Phase shifted converter realizes zero voltage switching (ZVS) with the use of leakage inductance of the main transformer, however, the realization of ZVS for lagging bridge leg is difficult. This paper proposes a c...Phase shifted converter realizes zero voltage switching (ZVS) with the use of leakage inductance of the main transformer, however, the realization of ZVS for lagging bridge leg is difficult. This paper proposes a current enhanced principle, and based on the principle, a novel phase shifted converter is proposed, which adds an auxi liary resonant net to the conventional full bridge converter to help the lagging bridge leg to realize ZVS. The principle and the design of the novel converter are analyzed, and the simulational and experimental results verify the principle.展开更多
In this paper, digital simulation techniques for dynamic and transient voltage performance studies, using accurate load and synchronous generator models have been proposed. Particular attention has been paid to the in...In this paper, digital simulation techniques for dynamic and transient voltage performance studies, using accurate load and synchronous generator models have been proposed. Particular attention has been paid to the induction motor load model. Accurate models of voltage supporting devices including OLTC transformer are derived. The system of differential equations based on the above models are converted into linear algebraic equations by use of the trapezoidal approximation formula. These are then written as difference equations to facilitate computational programming. For various contingencies a numerical iterative technique is used to obtain a simulation of the system voltage and angle profile. Various contingency tests on a 9-bus sample system and a 22-bus system prove the applicability of the package.展开更多
DC regulated power has play a decisive role status in the modem enterprise production and family life. With the development of science and technology, all kinds of computer simulation technology is increasingly rising...DC regulated power has play a decisive role status in the modem enterprise production and family life. With the development of science and technology, all kinds of computer simulation technology is increasingly rising, the paper simulate and compare common DC regulated power with adjustable DC regulated power by Altium Designer software, intuitively demonstrates the stabilizing effect of the circuit, and introduces the characteristics of adjustable DC regulated power. Using AD13 software simulate and design DC stabilized power supply circuit, calculated the main parameters of the circuit, simulated and analyzed the circuit working simulation process and the working state of the circuit, it can visually verify the results of the theoretical analysis, and get relevant conclusions.展开更多
Results of calculation the recovery voltages conditioned by capacitive currents switching-off by high voltage vacuum and auto-compression （SF6） circuit-breakers are presented in the article. The purpose of research ...Results of calculation the recovery voltages conditioned by capacitive currents switching-off by high voltage vacuum and auto-compression （SF6） circuit-breakers are presented in the article. The purpose of research was evaluating the maximum values of recovery voltages and also studying the dependence of recovery voltages on some influencing factors, especially on type of circuit-breaker presented in numerical models with its dielectric strength restoration law, chopping current and operation time. The research was carried out with using computer simulation.展开更多
On the basic of passive damping control, we do modeling and simulating in another approach to improve the vibration alleviating effect, the piezoelectric layer damping （PLD）, which is called active control. The piez...On the basic of passive damping control, we do modeling and simulating in another approach to improve the vibration alleviating effect, the piezoelectric layer damping （PLD）, which is called active control. The piezoelectric damping patches are under control of PID controller （matlab simulating） in voltage defference. Here, we use the software PRO/ENGINEER to design and model a wind turbine blade before using COMSOL to simulate the dynamic motion of the wind turbine blade and its interaction with aerodynamic force of wind in finite element method. Some different models are built-- the original turbine blade and the turbine blade with damping patches on different location and quantity. Then, according to the simulation results, we compare the effects of passive and active damping control, also the effect of patches locations and quantities under different wind speed. This research can provide a direction for future study about ways to decrease vibration of turbine blades.展开更多
With the increasing development of wind power,the scale of wind farms and unit capacity of wind turbines are getting larger and larger,and the impact of wind integration on power systems cannot be ignored.However,in m...With the increasing development of wind power,the scale of wind farms and unit capacity of wind turbines are getting larger and larger,and the impact of wind integration on power systems cannot be ignored.However,in most cases,the areas with a plenty of wind resources do not have strong grid structures.Furthermore,the characteristics of wind power dictate that wind turbines need to absorb reactive power during operation.Because of the strong correlation between voltage stability and systems' reactive power,the impacts of wind integration on voltage stability has become an important issue.Based on the power system simulation software DIgSILENT and combined analysis of actual practice,this paper investigates the impacts of two types of wind farms on voltage stability:namely a type of wind farms which are constituted by constant speed wind turbines based on common induction generators(IG) and another type of wind farms which are constituted by VSCF wind turbines based on doubly-fed induction generators(DFIG).Through investigation the critical fault clearing time is presented for different outputs of wind farms.Moreover,the impacts of static var compensator(SVC) and static synchronous compensator(STATCOM) on transient voltage stability in IG-based wind farms are studied to improve the security and stability of the Jiangsu power grid after the integration of large scale wind power.展开更多
