Abstract:Traditional methods for rotational speed measurement of centrifugal pump and their problems were analyzed. A new method for the rotational speed measurement was proposed based on motor current signal analysis(MCSA), then its mathematic equation was deduced using data processing theory. According to a principle that the frequency of current in stator windings is equal to the rotating speed frequency of the rotor when a centrifugal pump is driven by an AC motor, the frequency component of motor stator current was acquired by means of MCSA technology. Finally, the rotating speed frequency was detected from the current frequency spectrum. A trail experiment was designed according to this principle. During a test, the motor was fed by a frequency converter which could generate AC power with various frequencies, and the flow rate was adjusted, then the motor stator current was sampled by Hall effect sensors and a data acquisition card. After demodulation and fast Fourier transform(FFT), the rotating speed frequency was detected in frequency spectrum within a restricted range. To validate this method, a method based on rotor-stator interaction and an optical tachometer method were also used to get the speed. Compared with these two methods, the new method proposed was subject to an error less than 2%, and this accuracy has met the requirement of centrifugal pump monitoring, demonstrating a potential application in centrifugal pumps. What′s more, it is a sensorless method which can be realized in a better accuracy and more flexible applicability. This outcome is subject to application significance in some degree.
[1]张金凤,冒杰云,袁寿其,等. 变转速工况下汽车冷却水泵内外特性变化规律[J]. 流体机械, 2014,42(8):1-6. ZHANG Jinfeng,MAO Jieyun,YUAN Shouqi,et al. Effect of rotation speed on the inner flow and performance characteristics for an automobile cooling pump[J]. Fluid machinery,2014,42(8):1-6.(in Chinese)[2]余光伟,刘江山,范四辈,等. 基于虚拟仪器技术的速度测量系统 [J]. 仪表技术与传感器,2013(10):28-30. YU Guangwei,LIU Jiangshan,FAN Sibei,et al. Design of velocity measurement system based on virtual instrument technology[J]. Instrument technique and sensor,2013(10):28-30.(in Chinese)[3]李茂亮,高敬贝,贾仁松,等. 基于虚拟仪器技术的电动机转速测控系统设计 [J].电动机与控制应用,2010,37(7):20-23. LI Maoliang,GAO Jingbei,JIA Rensong,et al. Design of motor speed measurement and control system based on virtual instrument technology [J]. Electric machines & control application,2010,37(7):20-23.(in Chinese)[4]仲汝新. 智能化异步电动机转速测量系统研制 [D]. 合肥:合肥工业大学,2012.[5]潘中永,倪永燕,袁寿其,等. 基于动静干涉的离心泵转速测量机理与实验[J]. 农业机械学报,2010,41(3):81-85. PAN Zhongyong,NI Yongyan,YUAN Shouqi,et al. Experiment and mechanism of centrifugal pumps rotation speed measurement based on rotor-stator interaction [J]. Transactions of the CSAM,2010,41(3):81-85.(in Chinese)[6]骆寅,孙慧,卢加兴,等. 无传感器监测技术在离心泵中的应用研究综述[J]. 排灌机械工程学报,2015,33(6):547-552. LUO Yin,SUN Hui,LU Jiaxing,et al. Review for sensorless detection technology applied in centrifugal pumps[J]. Journal of drainage and irrigation machinery engineering,2015,33(6):547-552.(in Chinese)[7]NIASAR A H,VAHEDI A,MOGHBELLI H. Low-cost sensorless control of four-switch, brushless DC motor drive with direct back-EMF detection[J]. Journal of Zhejiang University(science A),2009,10(2):201-208.[8]时献江. 异步电动机及其驱动设备的无传感器故障诊断方法研究[D]. 哈尔滨:哈尔滨理工大学,2009.[9]周锋,王明渝,杜彦巍. 基于MCSA的异步电动机状态监测与故障诊断综述 [J]. 重庆大学学报(自然科学版),2005,28(1):49-52. ZHOU Feng,WANG Mingyu,DU Yanwei. Summary of on-line monitoring and fault diagnosis for induction motor based on MCSA [J]. Journal of Chongqing University(natural science edition),2005,28(1):49-52.(in Chinese)[10]STOPA M M,FILHO B J C,LAGE B L O. An evaluation of the MCSA method when applied to detect faults in motor driven loads [C]//Proceedings of the 36th IECON Annual Conference on IEEE Industrial Electronics Society,2010:760-765.[11]陈颖,李国平,张宁,等. 蜗壳喉部面积对离心泵非定常特性的影响[J].流体机械,2017,45(2):38-42. CHEN Ying,LI Guoping,ZHANG Ning,et al. Research on the influence of volute throat area on unsteady characteristics in a centrifugal pump [J]. Fluid machinery,2017, 45(2):38-42.(in Chinese)[12]杨敏官, 孙鑫恺, 高波,等. 离心泵内部非定常空化流动特征的数值分析[J]. 江苏大学学报(自然科学版),2012,33(4):408-413. YANG Minguan,SUN Xinkai,GAO Bo,et al. Numerical analysis of unsteady cavitating flow characteristic in centrifugal pump [J]. Journal of Jiangsu University(natural science edition),2012,33(4):408-413.(in Chinese)[13]刘厚林, 吕云, 王勇,等. 不等间距叶片对离心泵性能及压力脉动影响分析[J]. 农业工程学报, 2015,31(23):60-66. LIU Houlin,LYU Yun,WANG Yong,et al. Analysis about effect of unequal spacing blade on performance and pressure pulsation of centrifugal pump [J]. Transactions of the CSAE,2015,31(23):60-66.(in Chinese)