According to the B-H curve and structural dimensions of the snubber by the Fink- Baker Method, the inductive voltage and the eddy current of any core tape with the thickness of the saturated regions are derived when t...According to the B-H curve and structural dimensions of the snubber by the Fink- Baker Method, the inductive voltage and the eddy current of any core tape with the thickness of the saturated regions are derived when the accelerator breakdown occurs. Using the Ampere＇s law, in each core tape, the eddy current of the core lamination is equal to the arc current, and the relation of the thickness of the saturated regions for different laminations can be deduced. The total equivalent resistance of the snubber can be obtained. The transient eddy current model based on the stray capacitance and the equivalent resistance is analyzed, and the solving process is given in detail. The exponential time constant and the arc current are obtained. Then, the maximum width of the lamination and the minimum thickness of the core tape are determined. The experimental time constant of the eddy current obtained, with or without the bias current, is approximately the same as that by the analytical method, which proves the accuracy of the adopted assumptions and the analysis method.展开更多
A transformer type iron core snubber, as a protective device against the stray capacitance during the breakdown in EAST, is analyzed in detail. Three kinds of topology are presented. Then with the analysis for equival...A transformer type iron core snubber, as a protective device against the stray capacitance during the breakdown in EAST, is analyzed in detail. Three kinds of topology are presented. Then with the analysis for equivalent circuit, the ranges of three key parameters, i.e., secondary side resistance, leakage inductance and snubber inductance, are determined. By con- sidering the saturation of the magnetic material, a design principle is Mso presented. A nearly 1：10 core snubber is tested. It is proved that a high permeability core with secondary resistor can restrain the discharge current effectively.展开更多
The transformer core snubber （CS）, as one of the most important components in the EAST （experimental advanced superconducting tokamak） NBI （neutral beam injector） system, is designed to limit grid damage and pro...The transformer core snubber （CS）, as one of the most important components in the EAST （experimental advanced superconducting tokamak） NBI （neutral beam injector） system, is designed to limit grid damage and protect the ion source during periods of electrical breakdowns. A transformer core snubber is analyzed in detail in this paper. Several kinds of soft magnetic cores are presented and compared. With analysis and experiment on the basic characteristics of the cores, the most suitable materials are suggested. The circuit simulation code is established which could simulate faulty conditions with concentrated and distributed CS concepts. Based on the above work, an ion source CS is developed with series type of distributed topology. The CS has been subjected to experimental validation at 80 kV with a peak short-current of approximately 400 A in a real NBI system, which proves the accuracy of the adopted assumptions and the analysis method.展开更多
A special winding iron-core is designed to act as the snubber for the neutral beam injection （NBI） power supply （PS） system in EAST, which will limit the fault current and energy caused by occasional sparking in t...A special winding iron-core is designed to act as the snubber for the neutral beam injection （NBI） power supply （PS） system in EAST, which will limit the fault current and energy caused by occasional sparking in the NBI ion source. 50-50 Ni-Fe is chosen as the high-frequency magnetization material for the iron-core. Equations for the snubber is derived from the design of the iron-core. The iron-loss factor and eddy-current losses are found to increase in a sample experiment at a frequency from 1 kHz to 20 kHz. A 1：10 miniature of the iron-core is tested and performs well with a fine capability.展开更多
