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IEEE Conference on electromagnetic Field Computation

作者： Xiang Ren Ronghai Qu Dawei Li State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China

ISBN: (纸本)9781509010332

In this paper, a novel stator-Permanent magnet brushless machine with wound rotor is proposed. For this machine, the pole changing windings is used to modulate the magnetic field instead of salient structures, which is inherent with much less field harmonics. The structure and operation principle is introduced, and the performance is verified by FEA tools.

关键词： Stator windings Windings Rotors Harmonic analysis Vibrations Magnetic flux

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Reactive power compensation with improvement of current waveform quality for single-phase buck-type Dynamic Capacitor

Reactive power compensation with improvement of current wave...

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Annual IEEE Conference on Applied Power Electronics Conference and Exposition (APEC)

作者： Xinwen Chen Ke Dai Chen Xu Ziwei Dai Li Peng State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China

ISBN: (纸本)9781467395519

Due to relatively low cost and flexible performance, Dynamic Capacitor (D-CAP) is often designed to implement dynamic reactive power compensation, whose output current might distort under the effects of background harmonic voltage from the grid or non-ideal PWM mode caused by non-linear switch characteristics. This paper presents a reactive power compensation control strategy with waveform quality amelioration of output capacitive current for single-phase Buck-type D-CAP. Through establishing basic control equations, reactive power compensation principle and equivalent model of single-phase Buck-type D-CAP are analyzed. In order to suppress output harmonic current, duty ratio of Buck-type D-CAP is generated by means of introducing Even Harmonic Modulation (EHM). Then a selective current control strategy in multiple synchronous reference frames is adopted to track reactive power compensation current reference with nearly zero steady-state error and alleviate output current distortion with demanded harmonic components. Finally, a series of experimental results from single-phase Buck-type D-CAP laboratory prototype are provided to verify the validity of dynamic reactive power compensation and almost sinusoidal output current waveform optimizing method.

关键词： Harmonic analysis Reactive power Power harmonic filters Integrated circuits Capacitors Switches

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Real-time resonant magnetic perturbations feedback control system for tearing mode suppression on J-TEXT

Real-time resonant magnetic perturbations feedback control s...

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IEEE NPSS Conference on Real Time

作者： Wei Zheng Feiran Hu Ming Zhang Da Li Qiming Hu Hai Jin Yuan Pan State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Wuhan China

ISBN: (纸本)9781509020157

Tearing Modes (TMs) degrade the performance of tokamak plasma, and can even lead to disruption. Using externally exerted resonant magnetic perturbations (RMP) to suppress tearing mode is a promising and effective way. In order to suppress 2/1 tearing mode, 2/1 RMP applied in given phase region to stabilize magnetic island and accelerate island rotation. The RMP feedback control system acquires 15-channels Mirnov poloidal signals, processes the acquired data and calculates the phase in real-time; outputs RMP power supply control signal by comparing with the given phase to drive RMP coil. The feedback control system is based on NI C-RIO and mainly using LabVIEW to develop. The typical 2/1 mode magnetic island on J-TEXT rotates at a frequency from 2 KHz to 10 KHz. To ensure the control precision within 2 degrees, the control period must be within 500 ns. Due to acquired signals are noisy, the feedback control system uses a series of error correction methods in realtime to obtain accurate phase.

关键词： Decision support systems Real-time systems Indexes Error correction

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Force ripple minimization of a linear vernier permanent magnet machine for direct-drive servo applications

Force ripple minimization of a linear vernier permanent magn...

