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Jiaqiang Yang,Yongle Mao,Yangsheng Chen 대한전기학회 2017 Journal of Electrical Engineering & Technology Vol.12 No.3
Estimation errors of the rotor speed and position in sensorless control systems of Permanent Magnet Synchronous Motors (PMSM) will lead to low efficiency and dynamic-performance degradation. In this paper, a parallel-type extended nonlinear observer incorporating the nominal parameters is constructed in the stator-fixed reference frame, with rotor position, speed, and the load torque simultaneously estimated. The stability of the extended nonlinear observer is analyzed using the indirect Lyapunov’s method, and observer gains are selected according to the transfer functions of the speed and position estimators. Taking into account the parameter inaccuracies issue, explicit estimation error equations are derived based on the error dynamics of the closed-loop sensorless control system. An equivalent flux error is defined to represent the back Electromotive Force (EMF) error caused by the inaccurate motor parameters, and a compensation strategy is designed to suppress the estimation errors. The effectiveness of the proposed method has been validated through simulation and experimental results.
Jiaqiang Yang,Kai Le,Hui Chen,Xu Zhao,Xiaodong Xie,Yong Luo,Shusheng Xu,Weiming Liu 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.24 No.4
In this work, plasma pre-nitriding technique has been employed to enhance the bearing capacity for the TiN coating deposited on Ti6Al4V alloy by magnetron sputtering. The composition, morphology and mechanical property of the as-prepared samples were studied by the X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), Vickers micro-hardness tester and nanoindentater. The tribological properties are investigated using a rotary tribometer under dry sliding and oil lubrication, and the mechanism was also discussed in details. The results show that the plasma nitriding treatment produced a nitrided layer with thickness of 85 μm on the surface of Ti6Al4V alloy, which significantly enhanced the mechanical properties. Therefore, the as-prepared TiN coated sample with plasma pre-nitriding treatment exhibit more excellent mechanical properties possessing the maximum hardness values (26 GPa) and exceptional load bearing capacity (74 N) compared to single TiN-coated Ti6Al4V. Moreover, the tribological properties of sample with plasma pre-nitriding treatment was also significantly improved, which was attributed to the synergistic effect of the superior bearing performance of nitriding layer and the high hardness of TiN coating. Additionally, wear mechanisms were discussed in terms of wear track morphology after sliding test.
Yang, Jiaqiang,Mao, Yongle,Chen, Yangsheng The Korean Institute of Electrical Engineers 2017 Journal of Electrical Engineering & Technology Vol.12 No.3
Estimation errors of the rotor speed and position in sensorless control systems of Permanent Magnet Synchronous Motors (PMSM) will lead to low efficiency and dynamic-performance degradation. In this paper, a parallel-type extended nonlinear observer incorporating the nominal parameters is constructed in the stator-fixed reference frame, with rotor position, speed, and the load torque simultaneously estimated. The stability of the extended nonlinear observer is analyzed using the indirect Lyapunov's method, and observer gains are selected according to the transfer functions of the speed and position estimators. Taking into account the parameter inaccuracies issue, explicit estimation error equations are derived based on the error dynamics of the closed-loop sensorless control system. An equivalent flux error is defined to represent the back Electromotive Force (EMF) error caused by the inaccurate motor parameters, and a compensation strategy is designed to suppress the estimation errors. The effectiveness of the proposed method has been validated through simulation and experimental results.
차효정,Jiaqiang Li,Yifan Li,김슬옹,김윤희,권순기 한국고분자학회 2020 Macromolecular Research Vol.28 No.9
Here we report a polymeric semiconductor (ODATT) comprising alkoxy anthracene (ODA) and thienothiophene (TT) polymerized by stille coupling reaction with the Pd catalyst. The optical properties of the polymer:PC71BM blend films are used by the UV-Visible absorption spectroscopy. The ODATT blends with PC71BM exhibit a maximal power conversion efficiency of 2.2% via thermal annealing treatment. Morphological analysis of the polymer:PC71BM blend films demonstrate the influence of ODATT polymer segregation on device performance by atomic force microscopy and transmission electron microscopy. We confirmed that ODATT has enhanced fill factor after thermal annealing treatment from the reduced series and shunt resistance from morphological enhancement.
