A design for a Li-ion battery charger IC that can operate in a constant current-constant voltage （CC- CV） charge mode is proposed. In the CC-CV charge mode,the charger IC provides a constant charging current at the ...A design for a Li-ion battery charger IC that can operate in a constant current-constant voltage （CC- CV） charge mode is proposed. In the CC-CV charge mode,the charger IC provides a constant charging current at the beginning, and then the charging current begins to decrease before the battery voltage reaches its final value. After the battery voltage reaches its final value and remains constant,the charging current is further reduced. This approach prevents charging the battery with full current near its saturated voltage,which can cause heating. The novel design of the core of the charger IC realizes the proposed CC-CV charge mode. The chip was implemented in a CSMC 0.6μm CMOS mixed signal process. The experimental results verify the realization of the proposed CC- CV charge mode. The voltage of the battery after charging is 4. 1833V.展开更多
A novel onchip frequency compensation circuit for a voltagemode control DC/DC converter is pre sented. By employing an RC network in the two signal paths of an operational transconductance amplifier （OTA）, the propo...A novel onchip frequency compensation circuit for a voltagemode control DC/DC converter is pre sented. By employing an RC network in the two signal paths of an operational transconductance amplifier （OTA）, the proposed circuit generates two zeros to realize high closedloop stability. Meanwhile, full onchip integration is also achieved due to its simple structure. Hence, the number of offchip components and the board space is greatly reduced. The structure of the dual signal path OTA is also optimized to help get a better transition response. Im plemented in a 0.5 #m CMOS process, the voltage mode control DC/DC converter with the proposed frequency compensation circuit exhibits good stability. The test results show that both load and line regulations are less than 0.3%, and the output voltage can be recovered within 15 #s for a 400 mA load step. Moreover, the compensation components area is less than 2% of the die＇s area and the board space is also reduced by 11%. The efficiency of the whole chip can be up to 95%.展开更多
A feedback control system is needed to restrain plasma vertical displacement in EAST （Experimental Advanced Superconducting Toknmak）. A fast control power supply excites active feedback coils, which produces a magne...A feedback control system is needed to restrain plasma vertical displacement in EAST （Experimental Advanced Superconducting Toknmak）. A fast control power supply excites active feedback coils, which produces a magnetic field to control the plasma＇s displacement. With the development of EAST, new demands on the new fast control power supply have led to an enhanced ability of fast response and output current, as well as a new control mode. The structure of cascaded and paralleled H-bridges can meet the demand of extended capacity, and digital control can reMize current and voltage mixed control mode. The validity of the proposed scheme is confirmed by experiments.展开更多
The multiplicity of vector combinations for vectors of combined three-level inverters plays an important role, when deciding on the modulation scheme, to obtain minimum switching per inverter vector change, as describ...The multiplicity of vector combinations for vectors of combined three-level inverters plays an important role, when deciding on the modulation scheme, to obtain minimum switching per inverter vector change, as described in the next Section. This is not possible with reduced common-mode three-level inverter structure, obtained with a five-level cascaded H-bridge configuration, as the space vectors locations do not exhibit multiplicity. Moreover, the proposed configuration requires only two power supplies, whereas the scheme with the five-level H-bridge configuration requires six isolated power supplies.展开更多
The multiplicity of vector combinations for vectors of combined three-level inverters plays an important role, when deciding on the modulation scheme, to obtain minimum switching per inverter vector change, as describ...The multiplicity of vector combinations for vectors of combined three-level inverters plays an important role, when deciding on the modulation scheme, to obtain minimum switching per inverter vector change, as described in the next Section. This is not possible with reduced common-mode three-level inverter structure, obtained with a five-level cascaded H-bridge configuration, as the space vectors locations do not exhibit multiplicity. Moreover, the proposed configuration requires only two power supplies, whereas the scheme with the five-level H-bridge configuration requires six isolated power supplies.展开更多