A low-temperature superconducting quantum interference device(low-Tc SQUID)can improve the depth of exploration.However,a low-Tc SQUID may lose its lock owing to oscillations in the current or the occurrence of spikes...A low-temperature superconducting quantum interference device(low-Tc SQUID)can improve the depth of exploration.However,a low-Tc SQUID may lose its lock owing to oscillations in the current or the occurrence of spikes when the transmitter is switched off.If a low-Tc SQUID loses its lock,it becomes impossible for the low-Tc SQUID TEM system to function normally and stably for a long period of time.This hinders the practical use of the system.In field experiments,the transmitting current is accurately measured,the voltage overshoot and current spike data are recorded,and the gradient of the primary magnetic field at the center of the transmitting loop is calculated.After analyzing the results of field experiments,it was found that when the gradient of the primary magnetic field far exceeds the slew rate of a low-Tc SQUID,the low-Tc SQUID loses its lock.Based on the mechanisms of the transmitting oscillation,an RC serial and multi-parallel capacity snubber circuit used to suppress such oscillation is proposed.The results of simulation and field experiments show that,when using a 100 m×100 m transmitting loop,the gradient of the primary magnetic field is suppressed from 101.4 to 2.4 mT/s with a transmitting current of 40 A,and from 29.6 to 1.4 mT/s with a transmitting current of 20 A.Therefore,it can be concluded that the gradient of the primary magnetic field is below the slew rate of a low-Tc SQUID after adopting the proposed RC serial and multi-parallel capacity snubber circuit.In conclusion,the technique proposed in this paper solves the problem of a lost lock of a low-Tc SQUID,ensuring that the low-Tc SQUID TEM system functions stably for a long period of time,and providing technical assurance for ground TEM exploration at an additional depth.展开更多
A novel passive dual energy recovery snubber circuit is presented where energy trapped in the snubber inductor and capacitor is recovered into the both DC rail and load, without any active devices or resistors. The ma...A novel passive dual energy recovery snubber circuit is presented where energy trapped in the snubber inductor and capacitor is recovered into the both DC rail and load, without any active devices or resistors. The maximum over-shoot voltage on the switch is fixed, peak switch current is low, circuit reset is fast and the operational range of load current is wide. This circuit is suitable for use in high frequency, single ended power gate turn-off (GTO) thyrister choppers. Main design equations, some simulations and practical results are included.展开更多
The core snubber, as a passive protection device, can suppress arc current and absorb stored energy in stray capacitance during the electrical breakdown in accelerating electrodes of ITER NBI. In order to design the c...The core snubber, as a passive protection device, can suppress arc current and absorb stored energy in stray capacitance during the electrical breakdown in accelerating electrodes of ITER NBI. In order to design the core snubber of ITER, the control parameters of the arc peak current have been firstly analyzed by the Fink-Baker-Owren （FBO） method, which are used for designing the DIIID 100 kV snubber. The B-H curve can be derived from the measured voltage and current waveforms, and the hysteresis loss of the core snubber can be derived using the revised parallelogram method. The core snubber can be a simplified representation as an equivalent parallel resistance and inductance, which has been neglected by the FBO method. A simulation code including the parallel equivalent resistance and inductance has been set up. The simulation and experiments result in dramatically large arc shorting currents due to the parallel inductance effect. The case shows that the core snubber utilizing the FBO method gives more compact design.展开更多
The paper considers three common snubber circuits used on gate turn-off thyristor and/or insulated gate bipolar transistor inverters. The three snubbers are passive lossless circuits for power bridge legs, and the imp...The paper considers three common snubber circuits used on gate turn-off thyristor and/or insulated gate bipolar transistor inverters. The three snubbers are passive lossless circuits for power bridge legs, and the improvements and modifications to these snubber circuits are presented. The comparative features and operation of the three improved energy recovery snubbers are discussed and supported by PSPICE simulations and experimental results.展开更多