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IEEE Conference on electromagnetic Field Computation

作者： Yuting Gao Ronghai Qu Dawei Li Fengxiang Chen State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China

ISBN: (纸本)9781509010332

Linear vernier permanent magnet machines (LVPMMs) for direct-drive servo applications are attracting more and more attentions due to its high force density, easy maintenance, rapid dynamic response, etc. This paper proposes a new LVPMM structure which has a similar secondary as that of a regular linear PM machine, while its primary mover is composed of three modules, which are separated by flux barriers. Since high-precision servo systems have rigorous demands on the force ripple of the drive motors, two methods are introduced to minimize the force ripple of the LVPMM. One is to choose an optimal design of flux barriers; the other is to change the three-phase winding connection. The effectiveness of both methods are verified by time-stepping finite element analysis (FEA). It is found that the force ripple can be reduced from 10.6% to 2.4%.

关键词： Force Windings Optimization Forging Servomotors Minimization Stators

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A stator-PM consequent-pole vernier machine with hybrid excitation and DC-biased sinusoidal current

A stator-PM consequent-pole vernier machine with hybrid exci...

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IEEE Conference on electromagnetic Field Computation

作者： Shaofeng Jia Ronghai Qu Jian Li Dawei Li Wubin Kong Donglin Ye State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China

ISBN: (纸本)9781509010332

This paper proposes a novel hybrid excitation vernier permanent magnet machine (HE-VPM). The characteristics of the proposed machine are: 1) The PMs are embedded in the stator teeth, which is helpful for heat dissipation; 2) the rotor is salient structure without PMs and windings, which ensures the reliability of high speed running; 3) The non-overlapping concentrated winding shortens the end-winding, and improves the torque density, 4) Only half of the stator teeth possess PMs, and the total amount of PMs are decreased; 5) The DC current are injected to the armature coils, therefore, the exciting field can be adjusted flexibly. In this paper, the electromagnetic performance, including back-EMF, torque, etc. are analyzed with finite element analysis (FEA). The results show that the proposed machine exhibits flexible field adjustment capability, which may be suitable for applications requiring wide speed range operation. Besides, it is found that, compared with fed with the existing pure sinusoidal phase current, higher torque can be obtained with DC-biased phase current under constant stator copper loss.

关键词： Windings Torque Stator windings Topology Heating Rotors

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Commissioning of two RF operation modes for RF negative ion source experimental setup at HUST

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AIP Conference Proceedings 2017年第1期1869卷

作者： D. Li D. Chen K. Liu P. Zhao C. Zuo X. Wang H. Wang L. Zhang State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan China

An RF-driven negative ion source experimental setup, without a cesium oven and an extraction system, has been built at Huazhong University of Science and technology (HUST). The working gas is hydrogen, and the typical operational gas pressure is 0.3 Pa. The RF generator is capable of delivering up to 20 kW at 0.9 - 1.1 MHz, and has two operation modes, the fixed-frequency mode and auto-tuning mode. In the fixed-frequency mode, it outputs a steady RF forward power (Pf) at a fixed frequency. In the auto-tuning mode, it adjusts the operating frequency to seek and track the minimum standing wave ratio (SWR) during plasma discharge. To achieve fast frequency tuning, the RF signal source adopts a direct digital synthesizer (DDS). To withstand high SWR during the discharge, a tetrode amplifier is chosen as the final stage amplifier. The trend of maximum power reflection coefficient |ρ|2 at plasma ignition is presented at the fixed frequency of 1.02 MHz with the Pf increasing from 5 kW to 20 kW, which shows the maximum |ρ|2 tends to be “steady” under high RF power. The experiments in auto-tuning mode fail due to over-current protection of screen grid. The possible reason is the relatively large equivalent anode impedance caused by the frequency tuning. The corresponding analysis and possible solution are presented.

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A Method to Improve Torque Density and Reduce Magnetization Current in a Variable-Flux Flux-Intensifying Interior Permanent Magnet Machine

A Method to Improve Torque Density and Reduce Magnetization ...