Switching expansion reduction(SER) uses a switch valve to substitute the throttle valve to reduce pressure for high pressure pneumatics.The experiments indicate that the simulation model well predicts the actual chara...Switching expansion reduction(SER) uses a switch valve to substitute the throttle valve to reduce pressure for high pressure pneumatics.The experiments indicate that the simulation model well predicts the actual characteristics.The heat transfers and polytropic exponents of the air in expansion tank and supply tanks of SER have been studied on the basis of the experiments and the simulation model.Through the mathematical reasoning in this paper,the polytropic exponent can be calculated by the air mass,heat,and work exchanges of the pneumatic container.For the air in a constant volume tank,when the heat-absorption is large enough to raise air temperature in discharging process,the polytropic exponent is less than 1;when the air is experiencing a discharging and heat-releasing process,the polytropic exponent exceeds the specific heat ratio(the value of 1.4).展开更多
Surface properties of SiC power devices mostly depend on the passivation layer(PL).This layer has direct influence on electrical characteristics of devices.2D numerical simulation of forward and reverse characteristic...Surface properties of SiC power devices mostly depend on the passivation layer(PL).This layer has direct influence on electrical characteristics of devices.2D numerical simulation of forward and reverse characteristics with and without different(PLs)(SiO2,HfO2 and Si3N4) has been performed.Simulation results show that the breakdown voltage increases with increasing PL thickness,and there is a lesser significant effect on forward characteristics.The maximum breakdown voltage with and without SiO2 PL is 1240 V and 276 V,respectively.SiO2 PL has compatibility with SiC surface providing high breakdown voltage,6 and 8% higher than that of HfO2 and Si3N4 respectively.Low leakage current is observed which then further decreases on reducing the thickness of PL.Furthermore,variation of forward current with dielectric constant and thickness of PLs was observed.Finally,it is suggested that matches of our results with published experimental results indicate that the Sentaurus TCAD simulator is a predictive tool for the SiC Schottky barrier diode simulation.展开更多
p-GaN cap layer has been recognized as a commercial technology to manufacture enhanced-mode(E-mode)AlGaN/GaN high electron mobility transistor(HEMT);however,the difficult activation of Mg doping and etching damage of ...p-GaN cap layer has been recognized as a commercial technology to manufacture enhanced-mode(E-mode)AlGaN/GaN high electron mobility transistor(HEMT);however,the difficult activation of Mg doping and etching damage of p-GaN limit the further improvement of device performance.Thus,the more cost-effective cap layer has attracted wide attention in GaN-based HEMT.In this paper,p-type tin monoxide(p-SnO)was firstly investigated as a gate cap to realize E-mode AlGaN/GaN HEMT by both Silvaco simulation and experiment.Simulation results show that by simply adjusting the thickness(50 to 200 nm)or the doping concentration(3×10^(17)to 3×10^(18)cm^(-3))of p-SnO,the threshold voltage(V_(th))of HEMT can be continuously adjusted in the range from zero to 10 V.Simultaneously,the device demonstrated a drain current density above 120 mA mm^(-1),a gate breakdown voltage(V_(BG))of 7.5 V and a device breakdown voltage(V_(B))of 2470 V.What is more,the etching-free AlGaN/GaN HEMT with sputtered p-SnO gate cap were fabricated,and achieved a positive V_(th) of 1 V,V_(BG) of 4.2 V and V_(B) of 420 V,which confirms the application potential of the p-SnO film as a gate cap layer for E-mode GaN-based HEMT.This work is instructive to the design and manufacture of p-oxide gate cap E-mode AlGaN/GaN HEMT with low cost.展开更多
A novel off-state gate RHBD technique to mitigate the single-event transient(SET)in the differential data path of analog circuit is demonstrated in this paper.Simulation results present that this off-state gate techni...A novel off-state gate RHBD technique to mitigate the single-event transient(SET)in the differential data path of analog circuit is demonstrated in this paper.Simulation results present that this off-state gate technique could exploit charge sharing in differential circuits and reduce differential mode voltage perturbation effectively.It is indicated that this technique is more effective to mitigate SET than the differential charge cancellation(DCC)technique with less penalty.展开更多
文摘Phase shifted converter realizes zero voltage switching (ZVS) with the use of leakage inductance of the main transformer, however, the realization of ZVS for lagging bridge leg is difficult. This paper proposes a current enhanced principle, and based on the principle, a novel phase shifted converter is proposed, which adds an auxi liary resonant net to the conventional full bridge converter to help the lagging bridge leg to realize ZVS. The principle and the design of the novel converter are analyzed, and the simulational and experimental results verify the principle.
