In traction application,speed range of motor is an important index for motor drives.In AC motor control,the maximum speed of the motor is limited by the output voltage capability of the traditional three-phase inverte...In traction application,speed range of motor is an important index for motor drives.In AC motor control,the maximum speed of the motor is limited by the output voltage capability of the traditional three-phase inverter with star connenction of windings.Switching the star connection to delta connection in high-speed range can extend the speed range.In order to extend the speed operation region,star-delta switch proposed by many literatures relies on mechanical relay,which needs a dead zone of tens of milliseconds and seriously affects torque output.Besides,the traditional method will cause current overshoot during the switch transient process,decreasing the device security and reliability.Aiming at the defects existing in the star-delta hard switching,this paper proposes a star-delta soft switching method.Without adding extra power electronics devices,DC-bus capacitor is used to provide the path of zero axis current in the transient process,which helps to achieve the smooth torque output and zero current switch in the transient.Experiments have been done to validate the performance of the proposed method.The switching transient from star to delta connection in the motor drive can be much more stable than hard switching method.展开更多
By applying switch-signal theory, the interaction between MOS transmission switch-ing transistor and current signal in current-mode CMOS circuits is analyzed, and the theory oftransmission current-switches which is su...By applying switch-signal theory, the interaction between MOS transmission switch-ing transistor and current signal in current-mode CMOS circuits is analyzed, and the theory oftransmission current-switches which is suitable to current-mode CMOS circuits is proposed. Thecircuits, such as ternary full-adder etc., designed by using this theory have simpler circuit struc-tures and correct logic functions. It is confirmed that this theory is efficient in guiding the logicdesign of current-mode CMOS circuits at switch level.展开更多
In conformity with a fifth order RLC elliptic filter circuit prototype, it is easy to conceive the corresponding RC active filter circuit. Simple and feasible method presented here can be used to contrive...In conformity with a fifth order RLC elliptic filter circuit prototype, it is easy to conceive the corresponding RC active filter circuit. Simple and feasible method presented here can be used to contrive the equivalent switched capacitor filter circuit and switched current filter circuit. Consulting the technique data manual, we can expediently design a specific RLC filter. Therefore, it is of great convenience to design the switched current filter, which has the same performances. Such a kind of technology is useful in the domain of analogue sampled data signal processing.展开更多
A switched-current sample-and-hold circuit with low charge injection was proposed. To obtain low noise and charge injection, the zero-voltage switching was used to remove the signal-dependent charge injection, and the...A switched-current sample-and-hold circuit with low charge injection was proposed. To obtain low noise and charge injection, the zero-voltage switching was used to remove the signal-dependent charge injection, and the signal-independent charge injection was reduced by removing the feed-through voltage from the input port of the memory transistor directly. This current sample-and-hold circuit was implemented using CMOS 180 nm 1.8 V technology. For a 0.8 MHz sinusoidal signal input, the simulated signal-to-noise and distortion ratio and total harmonic distortion were improved from 53.74 dB and -51.24 dB to 56.53 dB and -54.36 dB at the sampling rate of 20 MHz respectively, with accuracy of 9.01 bit and power consumption of 0.44 mW.展开更多
A new switched-current(SI)biquadratic filter is presented which can simultaneouslyprovide the low-pass,high-pass and band-pass filters in a single building block.A symbol torepresent the universal SI integrator is als...A new switched-current(SI)biquadratic filter is presented which can simultaneouslyprovide the low-pass,high-pass and band-pass filters in a single building block.A symbol torepresent the universal SI integrator is also introduced.It can simplify the analysis and synthesisof SI networks.展开更多
A new analogue sampled-data active device, named as a switched-current operationalamplifier (SIOA), is presented. The use of active circuit elements may simplify drawing the circuitdiagram significantly greatly and ma...A new analogue sampled-data active device, named as a switched-current operationalamplifier (SIOA), is presented. The use of active circuit elements may simplify drawing the circuitdiagram significantly greatly and may permit easier analysis and synthesis of SI networks. Anumber of all pole and elliptic (second-or third-order) switched-current (SI) filters are derivedfrom the switched capacitor prototypes. These can be used as simple self-contained filters or asfilter sections in the cascaded realizations of a higher order transfer functions. To illustrate theapproach, a fifth-order low-pass filter is designed.展开更多
