A novel dual output phase-shift distribution transformer （ DOPSDT ） is proposed based on the electromagnetic filtering theory. First, its structural characteristics, winding connection mode and turn number ratio for...A novel dual output phase-shift distribution transformer （ DOPSDT ） is proposed based on the electromagnetic filtering theory. First, its structural characteristics, winding connection mode and turn number ratio for special phase shifting are investigated. Secondly, the balance formulation of harmonic magneto-motive forces is derived and the electromagnetic filtering principle of the DOPSDT is introduced. The harmonic mitigating performance under different nonlinear load conditions are also analyzed using the field-circuit coupled method, The analysis results show that the DOPSDT can mitigate the primary current distortion even under severe nonlinear load conditions. By applying the zero sequence flux cancellation and phase-shift techniques at their secondary windings, the DOPSDT can significantly reduce the 3rd, 5th, 7th, 9th, 15th, 17th and 19th harmonics within its secondary windings.展开更多
To reduce output voltage noise and improve dynamic response performance,this study designed a buck converter on the basis of secondary filters and adaptive voltage positioning(AVP).A hybrid control method was proposed...To reduce output voltage noise and improve dynamic response performance,this study designed a buck converter on the basis of secondary filters and adaptive voltage positioning(AVP).A hybrid control method was proposed for the compensation of the secondary filter.The introduction of a high-frequency feedback path,in addition to the traditional feedback path,effectively improved the influence of the secondary filter on the loop stability and direct current regulation performance.A small-signal model of the buck converter based on the proposed control method was derived,and the stability and selection of control parameters were analyzed.AVP is realized using an easy-to-implement and low-cost control method that was proposed to improve dynamic response performance by changing the low-frequency gain of the control loop and load regulation of the output voltage.The experimental results of the buck converter showed that the proposed method effectively reduced the output voltage noise by 50%and improved the dynamic response capability to meet the target requirements of mainstream electronic systems.展开更多
Scanning the absorption spectral line of water vapor through wavelength around 1368.597nm is successfully used to measure the value of micro-moisture content. The synchronous superposition average of original signal a...Scanning the absorption spectral line of water vapor through wavelength around 1368.597nm is successfully used to measure the value of micro-moisture content. The synchronous superposition average of original signal algorithm based on labview is innovated and applied to detecting weak spectrum absorption signal instead of low pass filter. Two data processing methods are used to get the concentration of water vapor in ppm： one is a general formula method which has newly deduced a general formula to calculate the concentration of gas with temperature and beam intensity ratio when the pressure is equal to or greater than 1 atm; the other is engineering calibration method which is proved to have high resolution and accuracy with the fitted curve of beam intensity ratio and concentration in ppm when the temperature changes form 258K to 305K and the pressure ranges from 1 atm to 5 atm.展开更多
基金The Program for Special Talent in Six Fields of Jiangsu Province (2011-ZBZZ-016)the Postdoctoral Science Foundation of Jiangsu Province (No. 0902038C)
文摘A novel dual output phase-shift distribution transformer （ DOPSDT ） is proposed based on the electromagnetic filtering theory. First, its structural characteristics, winding connection mode and turn number ratio for special phase shifting are investigated. Secondly, the balance formulation of harmonic magneto-motive forces is derived and the electromagnetic filtering principle of the DOPSDT is introduced. The harmonic mitigating performance under different nonlinear load conditions are also analyzed using the field-circuit coupled method, The analysis results show that the DOPSDT can mitigate the primary current distortion even under severe nonlinear load conditions. By applying the zero sequence flux cancellation and phase-shift techniques at their secondary windings, the DOPSDT can significantly reduce the 3rd, 5th, 7th, 9th, 15th, 17th and 19th harmonics within its secondary windings.
文摘To reduce output voltage noise and improve dynamic response performance,this study designed a buck converter on the basis of secondary filters and adaptive voltage positioning(AVP).A hybrid control method was proposed for the compensation of the secondary filter.The introduction of a high-frequency feedback path,in addition to the traditional feedback path,effectively improved the influence of the secondary filter on the loop stability and direct current regulation performance.A small-signal model of the buck converter based on the proposed control method was derived,and the stability and selection of control parameters were analyzed.AVP is realized using an easy-to-implement and low-cost control method that was proposed to improve dynamic response performance by changing the low-frequency gain of the control loop and load regulation of the output voltage.The experimental results of the buck converter showed that the proposed method effectively reduced the output voltage noise by 50%and improved the dynamic response capability to meet the target requirements of mainstream electronic systems.
基金This work was supported by Natural Science Foundation of China （60977058）, Science Fund for Distinguished Young Scholars of Shandong Province of China （JQ200819）, Research Award Fund for Outstanding Middle-aged＇ and Young Scientist of Shandong Province of China （2007BS08003）, Independent Innovation Foundation of Shandong University （IIFSDU2010JC002）.
文摘Scanning the absorption spectral line of water vapor through wavelength around 1368.597nm is successfully used to measure the value of micro-moisture content. The synchronous superposition average of original signal algorithm based on labview is innovated and applied to detecting weak spectrum absorption signal instead of low pass filter. Two data processing methods are used to get the concentration of water vapor in ppm： one is a general formula method which has newly deduced a general formula to calculate the concentration of gas with temperature and beam intensity ratio when the pressure is equal to or greater than 1 atm; the other is engineering calibration method which is proved to have high resolution and accuracy with the fitted curve of beam intensity ratio and concentration in ppm when the temperature changes form 258K to 305K and the pressure ranges from 1 atm to 5 atm.
