Integrated Ultrasonic Transducers (IUTs) have been developed for high-temperature nondestructive evaluation applications. In many field, it would be helpful if a pipe covered by a protective layer of about 10 cm thick...Integrated Ultrasonic Transducers (IUTs) have been developed for high-temperature nondestructive evaluation applications. In many field, it would be helpful if a pipe covered by a protective layer of about 10 cm thickness, which is under operation at several hundred Celsius, could be inspected from above the protective layer by an IUT. As a first step toward achieving the inspection of such a pipeline, an induction-based method using coils is presented together with IUTs. This study focuses on the effects of the separation distance (liftoff) between the coils on the ultrasonic signal strength and bandwidth of the IUTs. Ultrasonic signals were generated and received by the IUTs on a steel plate with a sufficient strength for thickness measurements when the liftoff was 20 cm. It was also shown that a ferrite disc together with the coils enhanced the received signal strength even when the liftoff was over 10 cm.展开更多
A novel magnetic integrated controllable reactor of transformer type(CRT)has the advantages of simple structure,flexible assembly,convenient maintenance and practicability.To analyze its operation characteristics accu...A novel magnetic integrated controllable reactor of transformer type(CRT)has the advantages of simple structure,flexible assembly,convenient maintenance and practicability.To analyze its operation characteristics accurately,we establish corresponding equivalent mathematical model considering magnetic leakage based on magnetic circuit and circuit dualistic transformation method.The distribution of magnetic leakage field of each winding is analyzed qualitatively,and the analytical calculation formulas of magnetizing inductance and leakage inductance of each winding are derived.Based on this,the analytical calculation formulas of short-circuit impedance and winding current of CRT under different working conditions are derived.The field-circuit coupling finite element model of the magnetic integrated CRT is established to simulate the current of each winding under different working conditions.The results show that the analytical calculation results of each winding current have good consistency with the finite element calculation results,indicating the validity of CRT equivalent mathematical model and correctness of the analytical formulas of leakage inductance,short-circuit impedance and winding current of CRT.The working winding current of CRT is increasing gradually with the operation of control winding in turn to realise the transition of CRT compensation capacity from zero to a rated value.展开更多
Induction motor is the most sought after motor in the industry for excellent performance characteristics and robustness. Developments in the Power Electronic circuitry have revolutionised the induction motor industry ...Induction motor is the most sought after motor in the industry for excellent performance characteristics and robustness. Developments in the Power Electronic circuitry have revolutionised the induction motor industry leading to the developments in various control strategies and circuits for motor control. Direct Torque Control (DTC) is one of the excellent control strategies preferred by industries for controlling the torque and flux in an induction machine. The main drawback of DTC is the presence of torque ripple which is slightly more than the acceptable limit. There are various parameters that introduce ripples in the electromagnetic torque, one of them being the type of inverter circuit. There are various types of inverter circuits available and the effect of each of them in the production of torque ripple is different. This work is an attempt to identify the influence of various multilevel inverter circuits on the torque ripple level and to propose the best inverter circuit. The influence of multilevel diode clamped inverter and cascaded H bridge inverter circuits on torque ripple minimization, is analysed using simulation studies for identifying the most suitable multilevel inverter circuit which gives minimum torque ripple. The results obtained from the simulation studies are validated by hardware implementation on 0.75 kW induction motor.展开更多
目前IC芯片呈现高速、高密度、低压大电流发展趋势,电源完整性(PI)问题日益突出,不合理的电源完整性设计将导致去耦电容器数量增多且达不到理想效果。文章针对电源完整性核心问题,即电源分配网络(power distribution network,PDN)进行研...目前IC芯片呈现高速、高密度、低压大电流发展趋势,电源完整性(PI)问题日益突出,不合理的电源完整性设计将导致去耦电容器数量增多且达不到理想效果。文章针对电源完整性核心问题,即电源分配网络(power distribution network,PDN)进行研究,提出一种基于目标阻抗的去耦电容器选择和安装的设计方法。首先从全频段PDN组成出发,分析电路板级电容等效模型、不同电容器组合去耦效果及优化方法;接着,针对电容器安装过程中引入的寄生电感对电容器去耦效果的影响,重点分析了电容器安装走线长度、宽度及过孔距离对回路寄生电感的影响;最后结合实际单板进行了PDN阻抗仿真优化。结果显示,优化后的PDN可以满足目标阻抗要求,减少了15%的电容器数量,降低了成本;同时改善了电源的完整性,提高了单板可靠性。展开更多
文摘Integrated Ultrasonic Transducers (IUTs) have been developed for high-temperature nondestructive evaluation applications. In many field, it would be helpful if a pipe covered by a protective layer of about 10 cm thickness, which is under operation at several hundred Celsius, could be inspected from above the protective layer by an IUT. As a first step toward achieving the inspection of such a pipeline, an induction-based method using coils is presented together with IUTs. This study focuses on the effects of the separation distance (liftoff) between the coils on the ultrasonic signal strength and bandwidth of the IUTs. Ultrasonic signals were generated and received by the IUTs on a steel plate with a sufficient strength for thickness measurements when the liftoff was 20 cm. It was also shown that a ferrite disc together with the coils enhanced the received signal strength even when the liftoff was over 10 cm.
