Metal-insulator-metal （MIM） capacitors with atomic-layer-deposited Al2O3 dielectric and reactively sputtered TaN electrodes in application to radio frequency integrated circuits have been characterized electrically....Metal-insulator-metal （MIM） capacitors with atomic-layer-deposited Al2O3 dielectric and reactively sputtered TaN electrodes in application to radio frequency integrated circuits have been characterized electrically. The capacitors exhibit a high density of about 6.05 fF/μm^2, a small leakage current of 4.8 × 10^-8 A/cm^2 at 3 V, a high breakdown electric field of 8.61 MV/cm as well as acceptable voltage coefficients of capacitance （VCCs） of 795 ppm/V2 and 268ppm/V at 1 MHz. The observed properties should be attributed to high-quality Al2O3 film and chemically stable TaN electrodes. Further, a logarithmically linear relationship between quadratic VCC and frequency is observed due to the change of relaxation time with carrier mobility in the dielectric. The conduction mechanism in the high field ranges is dominated by the Poole-Frenkel emission, and the leakage current in the low field ranges is likely to be associated with trap-assisted tunnelling. Meanwhile, the Al2O3 dielectric presents charge trapping under low voltage stresses, and defect generation under high voltage stresses, and it has a hard-breakdown performance.展开更多
When the circuit breaker cuts the electric current, an electric arc is created between its electrodes. The success or failure of breaking the electric current by the circuit breaker depends strongly on the physico-che...When the circuit breaker cuts the electric current, an electric arc is created between its electrodes. The success or failure of breaking the electric current by the circuit breaker depends strongly on the physico-chemical properties of the electric arc created, such as the composition of which depends on the material of the electrical contacts. In this work, we determine the equilibrium composition of the electric arc in the low voltage air circuit breaker with silver tin dioxide alloy contacts, in a temperature range from 500 K to 15,000 K and at atmospheric pressure. We use the Gibbs free energy minimization method and develop a computer code to determine the equilibrium composition of the created plasma. The analysis of the results obtained shows that O<sub>2</sub> particles with a dissociation energy of 5.114 eV, NO with a dissociation energy of 6.503 eV, and N<sub>2</sub> dissociation 9.756 eV dissociate around 3500 K, 5000 K, and 7500 K, respectively. We note that the electro-neutrality is established between the electrons and the cations: Ag<sup>+</sup> and NO<sup>+</sup>, for temperatures lower than 6500 K. For temperatures higher than 6500 K, the electro-neutrality is established between the electrons and the cations: N<sup>+</sup>, O<sup>+</sup>, and Ag<sup>+</sup>. The numerical density of the electrons increases when the proportion of the vapor of the electrical contacts increases in the mixture, in particular for temperatures lower than 11,000 K.展开更多
开关回路电阻是评价开关设备状态的重要参数之一,针对3/2接线方式变电站开关回路电阻在线评估问题,提出一种基于偏最小二乘法的在线计算方法。根据变电站开关电流数据和基尔霍夫定律,建立开关回路电阻的数学模型。为减小不同时刻电流工...开关回路电阻是评价开关设备状态的重要参数之一,针对3/2接线方式变电站开关回路电阻在线评估问题,提出一种基于偏最小二乘法的在线计算方法。根据变电站开关电流数据和基尔霍夫定律,建立开关回路电阻的数学模型。为减小不同时刻电流工况线性相关性带来的误差,采用偏最小二乘法求解开关回路电阻。最后,以采用3/2接线方式的某500 k V变电站为例,进行仿真计算。结果表明,采用偏最小二乘法能显著减小电流工况线性相关性带来的误差,相比于最小二乘法,精度更高。展开更多