This paper presents an improved,energy-efficient Model Predictive Current Control(MPCC)strategy based on centroid-based virtual voltage vector synthesis for three-phase inverter-fed induction motor drives in electric ...This paper presents an improved,energy-efficient Model Predictive Current Control(MPCC)strategy based on centroid-based virtual voltage vector synthesis for three-phase inverter-fed induction motor drives in electric vehicle(EV)applications.Unlike conventional finite-set MPCC methods that rely on cost function evaluation over discrete switching states,the proposed approach eliminates the need for look-up tables by employing a pre-defined set of virtual vectors.These centroid-based virtual voltage vectors are synthesized by combining two adjacent active vectors and two nonzero voltage vectors in opposite directions adjacent to the sector replacing the traditional switching set.They approximate the reference voltage vector in both magnitude and phase angle,thereby reducing current tracking error through a simplified cost function.The number of candidate vectors is reduced,preserving computational efficiency.Furthermore,the scheme ensures zero average common-mode voltage(CMV)per sampling interval by completely avoiding zero-voltage vectors(ZVVs).The proposed method reduces torque ripple by up to 17%compared to the conventional approach and lowers stator current total harmonic distortion(THD)by 37%,while ensuring evenly distributed switching transitions among inverter legs.This results in reduced switching losses and enhanced drive efficiency-particularly advantageous in EV applications.Experimental validation under the high-speed extra urban driving cycle(EUDC)and low-speed ECE-R15 cycle,including torque ripple and energy consumption analysis,confirms the effectiveness of the approach,achieving an overall efficiency of 83.3%.展开更多
A new insight into the constant current-constant voltage （CC-CV） charge protocol based on the spherical diffusion model was presented. From the model, the CV-charge process compensates, to a large extent, the capaci...A new insight into the constant current-constant voltage （CC-CV） charge protocol based on the spherical diffusion model was presented. From the model, the CV-charge process compensates, to a large extent, the capacity loss in the CC process, and the capacity loss increases with increasing the charging rate and decreases with increasing the lithium-ion diffusion coefficient and using a smaller r value （smaller particle-size and larger diffusion coefficient） and a lower charge rate will be helpful to decreasing the capacity loss. The results show that the CC and the CV charging processes, in some way, are complementary and the capacity loss during the CC charging process due to the large electrochemical polarization can be effectively compensated from the CV charging process.展开更多
A new approach for the design and implementation of a programmable voltage reference based on an improved current mode bandgap voltage reference is presented. The circuit is simulated and fabricated with Chartered 0....A new approach for the design and implementation of a programmable voltage reference based on an improved current mode bandgap voltage reference is presented. The circuit is simulated and fabricated with Chartered 0. 35μm mixed-signal technology. Measurements demonstrate that the temperature coefficient is ± 36. 3ppm/℃ from 0 to 100℃ when the VID inputs are 11110.As the supply voltage is varied from 2.7 to 5V, the voltage reference varies by about 5mV. The maximum glitch of the transient response is about 20mV at 125kHz. Depending on the state of the five VID inputs,an output voltage between 1.1 and 1.85V is programmed in increments of 25mV.展开更多
A new technique for the conversion of ladder based filter into CFOA based filter has been proposed. The technique uses signal flow graph and converts the existing LC ladder based filter into band pass & band stop ...A new technique for the conversion of ladder based filter into CFOA based filter has been proposed. The technique uses signal flow graph and converts the existing LC ladder based filter into band pass & band stop configurations. The design of band pass and band stop filter has been realized using the proposed technique. The proposed configuration is implemented using CFOA as an active device and all the capacitors are grounded. CFOA based circuits have greater linearity, high dynamic rate, high slew rate and high signal bandwidth. Simulation has been carried out using simulation software P Spice (v10.1). The simulation results have been demonstrated and discussed.展开更多
A new modified extended state observer(MESO)-based robustness voltage sliding mode control(SMC)strategy is proposed for an AC islanded microgrid under system uncertainties including system parameter and load variation...A new modified extended state observer(MESO)-based robustness voltage sliding mode control(SMC)strategy is proposed for an AC islanded microgrid under system uncertainties including system parameter and load variation.First,the disturbance effect on the system is regarded as a lumped uncertainty,and a state space model of the uncertain islanded microgrid system is established.Then,a modified extended state observer is designed to estimate external disturbances and internal perturbation.Finally,considering the lumped uncertainty,a sliding mode controller with a multi-power reaching law is proposed to enable the output voltage of the system to track its reference voltage rapidly and accurately,and to enhance the robustness of the system.The simulation results confirm that the proposed robustness voltage control strategy can perform satisfactory voltage control and demonstrate a strong capability to reject parameter and load variation.展开更多