An oil-tolerant and salt-resistant aqueous foam system for heavy oil transportation
Jie Sun,Jiaqiang Jing,Neima Brauner,Li Han,Amos Ullmann 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.68 No.-
An oil-tolerant and salt-resistant aqueous foam system was screened out as a possible lubricant to enable cold heavy oil transportation. The microstructures and viscoelasticity and effects of heavy oil, salt and temperature on the foam stability were investigated and new rheological and drainage models were established. The results indicate the foam with multilayered shells belongs to a special microcellular foam. The viscoelasticity could be neglected due to its low relaxation time. The drainage process can be divided into three stages. The foam with quality of 67.9% maintains great stability at high oil and salt concentrations and appropriate elevated temperature.
Pipeline transport of heavy crudes as stable foamy oil
Jie Sun,Jiaqiang Jing,Cheng Wu,Fei Xiao,Xiaoxuan Luo 한국공업화학회 2016 Journal of Industrial and Engineering Chemistry Vol.44 No.-
A new idea was proposed to transport heavy crudes as foamy oil at normal temperature. The effects offoaming agent type and concentration, foam stabilizer type and concentration, oil–water volume ratioand temperature on the formation and stability of foamy oil were evaluated. The foamy oil properties anddrag characteristics of foamy oilflow in small diameter pipes were investigated. The results indicate thatthe prepared stable foamy oil could be characterized as non-Newtonian power lawfluid. The predictedpressure drops were in good agreement with the measured ones. The significant dynamic viscosityreduction rates were obtained.
Yongle Mao,Jiaqiang Yang,Dejun Yin,Yangsheng Chen 전력전자학회 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.6
Mechanical and electrical parameter uncertainties cause dynamic and static estimation errors of the rotor speed and position, resulting in performance deterioration of sensorless control systems. This paper applies an extended nonlinear observer to interior permanent magnet synchronous motors (IPMSM) for the simultaneous estimation of the rotor speed and position. Two compensation methods are proposed to improve the observer performance against parameter uncertainties: an on-line rotational inertia adjustment approach that employs the gradient descent algorithm to suppress dynamic estimation errors, and an equivalent flux error compensation approach to eliminate static estimation errors caused by inaccurate electrical parameters. The effectiveness of the proposed control strategy is demonstrated by experimental tests.
Rongfeng Deng,Jiaqiang Yang,Wanben Huang,Zhebin Yang,Tangtang Gu,Senqing Zhuo 전력전자학회 2023 ICPE(ISPE)논문집 Vol.2023 No.-
The power factor (PF) and grid current distortion are two major issues for the promotion of variable frequency drive system with small film capacitors. This paper proposes an inverter current control method to shape the inverter current following grid current, and hence high PF can be obtained. Considering the cutoff effect of diode rectifier, the main components of the inverter current are analyzed. The inverter current loop with proportional integration multi-resonant (PI-MR) controller is proposed to regulate ac component with multi times of base frequency. Both the system loop stability and tracking performance are ensured with the proper parameters design. In addition, an error compensation method with the prediction of inverter current variation is developed to enhance the inverter current control, which improves the grid current performance with the sampled grid and dc-link voltage. Experimental results verify the validity of the proposed method and the PF is up to 0.987.
Qinglong An,Jiaqiang Dang 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.7 No.2
High cutting temperature will lead to a short tool life and a poor machining quality during titanium alloy machining. High efficiency cooling methods are always required to reduce the cutting temperature. In this paper, heat transfer experimental platform was set up and one-dimension heat transfer model was established to get critical heat flux (CHF) used to evaluate the cooling capacity of the cooling methods. The effect of cold mist jet (CMJ) was evaluated by transient heat transfer tests and titanium alloys cutting experiments, comparing with cold air jet, flood cooling and minimum quantity lubricant. The experimental results revealed that CMJ with a high CHF has a stronger cooling capacity than other cooling methods and has greatly reduced the cutting temperature in high-speed cutting of titanium alloys. And tool life and surface quality have been both improved with CMJ. This paper offered a way for evaluating the cooling effects of different cooling methods with heat transfer experiments.