We investigate the distribution of the switching current of a current-biased Josephson junction (CBJJ) and its dependence on the microwave frequency using two theoretical methods, one of which is the quantum traject...We investigate the distribution of the switching current of a current-biased Josephson junction (CBJJ) and its dependence on the microwave frequency using two theoretical methods, one of which is the quantum trajectory method and the other is the master equation method. Both the methods show that the distribution of the switching current of CBJJ will exhibit double peaks in a certain range of microwave frequency if proper microwave power is given, and the gap between the two peaks will increase with the microwave frequency. The obtained results can be used to identify the energy difference of the ground and first excited states in a Josephson junction for any bias current.展开更多
To miniaturize a very low level dc current amplifier and to improve its output response speed, the switched capacitor negative feedback circuit (SCNF), instead of the conventionally used high-ohmage resistor, is prese...To miniaturize a very low level dc current amplifier and to improve its output response speed, the switched capacitor negative feedback circuit (SCNF), instead of the conventionally used high-ohmage resistor, is presented in this paper. In our system, a switched capacitor filter (SCF) and an offset controller are also used to decrease vibrations and offset voltage at the output of the amplifier using SCNF. The theoretical output voltage of the very low level dc current amplifier using SCNF is obtained. The experimental results show that the unnecessary components of the amplifier’s output are much decreased, and that the response speed of the amplifier with both the SCNF and SCF is faster than that using high-ohmage resistor.展开更多
A crowbar impulse current circuit for testing the switch-type surge protective device (SPD) is presented. The crowbar circuit consists of a computer control circuit, a trigger voltage pulse generator, a main dischar...A crowbar impulse current circuit for testing the switch-type surge protective device (SPD) is presented. The crowbar circuit consists of a computer control circuit, a trigger voltage pulse generator, a main discharging switch, and a crowbar pseudospark switch. The active trigger technology was studied in the crowbar impulse current circuit. The circuit monitors the main discharging current and generates a trigger signal at a proper time for the crowbar pseudospark switch operation. The trigger characteristics of the main discharge switch and the crowbar pseu- dospark switch were investigated. By monitoring the preset applied capacitor voltage, the gap distance of the main discharging switch could be adjusted to ensure a discharging delay time less than 2 μs. Equipped with a surface ttashover trigger device made of high relative perimittivity dielectric material BaTiO3 (εr = 3460), the discharge delay time of the crowbar pseudospark switch is less than 85 ns, and the minimum operating voltage is less than 1% of its self-breakdown voltage. With a storage capacitor of 9 μF , an inductor of 18 μH and a crowbar pseudospark switch, a load of 30 mΩ and an applied capacitor voltage of 40 kV, an impulse current waveform of maximum 25 kA was generated with a rise time and time to half peak value of 17.2 μs and 336μs respectively.展开更多
Based on mirror-blocks,a totally coded algorithm(TCA) for switched-current(SI) network analysis in frequency domain is presented.The algorithm is simple,available,and suitable for any switched-current networks.A basis...Based on mirror-blocks,a totally coded algorithm(TCA) for switched-current(SI) network analysis in frequency domain is presented.The algorithm is simple,available,and suitable for any switched-current networks.A basis of analysis and design for switched-current networks via this algorithm is provided.展开更多
We perform micromagnetic simulations on the switching of magnetic vortex core by using spin-polarized currents through a three-nanocontact geometry. Our simulation results show that the current combination with an app...We perform micromagnetic simulations on the switching of magnetic vortex core by using spin-polarized currents through a three-nanocontact geometry. Our simulation results show that the current combination with an appropriate current flow direction destroys the symmetry of the total effective energy of the system so that the vortex core can be easier to excite,resulting in less critical current density and a faster switching process. Besides its fundamental significance, our findings provide an additional route to incorporating magnetic vortex phenomena into data storage devices.展开更多
This paper presents a new type of fault current limiter (FCL) based on fast closing switch, which is composed of a capacitor bank and a reactor in series. The main control component is a fast closing switch connecte...This paper presents a new type of fault current limiter (FCL) based on fast closing switch, which is composed of a capacitor bank and a reactor in series. The main control component is a fast closing switch connected in parallel with the capacitors, which is driven by the electromagnetic repulsion force. It can response the order within 1 ms. When fault occurs, the switch closes and the capacitors are bypassed, and the fault current is limited by the reactor. Simulation analysis and experiment show that the electromagnetic repulsion force actuator can meet the demand of fast closing switch, it is feasible to develop the FCL with low cost and high reliability.展开更多
