Zhijian Ling

Design and analysis of a new halbach magnetized magnetic screw for artificial hearts

This paper introduces a high-force-density linear actuator for an artificial heart, which is based on the concept of a magnetic screw-nut. The novelty of the proposed magnetic screw is adaptation of Halbach permanent-magnet (PM) array disposed helically. PMs are placed on both the screw and the nut. The configuration of the newly designed magnetic screws is presented, and its electromagnetic performances are analyzed. The proposed Halbach magnetized magnetic screw is evaluated as compared with a radially magnetized magnetic screw using the time-stepping finite-element method, verifying the advantages of the proposed structure.Due to the limited number of the donor hearts, artificial heart (AH) systems are required for the therapy of the terminal heart diseases. Existing electric-drive AHs employ the rotary blood pumps or linear motors, but suffering from blood damage and poor thrust density, respectively. Very recently, the concept of magnetic screw was proposed. The magnetic screw actuator integrated with permanent magnet (PM) brushless machine is capable of converting rotational motion into linear motion and vice versa. Since it offers high force density, wear-free, small size and light weight, magnetic screw actuator has a bright future in AH applications. The purpose of this paper is to propose and analyze a new magnetic screw with the halbach PM array, which offers improved force density.

Analysis of New Modular Linear Flux Reversal Permanent Magnet Motors

In this paper, a new modular linear flux reversal permanent magnet (M-LFRPM) motor is proposed and analyzed. The key of the proposed motor is to adopt a new modular mover structure, hence offering the desired fault-tolerant capability and an improved force performance. Utilizing the new modular mover structure, the magnet utilization ratio of the proposed motor is significantly enhanced as compared with the existing one, resulting in a higher thrust force density. Moreover, the back electromotive force of the proposed motor is symmetrical and sinusoidal due to its complementary PM magnetic circuits. For a fair comparison, the proposed motor is designed and built based on an existing M-LFRPM motor with the similar electromagnetic and geometrical parameters. Then, their force ripples are analyzed and decomposed using the frozen permeability method due to its high accuracy for force separation, revealing that the cogging and reluctance force ripples of the proposed motor counteract each other and are significantly reduced. Finally, the electromagnetic performance of both the motors is analyzed and compared using the time-stepping finite-element method, verifying that the proposed motor definitely offers the desired fault-tolerant capability and the improved force performance viz., the reduced cogging force and the improved thrust force compared with the existing one.

Design of a New Magnetic Screw With Discretized PMs

This paper introduces a new type of high-performance linear actuator that is attractive for many potential applications. Structure simplification and processing technology are quite essential in promoting the development of the magnetic screw. The novelty of the proposed magnetic screw is the adoption of a discretized permanent magnet (PM), discretized ferromagnetic iron, and an ideal helix ferromagnetic iron ring. The discretized ferromagnetic iron is sandwiched between the two discretized PMs for forming a cell, and the ideal helix ferromagnetic iron was surfaced on the specified lead composed of PM cells. The configuration of the newly designed magnetic screws is presented, and its electromagnetic performances are analyzed by using the time-stepping finite-element method, verifying the advantages of the proposed structure.

Comparison of Coaxial Magnetic Gears With and Without Magnetic Conducting Ring

This paper quantitatively compares four coaxial magnetic gears (CMGs) with and without magnetic conducting ring (MCR), which are artfully integrated into a permanent-magnet (PM) machine. In addition, different gear ratios are investigated for both topologies. By using the finite-element method, their torque and loss performances are compared and evaluated. Analysis results show that the CMGs without MCR and low gear ratio can offer higher pull-out torque and lower torque ripple, whereas the CMGs with MCR and low gear ratio have lower PM eddy current and iron loss. Finally, a 9/6 slot-pole CMG machine without MCR is prototyped for verification.

Design Optimization and Test of a Radially Magnetized Magnetic Screw With Discretized PMs

A magnetic screw is a new type of high force density linear actuator. One of the key challenges for realization of the magnetic screw concept is the manufacturing process of its helical permanent-magnet (PM) poles. Structure simplification and simple assembly process are essential in promoting the development of the magnetic screw. This paper studies several PM configurations employed to realize the magnetic screw and proposes a new structure, which can well approximate the helical magnetic poles in a very simple way. The electromagnetic performances are assessed analytically and by time-stepping finite-element analysis (FEA). Finally, both the analytical model and the FE results are validated by experiments based on a prototype machine.

A New Mover Separated Linear Magnetic-Field Modulated Motor for Long Stroke Applications

Linear magnetic-field modulated (LMFM) motor exhibits high thrust force by effectively employing the magnetic-field modulation effect. In this paper, a new mover separated LMFM (MS-LMFM) motor is proposed, which successfully alleviates the space confliction between permanent magnets (PMs) and windings in the existing LMFM motor. The structure and the operation principle of the existing and proposed motor are described, and the major design parameters are optimized for maximum thrust force. Moreover, electromagnetic performances of both motors are compared by finite-element method. Theoretical and simulation analysis shows that the proposed motor can exhibit enhanced force performance than the existing one under fixed copper loss. Simultaneously, reduced iron and PM losses can also be obtained by proposed motor. Finally, a 3-D modeling MS-LMFM motor is built for a global observation of motor structure and further verification of the 2-D analysis.

Design and analysis of a new HTS electromagnetic screw for artificial heart

Linear actuators provided thrust force and displacement for many applications.

Design of a high force density linear electromagnetic actuator based on magnetic screw

Linear actuators provide thrust force and displacement for many applications, ranging from artificial heart to automotive and aerospace actuation [1].

Electromagnetic Design and Analysis of a Novel Transmission System Supporting Multi-Path Power Flows for Electric Vehicles

This paper proposes a novel transmission system supporting multi-path power flows for electric vehicles (EVs). It mainly consists of a coaxial magnetic gear (CMG), a lock, a clutch, and two electric machines (EMs). The key feature of the CMG is that its modulating ring can rotate freely. One of the EMs is integrated with the CMG, which constitutes an integrated magnetic gear permanent magnet machine. And the other is connected to the inner rotor of the CMG through a clutch and a shaft with a lock. By toggling the clutch, controlling the states of the lock and the two EMs, the proposed transmission system can achieve flexible power splits. It is very interesting that one of the EM can play the role of a flywheel storage device when necessary, which is capable of buffering the energy from regenerative braking, so as to protect the battery. In this paper, the configuration of the transmission system is illustrated; its operating principle is elaborated. Then, the electromagnetic design is conducted to meet the demands arising from EVs. Finally, the electromagnetic performances are analyzed by using finite-element method, which verifies the rationality of the electromagnetic design.

Design and Analysis of a New HTS Electromagnetic Screw

The high-temperature superconductor (HTS) machines are more attractive due to the advantages of high power density and efficiency. This paper introduces a new HTS electromagnetic screw (HTS-EMS) that is developed for artificial heart. Two helical-shaped slots are introduced to the translator; the key to the HTS-EMS is that the HTS coils carrying dc currents are placed in the helical-shaped slots. The permanent-magnet array is placed in the rotor. Due to the high current density of the HTS coil, the power density of the HTS-EMS can be improved effectively. The electromagnetic performance of the HTS-EMS is analyzed, including the flux, thrust force, as well as torque. The proposed HTS-EMS is evaluated compared with the existing magnetic screw using time-stepping finite-element method, verifying the advantages of the proposed structure.