直流系统是支撑高比例新能源接入与灵活高效用能的重要技术方向。固态式直流断路器(solid state DC circuit breaker,SSCB)具有开断速度极快、无电弧、寿命长等优点,在中低压直流系统的故障保护中得到广泛应用。随着电力电子器件的发展...直流系统是支撑高比例新能源接入与灵活高效用能的重要技术方向。固态式直流断路器(solid state DC circuit breaker,SSCB)具有开断速度极快、无电弧、寿命长等优点,在中低压直流系统的故障保护中得到广泛应用。随着电力电子器件的发展,固态式直流断路器的拓扑结构、工作性能也在不断进步。为此基于逆阻型集成门极换流晶闸管(intergated gate commutate thyristor,IGCT),提出了一种新型的固态式直流断路器结构及设计方法,通流支路采用逆阻IGCT反并联结构实现双向通流,缓冲支路采用金属氧化物避雷器(metal oxide varistor,MOV)-电容结构来抑制过电压,吸能支路采用MOV吸收系统能量。进一步地,给出了关键元器件的参数设计方法,并验证了有效性;设计了性能良好的重力热管散热器,单个模块散热功率可达700 W;提出了主被动结合的控保策略,提高断路器的保护性能。最后,研制了固态式直流断路器样机,可用于750 V以内的低压直流系统,额定通流可达2 kA,可在百微秒内开断10 kA故障电流,成本低、体积小、高可靠,具有良好的应用前景。展开更多
基金supported by Research Fund for the Doctoral Program of Higher Education of China (No.20060248012)Shanghai-Canada Research Council cooperation (06SN07113)Auxiliary Heating Project of EAST upgrade, National Program on Key Basic Research Project (973 Program) of China (No.2010GB108003)
文摘According to the B-H curve and structural dimensions of the snubber by the Fink- Baker Method, the inductive voltage and the eddy current of any core tape with the thickness of the saturated regions are derived when the accelerator breakdown occurs. Using the Ampere＇s law, in each core tape, the eddy current of the core lamination is equal to the arc current, and the relation of the thickness of the saturated regions for different laminations can be deduced. The total equivalent resistance of the snubber can be obtained. The transient eddy current model based on the stray capacitance and the equivalent resistance is analyzed, and the solving process is given in detail. The exponential time constant and the arc current are obtained. Then, the maximum width of the lamination and the minimum thickness of the core tape are determined. The experimental time constant of the eddy current obtained, with or without the bias current, is approximately the same as that by the analytical method, which proves the accuracy of the adopted assumptions and the analysis method.
基金supported in part by Auxiliary Heating Project of EAST upgradein part by Ph. D foundation of State Education Ministry of China(No. 20060248012)
文摘A transformer type iron core snubber, as a protective device against the stray capacitance during the breakdown in EAST, is analyzed in detail. Three kinds of topology are presented. Then with the analysis for equivalent circuit, the ranges of three key parameters, i.e., secondary side resistance, leakage inductance and snubber inductance, are determined. By con- sidering the saturation of the magnetic material, a design principle is Mso presented. A nearly 1：10 core snubber is tested. It is proved that a high permeability core with secondary resistor can restrain the discharge current effectively.
基金supported by National Magnetic Confinement Fusion Science Program of China (Nos.2010GB108003, 2011GB113005-1)in part by the National Magnetic Confinement Fusion Science Program of China (No.2010GB108003)+1 种基金the State Basic Research Development Program of China (973 Program 2011GB113005-1)the Large Scientific Project of EAST Auxiliary Heating Upgrade
文摘The transformer core snubber （CS）, as one of the most important components in the EAST （experimental advanced superconducting tokamak） NBI （neutral beam injector） system, is designed to limit grid damage and protect the ion source during periods of electrical breakdowns. A transformer core snubber is analyzed in detail in this paper. Several kinds of soft magnetic cores are presented and compared. With analysis and experiment on the basic characteristics of the cores, the most suitable materials are suggested. The circuit simulation code is established which could simulate faulty conditions with concentrated and distributed CS concepts. Based on the above work, an ion source CS is developed with series type of distributed topology. The CS has been subjected to experimental validation at 80 kV with a peak short-current of approximately 400 A in a real NBI system, which proves the accuracy of the adopted assumptions and the analysis method.
