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Liansheng Zhang,Shuang Hao,Pengcheng Zhang,Qiangxian Huang,Rongjun Cheng,Ruijun Li,Ping Wang 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.24 No.12
Piezoelectric actuators have been widely applied to precision positioning platforms. However, the positioning accuracy of piezoelectric ceramic has been significantly affected by its characteristics of hysteresis. Owing to the voltage-keeping feature of capacitive load for piezoelectric ceramic, this paper has proposed a switch-based driving in sequence method, which alternately drives each layer of PZT by using switches. Based on the driving in sequence method, the proposed method is capable of reducing the hysteresis to 1/N of the hysteresis under traditional voltage driving method, while significantly lowering the scale and cost of hardware, compared with the previous driving in sequence method. Thus, it allows for application to hundreds of layers of piezoelectric ceramic. According to experiment results, the hysteresis under different frequencies from 0.1 to 500 Hz for homemade seven-layer piezoelectric ceramic can be reduced from 12.5 to 2.1%. Furtherly, the residual hysteresis can be corrected by applying a simple quadratic-polynomial feedforward control, and the hysteresis is constrained within 0.8%, even with feedforward parameters that are not strictly calibrated. The dual-amplifier driving in sequence method proposed in this paper can significantly reduce the hysteresis in open-loop control of piezoelectric stack actuators, effectively improving the positioning and driving performance and saving cost.
Yi-Wen Geng,Chen-Xi Wei,Rui-Cheng Chen,Liang Wang,Jia-Bin Xu,Shuang-Cheng Hao 전력전자학회 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.1
Due to the excessive zero-sequence voltage in dual three-level inverter fed open-end winding induction motor systems, zero-sequence circumfluence which is harmful to switching devices and insulation is then formed when operating in a single DC voltage source supplying mode. Traditionally, it is the mean value instead of instantaneous value of the zero-sequence voltage that is eliminated, through adjusting the durations of the operating vectors. A new strategy is proposed for zero-sequence voltage elimination, which utilizes unified voltage modulation and a decoupled SVPWM strategy to achieve two same-sized equivalent vectors for an angle of 120°, generated by two inverters independently. Both simulation and experimental results have verified its efficiency in the instantaneous value elimination of zero-sequence voltage.
Facile Synthesis of CdTe Nanorods from the Growth of Te Nanorods
Xu, Weiwei,Niu, Jinzhong,Zheng, Shuang,Tian, Guimin,Wu, Xinghui,Cheng, Yongguang,Hu, Xiaoyang,Liu, Shuaishuai,Hao, Haoshan Korean Chemical Society 2017 대한화학회지 Vol.61 No.4
One-dimensional CdTe nanorods (NRs) are obtained by the reaction of various Cd precursors with single crystalline Te nanorod templates, which are pre-synthesized from Te precursors by a simple and reproducible solvothermal method. Throughout the process, the diffraction intensity of different crystal facets of single crystalline Te NRs varied with reaction times. Finally, by alloying Cd ions along the axial direction of Te NRs, polycrystalline cubic phase CdTe NRs with diameters of 80-150 nm and length up to $1.2-2.4{\mu}m$ are obtained. The nucleation and growth processes of Te and CdTe NRs are discussed in details, and their properties are characterized by XRD, SEM, TEM, Raman scattering, and UV-vis absorption spectra. It was found that the key elements of synthesizing CdTe NRs such as reaction temperatures and Cd sources will strongly influence the final shape of CdTe NRs.
Guo Zhen,Tong Di,Zhao Yan-cheng,Chen Shuang,Nai Ji-qiu,Ye Ming-hao 대한전기학회 2024 Journal of Electrical Engineering & Technology Vol.19 No.1
Asynchronous motor is widely used in various industrial fields. When asynchronous motor works in case close to the rated load, it will run at maximum efficiency. However, most of the load is 50–100% of rated load and it will lead to the serious waste of energy. This paper proposes an efficiency optimization control strategy based on the grey wolf optimization algorithm to improve the operating efficiency of asynchronous motors at light loads. The motor loss model considering the change of iron loss is established and it makes the asynchronous motor model more accurate. The grey wolf optimization algorithm is used to find the optimized flux value. When the asynchronous motor operates at the optimal flux, the loss power of the motor is decreased and the operation efficiency improves effectively. The proposed method reduces the flux search time and improves the stability of the system. The simulation model is established and the simulation results are provided to verify the feasibility of the proposed control strategy achieving the global efficiency optimum of asynchronous motor.
Geng, Yi-Wen,Wei, Chen-Xi,Chen, Rui-Cheng,Wang, Liang,Xu, Jia-Bin,Hao, Shuang-Cheng The Korean Institute of Power Electronics 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.1
Due to the excessive zero-sequence voltage in dual three-level inverter fed open-end winding induction motor systems, zero-sequence circumfluence which is harmful to switching devices and insulation is then formed when operating in a single DC voltage source supplying mode. Traditionally, it is the mean value instead of instantaneous value of the zero-sequence voltage that is eliminated, through adjusting the durations of the operating vectors. A new strategy is proposed for zero-sequence voltage elimination, which utilizes unified voltage modulation and a decoupled SVPWM strategy to achieve two same-sized equivalent vectors for an angle of $120^{\circ}$, generated by two inverters independently. Both simulation and experimental results have verified its efficiency in the instantaneous value elimination of zero-sequence voltage.