A new ride through strategy is introduced in a three-level dual Z-source inverter, for isolation under semiconductor switching failure condition. Here the output will have no significant decrease in the amplitude and ...A new ride through strategy is introduced in a three-level dual Z-source inverter, for isolation under semiconductor switching failure condition. Here the output will have no significant decrease in the amplitude and quality. Instead of diodes, the triacs are added to the inverter source ends, as it can perform a bidirectional power transfer also it can operate well in both low and high voltage operating conditions. The faulted part can be isolated by simply altering the firing pulses for turning on/off the triacs using the carrier based SPWM technique and resulting in a boosting output with zero common mode voltage. Consequently, it forms a common floating point or null point with a zero common mode voltage. It is experimentally verified by using MATLAB, and digital oscilloscope.展开更多
The basic configuration of step up converter usually used in photovoltaic solar systems to increase the DC voltage generated at their outputs suffers from some drawbacks just like high ripple in the output voltage,gre...The basic configuration of step up converter usually used in photovoltaic solar systems to increase the DC voltage generated at their outputs suffers from some drawbacks just like high ripple in the output voltage,greater losses in the system and unstable dynamic behavior.To eliminate these drawbacks,this paper introduces a two-phase connection of step up converter with uncoupled smoothing reactors.Detailed analysis,simulation and control strategy have been proposed in this paper to investigate the advantages of using such connection with uncoupled reactors.This paper is intended to prove that two-phase connection with uncoupled reactors helps increasing the output power of the converter,minimizing its output ripple and making its control easier and more efficient.It also increases the converter chopping frequency and consequently decreases the size of smoothing reactors and filters used in the system.Concerning the design of such converters,it requires a long working period of time with a significant cost and specific technical tests at nominal operating points.Therefore,simulation can essentially decrease economic and development costs.Using modulation and simulation software techniques(Simplorer,Simulink,and Matlab)throughout this paper helped simulation of very fast the converter behavior and accurate determination of its dynamic characteristics.Moreover,the paper deals with modulation of voltage control technique using Matlab and Simplorer,thus regulating the converter output current and voltage.Simulation results show that this control technique provides robust output current and voltage of step up converters and is more feasible for their chopper up conversion technique.展开更多
Due to the advantages such as low line cost,low transmission loss,and high power supply reliability,DC distribution networks have become the main development trend for future distribution networks.In this paper,a typi...Due to the advantages such as low line cost,low transmission loss,and high power supply reliability,DC distribution networks have become the main development trend for future distribution networks.In this paper,a typical DC distribution network with multiple voltage levels is considered as a research object.It is proposed that the interface converters between DC buses with different voltage levels be implemented through the series-parallel combination of full-bridge LLC resonant converters.To realize the decentralized self-discipline control of DC voltage under various working conditions,different slack buses are prepared according to the voltage ranges of the DC buses,and the voltage regulation modes of the DC distribution network are divided into main voltage regulation mode,backup voltage regulation mode,and off-grid voltage droop regulation mode.By introducing a voltage coefficient related to DC voltage deviation as a basis for mode switching,the voltage fluctuations caused by slow switching between control modes in the method of traditional voltage margin control is reduced,facilitating fast and smooth switching between different voltage regulation modes.Finally,a simulation model for DC distribution networks is constructed utilizing MATLAB/Simulink.Simulation results verify the effectiveness and feasibility of the proposed voltage regulation modes and switching methods for DC distribution networks.Finally,an experimental platform is also constructed to verify the feasibility of the mode switching method proposed in this paper.展开更多
