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38 results on '"Li, Lingzhi"'

23. Sensorless Vector Control for Automotive Auxiliary Motors in the Full Speed Range

Author

Zeng Peihuang, Guo Xinhua, Junshuai Cao, Li Lingzhi, Chen Kun, and Li Zhaodai

Subjects
Vector control, Computer science, Control theory, business.industry, Range (aeronautics), Limit (music), Process (computing), Automotive industry, Torque, Synchronous motor, business, Position sensor
Abstract

Permanent magnet synchronous motor (PMSM) is widely applied to the car as the main drive motor and auxiliary motor. Usually these auxiliary motors have stable speed, small load changes, and there are space limit and large price ratio of position sensor and its supporting circuit in system. So it is essential and suitable to use sensor-less control in the full speed range. Start initial position angle range of If control is developed and is detected under stationary state, which can guarantee the stability and reliability of the motor starting process; And strategy of smooth switching from low speed to medium and high speed is designed by ensure that position angle and dq axis reference current are not mutated; and the algorithm of model reference adaptation control (MRAC) is designed.

Published
2019

24. A combination of combined weight and VIKOR method for multi-target threat assessment

Author

Li Lingzhi, Zhang Mingshuang, and Xu Kehu

Subjects
Set (abstract data type), Mathematical optimization, Multi target, VIKOR method, Computer science, Compromise, media_common.quotation_subject, Rank (computer programming), Rationality, Context (language use), Sensitivity (control systems), Threat assessment, media_common
Abstract

Aiming at the problem of multi-target threat assessment on the ground battlefield, a threat assessment model combining combined weight and multi-criteria optimization compromise decision-making (VIKOR) method is proposed. The model considers the expert weight and position weight comprehensively, and uses the intuitionistic fuzzy set(IFS) theory to solve the subjective and objective weight respectively, and then, a combined weight model based on the least deviation is constructed. The VIKOR method is introduced to evaluate and rank multi-target in the context of a combat exercise situation, and a reasonable evaluation result is obtained. The comparative analysis and sensitivity analysis of the model further verify the rationality and effectiveness of the method.

Published
2019

25. A Parity-Time-Symmetric Optoelectronic Oscillator Based on Non-Reciprocal Electro-Optic Modulation.

Author

Fan, Jinying, Li, Lingzhi, Zhang, Jiejun, Feng, Xinhuan, Guan, Bai-Ou, and Yao, Jianping

Abstract

In this paper, we propose and experimentally demonstrate a parity-time- (PT-) symmetric optoelectronic oscillator (OEO) based on non-reciprocal electro-optic modulation for the generation of a microwave signal with a low phase noise. In the proposed OEO, two mutually coupled optoelectronic loops with one having a gain and the other a loss are implemented based on the copropagating and counterpropagating modulation in a traveling-wave electro-optic Mach-Zehnder modulator (MZM), to achieve PT symmetry. Due to the non-reciprocity of the travelling-wave MZM, the modulation indices are different for the copropagating and counterpropagating light waves in relative to the applied microwave signal, which is then interpreted as different microwave round-trip gains for the mutually coupled optoelectronic loops. Once the gain/loss coefficient is greater than the coupling coefficient, the PT symmetry is broken, and single-mode oscillation is achieved. The proposed OEO is experimentally demonstrated. A 10-GHz microwave signal with a phase noise of −110 dBc/Hz at an offset frequency of 10 kHz and a sidemode suppression ratio of 42 dB is generated. The work provides a new solution to overcome the mode selection problem in a long-cavity OEO. Since a single physical loop is employed, the proposed PT-symmetric OEO has the simplest architecture as compared to any existing PT-symmetric OEOs. [ABSTRACT FROM AUTHOR]

Published
2021
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29. Analytic calculation and analysis of the magnetic field for the single-phase two-limb transformer

Author

Pan Jie, Hu Yiwei, Li Lingzhi, Zheng Jing, Huang Hai, and Zhang Jiangong

Subjects
Physics, 020209 energy, Condition monitoring, 02 engineering and technology, Mechanics, Magnetic flux density distribution, law.invention, Magnetic field, Vibration, symbols.namesake, Maxwell's equations, law, Electromagnetic coil, 0202 electrical engineering, electronic engineering, information engineering, symbols, Single phase, Transformer
Abstract

The vibration analysis method is widely used in transformer diagnosis. However, to our knowledge, the researches about the magnetic field for the vibration method are mainly based on numerical modelling rather than analytic calculation. But the analytic calculation is quite essential for the application of the vibration method. This paper calculates and simulates the magnetic flux density distribution of the winding and core in a single-phase two-limb transformer, respectively based on the Biot-Savart law and Maxwell's equations. The proposed results and simulations are consistent with the precedent researches. It is believed that this analytic calculation and analysis of the transformer magnetic field may help developing the transformer condition monitoring and fault diagnosis based on the vibration analysis method.

Published
2017

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