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Experimental analysis of DC pre-excitation for 3-level inverter-motor system

Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering 2006年第3期26卷 159-163页

作者： Bai, Hua Zhao, Zheng-Ming Hu, Xian Chen, Xin State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing 100084 China South Automation Company Nanjing 210003 China

In the AC adjusting speed system, the significant current impulse frequently occurs in the starting process while the output torque is sufficient. This would damage the power electronics device, cause the unbalance of neutral point in three-level NPC topology, and deteriorate the starting performance. In this paper, a DC pre-excitation strategy, which limits the starting current and enhances the electromagnetic torque via establishing the flux linkage before starting process, is proposed to the three-level inverter under analysis on the mechanism of the above large current. The relevant experiments present its eminent effect on the 380 V/160 kW inverter-motor system. Also this paper discuss the feasibility of its application in high voltage high power inverter.

关键词： Induction motors

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A ratio variation of equivalent instantaneous inductance based method to identify magnetizing inrush in transformers

A ratio variation of equivalent instantaneous inductance bas...

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ICEMS 2005: 8th International Conference on Electrical Machines nd systems

作者： Bi, D.Q. Wang, X.H. Liang, W.X. Wang, W.J. State Key Laboratory of Control and Simulation of Power System Tsinghua University Beijing 100084 China

ISBN: (纸本)7506274078

In terms of the characteristic of instantaneous magnetizing inductance reflecting the saturation stage in transformer, an improved method is proposed to distinguish between the magnetizing inrush current and short-circuit fault based on the ratio of average equivalent instantaneous inductances between the non-saturation and the saturation zone, which are divided according to a threshold of differential current. During the inrush, the value of equivalent instantaneous inductance varies severely from small to large as the transformer entering into the saturation and withdrawing from it, so the ratio of average equivalent instantaneous inductances between the non-saturation and the saturation zone is very large in one cycle. However, for the short-circuit fault in transformer, the equivalent instantaneous inductance is very small, and keeps little variation, so the ratio is approximately equal to one. The principle and setting of this method is simple and easy, and its identification time is short. The experimental results verify that the method is correct and effective.

关键词： Electric transformers

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Design and experiments of two glued axially-laminated synchronous reluctance permanent magnetic motors

Design and experiments of two glued axially-laminated synchr...

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Sixth International Conference on power Electronics and Drive systems, PEDS 2005

作者： Guo, Wei Zhao, Zhengmlng Department of Electrical Engineering Tsinghua University State Key Laboratory of Control and Simulation of Power System and Generation Equipment Beijing China

ISBN: (纸本)0780392965

Two axially-laminated Glued Axially-Laminated Synchronous Reluctance Permanent Magnetic (SR-PM) motors are designed and tested. Compared to general Axially-Laminated Synchronous Reluctance (SR) motors, the steel bracket is replaced with iron lamination for reduction of iron loss in rotor. The axially-laminated Iron and magnet are glued on the bracket with high strength cement with the help of special clamping device. Then the rotor Is grinded to the cylinder and a stainless steel rotor sleeve is added to enhance the strength. The design flow starts with initial sizes trade-off and static performance analysis followed by high speed performance validation and dynamic operation simulations. The electromagnetic parameters measurement, no-load and load test are carried out on test bed to verify the design. The comparison of these two sample motors are given for future design reference. It can be concluded that very poor max energy product PM material is not a good choice for application that requires high power density. © 2005 IEEE.

关键词： Reluctance motors

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The analysis of stator MMF and the calculation of rotor losses in a 12-phase high speed asynchronous generator

The analysis of stator MMF and the calculation of rotor loss...

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ICEMS 2005: 8th International Conference on Electrical Machines and systems

作者： Cheng, Luo Xiangheng, Wang Puqi, Ning Department of Electrical Engineering State Key Laboratory of Control and Simulation of Power System and Generation Equipments Tsinghua University Beijing 100084 China

ISBN: (纸本)7506274078

To research the influence of multi-phase winding to generators and calculate the losses in solid rotors, the stator mint of a 12-phase asynchronous generator have been well analyzed and finite element method by ANSYS software has been applied to get the accurate losses in the rotor through both harmonic and transient 2-D analysis. The relationship between stator harmonic current and stator harmonic mint has been deduced and proved through ANSYS software to some extent, and rotor losses produced by both stator fundamental current and stator total current have also been obtained and compared. The results show that 12-phase stator winding with appropriate short pitch can effectively eliminate or reduce many mmf produced by stator fundamental and harmonic current and rotor losses are mainly produced by stator fundamental current.

关键词： Asynchronous generators

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A computer control and monitoring system for high power converters

A computer control and monitoring system for high power conv...

