For the traditional methods of rotor position estimation for permanent magnet synchronous motor(PMSM),the phase shift caused by the introduction of filter will affect the accuracy of rotor position estimation to some ...For the traditional methods of rotor position estimation for permanent magnet synchronous motor(PMSM),the phase shift caused by the introduction of filter will affect the accuracy of rotor position estimation to some extent.This paper presents an improved rotor position estimation method for high frequency square wave signal injection without filter.Firstly,the traditional method injects high-frequency pulse vibration signals into the estimated shafting,and the proposed method injects high-frequency square wave signals into the estimated shafting to avoid the introduction of filters in the process of extracting rotor position information.Then,the rotor position signal is decoupled in the stationary shafting,and the rotor position error after demodulation is processed by PLL.The system realized the signal processing of rotor position without filter,which improved the convergence speed and estimation precision of rotor position and the dynamic response performance of the system.The simulation results showed that the proposed method had fast convergence speed and small phase delay,and better improved the precision of rotor position detection.展开更多
Micro-arc oxidation （MAO） process was carried out on AZ91D alloy in alkaline borate solution using an alternative square-wave power source with different parameters. The effects of voltage, frequency and duty cycle ...Micro-arc oxidation （MAO） process was carried out on AZ91D alloy in alkaline borate solution using an alternative square-wave power source with different parameters. The effects of voltage, frequency and duty cycle on the coatings were investigated by orthogonal experiment. It is found that the thickness of coatings increases with the increase of voltage and duty cycle, but decreases with the increase of frequency. The structure and morphology of the coatings also depend on voltage, frequency and duty cycle. The coatings become more porous and crack with increasing voltage and duty cycle. The coating is thin and transparent when the voltage is lower than 120 V. The corrosion resistances of different coatings were evaluated by polarization curves and electrochemical impedance spectroscopy （EIS） in 3.5% NaCl （mass fraction） solution. When the optimized values of voltage, frequency and duty cycle are 140 V, 2 000 Hz and 0.4, respectively, the anodic coating shows the best corrosion resistance.展开更多
The degradation of acid orange II(AO II)by a nanoporous Fe-Si-B(NP-Fe Si B)electrode under the pulsed square-wave potential has been investigated in this research.Defect-enriched NP-Fe Si B electrode was fabricated th...The degradation of acid orange II(AO II)by a nanoporous Fe-Si-B(NP-Fe Si B)electrode under the pulsed square-wave potential has been investigated in this research.Defect-enriched NP-Fe Si B electrode was fabricated through dealloying of annealed Fe_(76)Si_(9)B_(15)amorphous ribbons.The results of UV-vis spectra and FTIR indicated that AO II solution was degraded efficiently into unharmful molecules H_(2)O and CO_(2)on NPFe Si B electrode within 5 mins under the square-wave potential of±1.5 V.The degradation efficiency of the NP-Fe Si B electrode remains 98.9%even after 5-time recycling.The large amount of active surface area of the nanoporous Fe Si B electrode with lattice disorders and stacking faults,and alternate electrochemical redox reactions were mainly responsible for the excellent degradation performance of the NP-Fe Si B electrode.The electrochemical pulsed square-wave process accelerated the redox of Fe element in Fe-based nanoporous electrode and promoted the generation of hydroxyl radicals(·OH)with strong oxidizability as predominant oxidants for the degradation of azo dye molecules,which was not only beneficial to improving the catalytic degradation activity,but also beneficial to enhancing the reusability of the nanoporous electrode.This work provides a highly possibility to efficiently degrade azo dyes and broadens the application fields of nanoporous metals.展开更多
针对三相电网不平衡故障下的电压型PWM整流器的直流电压二次纹波和网侧电流谐波,研究了一种纹波抑制方法。基于传统的双闭环控制结构,提出电网不对称故障下参考电流计算方法。利用模型预测控制取代电流环PI控制,结合PWM调制环节固定开...针对三相电网不平衡故障下的电压型PWM整流器的直流电压二次纹波和网侧电流谐波,研究了一种纹波抑制方法。基于传统的双闭环控制结构,提出电网不对称故障下参考电流计算方法。利用模型预测控制取代电流环PI控制,结合PWM调制环节固定开关频率,根据电流预测模型和电流误差最小原则,不仅减小了网侧电流谐波和直流母线侧电压纹波,而且降低了平均开关次数进而减少了器件损耗。通过建立的交流侧110 V、直流侧300 V、输出功率0.7 k W的实验平台进行了实验验证,表明该系统具有良好的稳态性能。仿真结果和实验结果验证了所提出控制方法的有效性以及理论分析的正确性。展开更多
