In this paper, a hybrid control strategy for a matrix converter fed wind energy conversion system is presented. Since the wind speed may vary, output parameters like power, frequency and voltage may fluctuate. Hence i...In this paper, a hybrid control strategy for a matrix converter fed wind energy conversion system is presented. Since the wind speed may vary, output parameters like power, frequency and voltage may fluctuate. Hence it is necessary to design a system that regulates output parameters, such as voltage and frequency, and thereby provides a constant voltage and frequency output from the wind energy conversion system. Matrix converter is used in the proposed solution as the main power conditioner as a more efficient alternative when compared to traditional back-back converter structure. To control the output voltage, a vector modulation based refined control structure is used. A power tracker is included to maximize the mechanical output power of the turbine. Over current protection and clamp circuit input protection have been introduced to protect the system from over current. It reduces the spikes generated at the output of the converter. The designed system is capable of supplying an output voltage of constant frequency and amplitude within the expected ranges of input during the operation. The matrix converter control using direct modulation method, modified Venturini modulation method and vector modulation method was simulated, the results were compared and it was inferred that vector modulation method was superior to the other two methods. With the proposed technique, voltage transfer ratio and harmonic profile have been improved compared to the other two modulation techniques. The behaviour of the system is corroborated by MATLAB Simulink, and hardware is realized using an FPGA controller. Experimental results are found to be matching with the simulation results.展开更多
A novel low-temperature alkaline smelting process is proposed to convert and separate amphoteric metals in crushed metal enrichment originated from waste printed circuit boards. The central composite design was used t...A novel low-temperature alkaline smelting process is proposed to convert and separate amphoteric metals in crushed metal enrichment originated from waste printed circuit boards. The central composite design was used to optimize the operating parameters,in which mass ratio of Na OH-to-CME, smelting temperature and smelting time were chosen as the variables, and the conversions of amphoteric metals tin, lead, aluminum and zinc were response parameters. Second-order polynomial models of high significance and3 D response surface plots were constructed to show the relationship between the responses and the variables. Optimum area of80%-85% Pb conversion and over 95% Sn conversion was obtained by the overlaid contours at mass ratio of Na OH-to-CME of4.5-5.0, smelting temperature of 653-723 K, smelting time of 90-120 min. The models were validated experimentally in the optimum area, and the results demonstrate that these models are reliable and accurate in predicting the smelting process.展开更多
Through theoretical analyses of the Shockley equation and the difference between a practical P-N junction and its ideal model, the mathematical models of P-N junction and solar cells had been obtained. With Matlab sof...Through theoretical analyses of the Shockley equation and the difference between a practical P-N junction and its ideal model, the mathematical models of P-N junction and solar cells had been obtained. With Matlab software, the V-I characteristics of diodes and solar cells were simulated, and a computer simulation model of the solar cells based on P-N junction was also established. Based on the simulation model, the influences of solar cell’s internal resistances on open-circuit voltage and short-circuit current under certain illumination were numerically analyzed and solved. The simulation results showed that the equivalent series resistance and shunt resistance could strongly affect the V-I characteristics of solar cell, but their influence styles were different.展开更多
As the scaling down of Si devices in the range less than few nm has been expedited up to a physical limit of Si,low dimensional materials have been regarded as one of next generation semiconductors.Among a variety of ...As the scaling down of Si devices in the range less than few nm has been expedited up to a physical limit of Si,low dimensional materials have been regarded as one of next generation semiconductors.Among a variety of applications,studies on photodetectors have been actively investigated with their novel optical properties as well as astonishing electrical properties.However,most of research has focused on single device-type photodetector(i.e.,photo-diode or photo-transistor).Contrary to common photodetector,light-to-frequency circuits(LFCs)are based on frequency reading with photosensitive ring oscillators,which has better noise immunity and reduced system complexity,thus,can be utilized to novel application even in internet of things(loT)and bio&medical fields.In this review,low dimensional materials based circuit level photodetectors,which are core elements as the form of either inverters or ring oscillators for demonstration of LFCs,are introduced.Along with the introduction of low dimensional materials and their optical properties for optoelectronics,a fundamental concept for LFCs is specifically described.Thereafter,research progress on low dimensional material based photosensitive inverters is addressed according to the types of devices.Furthermore,as one of practical method for the improvement of photodetector performance,molecular doping technology is presented.Lastly,complete system of LFCs and its digitization for demonstration of production level,and potential application in the respective four aspects,(i)medical SpO_(2) detection,(ii)biological fluidic system,(iii)auto-lighting in agriculture,and(iv)optical feedback and sensing systems,are presented as systematic way to address the envisioned practical applications for the future displays including virtual reality and augmented reality,and others.As a remark,LFCs based on low dimensional semiconductors are expected to be one of core components in trillion’s sensor area.展开更多
文摘In this paper, a hybrid control strategy for a matrix converter fed wind energy conversion system is presented. Since the wind speed may vary, output parameters like power, frequency and voltage may fluctuate. Hence it is necessary to design a system that regulates output parameters, such as voltage and frequency, and thereby provides a constant voltage and frequency output from the wind energy conversion system. Matrix converter is used in the proposed solution as the main power conditioner as a more efficient alternative when compared to traditional back-back converter structure. To control the output voltage, a vector modulation based refined control structure is used. A power tracker is included to maximize the mechanical output power of the turbine. Over current protection and clamp circuit input protection have been introduced to protect the system from over current. It reduces the spikes generated at the output of the converter. The designed system is capable of supplying an output voltage of constant frequency and amplitude within the expected ranges of input during the operation. The matrix converter control using direct modulation method, modified Venturini modulation method and vector modulation method was simulated, the results were compared and it was inferred that vector modulation method was superior to the other two methods. With the proposed technique, voltage transfer ratio and harmonic profile have been improved compared to the other two modulation techniques. The behaviour of the system is corroborated by MATLAB Simulink, and hardware is realized using an FPGA controller. Experimental results are found to be matching with the simulation results.