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ICEMS 2005: 8th International Conference on Electrical Machines nd systems

作者： Rong, Yi Zhenming, Zhao Xiaoying, Sun Liqiang, Yuan Jue, Qian Department of Electrical Engineering State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing 100086 China

ISBN: (纸本)7506274078

Computer control and monitoring system (CCMS) is quite important for high power converters (HPCs) operation. This paper presents a novel CCMS, which integrates a database management system (DBMS) into the monitoring software to get the beneficial features such as simple configuration and compact structure. In its communication system, an advanced optical fiber communication (OFC) technology is applied and priority-based communications is proposed to improve the reliability and the real time of the communications. Furthermore, a friendly standard Windows human-machine interface (HMI) is provided. The reliability and performance of the system are verified by system tests and practical operations.

关键词： power converters

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PEEC method for modeling current distribution in grounding plane

PEEC method for modeling current distribution in grounding p...

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ICEMS 2005: 8th International Conference on Electrical Machines nd systems

作者： Hau, Beibei Sun, Xudong Jiang, Jianguo State Key Laboratory of Control and Simulation of Power System and Generation Equipment Dept. of Electrical Engineering Tsinghua University Beijing 100084 China

ISBN: (纸本)7506274078

In view of the impossibility of current measurement in actual grounding plane in power electronic equipment, an equivalent circuit model is set up in this paper using the partial element equivalent circuit (PEEC) method to simulate and calculate current distribution in grounding plane. The inductance parameters calculated are fairly coincident with experiment results, and some conclusions of current distribution are summarized. It is shown that the equivalent circuit model using PEEC method presented in this paper is a feasible and promising way to model and calculate current distribution in grounding plane.

关键词： Electric load distribution

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Accurate flux observer based on distributed multi-processor in MV adjustable speed drive systems

Accurate flux observer based on distributed multi-processor ...

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ICEMS 2005: 8th International Conference on Electrical Machines and systems

作者： Shu, Liu Jianzheng, Liu Zhengming, Zhao Liqiang, Yuan Hua, Bai Haitao, Zhang Department of Electrical Engineering and Applied Electronic Technology State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing 100084 China

ISBN: (纸本)7506274078

This paper presents an accurate flux observer used in distributed multi-processor (DMP) adjustable speed drive systems. The stator flux linkage is estimated with a full-order observer, while the rotor speed is identified by using Lyapunov theorem. In order to improve the system performance in a wide speed range, the stator resistance is estimated simultaneously. In this paper, the structure of the DMP system, the principle of the full-order observer and the method for identifying the rotor speed and state resistance are all described in details. Relevant simulation results based on MATLAB/SIMULINK are given to prove the performance of the method. Experiments of a real system also verify the feasibility of this scheme.

关键词： Microprocessor chips

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A ratio variation of equivalent instantaneous inductance based method to identify magnetizing inrush in transformers

A ratio variation of equivalent instantaneous inductance bas...

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International Conference on Electrical Machines and systems (ICEMS)

作者： D.Q. Bi X.H. Wang W.X. Liang W.J. Wang State Key Laboratory of Control and Simulation of Power System Tsinghua University Beijing China

关键词： Inductance Surge protection Saturation magnetization Circuit faults Transformer cores Magnetic cores Magnetic circuits Capacitance Fault diagnosis Bismuth

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A computer control and monitoring system for high power converters

A computer control and monitoring system for high power conv...

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International Conference on Electrical Machines and systems (ICEMS)

作者： Rong Yi Zhenming Zhao Xiaoying Sun Liqiang Yuan Jue Qian Department of Electrical Engineering State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China

ISBN: (纸本)7506274078

关键词： control systems Computerized monitoring Communication system control Electromagnetic interference Diodes power engineering computing power system simulation Optical fiber communication Real time systems Man machine systems

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Optimum parameters and maximum torque performances of the synchronous reluctance machine

Optimum parameters and maximum torque performances of the sy...

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International Conference on Electrical Machines and systems (ICEMS)

作者： Wang Shijing Zhao Zhengming Guo Wei State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing China

The permanent magnet assisted synchronous reluctance (SR-PM) machine can not only offer higher torque capacity and improved power factors compared with the conventional synchronous reluctance machine, but also own wider adjustable speed range compared with the permanent magnet machine. This paper presents a new method to optimize the key parameters of the machine under keeping the torque of the machine as large as possible by controlling the stator current. Nonlinear optimization and functional analysis are used to obtain the maximal torque at a certain speed. The investigation of many groups of the parameter data shows that the performance of a machine is influenced by various factors such as magnetic materials, the quantities of the material in the rotor, the turns of windings in the stator and so on. The best one should be chosen for applications. The trend of all the curves verifies the simulation results.

关键词： Reluctance machines Magnetic materials Permanent magnets Reactive power Permanent magnet machines Optimization methods Torque control Functional analysis Stator windings Machine windings

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