针对3/2接线方式变电站开关设备回路电阻的在线计算问题,提出一种基于电流和有功功率测量的在线评估方法。利用基尔霍夫定律和焦耳定律建立开关设备回路电阻的数学模型,将计算开关设备回路电阻的问题转化为线性最优规划问题。在求解最...针对3/2接线方式变电站开关设备回路电阻的在线计算问题,提出一种基于电流和有功功率测量的在线评估方法。利用基尔霍夫定律和焦耳定律建立开关设备回路电阻的数学模型,将计算开关设备回路电阻的问题转化为线性最优规划问题。在求解最优规划问题的过程中,采用遗传算法可大大减少求解规划问题的难度,避免最终结果陷入局部最优解。以采用3/2接线方式的某500 k V变电站的实测电流和有功功率数据进行仿真计算,验证该方法的有效性。展开更多
针对3/2接线方式开关设备回路电阻的在线评估问题,提出了一种基于电流测量的在线评估方法。利用基尔霍夫定律和欧姆定律建立3/2接线方式开关站开关设备的数学模型,将求解开关设备电阻的问题转化为求解非齐次线性方程组的问题。在求解过...针对3/2接线方式开关设备回路电阻的在线评估问题,提出了一种基于电流测量的在线评估方法。利用基尔霍夫定律和欧姆定律建立3/2接线方式开关站开关设备的数学模型,将求解开关设备电阻的问题转化为求解非齐次线性方程组的问题。在求解过程中,对于存在相关性的方程组系数矩阵,利用条件数的大小作为选取方程组系数矩阵组合的判断依据对数学模型进行优化可有效提高求解精度,从而提高评估的质量。以某500 k V开关站的实测电流数据进行仿真计算,验证了本方法的有效性。展开更多
A 3D Magnetohydrodynamics （MHD） arc model in conjunction with an arc move- ment model is applied to simulate the arc rotation as well as to solve its effect on the pressure in an auto-expansion circuit breaker. The ...A 3D Magnetohydrodynamics （MHD） arc model in conjunction with an arc move- ment model is applied to simulate the arc rotation as well as to solve its effect on the pressure in an auto-expansion circuit breaker. The rotation of the arc driven by an external electromagnetic force is simulated in the case with 200 kA of the short circuit current and 16 ms of arc duration. The arc rotating process and the speed of arc rotation have been obtained in the simulation. A comparison of the pressure in the expansion volume with and without an external magnetic field has been carried out based on the calculation results of two cases. The results of the simulation reveal that the arc rotation, which causes more energy exchange between the arc and its sur- rounding gas, can evidently bring about the pressurization in the expansion volume, which would contribute to more effective arc quenching at current zero and further reducing operation power.展开更多
基金Project supported by the National Natural Science Foundation of China （Grant No 90607023）, Shanghai Pujiang Program （Grant No 05PJ14017）, SRF for R0CS, SEM, and the Micro/Nano-electronics Science and Technology Innovation Platform （985） and the Ministry of Education of China in the International Research Training Group ＂Materials and Concepts for Advanced Interconnects
文摘Metal-insulator-metal （MIM） capacitors with atomic-layer-deposited Al2O3 dielectric and reactively sputtered TaN electrodes in application to radio frequency integrated circuits have been characterized electrically. The capacitors exhibit a high density of about 6.05 fF/μm^2, a small leakage current of 4.8 × 10^-8 A/cm^2 at 3 V, a high breakdown electric field of 8.61 MV/cm as well as acceptable voltage coefficients of capacitance （VCCs） of 795 ppm/V2 and 268ppm/V at 1 MHz. The observed properties should be attributed to high-quality Al2O3 film and chemically stable TaN electrodes. Further, a logarithmically linear relationship between quadratic VCC and frequency is observed due to the change of relaxation time with carrier mobility in the dielectric. The conduction mechanism in the high field ranges is dominated by the Poole-Frenkel emission, and the leakage current in the low field ranges is likely to be associated with trap-assisted tunnelling. Meanwhile, the Al2O3 dielectric presents charge trapping under low voltage stresses, and defect generation under high voltage stresses, and it has a hard-breakdown performance.