针对电力机车牵引变流器中故障率最高的单相脉宽调制(pulse width modulation,PWM)整流器,提出一种流形学习算法融合多域特征的故障诊断方法。根据整流器在不同工作状态下的时域、频域和时频域特征构建多域特征向量;采用Hessian局部线...针对电力机车牵引变流器中故障率最高的单相脉宽调制(pulse width modulation,PWM)整流器,提出一种流形学习算法融合多域特征的故障诊断方法。根据整流器在不同工作状态下的时域、频域和时频域特征构建多域特征向量;采用Hessian局部线性嵌入(Hessian local linear embedding,HLLE)算法融合多域特征,根据故障样本数和聚类结果,解决高维数据中固有维数和最近邻数选取困难的问题,得到用于描述故障特征的最优低维特征向量,减少特征之间的冲突和冗余;采用支持向量机进行模式识别,实现对整流器的故障诊断。结果表明:对不同的输出电压,不同的训练和测试比,15种故障模式均具有较高的诊断率。与其他方法相比,本文方法具有较好的融合效果和较强的鲁棒性。展开更多
The pressing environmental concerns and the depletion of fossil fuel reserves necessitate a transition toward sustainable energy sources.Ethanol,a renewable biomass-derived fuel,is a promising alternative due to its a...The pressing environmental concerns and the depletion of fossil fuel reserves necessitate a transition toward sustainable energy sources.Ethanol,a renewable biomass-derived fuel,is a promising alternative due to its availability and high energy density.This study investigates the synthesis of gold nanoparticles(Au NPs)via a square-wave pulse deposition technique,aiming to enhance catalytic activity for ethanol electrooxidation.By varying pulse durations,we were able to exert precise control over Au NP size and distribution without stabilizing agents.Characterization using field emission scanning electron microscopy and X-ray diffraction techniques confirmed the formation of clustered nanoparticles of metallic gold phase.Electrochemical characteristics analyses revealed that Au NPs synthesized with a 900 ms pulse duration exhibited the lowest charge transfer resistance and the highest electrochemically active surface area.The electrocatalytic performance test of these Au NPs demonstrated an anodic current density of 2.5 mA cm^-(2)and a Tafel slope of 78 mV dec^(-1),indicating superior catalytic performance and reaction kinetics.Additionally,the Au NPs showed high resistance to poisoning,as evidenced by a low j_(b)/j_(f)ratio of 0.28 and stable chronoamperometric response.These findings underscore the potential of this synthesis method for producing high-performance electrocatalysts utilized in exploiting ethanol's potential as an environmentally friendly energy carrier.展开更多
基金supported by National Natural Science Foundation of China(No.61863023)Lanzhou Talent Innovation and Entrepreneurship Project Task Contract(No.2019-RC-103).
文摘For the traditional methods of rotor position estimation for permanent magnet synchronous motor(PMSM),the phase shift caused by the introduction of filter will affect the accuracy of rotor position estimation to some extent.This paper presents an improved rotor position estimation method for high frequency square wave signal injection without filter.Firstly,the traditional method injects high-frequency pulse vibration signals into the estimated shafting,and the proposed method injects high-frequency square wave signals into the estimated shafting to avoid the introduction of filters in the process of extracting rotor position information.Then,the rotor position signal is decoupled in the stationary shafting,and the rotor position error after demodulation is processed by PLL.The system realized the signal processing of rotor position without filter,which improved the convergence speed and estimation precision of rotor position and the dynamic response performance of the system.The simulation results showed that the proposed method had fast convergence speed and small phase delay,and better improved the precision of rotor position detection.
基金Project (50801056) supported by the National Natural Science Foundation of ChinaProject (2005DKA10400-Z20) supported by the National R&D Infrastructure and Facility Development Program of ChinaProject supported by the Zijin Project of Zhejiang University, China
文摘Micro-arc oxidation （MAO） process was carried out on AZ91D alloy in alkaline borate solution using an alternative square-wave power source with different parameters. The effects of voltage, frequency and duty cycle on the coatings were investigated by orthogonal experiment. It is found that the thickness of coatings increases with the increase of voltage and duty cycle, but decreases with the increase of frequency. The structure and morphology of the coatings also depend on voltage, frequency and duty cycle. The coatings become more porous and crack with increasing voltage and duty cycle. The coating is thin and transparent when the voltage is lower than 120 V. The corrosion resistances of different coatings were evaluated by polarization curves and electrochemical impedance spectroscopy （EIS） in 3.5% NaCl （mass fraction） solution. When the optimized values of voltage, frequency and duty cycle are 140 V, 2 000 Hz and 0.4, respectively, the anodic coating shows the best corrosion resistance.
