circuit leakage flux and cogging effect. In this paper, the machine structure, operation principle, and theoretical modeling are introduced, with its electromagnetic performance evaluated by using the finite-element method. A prototype is also built for the experimental verification, and relevant test results agree well with the finite-element predications. [ABSTRACT FROM AUTHOR]

Torque motor is one key component that directly influences the dynamic performance of jet pipe servo valve in aircraft. In this paper, a novel torque motor with hybrid-magnetization pole arrays is proposed. By changing the magnetization patterns of permanent magnets, the torque motor can significantly improve the output torque by range of 47–52% compared with traditional designs, while maintaining the system size and mass. The design concept and operating principle of the torque motor is presented. The magnetic field distribution is formulated analytically with equivalent magnetic circuit. Different from conventional study, the flux leakage of the permanent magnets and coils is included to improve the model precision. Subsequently, the output torque is derived mathematically from the airgap flux. Following that, the numerical calculation is conducted to validate the mathematical models of magnetic field and output torque. The design optimization is then carried out. One research prototype that can be mounted with either conventional magnet or the proposed hybrid array has been developed. The test rigs are constructed and experiments are conducted on the prototype. Both numerical computation and experimental results verify the significant improvement of torque generation of the proposed hybrid magnetization torque motor. [ABSTRACT FROM AUTHOR]

Flux-weakening capability of permanent-magnet synchronous machines (PMSMs) is fundamentally determined by d- and q -axis inductances. Based on axial flux permanent-magnet machines (AFPMs), this paper extracts the intrinsic factors that influence the d- and q-axis inductances of PMSMs, meanwhile revealing the fact that the d- and q-axis inductances of fractional slot concentrated winding machines are not inevitably larger than that of distributed ones. The proportion of each of the d- and q-axis component inductances for multigap AFPMs is first studied. By analyzing armature inductance in conjunction with differential leakage inductance, this paper introduces a novel parameter to decouple the influence of slot-pole combinations and physical dimensions so that the “inductance ability” of different slot-pole combinations can be quantified. An improved method of calculating the slot leakage inductance of semiclosed slots is then put forward, which proves to be more accurate than the conventional method. The investigations and conclusion in this paper are not restricted to AFPMs but applicable to radial flux permanent-magnet machines as well. Validations of various slot-pole combinations are carried out with finite-element analysis and experiments. [ABSTRACT FROM PUBLISHER]

The rotary type electromagnetic actuator is often used in the electromagnetic mechanical components design, such as high-sensibility switch, signal electromagnetic relay, and so on. This type of actuator is required to have high conversion speed and action frequency, high signal reliability, and low power consumption per volume. In this paper, a new type of rotary electromagnetic actuator with permanent magnet (PM) is designed. Based on the polarity characteristics of PM, a couple of coils are designed in diagonal direction. A flux guide path is designed to optimize the magnetic circuit. PM is applied as the armature, and the electromagnetic system and the contact system are designed individually, which can achieve a high level maximum space utilization. In order to study the characteristic of PM, the PM is divided into several subsections. The migration analysis of the working point based on analytic model is carried on for the selection of PM, and the precise static characteristics of the actuator are analyzed by the finite-element model. The prototype actuator is assembled and tested, and the advantages of fast conversion speed and high reliability is verified by the test. [ABSTRACT FROM AUTHOR]

Severe leakage flux is a long-existed drawback in the transverse-flux permanent magnet machines (TFPMs), which results in a low permanent magnet (PM) utilization rate and prominent cogging torque in TFPMs. Aiming to solve this problem, this paper presents a novel consequent-pole transverse-flux machine (CP-TFM). The key is to artificially shift the upper and lower salient-pole rotors with a half-pole pitch and connect them with a ring-shaped core. Therefore, a complementary magnetic circuit is constructed to reduce the flux leakage between the adjacent poles as well as improve the PM utilization rate. To verify the feasibility of design, a 3-D finite-element model is established and its electromagnetic performance is evaluated. With the same peripheral dimension and copper loss, a quantitative comparison is carried out between the proposed CP-TFM and conventional TFPM. Finite-element simulation results reveal that compared to its contrast, the proposed solution can almost double the PM utilization ratio and effectively reduce the cogging torque. [ABSTRACT FROM AUTHOR]

Permanent magnets have long been known to store magnetic energy in the alignment of the magnetic domains within the material. This paper investigates the possibility of constructing a magnetic device that can effectively extract the stored potential energy from permanent magnets and convert that energy into electrical energy. The concept stemmed from a number of patents that claimed to effectively extract energy from strong neodymium or samarium cobalt magnets on a macroscopic scale using specially designed magnetic flux paths. Their method uses one of several different techniques to switch permanent magnet flux between alternating paths and electrical energy is extracted from coils intercepting this flux as it changes within the core. Using experimental testing, magnetic simulations, and theoretical predictions, our research examined this question. The experimental results indicate that the devices tested do not effectively extract magnetic energy from the magnetized materials under test, indicating that the design is not suitable for use as a magnetic battery. [ABSTRACT FROM AUTHOR]

This paper presents a novel multiphase permanent-magnet (PM) synchronous machinery series adopting two adjacent coils per phase and modular stator. Machine design principles, including modular stator design, segmental interior PM-assisted rotor design, and winding factor improvement, are investigated. Moreover, analytical modeling of winding inductance is developed to provide insights into the magnetic circuit of this type of machine. The proposed machinery series is suitable for wheel-driving electric vehicles attributing to their high magnetic isolation feature, good flux-weakening capability, and feasibility of modular fabrication. [ABSTRACT FROM AUTHOR]