文摘A special winding iron-core is designed to act as the snubber for the neutral beam injection （NBI） power supply （PS） system in EAST, which will limit the fault current and energy caused by occasional sparking in the NBI ion source. 50-50 Ni-Fe is chosen as the high-frequency magnetization material for the iron-core. Equations for the snubber is derived from the design of the iron-core. The iron-loss factor and eddy-current losses are found to increase in a sample experiment at a frequency from 1 kHz to 20 kHz. A 1：10 miniature of the iron-core is tested and performs well with a fine capability.
基金Project(XDB 0420200)supported by Strategy Priority Research Program(B)of China
文摘A low-temperature superconducting quantum interference device(low-Tc SQUID)can improve the depth of exploration.However,a low-Tc SQUID may lose its lock owing to oscillations in the current or the occurrence of spikes when the transmitter is switched off.If a low-Tc SQUID loses its lock,it becomes impossible for the low-Tc SQUID TEM system to function normally and stably for a long period of time.This hinders the practical use of the system.In field experiments,the transmitting current is accurately measured,the voltage overshoot and current spike data are recorded,and the gradient of the primary magnetic field at the center of the transmitting loop is calculated.After analyzing the results of field experiments,it was found that when the gradient of the primary magnetic field far exceeds the slew rate of a low-Tc SQUID,the low-Tc SQUID loses its lock.Based on the mechanisms of the transmitting oscillation,an RC serial and multi-parallel capacity snubber circuit used to suppress such oscillation is proposed.The results of simulation and field experiments show that,when using a 100 m×100 m transmitting loop,the gradient of the primary magnetic field is suppressed from 101.4 to 2.4 mT/s with a transmitting current of 40 A,and from 29.6 to 1.4 mT/s with a transmitting current of 20 A.Therefore,it can be concluded that the gradient of the primary magnetic field is below the slew rate of a low-Tc SQUID after adopting the proposed RC serial and multi-parallel capacity snubber circuit.In conclusion,the technique proposed in this paper solves the problem of a lost lock of a low-Tc SQUID,ensuring that the low-Tc SQUID TEM system functions stably for a long period of time,and providing technical assurance for ground TEM exploration at an additional depth.
基金Supported by the National Nature Science Foundation of Chinathe Royal Society of UK
文摘A novel passive dual energy recovery snubber circuit is presented where energy trapped in the snubber inductor and capacitor is recovered into the both DC rail and load, without any active devices or resistors. The maximum over-shoot voltage on the switch is fixed, peak switch current is low, circuit reset is fast and the operational range of load current is wide. This circuit is suitable for use in high frequency, single ended power gate turn-off (GTO) thyrister choppers. Main design equations, some simulations and practical results are included.
基金supported by National Program on Key Basic Research Project of ITER Core Snubber in China (973 Program) (No.2010GB108003)
文摘The core snubber, as a passive protection device, can suppress arc current and absorb stored energy in stray capacitance during the electrical breakdown in accelerating electrodes of ITER NBI. In order to design the core snubber of ITER, the control parameters of the arc peak current have been firstly analyzed by the Fink-Baker-Owren （FBO） method, which are used for designing the DIIID 100 kV snubber. The B-H curve can be derived from the measured voltage and current waveforms, and the hysteresis loss of the core snubber can be derived using the revised parallelogram method. The core snubber can be a simplified representation as an equivalent parallel resistance and inductance, which has been neglected by the FBO method. A simulation code including the parallel equivalent resistance and inductance has been set up. The simulation and experiments result in dramatically large arc shorting currents due to the parallel inductance effect. The case shows that the core snubber utilizing the FBO method gives more compact design.
基金Supported by the Zhejiang Province Nature Science Foundation of Chinathe Royal Society of U.K.
文摘The paper considers three common snubber circuits used on gate turn-off thyristor and/or insulated gate bipolar transistor inverters. The three snubbers are passive lossless circuits for power bridge legs, and the improvements and modifications to these snubber circuits are presented. The comparative features and operation of the three improved energy recovery snubbers are discussed and supported by PSPICE simulations and experimental results.
