Jiangui Li

A New Efficient Permanent-Magnet Vernier Machine for Wind Power Generation

This paper proposes a new outer-rotor permanent-magnet (PM) vernier machine for direct-drive wind power generation, which can offer low-speed operation to directly capture wind power, and enable high-speed rotating field design to maximize the power density. Compared with its mechanical gear counterpart, the proposed machine can eliminate the mechanical wear and tear as well as gear transmission loss, thus improving the generation reliability and efficiency. The key is to newly introduce the flux-modulation poles which can effectively modulate the high-speed rotating field of the armature windings and the low-speed rotating field of the PM outer rotor. By using the time-stepping finite-element method, the proposed machine can be accurately analyzed. Hence, its performances are quantitatively compared with other PM vernier machines, thus verifying its validity.

A Novel Coaxial Magnetic Gear Using Bulk HTS for Industrial Applications

In this paper, a novel coaxial magnetic gear (CMG) using bulk high temperature superconductors (HTS) is proposed. By substituting bulk HTS for ferromagnetic material, a novel stationary ring is resulted, which can not only provide the desired field modulation effect but also suppress the end-effects that commonly occurred in the traditional CMG. The performance of the proposed bulk HTS CMG is assessed and then verified by using finite element analysis.

Design and Analysis of a HTS Brushless Doubly-Fed Doubly-Salient Machine

This paper proposes a novel high-temperature superconductor (HTS) brushless doubly-fed doubly-salient (BDFDS) machine, which can effectively improve the performance of this kind of BDFDS machines. In addition, a new criterion of winding arrangement with the outer-rotor topology is adopted for the proposed machine design, which can further benefit the machine characteristics. Moreover, two natural operation modes for the proposed machine are discussed. The corresponding calculation results are given to prove the validity of the proposed machine.

Harmonic Analysis and Comparison of Permanent Magnet Vernier and Magnetic-Geared Machines

In this paper, harmonic analysis and comparison of permanent magnet vernier (PMV) and magnetic-geared (MGd) machines are presented. The key is to analytically solve the governing Laplacian/quasi-Poissonian field equations in the air-gap regions. By using the time-stepping finite-element method, the analytical method is verified. Hence, the performances of the PMV machine are quantitatively compared with that of the MGd machine. The results show that the PMV machine can offer higher no-load EMF and higher torque-handling capability than its counterpart. Finally, the experimental result is given to further verify the validity of the analysis.

A Novel HTS PM Vernier Motor for Direct-Drive Propulsion

In this paper, a novel high-temperature superconductor (HTS) permanent magnet (PM) vernier motor is proposed for direct-drive propulsion, which can directly offer the low-speed high-torque capability and the high-speed rotating field design to eliminate the gearing mechanism and maximize the power density, respectively. The key is to newly introduce HTS bulks to flux-modulation poles that can effectively modulate between the high-speed rotating field of armature windings and the low-speed rotating field of the PM outer rotor. Also, the use of HTS bulks can greatly reduce the flux leakage and hence improve the torque density. Based on using the finite element method, the motor performances are analysed. Hence, the validity of the proposed motor is verified.

Analytical study and corresponding experiments for a new resonant magnetic charger with circular spiral coils

This study proposes a new resonant magnetic charger comprising circular spiral coils that operate with a strong coupling effect between the transmitter and the receiver. The two spiral coils are fitted with additional copper tapes to serve as resonant transmitter and receiver coils. The magnetic flux distributions are calculated using temporal coupled mode theory. Analysis results show that the proposed system can dramatically improve the efficiency and extend the power transfer distance. Experiments have been carried out in order to verify the performance of the system. In particular, the trends of output voltages when either the operating frequencies or the transfer distances are changing are reported. The system efficiency obtained experimentally is also given. Both calculated and measured results are in good agreement.

Simulation of a Tubular Linear Magnetic Gear Using HTS Bulks for Field Modulation

A tubular linear magnetic gear is proposed, which newly utilizes high temperature superconductor (HTS) bulks for its field modulation. Compared to the conventional one, the proposed topology can significantly reduce the leakage flux, hence improving its force transmission capacity. By using the magnetic circuit modeling, the analytical formulae of air-gap flux density and thrust force are firstly derived. Then, the finite element method (FEM) is employed to validate the performance of the proposed linear magnetic gear.

A Linear Doubly-Salient HTS Machine for Wave Energy Conversion

This paper proposes a linear doubly-salient high-temperature superconductor (HTS) machine for wave energy conversion, which is composed of a tubular stator and a tubular translator. Since the translator is a simple iron core with salient poles, it is so robust that it can be directly coupled with the reciprocating buoy. The stator consists of an iron core with salient poles, DC HTS field windings and 3-phase HTS concentrated armature windings. By using the finite element analysis, the proposed machine is quantitatively compared with its permanent magnet and copper-winding counterparts. Hence, it validates that its performance, especially the power density, can be improved greatly.

Design and Analysis of a HTS Vernier PM Machine

This paper proposes a novel high-temperature superconductor (HTS) vernier permanent-magnet machine which can offer low-speed high-torque operation under line frequency. The key is to newly introduce the flux-modulation poles which modulate the high-speed rotating field in the stator to become the low-speed rotating field in the airgap. Also, the use of HTS armature windings can greatly reduce the power loss and improve the power density. By using the time-stepping finite element method, the machine performances are analyzed. Hence, the validity of the proposed machine is verified.

Performance and Cost Comparison of Permanent-Magnet Vernier Machines

This paper presents a quantitative comparison of two direct-drive outer-rotor permanent-magnet vernier (PMV) machines-namely the pole-splitting permanent-magnet vernier machine and vernier hybrid machine with emphasis on their performances and costs. The operating principles of two machines are discussed and their steady-state and transient performances are analyzed using the time-stepping finite element method. The overall weights and costs are also evaluated. The comparison results can be used to assess the validity of the designs of PMV machines.