Mining shovel is a crucial piece of equipment for high-efficiency production in open-pit mining and stands as one of the largest energy consumption sources in mining.However,substantial energy waste occurs during the ...Mining shovel is a crucial piece of equipment for high-efficiency production in open-pit mining and stands as one of the largest energy consumption sources in mining.However,substantial energy waste occurs during the descent of the hoisting system or the deceleration of the slewing platform.To reduce the energy loss,an innovative hydrau-lic-electric hybrid drive system is proposed,in which a hydraulic pump/motor connected with an accumulator is added to assist the electric motor to drive the hoisting system or slewing platform,recycling kinetic and potential energy.The utilization of the kinetic and potential energy reduces the energy loss and installed power of the min-ing shovel.Meanwhile,the reliability of the mining shovel pure electric drive system also can be increased.In this paper,the hydraulic-electric hybrid driving principle is introduced,a small-scale testbed is set up to verify the feasibil-ity of the system,and a co-simulation model of the proposed system is established to clarify the system operation and energy characteristics.The test and simulation results show that,by adopting the proposed system,compared with the traditional purely electric driving system,the peak power and energy consumption of the hoisting electric motor are reduced by 36.7%and 29.7%,respectively.Similarly,the slewing electric motor experiences a significant decrease in peak power by 86.9%and a reduction in energy consumption by 59.4%.The proposed system expands the application area of the hydraulic electric hybrid drive system and provides a reference for its application in over-sized and super heavy equipment.展开更多
Today, along with the prevalent use of portable equipment, wireless, and other battery powered systems, the demand for amplifiers with a high gain-bandwidth product(GBW), slew rate(SR), and at the same time very l...Today, along with the prevalent use of portable equipment, wireless, and other battery powered systems, the demand for amplifiers with a high gain-bandwidth product(GBW), slew rate(SR), and at the same time very low static power dissipation is growing. In this work, an operational transconductance amplifier(OTA) with an enhanced SR is proposed. By inserting a sensing resistor in the input port of the current mirror in the OTA, the voltage drop across the resistor is converted into an output current containing a term in proportion to the square of the voltage, and then the SR of the proposed OTA is significantly enhanced and the current dissipation can be reduced. The proposed OTA is designed and simulated with a 0.5μm complementary metal oxide semiconductor(CMOS) process. The simulation results show that the SR is 4.54V/μs, increased by 8.25 times than that of the conventional design, while the current dissipation is only 87.3%.展开更多
A calculation method of fatigue life for slewing bearings under combined radial, axial and tilting moment loads was proposed. Single row four-point contact ball slewing bearing being used as a case, the statics model ...A calculation method of fatigue life for slewing bearings under combined radial, axial and tilting moment loads was proposed. Single row four-point contact ball slewing bearing being used as a case, the statics model of the slewing bearing was established and a set of equilibrium equations were obtained. By solving the equilibrium equatioas, the rolling element loads were obtained and the equivalent rolling element loads were calculated further. By using the geometrical parameters of the bearing, the rating rolling element loads were calculated, and the fa- tigue life of the bearing was calculated by using the rating rolling element loads and the equivalent rolling element loads. A calculation example shows the feasibility of the proposed method.展开更多