文摘In this paper, digital simulation techniques for dynamic and transient voltage performance studies, using accurate load and synchronous generator models have been proposed. Particular attention has been paid to the induction motor load model. Accurate models of voltage supporting devices including OLTC transformer are derived. The system of differential equations based on the above models are converted into linear algebraic equations by use of the trapezoidal approximation formula. These are then written as difference equations to facilitate computational programming. For various contingencies a numerical iterative technique is used to obtain a simulation of the system voltage and angle profile. Various contingency tests on a 9-bus sample system and a 22-bus system prove the applicability of the package.
文摘DC regulated power has play a decisive role status in the modem enterprise production and family life. With the development of science and technology, all kinds of computer simulation technology is increasingly rising, the paper simulate and compare common DC regulated power with adjustable DC regulated power by Altium Designer software, intuitively demonstrates the stabilizing effect of the circuit, and introduces the characteristics of adjustable DC regulated power. Using AD13 software simulate and design DC stabilized power supply circuit, calculated the main parameters of the circuit, simulated and analyzed the circuit working simulation process and the working state of the circuit, it can visually verify the results of the theoretical analysis, and get relevant conclusions.
文摘Results of calculation the recovery voltages conditioned by capacitive currents switching-off by high voltage vacuum and auto-compression （SF6） circuit-breakers are presented in the article. The purpose of research was evaluating the maximum values of recovery voltages and also studying the dependence of recovery voltages on some influencing factors, especially on type of circuit-breaker presented in numerical models with its dielectric strength restoration law, chopping current and operation time. The research was carried out with using computer simulation.
文摘On the basic of passive damping control, we do modeling and simulating in another approach to improve the vibration alleviating effect, the piezoelectric layer damping （PLD）, which is called active control. The piezoelectric damping patches are under control of PID controller （matlab simulating） in voltage defference. Here, we use the software PRO/ENGINEER to design and model a wind turbine blade before using COMSOL to simulate the dynamic motion of the wind turbine blade and its interaction with aerodynamic force of wind in finite element method. Some different models are built-- the original turbine blade and the turbine blade with damping patches on different location and quantity. Then, according to the simulation results, we compare the effects of passive and active damping control, also the effect of patches locations and quantities under different wind speed. This research can provide a direction for future study about ways to decrease vibration of turbine blades.
文摘With the increasing development of wind power,the scale of wind farms and unit capacity of wind turbines are getting larger and larger,and the impact of wind integration on power systems cannot be ignored.However,in most cases,the areas with a plenty of wind resources do not have strong grid structures.Furthermore,the characteristics of wind power dictate that wind turbines need to absorb reactive power during operation.Because of the strong correlation between voltage stability and systems' reactive power,the impacts of wind integration on voltage stability has become an important issue.Based on the power system simulation software DIgSILENT and combined analysis of actual practice,this paper investigates the impacts of two types of wind farms on voltage stability:namely a type of wind farms which are constituted by constant speed wind turbines based on common induction generators(IG) and another type of wind farms which are constituted by VSCF wind turbines based on doubly-fed induction generators(DFIG).Through investigation the critical fault clearing time is presented for different outputs of wind farms.Moreover,the impacts of static var compensator(SVC) and static synchronous compensator(STATCOM) on transient voltage stability in IG-based wind farms are studied to improve the security and stability of the Jiangsu power grid after the integration of large scale wind power.
