Firstly, relevant stress properties of millisecond level breaking process and microsecond level commutation process of hybrid HVDC circuit breaker are studied in detail on the basis of the analysis for the application...Firstly, relevant stress properties of millisecond level breaking process and microsecond level commutation process of hybrid HVDC circuit breaker are studied in detail on the basis of the analysis for the application environment and topological structure and operating principles of hybrid circuit breakers, and key stress parameters in transient state process of two time dimensions are extracted. The established digital simulation circuit for PSCAD/EMTDC device-level operation of the circuit breaker has verified the stress properties of millisecond level breaking process and microsecond level commutation process. Then, equivalent test method, circuits and parameters based on LC power supply are proposed on the basis of stress extraction. Finally, the results of implemented breaking tests for complete 200 kV circuit breaker, 100 kV and 50 kV circuit breaker units, as well as single power electronic module have verified the accuracy of the simulation circuit and mathematical analysis. The result of this paper can be a guide to electrical structure and test system design of hybrid HVDC circuit breaker.展开更多
为了解决软击穿导致的压控磁各向异性磁隧道结(voltage-controlled magnetic anisotropy magnetic tunnel junction,VCMA-MTJ)及其读电路性能下降的问题,在对VCMA-MTJ软击穿机理深入分析的基础上,修正了VCMA-MTJ的电学模型,设计了一种...为了解决软击穿导致的压控磁各向异性磁隧道结(voltage-controlled magnetic anisotropy magnetic tunnel junction,VCMA-MTJ)及其读电路性能下降的问题,在对VCMA-MTJ软击穿机理深入分析的基础上,修正了VCMA-MTJ的电学模型,设计了一种具有固定参考电阻的VCMA-MTJ读电路和一种具有参考电阻调控单元的VCMA-MTJ读电路,研究了软击穿对VCMA-MTJ电阻R_(t)、隧穿磁阻比率M、软击穿时间T_(s)以及VCMA-MTJ读电路读错误率的影响。结果表明:软击穿的出现会导致R_(t)和M均随应力时间t的增加而降低,T_(s)随氧化层厚度t_(ox)的增大而缓慢增加,却随脉冲电压V_(b)的增大而迅速减少,与反平行态相比,平行态的T_(s)更短且M降低50%所需时间更少;具有固定参考电阻的VCMA-MTJ读电路可有效避免读“0”错误率的产生,但读“1”错误率却随t的增加而上升,而具有参考电阻调控单元的VCMA-MTJ读电路可在保持读“0”正确率的同时,对读“1”错误率改善达54%,在一定程度上削弱了软击穿对VCMA-MTJ读电路的影响。展开更多
The equivalent circuit with complex physical constants for a piezoelectric ceramic in thickness mode is established. In the equivalent circuit, electric components （equivalent circuit parameters） are connected to re...The equivalent circuit with complex physical constants for a piezoelectric ceramic in thickness mode is established. In the equivalent circuit, electric components （equivalent circuit parameters） are connected to real and imaginary parts of complex physical coefficients of piezoelectric materials. Based on definitions of dissipation factors, three of them （dielectric, elastic and piezoelectric dissipation factors） are represented by equivalent circuit parameters. Since the equivalent circuit parameters are detectable, the dissipation factors can be easily obtained. In the experiments, the temperature and the stress responses of the three dissipation factors are measured.展开更多
基金supported by SGCC Scientific and Technological Project(52110116004W)
文摘Firstly, relevant stress properties of millisecond level breaking process and microsecond level commutation process of hybrid HVDC circuit breaker are studied in detail on the basis of the analysis for the application environment and topological structure and operating principles of hybrid circuit breakers, and key stress parameters in transient state process of two time dimensions are extracted. The established digital simulation circuit for PSCAD/EMTDC device-level operation of the circuit breaker has verified the stress properties of millisecond level breaking process and microsecond level commutation process. Then, equivalent test method, circuits and parameters based on LC power supply are proposed on the basis of stress extraction. Finally, the results of implemented breaking tests for complete 200 kV circuit breaker, 100 kV and 50 kV circuit breaker units, as well as single power electronic module have verified the accuracy of the simulation circuit and mathematical analysis. The result of this paper can be a guide to electrical structure and test system design of hybrid HVDC circuit breaker.
文摘为了解决软击穿导致的压控磁各向异性磁隧道结(voltage-controlled magnetic anisotropy magnetic tunnel junction,VCMA-MTJ)及其读电路性能下降的问题,在对VCMA-MTJ软击穿机理深入分析的基础上,修正了VCMA-MTJ的电学模型,设计了一种具有固定参考电阻的VCMA-MTJ读电路和一种具有参考电阻调控单元的VCMA-MTJ读电路,研究了软击穿对VCMA-MTJ电阻R_(t)、隧穿磁阻比率M、软击穿时间T_(s)以及VCMA-MTJ读电路读错误率的影响。结果表明:软击穿的出现会导致R_(t)和M均随应力时间t的增加而降低,T_(s)随氧化层厚度t_(ox)的增大而缓慢增加,却随脉冲电压V_(b)的增大而迅速减少,与反平行态相比,平行态的T_(s)更短且M降低50%所需时间更少;具有固定参考电阻的VCMA-MTJ读电路可有效避免读“0”错误率的产生,但读“1”错误率却随t的增加而上升,而具有参考电阻调控单元的VCMA-MTJ读电路可在保持读“0”正确率的同时,对读“1”错误率改善达54%,在一定程度上削弱了软击穿对VCMA-MTJ读电路的影响。
基金Project supported by the National Natural Science Foundation of China （Grant No 50278098）.
文摘The equivalent circuit with complex physical constants for a piezoelectric ceramic in thickness mode is established. In the equivalent circuit, electric components （equivalent circuit parameters） are connected to real and imaginary parts of complex physical coefficients of piezoelectric materials. Based on definitions of dissipation factors, three of them （dielectric, elastic and piezoelectric dissipation factors） are represented by equivalent circuit parameters. Since the equivalent circuit parameters are detectable, the dissipation factors can be easily obtained. In the experiments, the temperature and the stress responses of the three dissipation factors are measured.