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IEEE Conference on Vehicle Power and Propulsion (VPPC)

作者： Yang Lu Jian Li Ronghai Qu Afang Sun Haiyang Fang State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China

ISBN: (纸本)9781509035298

This paper mainly proposes a method to improve torque density and reduce magnetization current of a variable- flux flux-intensifying interior permanent magnet machine (VFI-IPM) which utilizes low coercive-force magnet material AlNiCo. Since the d-axis inductance is higher than q-axis inductance in the VFI-IPM and the saliency ratio is not that high as conventional IPM machine, the reluctance torque of the VFI-IPM is low which is not favorable for high torque density and wide constant power region. What's more, the remnant magnetism of AlNiCo is always lower than rare-earth magnets, leading to a lower torque output. So it's necessary to take measures to obtain high torque density. On the other hand, the magnetization current of VFI-IPM is a key parameter for inverter rating which affects the cost the machine directly. Therefore, it's also needed to investigate methods to reduce the magnetization current. A method is proposed to improve the torque density and reduce the magnetization current based on the original topology of the VFI-IPM which includes the process for rotor molding.

关键词： Rotors Torque Magnetization Magnetic flux Inductance Bridge circuits Magnetic circuits

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Interaction analysis of multi VSCs integrated into weak grid in current control time-scale

Interaction analysis of multi VSCs integrated into weak grid...

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IEEE General Meeting Power& Energy Society

作者： Yabing Yan Xiaoming Yuan Jiabing Hu State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China

ISBN: (纸本)9781509041695

This paper investigates the dynamic interaction of multi grid-connected voltage source converters (VSCs) in the current control time-scale. To illustrate the physical mechanism of interaction, a model is proposed based on the physical motion law of VSC's controlled current in frequency domain. The proposed model distinguishes the current control of VSCs into two branches, namely the self-stabilizing loop and interacting loop, according to their different physical influences on the inductor current. The analysis of a two-converter system reveals that the interaction caused by fast dynamic current control can decrease the positive damping on controlled current through the interacting loop and deteriorate system stability. Time-domain simulation results of a two-converter system implemented in MATLAB/Simulink validate the correctness of analysis and the effectiveness of the proposed model.

关键词： Power conversion MATLAB Mathematical model Legged locomotion

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Improved torque and flux weakening capability for flux modulated machines by injecting DC currents into the armature windings

Improved torque and flux weakening capability for flux modul...

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IEEE Conference on electromagnetic Field Computation

作者： Shaofeng Jia Ronghai Qu Dawei Li Jian Li Wubin Kong State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China

ISBN: (纸本)9781509010332

Flux modulated machines (FMMs) are well known for their features of high torque density. In this paper, the DC currents are innovatively injected into the armature coils which are arranged in a specific way in FMMs, and the electromagnetic performance are analyzed by the finite element analysis (FEA). The results show that the electromagnetic torque contains not only the pre-existing PM torque, but also the additional torque produced by the DC current interacted with the AC armature current. What is more, it is found that the torque is improved under the constant copper loss compared with when fed with regular pure sinusoidal current. Besides, the flux weakening capability is greatly enhanced since the exciting field can be easily adjusted by the injected DC current, therefore, it can be inferred that the constant power speed range is extended.

关键词： Torque Windings Coils Copper Stator windings

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Comparison of stator DC current excited vernier reluctance machines with different field winding configurations

Comparison of stator DC current excited vernier reluctance m...

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IEEE Conference on electromagnetic Field Computation

作者： Shaofeng Jia Ronghai Qu Jian Li Dawei Li Hanxiao Lu State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China

ISBN: (纸本)9781509010332

This paper compares the electromagnetic performance of stator DC current excited vernier reluctance machines (DC-VRMs) with different Field winding configurations. Using the theoretical analysis and finite element analysis (FEA), the back-EMF, and torque capability, etc. are compared. The results show that the field winding arrangement has a great and various effect on the machine torque capability, and generally, machines with field winding alternating polarity arranged exhibit a high average torque but with high torque ripple, while machines with field winding identically arranged show a low and smooth torque.

关键词： Windings Torque Load modeling Stator windings Reluctance machines

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