Novel Uncontrolled 20-Pulse AC-DC Converters to Reduce Harmonics of the Excitation Current

2021 ◽  
Author(s):  
Md. Shoaib Akther ◽  
Abdullah Al Shakil ◽  
S.M. Shams-E-Mukit ◽  
Md. Rasheduzzaman Saidy
Keyword(s):  
Excitation Current

White LED Energy-Efficient Drive Technology Based on Luminescent Relaxation Properties

2011 ◽  
Vol 347-353 ◽  
pp. 1494-1497
Author(s):  
Yi Zhang ◽  
Jing Han ◽  
Lian Fa Bai ◽  
Qian Chen ◽  
Guo Hua Gu
Keyword(s):  
High Performance ◽  
Leading Edge ◽  
Pulse Excitation ◽  
White Led ◽  
Excitation Current ◽  
Effective Utilization ◽  
Relaxation Properties ◽  
Attenuation Characteristic ◽  
Driving Model ◽  
Core Idea

This study is a high-performance, energy-saving drive technology for all pcLED based on luminescence relaxation properties. Its core idea is coordination between power driving model and pcLED relaxation properties. Compared with relative small pulse width, forward pulse excitation current can make pcLED luminescence tends to its saturation peak rapidly during this period because of the steep leading edge of relaxation properties. And in the vacant period of forward pulse excitation current, because of the chosen of best duty cycle, it will be the most effective utilization for luminescence afterglow which has slow attenuation characteristic.

Development of the Meridian-Visualizing System that Superimposes a Bio-signal upon a Body Image

2004 ◽  
Vol 32 (04) ◽  
pp. 631-640
Author(s):  
Dong-Myong Jeong ◽  
Yong-Heum Lee ◽  
Myeong Soo Lee
Keyword(s):  
Body Image ◽  
Skin Resistance ◽  
The Body ◽  
Acupuncture Points ◽  
Identification System ◽  
Electrode Position ◽  
Excitation Current ◽  
System A ◽  
Dc Excitation ◽  
Single Power

The precise selection and the identification of acupuncture points are essential for the diagnosis and treatment of patients in Oriental medicine. In this study, we have developed a meridian identification system using Single-Power Alternating Current (SPAC), which discriminates between true acupoints and non-acupoints. The SPAC system is not affected by skin resistance or pressure and is more accurate than the existing meridian location system, which uses direct current (DC) excitation current. The accuracy of the meridian location is ensured with the SPAC system because it has the highest sensitivity and the lowest effect on the human body. A microprocessor is used to enhance reliability and increase the accuracy of the SPAC measurements. Current distribution is displayed using an image that overlays the measured skin current on the body image. The positions of the acupoints are then displayed on the body image. This method visualizes the meridian by measuring skin current with an improved electrode using the acupoint discrimination system. A computer display shows the transmitted current as a color related to the electrode position. We demonstrated that by changing the point of measurement on the skin and tracing the electrode on the screen, it is possible to visualize acupoints and meridian phenomena using the color display.

Magnetostrictive Methods of Detecting Torque from Case-Hardened Steel Shafts

1994 ◽  
Vol 360 ◽  
Author(s):  
Ichiro Sasada
Keyword(s):  
Excitation Frequency ◽  
Total Power ◽  
Optimum Operating ◽  
Torque Sensor ◽  
Excitation Current ◽  
Optimum Operating Condition ◽  
Operating Condition ◽  
Nickel Chromium ◽  
Low Profile ◽  
Molybdenum Steel

AbstractThis paper begins with a review of the current problems associated with the application of conventional magnetic-head-type shaft torque sensors. These sensors were first proposedin 1954. Newly developed low-profile magnetic heads for torque sensors which address the problems of the older type of sensors are then presented. The torque sensor which uses the lowprofile pick-up heads is described in detail. Experimental results showing the basicperformance of the torque sensor with carburized nickel chromium molybdenum steel shafts (SNCM 420 in JIS) are then described. In this combination of the heads and the shaft, thehysteresis of the inputoutput relationship is generally small and shows that the direction of traversal around the hysteresis loop changes as the amplitude of the excitation current changes. It is shown that an optimum operating condition exists for the torque sensorin which the hysteresis achieves a minimum value yet the sensitivity remains high. In a particular combination studied in this paper, the optimum excitation current was 0.3 A at the excitation frequency 60 kHz, where the total power loss at the pick-up heads was 0.37W. Under this operating condition, the hysteresis was extremely small, and the linearity was better than 0.6%.

Development of a boring bar with magneto rheological fluid damping and assessment of its dynamic characteristics

2017 ◽  
Vol 24 (14) ◽  
pp. 3094-3106 ◽  
Author(s):  
CV Biju ◽  
MS Shunmugam
Keyword(s):  
Modal Parameters ◽  
Model Parameters ◽  
Excitation Current ◽  
Mr Fluid ◽  
Boring Bar ◽  
Chatter Suppression ◽  
Damping Characteristics ◽  
Fluid Damping ◽  
Variable Damping ◽  
Magneto Rheological

The boring operation is prone to chatter as the boring bar is slender and has an overhang. For chatter suppression, passive, semi-active or active control methods can be employed. In the present work, a boring bar has been specially designed to transfer vibration to a cantilever bar surrounded by magneto rheological (MR) fluid. The MR fluid when exposed to electromagnetic flux changes its rheological property within a certain range. Thus, the boring bar is able to exhibit variable damping characteristics by changing the excitation current. The modal parameters are experimentally obtained through an impact test and a shaker test. The variation of modal parameters with excitation current is discussed. A stability lobe diagram is also developed from the model parameters, showing safe and unsafe regions for operation. The semi-active boring bar developed in the present work can be used for the suppression of chatter during the boring operation.

scholarly journals Analysis of Nonlinear Dynamic Characteristics of a Mechanical-Electromagnetic Vibration System with Rubbing

2019 ◽  
Vol 9 (21) ◽  
pp. 4612
Author(s):  
Yiming Li ◽  
Zhilong Huang ◽  
He Li ◽  
Guiqiu Song
Keyword(s):  
Friction Coefficient ◽  
Dynamic Characteristics ◽  
Chaotic Motion ◽  
Nonlinear Dynamic ◽  
Response Amplitude ◽  
Jump Discontinuity ◽  
Excitation Current ◽  
Radial Stiffness ◽  
Chaotic Region ◽  
Coupling System

In this study, a rotor-bearing-runner system (RBRS) considering multiple nonlinear factors is established, and the complex nonlinear dynamic behavior of the coupling system is studied. The effects of excitation current, radial stiffness, and friction coefficient on dynamic characteristics are analyzed by numerical simulation. The research results show that the dynamic properties of the coupling system caused by different nonlinear factors are interactional. With the changes of different parameters, the RBRS presents multiple motion states, including periodic-n, quasi-periodic, and chaotic motion. The increase of the excitation current Ij has a certain inhibitory effect on the response amplitude of the system and makes the motion state of the system more complex, the chaotic motion wider, and the jump discontinuity enhanced. With the increase of radial stiffness kr, the motion complexity of the coupling system increases, the chaotic region increases, the response amplitude increases, and the vibration intensity increases. With the increase of the friction coefficient μ, the chaotic region increases first and decreases, the different motions alternate frequently, and the response amplitude gradually increases. This study can not only help to understand the dynamic characteristics of RBRS, but also help the stable operation of the generator set.

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