基金Weinan Science and Technology Plan Project(No.2020ZDYF-JCYJ-177)General Special Scientific Research Projects of Education Department of Shaanxi Provincial Government(No.21JK0582)+2 种基金Young and Middle-aged Scientific and Technological Talents Project of Shaanxi Railway Institute(No.KJRC202001)Scientific Research Fund Project of Shaanxi Railway Institute(No.KY2021-34)Science and Technology Innovation Team of Shaanxi Railway Institute(No.KJTD201901)。
文摘A novel magnetic integrated controllable reactor of transformer type(CRT)has the advantages of simple structure,flexible assembly,convenient maintenance and practicability.To analyze its operation characteristics accurately,we establish corresponding equivalent mathematical model considering magnetic leakage based on magnetic circuit and circuit dualistic transformation method.The distribution of magnetic leakage field of each winding is analyzed qualitatively,and the analytical calculation formulas of magnetizing inductance and leakage inductance of each winding are derived.Based on this,the analytical calculation formulas of short-circuit impedance and winding current of CRT under different working conditions are derived.The field-circuit coupling finite element model of the magnetic integrated CRT is established to simulate the current of each winding under different working conditions.The results show that the analytical calculation results of each winding current have good consistency with the finite element calculation results,indicating the validity of CRT equivalent mathematical model and correctness of the analytical formulas of leakage inductance,short-circuit impedance and winding current of CRT.The working winding current of CRT is increasing gradually with the operation of control winding in turn to realise the transition of CRT compensation capacity from zero to a rated value.
文摘Induction motor is the most sought after motor in the industry for excellent performance characteristics and robustness. Developments in the Power Electronic circuitry have revolutionised the induction motor industry leading to the developments in various control strategies and circuits for motor control. Direct Torque Control (DTC) is one of the excellent control strategies preferred by industries for controlling the torque and flux in an induction machine. The main drawback of DTC is the presence of torque ripple which is slightly more than the acceptable limit. There are various parameters that introduce ripples in the electromagnetic torque, one of them being the type of inverter circuit. There are various types of inverter circuits available and the effect of each of them in the production of torque ripple is different. This work is an attempt to identify the influence of various multilevel inverter circuits on the torque ripple level and to propose the best inverter circuit. The influence of multilevel diode clamped inverter and cascaded H bridge inverter circuits on torque ripple minimization, is analysed using simulation studies for identifying the most suitable multilevel inverter circuit which gives minimum torque ripple. The results obtained from the simulation studies are validated by hardware implementation on 0.75 kW induction motor.
文摘目前IC芯片呈现高速、高密度、低压大电流发展趋势,电源完整性(PI)问题日益突出,不合理的电源完整性设计将导致去耦电容器数量增多且达不到理想效果。文章针对电源完整性核心问题,即电源分配网络(power distribution network,PDN)进行研究,提出一种基于目标阻抗的去耦电容器选择和安装的设计方法。首先从全频段PDN组成出发,分析电路板级电容等效模型、不同电容器组合去耦效果及优化方法;接着,针对电容器安装过程中引入的寄生电感对电容器去耦效果的影响,重点分析了电容器安装走线长度、宽度及过孔距离对回路寄生电感的影响;最后结合实际单板进行了PDN阻抗仿真优化。结果显示,优化后的PDN可以满足目标阻抗要求,减少了15%的电容器数量,降低了成本;同时改善了电源的完整性,提高了单板可靠性。
