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
We present a theoretical study of electromagnetically induced transparency （EIT） in a superconducting quantum circuit with a tunable V-shaped energy spectrum derived from two superconducting Josephson charge qubits ...We present a theoretical study of electromagnetically induced transparency （EIT） in a superconducting quantum circuit with a tunable V-shaped energy spectrum derived from two superconducting Josephson charge qubits coupled with each other through a superconducting quantum interference device. Using the density matrix formalism and the steady-state approximation, we obtain the analytical expressions of the first-order matrix element associated with the absorption and dispersion of the probe field for two different V-type schemes. Our results show that, for this superconducting quantum system, it is possible to realize a remarkable phenomenon that dynamic conversion between EIT and EIT with amplification without population inversion. Such a unique optical feature has potential applications in quantum optical devices and quantum information processing.展开更多
为了更精确预测基于0.18μm工艺的40 V NLDMOS器件实际应用条件下的热载流子寿命,介绍了一种通过可靠性测试和计算机辅助数学解析相结合的热载流子可靠性寿命预计方法。该方法基于实际直流状态下的热载流注入测试数据,结合TCAD仿真,对...为了更精确预测基于0.18μm工艺的40 V NLDMOS器件实际应用条件下的热载流子寿命,介绍了一种通过可靠性测试和计算机辅助数学解析相结合的热载流子可靠性寿命预计方法。该方法基于实际直流状态下的热载流注入测试数据,结合TCAD仿真,对测试结果进行了线性函数、多次函数、幂函数、指数函数及Dreesen R函数拟合;通过分析当前业界LDMOS器件的热载流子注入测试主流模型预测精度的局限性,找出了最优热载流子模型,提出了适合Python语言编程的改进型Dreesen R模型;通过数学解析推导方法以及基于Python语言的计算机辅助编程计算,得出了栅极以及漏极全工作电压范围内的热载流子参数退化曲线;通过模拟工作波形不同上升沿及下降沿的函数曲线、上升及下降时间以及不同占空比,得出随着时间变化的交直流转换因子曲线。最终新的测试项目可以通过不同电压下的直流状态下测试结果以及已经得到的交直流转换因子曲线,来直接获取工作场景交流状态的热载流子寿命。该评估方法解决了采用直流状态下的测试来解决现场复杂应用波形的热载流子寿命评估难题,较大节省了测试时间,提高了寿命预测精度。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Project supported by the National Natural Science Foundation of China(Grant No.11274132)the Natural Science Foundation of Hubei Province,China
文摘We present a theoretical study of electromagnetically induced transparency （EIT） in a superconducting quantum circuit with a tunable V-shaped energy spectrum derived from two superconducting Josephson charge qubits coupled with each other through a superconducting quantum interference device. Using the density matrix formalism and the steady-state approximation, we obtain the analytical expressions of the first-order matrix element associated with the absorption and dispersion of the probe field for two different V-type schemes. Our results show that, for this superconducting quantum system, it is possible to realize a remarkable phenomenon that dynamic conversion between EIT and EIT with amplification without population inversion. Such a unique optical feature has potential applications in quantum optical devices and quantum information processing.
文摘为了更精确预测基于0.18μm工艺的40 V NLDMOS器件实际应用条件下的热载流子寿命,介绍了一种通过可靠性测试和计算机辅助数学解析相结合的热载流子可靠性寿命预计方法。该方法基于实际直流状态下的热载流注入测试数据,结合TCAD仿真,对测试结果进行了线性函数、多次函数、幂函数、指数函数及Dreesen R函数拟合;通过分析当前业界LDMOS器件的热载流子注入测试主流模型预测精度的局限性,找出了最优热载流子模型,提出了适合Python语言编程的改进型Dreesen R模型;通过数学解析推导方法以及基于Python语言的计算机辅助编程计算,得出了栅极以及漏极全工作电压范围内的热载流子参数退化曲线;通过模拟工作波形不同上升沿及下降沿的函数曲线、上升及下降时间以及不同占空比,得出随着时间变化的交直流转换因子曲线。最终新的测试项目可以通过不同电压下的直流状态下测试结果以及已经得到的交直流转换因子曲线,来直接获取工作场景交流状态的热载流子寿命。该评估方法解决了采用直流状态下的测试来解决现场复杂应用波形的热载流子寿命评估难题,较大节省了测试时间,提高了寿命预测精度。