To decrease breakdown time and improve machine operation reliability,accurate residual useful life(RUL) prediction has been playing a critical role in condition based monitoring.A data fusion method was proposed to ac...To decrease breakdown time and improve machine operation reliability,accurate residual useful life(RUL) prediction has been playing a critical role in condition based monitoring.A data fusion method was proposed to achieve online RUL prediction of slewing bearings,which consisted of a reliability based RUL prediction model and a data driven failure rate(FR) estimation model.Firstly,an RUL prediction model was developed based on modified Weibull distribution to build the relationship between RUL and FR.Secondly,principal component analysis(PCA) was introduced to process multi-dimensional life-cycle vibration signals,and continuous squared prediction error(CSPE) and its time-domain features were employed as equipment performance degradation features.Afterwards,an FR estimation model was established on basis of the degradation features and relevant FRs using simplified fuzzy adaptive resonance theory map(SFAM) neural network.Consequently,real-time FR of equipment can be obtained through FR estimation model,and then accurate RUL can be calculated through the RUL prediction model.Results of a slewing bearing life test show that CSPE is an effective indicator of performance degradation process of slewing bearings,and that by combining actual load condition and real-time monitored data,the calculation time is reduced by 87.3%and the accuracy is increased by 0.11%,which provides a potential for online RUL prediction of slewing bearings and other various machineries.展开更多
风电机组的偏航轴承和变桨轴承、航天发射塔架的回转支承轴承、起重机和挖掘机的转盘轴承等,都具有低速往复运转的特点。低速往复运转轴承的故障诊断极具挑战:低速工况下损伤接触的冲击力小,损伤冲击信号弱;减速换向冲击信号对故障冲击...风电机组的偏航轴承和变桨轴承、航天发射塔架的回转支承轴承、起重机和挖掘机的转盘轴承等,都具有低速往复运转的特点。低速往复运转轴承的故障诊断极具挑战:低速工况下损伤接触的冲击力小,损伤冲击信号弱;减速换向冲击信号对故障冲击信号的干扰大;覆盖多个往复运转行程的长信号不具有周期性,等等。为了解决上述问题,提出一种基于调制信号双谱(Modulation Signal Bispectrum,MSB)切片总体平均的低速往复运转轴承故障诊断方法。首先,利用转速跟踪过零点对振动信号进行信号重采样处理,并依据编码器信号从重采样信号中分离出单个行程的短信号集合;然后,对每一个短信号进行MSB分析,生成MSB的载波切片谱,根据载波切片谱寻找最优载波频率及其对应的调制信号切片谱;最后,对短信号集合的MSB调制信号切片谱进行总体平均,生成切片谱总体平均特征。故障试验数据验证结果表明,MSB切片总体平均特征能够有效诊断低速往复运转轴承的故障。展开更多
内齿式回转支承兼有滚动轴承的回转支承特点和齿轮啮合传动特点,在联合载荷作用下其动态性能的影响因素众多,容易出现轮齿磨损或断齿、套圈滚道磨损和运行精度变差等问题。综合考虑钢球与内外套圈滚道、保持架兜孔的动态接触作用及内齿...内齿式回转支承兼有滚动轴承的回转支承特点和齿轮啮合传动特点,在联合载荷作用下其动态性能的影响因素众多,容易出现轮齿磨损或断齿、套圈滚道磨损和运行精度变差等问题。综合考虑钢球与内外套圈滚道、保持架兜孔的动态接触作用及内齿圈轮齿间的啮合传动作用,建立了内齿式回转支承参数化多体接触动力学模型。分析了沟道曲率半径、保持架兜孔孔径、初始接触角和轮齿变位系数等关键设计参数对回转支承齿轮啮合力、1号钢球与N1滚道的接触力、内齿圈质心轴向和径向振动位移的影响规律。在此基础上,采用试验设计(design of experiment,DOE)方法,对内齿式回转支承的关键设计参数进行全因子试验设计及计算,获得了多参数影响下回转支承的动态性能。结合线性加权法,运用统一量纲法和权系数法构造新的多目标优化函数,提出了回转支承动态性能的多变量多目标优化设计方法,得到回转支承的轮齿啮合力下降了49.27%,1号钢球与N1滚道的接触力下降了29.6%,内齿圈质心轴向振动位移减小了5.41%,内齿圈质心径向位移减小了15.88%,回转支承的性能得到了优化。研究结果为回转支承的动态设计提供了参考。展开更多
To drive the backplane of a liquid crystal display device and achieve different kinds of grey levels, a high-slew-rate operational amplifier with constant-gin input stage is presented. A Zener-diode structure is inser...To drive the backplane of a liquid crystal display device and achieve different kinds of grey levels, a high-slew-rate operational amplifier with constant-gin input stage is presented. A Zener-diode structure is inserted between the tails of the complementary input pairs to keep the grn of the input stage constant. A novel slew rate enhancement circuit is implemented to achieve a very high slew rate. The chip has been implemented in a 0.5μm CMOS process and the chip area of the operational amplifier circuit is 0.11 mm^2. The testing results indicate that in the 5-8 V input range, the maximum gm fluctuation is only 4.2%. The result exhibits a high slew rate of 111 V/μs and 102 V/μs for the rising and falling edges under a 20 pF capacitance load, and the low frequency gain is up to 109 dB with a phase margin of 70 ℃.展开更多
An ultra-low power output-capacitorless low-dropout(LDO) regulator with a slew-rate-enhanced(SRE)circuit is introduced. The increased slew rate is achieved by sensing the transient output voltage of the LDO and th...An ultra-low power output-capacitorless low-dropout(LDO) regulator with a slew-rate-enhanced(SRE)circuit is introduced. The increased slew rate is achieved by sensing the transient output voltage of the LDO and then charging(or discharging) the gate capacitor quickly. In addition, a buffer with ultra-low output impedance is presented to improve line and load regulations. This design is fabricated by SMIC 0.18 μm CMOS technology. Experimental results show that, the proposed LDO regulator only consumes an ultra-low quiescent current of 1.2 μA.The output current range is from 10 μA to 200 m A and the corresponding variation of output voltage is less than 40 m V. Moreover, the measured line regulation and load regulation are 15.38 m V/V and 0.4 m V/m A respectively.展开更多
基金Supported by National Natural Science Foundation of China(Grant No.U1910211)National Key Research and Development Program of China(Grant No.2021YFB2011903).