A novel current chopping mode was used in a switched reluctance motor drive system to make full use of the characteristics of digital signal processor (DSP) TMS320F240. The necessity of this 180° phase-shift curr...A novel current chopping mode was used in a switched reluctance motor drive system to make full use of the characteristics of digital signal processor (DSP) TMS320F240. The necessity of this 180° phase-shift current control (PSCC) mode is introduced first and then the principle of PSCC covering both hardware requirement and software programming is described in detail. The analysis made indicated that with this mode, the chopping frequency in winding can reach 20 kHz with 10 kHz power switches and the control frequency can reach 40 kHz at the same time. Subsequently, based on the linear and nonlinear mathematical models of the switched reluctance motor (SRM), some simulation work has been done. The simulation results show that when this mode is applied to SRM drive (SRD) system, the current waveform becomes better. So the ripple of the torque is reduced simultaneously and the vibration and acoustic noise are reduced involuntarily. Stationary tests show that the acoustic noise is greatly diminished. Finally, some experiments were made using a 50 kW SRD system for electric vehicle (EV). Experimental results indicate that this mode can be implemented feasibly and it has a good action on the SRD system.展开更多
The characteristics of the triggered vacuum switch (TVS) are obviously influenced by the emission current ie and emission charge of the trigger device. In this paper, an RC charge collector is designed, and the char...The characteristics of the triggered vacuum switch (TVS) are obviously influenced by the emission current ie and emission charge of the trigger device. In this paper, an RC charge collector is designed, and the characteristics of emission current ie and collecting charge Qc of the trigger device are studied. The experimental results indicate that the emission current ie which is produced by the initial plasma has both positive and negative components, and the polarity of the emission current ie depends mainly on the polarity of the bias voltage UBias. The emission current ie and collecting charge Qe increase with the increase of the trigger voltage Utr and the bias voltage UBias. The emission efficient r] increases linearly with the increase of the bias voltage UBias. When the gap distance is 15 mm and bias voltage UBias is 160 V and trigger voltage Utr is 2.6 kV, the emission efficiency r/reaches 6%展开更多
A new type of fault current limiter (FCL) with series compensation based fast-closing switch is proposed. It is composed of a capacitor bank and a reactor in series. The main control component is a fast-closing switch...A new type of fault current limiter (FCL) with series compensation based fast-closing switch is proposed. It is composed of a capacitor bank and a reactor in series. The main control component is a fast-closing switch connected in parallel with the capacitors, which is driven by the electromagnetic repulsion force. When fault occurs, the switch closes and bypasses the capacitors, and the fault is limited by the reactor then. Simulated analysis and experiments show that it is feasible to develop the FCL with low cost and high reliability. The effectiveness of transient stability for power system is evaluated by digital simulation.展开更多
文摘In traction application,speed range of motor is an important index for motor drives.In AC motor control,the maximum speed of the motor is limited by the output voltage capability of the traditional three-phase inverter with star connenction of windings.Switching the star connection to delta connection in high-speed range can extend the speed range.In order to extend the speed operation region,star-delta switch proposed by many literatures relies on mechanical relay,which needs a dead zone of tens of milliseconds and seriously affects torque output.Besides,the traditional method will cause current overshoot during the switch transient process,decreasing the device security and reliability.Aiming at the defects existing in the star-delta hard switching,this paper proposes a star-delta soft switching method.Without adding extra power electronics devices,DC-bus capacitor is used to provide the path of zero axis current in the transient process,which helps to achieve the smooth torque output and zero current switch in the transient.Experiments have been done to validate the performance of the proposed method.The switching transient from star to delta connection in the motor drive can be much more stable than hard switching method.
基金Supported by National Natural Science Foundation of China
文摘By applying switch-signal theory, the interaction between MOS transmission switch-ing transistor and current signal in current-mode CMOS circuits is analyzed, and the theory oftransmission current-switches which is suitable to current-mode CMOS circuits is proposed. Thecircuits, such as ternary full-adder etc., designed by using this theory have simpler circuit struc-tures and correct logic functions. It is confirmed that this theory is efficient in guiding the logicdesign of current-mode CMOS circuits at switch level.