文摘When the circuit breaker cuts the electric current, an electric arc is created between its electrodes. The success or failure of breaking the electric current by the circuit breaker depends strongly on the physico-chemical properties of the electric arc created, such as the composition of which depends on the material of the electrical contacts. In this work, we determine the equilibrium composition of the electric arc in the low voltage air circuit breaker with silver tin dioxide alloy contacts, in a temperature range from 500 K to 15,000 K and at atmospheric pressure. We use the Gibbs free energy minimization method and develop a computer code to determine the equilibrium composition of the created plasma. The analysis of the results obtained shows that O<sub>2</sub> particles with a dissociation energy of 5.114 eV, NO with a dissociation energy of 6.503 eV, and N<sub>2</sub> dissociation 9.756 eV dissociate around 3500 K, 5000 K, and 7500 K, respectively. We note that the electro-neutrality is established between the electrons and the cations: Ag<sup>+</sup> and NO<sup>+</sup>, for temperatures lower than 6500 K. For temperatures higher than 6500 K, the electro-neutrality is established between the electrons and the cations: N<sup>+</sup>, O<sup>+</sup>, and Ag<sup>+</sup>. The numerical density of the electrons increases when the proportion of the vapor of the electrical contacts increases in the mixture, in particular for temperatures lower than 11,000 K.
文摘开关回路电阻是评价开关设备状态的重要参数之一,针对3/2接线方式变电站开关回路电阻在线评估问题,提出一种基于偏最小二乘法的在线计算方法。根据变电站开关电流数据和基尔霍夫定律,建立开关回路电阻的数学模型。为减小不同时刻电流工况线性相关性带来的误差,采用偏最小二乘法求解开关回路电阻。最后,以采用3/2接线方式的某500 k V变电站为例,进行仿真计算。结果表明,采用偏最小二乘法能显著减小电流工况线性相关性带来的误差,相比于最小二乘法,精度更高。
文摘针对3/2接线方式变电站开关设备回路电阻的在线计算问题,提出一种基于电流和有功功率测量的在线评估方法。利用基尔霍夫定律和焦耳定律建立开关设备回路电阻的数学模型,将计算开关设备回路电阻的问题转化为线性最优规划问题。在求解最优规划问题的过程中,采用遗传算法可大大减少求解规划问题的难度,避免最终结果陷入局部最优解。以采用3/2接线方式的某500 k V变电站的实测电流和有功功率数据进行仿真计算,验证该方法的有效性。
文摘针对3/2接线方式开关设备回路电阻的在线评估问题,提出了一种基于电流测量的在线评估方法。利用基尔霍夫定律和欧姆定律建立3/2接线方式开关站开关设备的数学模型,将求解开关设备电阻的问题转化为求解非齐次线性方程组的问题。在求解过程中,对于存在相关性的方程组系数矩阵,利用条件数的大小作为选取方程组系数矩阵组合的判断依据对数学模型进行优化可有效提高求解精度,从而提高评估的质量。以某500 k V开关站的实测电流数据进行仿真计算,验证了本方法的有效性。
基金supported by National Natural Science Foundation of China (Nos.51177005 and 51477004)
文摘A 3D Magnetohydrodynamics （MHD） arc model in conjunction with an arc move- ment model is applied to simulate the arc rotation as well as to solve its effect on the pressure in an auto-expansion circuit breaker. The rotation of the arc driven by an external electromagnetic force is simulated in the case with 200 kA of the short circuit current and 16 ms of arc duration. The arc rotating process and the speed of arc rotation have been obtained in the simulation. A comparison of the pressure in the expansion volume with and without an external magnetic field has been carried out based on the calculation results of two cases. The results of the simulation reveal that the arc rotation, which causes more energy exchange between the arc and its sur- rounding gas, can evidently bring about the pressurization in the expansion volume, which would contribute to more effective arc quenching at current zero and further reducing operation power.