Permanent magnetic actuators (PMAs) have been widely used in medium-voltage vacuum circuit breakers (VCBs) due to their high reliability and controllability. However, a conventional bistable PMA cannot be adopted in power equipment for the transmission voltage level such as 126 kV VCBs directly because of its low-velocity characteristics. The objective of this paper is to propose a multimagnetic circuit PMA to satisfy the high-velocity requirements for 126 kV VCBs. The novel PMA is a bistable and axisymmetric structure, including holding and driving components whose magnetic circuits are separated. Air gaps are specifically designed in the magnetic circuits to improve the velocity performance of the novel PMA. Both static and dynamic characteristics of the novel PMA model have been calculated through finite-element software coupled with multi-body dynamics software. Furthermore, a prototype of the PMA has been developed according to the calculation results. The experimental results on the prototype have shown that the velocity characteristics of the PMA are able to meet the requirements of a 126 kV VCB and agree well with the simulation results. [ABSTRACT FROM PUBLISHER]

The conventional linear flux-switching permanent-magnet (FSPM) motors directly split from a rotary FSPM motor suffer from drawbacks such as unbalanced magnetic circuit of end coil, bigger cogging force, and force ripple. In this paper, to reduce cogging force and thrust force ripple, some complementary and modular linear FSPM (LFSPM) (MLFSPM) motors with mover/stator pole pitch ratio \taum/\taus of about one, namely, \taum/\taus = 10/12, 11/12, 12/12, 13/12, 14/12, 15/12, will be investigated using finite-element method (FEM) and experimental method at first. Then, another new LFSPM motor with \taum/\taus =\break 3 is analyzed. Based on \taum/\taus = 3, some new MLFSPM motors are designed, investigated, and compared using FEM. To fully investigate these motors, the optimal MLFSPM motor with \taum/\taus = 3 is quantitatively compared with the two optimal motors with \taum/\taus \approx 1. Finally, the general design principle for this series of MLFSPM motors with different \taum/\taus values is concluded. [ABSTRACT FROM PUBLISHER]

Fault current limiters are devices that limit currents in electrical networks during a fault event, such as power lines touching or arcing due to tree branches. In this paper, two designs for small-scale saturated-core fault current limiters are discussed: one that uses DC coils to saturate the cores, and one that uses a hybrid design with DC coils and permanent magnet blocks. The hybrid design is found to meet the same performance criteria with a 50% reduction in energy consumption when compared to the DC coil only design. [ABSTRACT FROM AUTHOR]

This paper proposes a novel linear electromagnetic actuator (LEA) for auto-focusing of compact phone cameras. An LEA consists of permanent magnets, iron cores, and coils, which are all magnetic circuit components. When coils are powered, induced magnetic field generates N and S poles around iron cores. Thus, unlike voice coil motors (VCMs) that employ the Lorentz force, the motion of the moving part in this study is arisen from a property-same poles repel each other while opposite poles attract each other. When compared to conventional VCM actuators in simulation results, the proposed LEA generates larger force, whereas using smaller current. [ABSTRACT FROM AUTHOR]

This paper presents novel overlapping ironless windings for permanent magnet planar motors, which have high winding factors and make full use of the magnetic field of the magnet array in the planar motor. A simple analytical model of the planar motors is developed and validated by finite-element method first. Then the winding factors of the ironless windings are derived and used to simplify the analytical model. Furthermore, the design rules of the ironless windings for the planar motor are obtained from the analytical model with winding factors and the ironless windings are optimized for maximum steepness of the planar motor. Compared with the nonoverlapping ironless windings, the novel overlapping ironless windings have a much (up to 25%) larger force with the same copper loss and nearly the same size when the coils of the windings have a large length/width ratio. [ABSTRACT FROM PUBLISHER]

In this paper, we propose a novel structure of permanent-magnet-biased axial hybrid magnetic bearing. It has four segments of poles to control three degrees of freedom (3-DOF). Based on the inner and outer air gaps in conventional axial magnetic bearings, a novel air gap, called the subsidiary air gap, is constructed between the permanent magnet and the stator poles. This air gap separates the bias flux paths from the control flux paths. As a result, lower power loss of the axial magnetic bearing can be achieved due to lower magnetic reluctance of the control flux paths. Furthermore, by means of the equivalent magnetic circuit method and the 3-D finite-element method (FEM), we analyze and model the 3-DOF axial hybrid magnetic bearing. Experimental results show that the presented axial magnetic bearing has good control performance and little coupling among X, Y, and Z directions. However, the rotational power loss will be large at high speed because of the alternating flux density in the thrust plate produced by four segments of stator poles. Therefore, we propose a novel stator, named the parallel-slot stator, and novel thrust plate to reduce the rotational power loss effectively, which is assembled by DT4 and nanocrystalline materials. Meanwhile, we have designed and assembled an axial hybrid magnetic bearing prototype with the novel stator and thrust plate, which is applied in the five-degrees-of-freedom reaction flywheel system with angular momentum of 15 Nms at 5000 r/min. It is validated by the experimental results. [ABSTRACT FROM AUTHOR]