文摘In conformity with a fifth order RLC elliptic filter circuit prototype, it is easy to conceive the corresponding RC active filter circuit. Simple and feasible method presented here can be used to contrive the equivalent switched capacitor filter circuit and switched current filter circuit. Consulting the technique data manual, we can expediently design a specific RLC filter. Therefore, it is of great convenience to design the switched current filter, which has the same performances. Such a kind of technology is useful in the domain of analogue sampled data signal processing.
基金Supported by National Natural Science Foundation of China(No.61036004 and No.61076024)
文摘A switched-current sample-and-hold circuit with low charge injection was proposed. To obtain low noise and charge injection, the zero-voltage switching was used to remove the signal-dependent charge injection, and the signal-independent charge injection was reduced by removing the feed-through voltage from the input port of the memory transistor directly. This current sample-and-hold circuit was implemented using CMOS 180 nm 1.8 V technology. For a 0.8 MHz sinusoidal signal input, the simulated signal-to-noise and distortion ratio and total harmonic distortion were improved from 53.74 dB and -51.24 dB to 56.53 dB and -54.36 dB at the sampling rate of 20 MHz respectively, with accuracy of 9.01 bit and power consumption of 0.44 mW.
基金Supported by the National Natural Science Foundation of China for the Young
文摘A new switched-current(SI)biquadratic filter is presented which can simultaneouslyprovide the low-pass,high-pass and band-pass filters in a single building block.A symbol torepresent the universal SI integrator is also introduced.It can simplify the analysis and synthesisof SI networks.
基金Project supported by the National Natural Science Foundation of China
文摘A new analogue sampled-data active device, named as a switched-current operationalamplifier (SIOA), is presented. The use of active circuit elements may simplify drawing the circuitdiagram significantly greatly and may permit easier analysis and synthesis of SI networks. Anumber of all pole and elliptic (second-or third-order) switched-current (SI) filters are derivedfrom the switched capacitor prototypes. These can be used as simple self-contained filters or asfilter sections in the cascaded realizations of a higher order transfer functions. To illustrate theapproach, a fifth-order low-pass filter is designed.
基金Supported by the National Basic Research Program of China under Grant Nos 2011CBA00107,2011CB922104 and2011CBA00202the National Natural Science Foundation of China under Grant Nos 61371036,11234006,11227904 and 11474154+3 种基金the Natural Science Foundation of Jiangsu Province under Grant No BK2012013the Specialized Research Fund for the Doctoral Program of Higher Education of China under Grant No 20120091110030the Dengfeng Project B of Nanjing University,Jiangsu Key Laboratory of Advanced Manipulating Techniques of Electromagnetic Wavesthe Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘We investigate the distribution of the switching current of a current-biased Josephson junction (CBJJ) and its dependence on the microwave frequency using two theoretical methods, one of which is the quantum trajectory method and the other is the master equation method. Both the methods show that the distribution of the switching current of CBJJ will exhibit double peaks in a certain range of microwave frequency if proper microwave power is given, and the gap between the two peaks will increase with the microwave frequency. The obtained results can be used to identify the energy difference of the ground and first excited states in a Josephson junction for any bias current.
文摘To miniaturize a very low level dc current amplifier and to improve its output response speed, the switched capacitor negative feedback circuit (SCNF), instead of the conventionally used high-ohmage resistor, is presented in this paper. In our system, a switched capacitor filter (SCF) and an offset controller are also used to decrease vibrations and offset voltage at the output of the amplifier using SCNF. The theoretical output voltage of the very low level dc current amplifier using SCNF is obtained. The experimental results show that the unnecessary components of the amplifier’s output are much decreased, and that the response speed of the amplifier with both the SCNF and SCF is faster than that using high-ohmage resistor.
文摘A crowbar impulse current circuit for testing the switch-type surge protective device (SPD) is presented. The crowbar circuit consists of a computer control circuit, a trigger voltage pulse generator, a main discharging switch, and a crowbar pseudospark switch. The active trigger technology was studied in the crowbar impulse current circuit. The circuit monitors the main discharging current and generates a trigger signal at a proper time for the crowbar pseudospark switch operation. The trigger characteristics of the main discharge switch and the crowbar pseu- dospark switch were investigated. By monitoring the preset applied capacitor voltage, the gap distance of the main discharging switch could be adjusted to ensure a discharging delay time less than 2 μs. Equipped with a surface ttashover trigger device made of high relative perimittivity dielectric material BaTiO3 (εr = 3460), the discharge delay time of the crowbar pseudospark switch is less than 85 ns, and the minimum operating voltage is less than 1% of its self-breakdown voltage. With a storage capacitor of 9 μF , an inductor of 18 μH and a crowbar pseudospark switch, a load of 30 mΩ and an applied capacitor voltage of 40 kV, an impulse current waveform of maximum 25 kA was generated with a rise time and time to half peak value of 17.2 μs and 336μs respectively.