基金Projects(51074190,51234009)supported by the National Natural Science Foundation of ChinaProject(2014DFA90520)supported by International Cooperation Program of Ministry of Science of ChinaProject(20110162110049)supported by the Doctoral Scientific Fund Project of the Ministry of Education of China
文摘A novel low-temperature alkaline smelting process is proposed to convert and separate amphoteric metals in crushed metal enrichment originated from waste printed circuit boards. The central composite design was used to optimize the operating parameters,in which mass ratio of Na OH-to-CME, smelting temperature and smelting time were chosen as the variables, and the conversions of amphoteric metals tin, lead, aluminum and zinc were response parameters. Second-order polynomial models of high significance and3 D response surface plots were constructed to show the relationship between the responses and the variables. Optimum area of80%-85% Pb conversion and over 95% Sn conversion was obtained by the overlaid contours at mass ratio of Na OH-to-CME of4.5-5.0, smelting temperature of 653-723 K, smelting time of 90-120 min. The models were validated experimentally in the optimum area, and the results demonstrate that these models are reliable and accurate in predicting the smelting process.
文摘Through theoretical analyses of the Shockley equation and the difference between a practical P-N junction and its ideal model, the mathematical models of P-N junction and solar cells had been obtained. With Matlab software, the V-I characteristics of diodes and solar cells were simulated, and a computer simulation model of the solar cells based on P-N junction was also established. Based on the simulation model, the influences of solar cell’s internal resistances on open-circuit voltage and short-circuit current under certain illumination were numerically analyzed and solved. The simulation results showed that the equivalent series resistance and shunt resistance could strongly affect the V-I characteristics of solar cell, but their influence styles were different.
基金supported by the Incheon National University Research Grant(2018-0100)in 2018,Incheon,Republic of Korea.
文摘As the scaling down of Si devices in the range less than few nm has been expedited up to a physical limit of Si,low dimensional materials have been regarded as one of next generation semiconductors.Among a variety of applications,studies on photodetectors have been actively investigated with their novel optical properties as well as astonishing electrical properties.However,most of research has focused on single device-type photodetector(i.e.,photo-diode or photo-transistor).Contrary to common photodetector,light-to-frequency circuits(LFCs)are based on frequency reading with photosensitive ring oscillators,which has better noise immunity and reduced system complexity,thus,can be utilized to novel application even in internet of things(loT)and bio&medical fields.In this review,low dimensional materials based circuit level photodetectors,which are core elements as the form of either inverters or ring oscillators for demonstration of LFCs,are introduced.Along with the introduction of low dimensional materials and their optical properties for optoelectronics,a fundamental concept for LFCs is specifically described.Thereafter,research progress on low dimensional material based photosensitive inverters is addressed according to the types of devices.Furthermore,as one of practical method for the improvement of photodetector performance,molecular doping technology is presented.Lastly,complete system of LFCs and its digitization for demonstration of production level,and potential application in the respective four aspects,(i)medical SpO_(2) detection,(ii)biological fluidic system,(iii)auto-lighting in agriculture,and(iv)optical feedback and sensing systems,are presented as systematic way to address the envisioned practical applications for the future displays including virtual reality and augmented reality,and others.As a remark,LFCs based on low dimensional semiconductors are expected to be one of core components in trillion’s sensor area.