文摘Mining shovel is a crucial piece of equipment for high-efficiency production in open-pit mining and stands as one of the largest energy consumption sources in mining.However,substantial energy waste occurs during the descent of the hoisting system or the deceleration of the slewing platform.To reduce the energy loss,an innovative hydrau-lic-electric hybrid drive system is proposed,in which a hydraulic pump/motor connected with an accumulator is added to assist the electric motor to drive the hoisting system or slewing platform,recycling kinetic and potential energy.The utilization of the kinetic and potential energy reduces the energy loss and installed power of the min-ing shovel.Meanwhile,the reliability of the mining shovel pure electric drive system also can be increased.In this paper,the hydraulic-electric hybrid driving principle is introduced,a small-scale testbed is set up to verify the feasibil-ity of the system,and a co-simulation model of the proposed system is established to clarify the system operation and energy characteristics.The test and simulation results show that,by adopting the proposed system,compared with the traditional purely electric driving system,the peak power and energy consumption of the hoisting electric motor are reduced by 36.7%and 29.7%,respectively.Similarly,the slewing electric motor experiences a significant decrease in peak power by 86.9%and a reduction in energy consumption by 59.4%.The proposed system expands the application area of the hydraulic electric hybrid drive system and provides a reference for its application in over-sized and super heavy equipment.
基金supported in part by the National Natural Science Foundation of China under Grant No.61274027the National Key Laboratory of Analog Integrated Circuit under Grant No.9140c90503140c09048
文摘Today, along with the prevalent use of portable equipment, wireless, and other battery powered systems, the demand for amplifiers with a high gain-bandwidth product(GBW), slew rate(SR), and at the same time very low static power dissipation is growing. In this work, an operational transconductance amplifier(OTA) with an enhanced SR is proposed. By inserting a sensing resistor in the input port of the current mirror in the OTA, the voltage drop across the resistor is converted into an output current containing a term in proportion to the square of the voltage, and then the SR of the proposed OTA is significantly enhanced and the current dissipation can be reduced. The proposed OTA is designed and simulated with a 0.5μm complementary metal oxide semiconductor(CMOS) process. The simulation results show that the SR is 4.54V/μs, increased by 8.25 times than that of the conventional design, while the current dissipation is only 87.3%.
文摘A calculation method of fatigue life for slewing bearings under combined radial, axial and tilting moment loads was proposed. Single row four-point contact ball slewing bearing being used as a case, the statics model of the slewing bearing was established and a set of equilibrium equations were obtained. By solving the equilibrium equatioas, the rolling element loads were obtained and the equivalent rolling element loads were calculated further. By using the geometrical parameters of the bearing, the rating rolling element loads were calculated, and the fa- tigue life of the bearing was calculated by using the rating rolling element loads and the equivalent rolling element loads. A calculation example shows the feasibility of the proposed method.
基金Projects(51375222,51175242)supported by the National Natural Science Foundation of China
文摘To decrease breakdown time and improve machine operation reliability,accurate residual useful life(RUL) prediction has been playing a critical role in condition based monitoring.A data fusion method was proposed to achieve online RUL prediction of slewing bearings,which consisted of a reliability based RUL prediction model and a data driven failure rate(FR) estimation model.Firstly,an RUL prediction model was developed based on modified Weibull distribution to build the relationship between RUL and FR.Secondly,principal component analysis(PCA) was introduced to process multi-dimensional life-cycle vibration signals,and continuous squared prediction error(CSPE) and its time-domain features were employed as equipment performance degradation features.Afterwards,an FR estimation model was established on basis of the degradation features and relevant FRs using simplified fuzzy adaptive resonance theory map(SFAM) neural network.Consequently,real-time FR of equipment can be obtained through FR estimation model,and then accurate RUL can be calculated through the RUL prediction model.Results of a slewing bearing life test show that CSPE is an effective indicator of performance degradation process of slewing bearings,and that by combining actual load condition and real-time monitored data,the calculation time is reduced by 87.3%and the accuracy is increased by 0.11%,which provides a potential for online RUL prediction of slewing bearings and other various machineries.