文摘Based on mirror-blocks,a totally coded algorithm(TCA) for switched-current(SI) network analysis in frequency domain is presented.The algorithm is simple,available,and suitable for any switched-current networks.A basis of analysis and design for switched-current networks via this algorithm is provided.
基金supported by the China Postdoctoral Science Foundation(Grant No.2013M541286)the Science and Technology Planning Project of Jilin Province,China(Grant Nos.20140520109JH and 20150414003GH)the “Twelfth Five year” Scientific and Technological Research Project of Department of Education of Jilin Province,China
文摘We perform micromagnetic simulations on the switching of magnetic vortex core by using spin-polarized currents through a three-nanocontact geometry. Our simulation results show that the current combination with an appropriate current flow direction destroys the symmetry of the total effective energy of the system so that the vortex core can be easier to excite,resulting in less critical current density and a faster switching process. Besides its fundamental significance, our findings provide an additional route to incorporating magnetic vortex phenomena into data storage devices.
文摘This paper presents a new type of fault current limiter (FCL) based on fast closing switch, which is composed of a capacitor bank and a reactor in series. The main control component is a fast closing switch connected in parallel with the capacitors, which is driven by the electromagnetic repulsion force. It can response the order within 1 ms. When fault occurs, the switch closes and the capacitors are bypassed, and the fault current is limited by the reactor. Simulation analysis and experiment show that the electromagnetic repulsion force actuator can meet the demand of fast closing switch, it is feasible to develop the FCL with low cost and high reliability.
文摘A novel current chopping mode was used in a switched reluctance motor drive system to make full use of the characteristics of digital signal processor (DSP) TMS320F240. The necessity of this 180° phase-shift current control (PSCC) mode is introduced first and then the principle of PSCC covering both hardware requirement and software programming is described in detail. The analysis made indicated that with this mode, the chopping frequency in winding can reach 20 kHz with 10 kHz power switches and the control frequency can reach 40 kHz at the same time. Subsequently, based on the linear and nonlinear mathematical models of the switched reluctance motor (SRM), some simulation work has been done. The simulation results show that when this mode is applied to SRM drive (SRD) system, the current waveform becomes better. So the ripple of the torque is reduced simultaneously and the vibration and acoustic noise are reduced involuntarily. Stationary tests show that the acoustic noise is greatly diminished. Finally, some experiments were made using a 50 kW SRD system for electric vehicle (EV). Experimental results indicate that this mode can be implemented feasibly and it has a good action on the SRD system.
基金supported by National Natural Science Foundation of China(No.51177131)the Fundamental Research Funds for the Central Universities of China(No.xjj20100159)
文摘The characteristics of the triggered vacuum switch (TVS) are obviously influenced by the emission current ie and emission charge of the trigger device. In this paper, an RC charge collector is designed, and the characteristics of emission current ie and collecting charge Qc of the trigger device are studied. The experimental results indicate that the emission current ie which is produced by the initial plasma has both positive and negative components, and the polarity of the emission current ie depends mainly on the polarity of the bias voltage UBias. The emission current ie and collecting charge Qe increase with the increase of the trigger voltage Utr and the bias voltage UBias. The emission efficient r] increases linearly with the increase of the bias voltage UBias. When the gap distance is 15 mm and bias voltage UBias is 160 V and trigger voltage Utr is 2.6 kV, the emission efficiency r/reaches 6%
文摘A new type of fault current limiter (FCL) with series compensation based fast-closing switch is proposed. It is composed of a capacitor bank and a reactor in series. The main control component is a fast-closing switch connected in parallel with the capacitors, which is driven by the electromagnetic repulsion force. When fault occurs, the switch closes and bypasses the capacitors, and the fault is limited by the reactor then. Simulated analysis and experiments show that it is feasible to develop the FCL with low cost and high reliability. The effectiveness of transient stability for power system is evaluated by digital simulation.