基金supported by the National Natural Science Foundation of China (No.50575202)
文摘Switching expansion reduction(SER) uses a switch valve to substitute the throttle valve to reduce pressure for high pressure pneumatics.The experiments indicate that the simulation model well predicts the actual characteristics.The heat transfers and polytropic exponents of the air in expansion tank and supply tanks of SER have been studied on the basis of the experiments and the simulation model.Through the mathematical reasoning in this paper,the polytropic exponent can be calculated by the air mass,heat,and work exchanges of the pneumatic container.For the air in a constant volume tank,when the heat-absorption is large enough to raise air temperature in discharging process,the polytropic exponent is less than 1;when the air is experiencing a discharging and heat-releasing process,the polytropic exponent exceeds the specific heat ratio(the value of 1.4).
基金the Higher Education Commission of Pakistan for providing financial support as indigenous scholarship Batch-IV
文摘Surface properties of SiC power devices mostly depend on the passivation layer(PL).This layer has direct influence on electrical characteristics of devices.2D numerical simulation of forward and reverse characteristics with and without different(PLs)(SiO2,HfO2 and Si3N4) has been performed.Simulation results show that the breakdown voltage increases with increasing PL thickness,and there is a lesser significant effect on forward characteristics.The maximum breakdown voltage with and without SiO2 PL is 1240 V and 276 V,respectively.SiO2 PL has compatibility with SiC surface providing high breakdown voltage,6 and 8% higher than that of HfO2 and Si3N4 respectively.Low leakage current is observed which then further decreases on reducing the thickness of PL.Furthermore,variation of forward current with dielectric constant and thickness of PLs was observed.Finally,it is suggested that matches of our results with published experimental results indicate that the Sentaurus TCAD simulator is a predictive tool for the SiC Schottky barrier diode simulation.
基金supported by the National Natural Science Foundation of China(62003151,61925404,62074122,and 61904139)the Key Research and Development Program in Shaanxi Province(2016KTZDGY-03-01)。
文摘p-GaN cap layer has been recognized as a commercial technology to manufacture enhanced-mode(E-mode)AlGaN/GaN high electron mobility transistor(HEMT);however,the difficult activation of Mg doping and etching damage of p-GaN limit the further improvement of device performance.Thus,the more cost-effective cap layer has attracted wide attention in GaN-based HEMT.In this paper,p-type tin monoxide(p-SnO)was firstly investigated as a gate cap to realize E-mode AlGaN/GaN HEMT by both Silvaco simulation and experiment.Simulation results show that by simply adjusting the thickness(50 to 200 nm)or the doping concentration(3×10^(17)to 3×10^(18)cm^(-3))of p-SnO,the threshold voltage(V_(th))of HEMT can be continuously adjusted in the range from zero to 10 V.Simultaneously,the device demonstrated a drain current density above 120 mA mm^(-1),a gate breakdown voltage(V_(BG))of 7.5 V and a device breakdown voltage(V_(B))of 2470 V.What is more,the etching-free AlGaN/GaN HEMT with sputtered p-SnO gate cap were fabricated,and achieved a positive V_(th) of 1 V,V_(BG) of 4.2 V and V_(B) of 420 V,which confirms the application potential of the p-SnO film as a gate cap layer for E-mode GaN-based HEMT.This work is instructive to the design and manufacture of p-oxide gate cap E-mode AlGaN/GaN HEMT with low cost.
基金supported by the State Key Program of the National Natural Science Foundation of China(Grant No.60836004)the National Natural Science Foundation of China(Grant No.61376109)
文摘A novel off-state gate RHBD technique to mitigate the single-event transient(SET)in the differential data path of analog circuit is demonstrated in this paper.Simulation results present that this off-state gate technique could exploit charge sharing in differential circuits and reduce differential mode voltage perturbation effectively.It is indicated that this technique is more effective to mitigate SET than the differential charge cancellation(DCC)technique with less penalty.