Electric locomotives on the horizon will integrate SiC inverters,promising quicker switching and lower losses than traditional setups.However,in addition to the steep rising edge,the inverter-fed motor drive system fa...Electric locomotives on the horizon will integrate SiC inverters,promising quicker switching and lower losses than traditional setups.However,in addition to the steep rising edge,the inverter-fed motor drive system faces challenges such as high common-mode voltage(CMV)and high motor terminal surge voltage swing rate(dv/dt).To tackle these hurdles,this paper proposes a novel tailored traction control system for three-phase locomotive motors.This innovative strategy utilises nearstate space vector pulse width modulation(NSVPWM),selectively removing space vectors with high CMV to generate modulation signals.Complemented by a slew rate capacitor configuration,the aim is to reduce CMV while effectively suppressing motor-side voltage slew rate.To validate this approach,experimental waveforms from on-site inverter-fed motor drive systems have been analysed to derive high-frequency parameters of long-line cables and variable frequency motors to mimic real locomotive operating conditions better.Through experimental research and comparative simulations against traditional methods,this study reveals a significant 33.3%reduction in CMV compared to traditional systems.Furthermore,it achieves an impressive decrease in the rise/fall slope,down to 86.6%,while ensuring nearly zero electrical power consumption.展开更多
The implementation of modular multilevel converters(MMC)in an electric ship to create a medium voltage direct current(MVDC)energy conversion system that is efficient,small,dependable,and easily scalable has garnered c...The implementation of modular multilevel converters(MMC)in an electric ship to create a medium voltage direct current(MVDC)energy conversion system that is efficient,small,dependable,and easily scalable has garnered considerable interest.In this research,an improved two-step nearest level control(E-NLC)is presented for MMC with a three-level submodule(3L-SM)as the rectifier of the electric ship power generation units in order to ease the economical and reliable operation of MMCs in MVDC systems.To achieve DC fault-clearing capability,the use of MMC with 3L-SM minimizes the number of switching devices when compared to the regular MMC topology.The suggested E-NLC scheme aims to reduce total harmonic distortion(THD)and achieve the nearest zero common mode voltage(CMV).The output voltage vector of the three phases is tuned using eight candidate vectors capable of suppressing CMV rather than the nearest-level vector,and the rounding function is modified to improve harmonic performance by increasing the approximation between stepped and modulated waves.The generator-connected MMC with THD reduction and CMV elimination maximizes the mover's protection in the generating unit of the electric ship's MVDC system.Simulation and experiment results validate the efficacy of the suggested approach with respect to steady-state and dynamic-state performance.展开更多
In this paper, different electrical measurement and operation methods of resistive random access memory （RRAM） have been summarized, including voltage sweeping mode （VSM）, current sweeping mode （CSM）, co lstant ...In this paper, different electrical measurement and operation methods of resistive random access memory （RRAM） have been summarized, including voltage sweeping mode （VSM）, current sweeping mode （CSM）, co lstant current stress （CCS）, constant voltage stress （CVS）, rectangular pulse mode （RPM）, and triangle pulse mode （TPM）. Meanwhile, the effects of these meas- urement methods on the forming, set, reset and read operation as well as endurance performance have been compared. Finally, their respective controllability of various resistive switching parameters have been summar zeal and analyzed.展开更多
The paper presents a five-level common ground type(5L-CGT),transformer-less inverter topology with double voltage boosting.The proposed inverter uses eight switches and two capacitors,charged at input voltage level.Th...The paper presents a five-level common ground type(5L-CGT),transformer-less inverter topology with double voltage boosting.The proposed inverter uses eight switches and two capacitors,charged at input voltage level.The inverter in its basic form acts as a string inverter for low-power PV applications.However,it can be extended to work as a scalable multi-level inverter with higher power handling capability to act as a centralized inverter.The working of the inverter with the sizing of the components is presented with mathematical analysis.The efficiency of the proposed PV inverter is found using thermal losses associated with switches using PLECS software.A prototype of 1 kW has been designed,and experimentation has been carried out.Various loads with a lagging power factor up to 0.6 have been tested with the inverter to establish the usability of the proposed inverter in a worst-case emulated homeuse scenario.The total harmonic distortion(THD)at the output has been recorded using a power quality analyzer with voltage and current THD values of 4.5%and 2.5%,respectively,which lies within the limits of IEEE 519 standards.The highest power conversion efficiency of the inverter has been recorded to be 96.20%.展开更多