文摘风电机组的偏航轴承和变桨轴承、航天发射塔架的回转支承轴承、起重机和挖掘机的转盘轴承等,都具有低速往复运转的特点。低速往复运转轴承的故障诊断极具挑战:低速工况下损伤接触的冲击力小,损伤冲击信号弱;减速换向冲击信号对故障冲击信号的干扰大;覆盖多个往复运转行程的长信号不具有周期性,等等。为了解决上述问题,提出一种基于调制信号双谱(Modulation Signal Bispectrum,MSB)切片总体平均的低速往复运转轴承故障诊断方法。首先,利用转速跟踪过零点对振动信号进行信号重采样处理,并依据编码器信号从重采样信号中分离出单个行程的短信号集合;然后,对每一个短信号进行MSB分析,生成MSB的载波切片谱,根据载波切片谱寻找最优载波频率及其对应的调制信号切片谱;最后,对短信号集合的MSB调制信号切片谱进行总体平均,生成切片谱总体平均特征。故障试验数据验证结果表明,MSB切片总体平均特征能够有效诊断低速往复运转轴承的故障。
文摘内齿式回转支承兼有滚动轴承的回转支承特点和齿轮啮合传动特点,在联合载荷作用下其动态性能的影响因素众多,容易出现轮齿磨损或断齿、套圈滚道磨损和运行精度变差等问题。综合考虑钢球与内外套圈滚道、保持架兜孔的动态接触作用及内齿圈轮齿间的啮合传动作用,建立了内齿式回转支承参数化多体接触动力学模型。分析了沟道曲率半径、保持架兜孔孔径、初始接触角和轮齿变位系数等关键设计参数对回转支承齿轮啮合力、1号钢球与N1滚道的接触力、内齿圈质心轴向和径向振动位移的影响规律。在此基础上,采用试验设计(design of experiment,DOE)方法,对内齿式回转支承的关键设计参数进行全因子试验设计及计算,获得了多参数影响下回转支承的动态性能。结合线性加权法,运用统一量纲法和权系数法构造新的多目标优化函数,提出了回转支承动态性能的多变量多目标优化设计方法,得到回转支承的轮齿啮合力下降了49.27%,1号钢球与N1滚道的接触力下降了29.6%,内齿圈质心轴向振动位移减小了5.41%,内齿圈质心径向位移减小了15.88%,回转支承的性能得到了优化。研究结果为回转支承的动态设计提供了参考。
基金supported by the National Natural Science Foundation of China(No.60876023)
文摘To drive the backplane of a liquid crystal display device and achieve different kinds of grey levels, a high-slew-rate operational amplifier with constant-gin input stage is presented. A Zener-diode structure is inserted between the tails of the complementary input pairs to keep the grn of the input stage constant. A novel slew rate enhancement circuit is implemented to achieve a very high slew rate. The chip has been implemented in a 0.5μm CMOS process and the chip area of the operational amplifier circuit is 0.11 mm^2. The testing results indicate that in the 5-8 V input range, the maximum gm fluctuation is only 4.2%. The result exhibits a high slew rate of 111 V/μs and 102 V/μs for the rising and falling edges under a 20 pF capacitance load, and the low frequency gain is up to 109 dB with a phase margin of 70 ℃.
基金Project supported by the National Natural Science Foundation of China(Nos.61401137,61404043,61674049)
文摘An ultra-low power output-capacitorless low-dropout(LDO) regulator with a slew-rate-enhanced(SRE)circuit is introduced. The increased slew rate is achieved by sensing the transient output voltage of the LDO and then charging(or discharging) the gate capacitor quickly. In addition, a buffer with ultra-low output impedance is presented to improve line and load regulations. This design is fabricated by SMIC 0.18 μm CMOS technology. Experimental results show that, the proposed LDO regulator only consumes an ultra-low quiescent current of 1.2 μA.The output current range is from 10 μA to 200 m A and the corresponding variation of output voltage is less than 40 m V. Moreover, the measured line regulation and load regulation are 15.38 m V/V and 0.4 m V/m A respectively.