基金financially supported by Shi-changxu Innovation Center for Advanced Materials,Institute of Metal Research,Chinese Academy of Sciences,the National Natural Science Foundation of China(51790484,51671106)Chinese Academy of Sciences(ZDBSLY-JSC023)Fundamental Research Funds for the Central Universities(30919011404)。
文摘The degradation of acid orange II(AO II)by a nanoporous Fe-Si-B(NP-Fe Si B)electrode under the pulsed square-wave potential has been investigated in this research.Defect-enriched NP-Fe Si B electrode was fabricated through dealloying of annealed Fe_(76)Si_(9)B_(15)amorphous ribbons.The results of UV-vis spectra and FTIR indicated that AO II solution was degraded efficiently into unharmful molecules H_(2)O and CO_(2)on NPFe Si B electrode within 5 mins under the square-wave potential of±1.5 V.The degradation efficiency of the NP-Fe Si B electrode remains 98.9%even after 5-time recycling.The large amount of active surface area of the nanoporous Fe Si B electrode with lattice disorders and stacking faults,and alternate electrochemical redox reactions were mainly responsible for the excellent degradation performance of the NP-Fe Si B electrode.The electrochemical pulsed square-wave process accelerated the redox of Fe element in Fe-based nanoporous electrode and promoted the generation of hydroxyl radicals(·OH)with strong oxidizability as predominant oxidants for the degradation of azo dye molecules,which was not only beneficial to improving the catalytic degradation activity,but also beneficial to enhancing the reusability of the nanoporous electrode.This work provides a highly possibility to efficiently degrade azo dyes and broadens the application fields of nanoporous metals.
文摘针对三相电网不平衡故障下的电压型PWM整流器的直流电压二次纹波和网侧电流谐波,研究了一种纹波抑制方法。基于传统的双闭环控制结构,提出电网不对称故障下参考电流计算方法。利用模型预测控制取代电流环PI控制,结合PWM调制环节固定开关频率,根据电流预测模型和电流误差最小原则,不仅减小了网侧电流谐波和直流母线侧电压纹波,而且降低了平均开关次数进而减少了器件损耗。通过建立的交流侧110 V、直流侧300 V、输出功率0.7 k W的实验平台进行了实验验证,表明该系统具有良好的稳态性能。仿真结果和实验结果验证了所提出控制方法的有效性以及理论分析的正确性。
文摘针对电力机车牵引变流器中故障率最高的单相脉宽调制(pulse width modulation,PWM)整流器,提出一种流形学习算法融合多域特征的故障诊断方法。根据整流器在不同工作状态下的时域、频域和时频域特征构建多域特征向量;采用Hessian局部线性嵌入(Hessian local linear embedding,HLLE)算法融合多域特征,根据故障样本数和聚类结果,解决高维数据中固有维数和最近邻数选取困难的问题,得到用于描述故障特征的最优低维特征向量,减少特征之间的冲突和冗余;采用支持向量机进行模式识别,实现对整流器的故障诊断。结果表明:对不同的输出电压,不同的训练和测试比,15种故障模式均具有较高的诊断率。与其他方法相比,本文方法具有较好的融合效果和较强的鲁棒性。
基金supported by the National Research and Innovation Agency(BRIN)and Lembaga Pengelola Dana Pendidikan(LPDP)Ministry of Finance,Republic of Indonesia through Riset dan Inovasi Untuk Indonesia Maju(RIIM)scheme batch 2 with contract number 1/PG.02.00.PT/LPPM/IV/2024(110/IV/KS/11/2022).
文摘The pressing environmental concerns and the depletion of fossil fuel reserves necessitate a transition toward sustainable energy sources.Ethanol,a renewable biomass-derived fuel,is a promising alternative due to its availability and high energy density.This study investigates the synthesis of gold nanoparticles(Au NPs)via a square-wave pulse deposition technique,aiming to enhance catalytic activity for ethanol electrooxidation.By varying pulse durations,we were able to exert precise control over Au NP size and distribution without stabilizing agents.Characterization using field emission scanning electron microscopy and X-ray diffraction techniques confirmed the formation of clustered nanoparticles of metallic gold phase.Electrochemical characteristics analyses revealed that Au NPs synthesized with a 900 ms pulse duration exhibited the lowest charge transfer resistance and the highest electrochemically active surface area.The electrocatalytic performance test of these Au NPs demonstrated an anodic current density of 2.5 mA cm^-(2)and a Tafel slope of 78 mV dec^(-1),indicating superior catalytic performance and reaction kinetics.Additionally,the Au NPs showed high resistance to poisoning,as evidenced by a low j_(b)/j_(f)ratio of 0.28 and stable chronoamperometric response.These findings underscore the potential of this synthesis method for producing high-performance electrocatalysts utilized in exploiting ethanol's potential as an environmentally friendly energy carrier.