A general growth is being seen in the use of renewable energy resources,and photovoltaic cells are becoming increasingly popular for converting green renewable solar energy into electricity.Since the voltage produced ...A general growth is being seen in the use of renewable energy resources,and photovoltaic cells are becoming increasingly popular for converting green renewable solar energy into electricity.Since the voltage produced by pho-tovoltaic cells is DC,an inverter is required to connect them to the grid with or without transformers.Transformerless inverters are often used for their low cost and low power loss,and light weight.However,these inverters suffer from leakage current in the system,a challenge that needs to be addressed.In this paper,a topology with two alternative connection models is presented to stabilize the common mode voltage and reduce the leakage current.The output voltage characteristic of the proposed inverter is five-level,which reduces the harmonic distortion in the output cur-rent compared to the two-and three-level inverters.The operation modes and output of the proposed topology are described and analyzed.The structures of the proposed inverter are simulated in MATLAB/Simulink and are compared with some well-known structures.Results show that the proposed structure with both connection models effectively reduces leakage current and improves grid current THD.展开更多
文摘A design for a Li-ion battery charger IC that can operate in a constant current-constant voltage （CC- CV） charge mode is proposed. In the CC-CV charge mode,the charger IC provides a constant charging current at the beginning, and then the charging current begins to decrease before the battery voltage reaches its final value. After the battery voltage reaches its final value and remains constant,the charging current is further reduced. This approach prevents charging the battery with full current near its saturated voltage,which can cause heating. The novel design of the core of the charger IC realizes the proposed CC-CV charge mode. The chip was implemented in a CSMC 0.6μm CMOS mixed signal process. The experimental results verify the realization of the proposed CC- CV charge mode. The voltage of the battery after charging is 4. 1833V.
基金Project supported by the National Natural Science Foundation of China(No.60876023)the Fundamental Research Funds for the Central Universities,China(No.K50511020031 )
文摘A novel onchip frequency compensation circuit for a voltagemode control DC/DC converter is pre sented. By employing an RC network in the two signal paths of an operational transconductance amplifier （OTA）, the proposed circuit generates two zeros to realize high closedloop stability. Meanwhile, full onchip integration is also achieved due to its simple structure. Hence, the number of offchip components and the board space is greatly reduced. The structure of the dual signal path OTA is also optimized to help get a better transition response. Im plemented in a 0.5 #m CMOS process, the voltage mode control DC/DC converter with the proposed frequency compensation circuit exhibits good stability. The test results show that both load and line regulations are less than 0.3%, and the output voltage can be recovered within 15 #s for a 400 mA load step. Moreover, the compensation components area is less than 2% of the die＇s area and the board space is also reduced by 11%. The efficiency of the whole chip can be up to 95%.
基金supported by ITER Program of China(973 Program)(No.2011GB109002)National Natural Science Foundation of China(No.11275056)Hefei University of Technology Doctor Research Foundation of China(No.2011HGBZ1292)
文摘A feedback control system is needed to restrain plasma vertical displacement in EAST （Experimental Advanced Superconducting Toknmak）. A fast control power supply excites active feedback coils, which produces a magnetic field to control the plasma＇s displacement. With the development of EAST, new demands on the new fast control power supply have led to an enhanced ability of fast response and output current, as well as a new control mode. The structure of cascaded and paralleled H-bridges can meet the demand of extended capacity, and digital control can reMize current and voltage mixed control mode. The validity of the proposed scheme is confirmed by experiments.
文摘The multiplicity of vector combinations for vectors of combined three-level inverters plays an important role, when deciding on the modulation scheme, to obtain minimum switching per inverter vector change, as described in the next Section. This is not possible with reduced common-mode three-level inverter structure, obtained with a five-level cascaded H-bridge configuration, as the space vectors locations do not exhibit multiplicity. Moreover, the proposed configuration requires only two power supplies, whereas the scheme with the five-level H-bridge configuration requires six isolated power supplies.
文摘The multiplicity of vector combinations for vectors of combined three-level inverters plays an important role, when deciding on the modulation scheme, to obtain minimum switching per inverter vector change, as described in the next Section. This is not possible with reduced common-mode three-level inverter structure, obtained with a five-level cascaded H-bridge configuration, as the space vectors locations do not exhibit multiplicity. Moreover, the proposed configuration requires only two power supplies, whereas the scheme with the five-level H-bridge configuration requires six isolated power supplies.
文摘This paper presents an improved,energy-efficient Model Predictive Current Control(MPCC)strategy based on centroid-based virtual voltage vector synthesis for three-phase inverter-fed induction motor drives in electric vehicle(EV)applications.Unlike conventional finite-set MPCC methods that rely on cost function evaluation over discrete switching states,the proposed approach eliminates the need for look-up tables by employing a pre-defined set of virtual vectors.These centroid-based virtual voltage vectors are synthesized by combining two adjacent active vectors and two nonzero voltage vectors in opposite directions adjacent to the sector replacing the traditional switching set.They approximate the reference voltage vector in both magnitude and phase angle,thereby reducing current tracking error through a simplified cost function.The number of candidate vectors is reduced,preserving computational efficiency.Furthermore,the scheme ensures zero average common-mode voltage(CMV)per sampling interval by completely avoiding zero-voltage vectors(ZVVs).The proposed method reduces torque ripple by up to 17%compared to the conventional approach and lowers stator current total harmonic distortion(THD)by 37%,while ensuring evenly distributed switching transitions among inverter legs.This results in reduced switching losses and enhanced drive efficiency-particularly advantageous in EV applications.Experimental validation under the high-speed extra urban driving cycle(EUDC)and low-speed ECE-R15 cycle,including torque ripple and energy consumption analysis,confirms the effectiveness of the approach,achieving an overall efficiency of 83.3%.
基金Projects(20676152, 20876178) supported by the National Natural Science Foundation of China
文摘A new insight into the constant current-constant voltage （CC-CV） charge protocol based on the spherical diffusion model was presented. From the model, the CV-charge process compensates, to a large extent, the capacity loss in the CC process, and the capacity loss increases with increasing the charging rate and decreases with increasing the lithium-ion diffusion coefficient and using a smaller r value （smaller particle-size and larger diffusion coefficient） and a lower charge rate will be helpful to decreasing the capacity loss. The results show that the CC and the CV charging processes, in some way, are complementary and the capacity loss during the CC charging process due to the large electrochemical polarization can be effectively compensated from the CV charging process.
文摘A new approach for the design and implementation of a programmable voltage reference based on an improved current mode bandgap voltage reference is presented. The circuit is simulated and fabricated with Chartered 0. 35μm mixed-signal technology. Measurements demonstrate that the temperature coefficient is ± 36. 3ppm/℃ from 0 to 100℃ when the VID inputs are 11110.As the supply voltage is varied from 2.7 to 5V, the voltage reference varies by about 5mV. The maximum glitch of the transient response is about 20mV at 125kHz. Depending on the state of the five VID inputs,an output voltage between 1.1 and 1.85V is programmed in increments of 25mV.
文摘A new technique for the conversion of ladder based filter into CFOA based filter has been proposed. The technique uses signal flow graph and converts the existing LC ladder based filter into band pass & band stop configurations. The design of band pass and band stop filter has been realized using the proposed technique. The proposed configuration is implemented using CFOA as an active device and all the capacitors are grounded. CFOA based circuits have greater linearity, high dynamic rate, high slew rate and high signal bandwidth. Simulation has been carried out using simulation software P Spice (v10.1). The simulation results have been demonstrated and discussed.
文摘A new modified extended state observer(MESO)-based robustness voltage sliding mode control(SMC)strategy is proposed for an AC islanded microgrid under system uncertainties including system parameter and load variation.First,the disturbance effect on the system is regarded as a lumped uncertainty,and a state space model of the uncertain islanded microgrid system is established.Then,a modified extended state observer is designed to estimate external disturbances and internal perturbation.Finally,considering the lumped uncertainty,a sliding mode controller with a multi-power reaching law is proposed to enable the output voltage of the system to track its reference voltage rapidly and accurately,and to enhance the robustness of the system.The simulation results confirm that the proposed robustness voltage control strategy can perform satisfactory voltage control and demonstrate a strong capability to reject parameter and load variation.
文摘A new ride through strategy is introduced in a three-level dual Z-source inverter, for isolation under semiconductor switching failure condition. Here the output will have no significant decrease in the amplitude and quality. Instead of diodes, the triacs are added to the inverter source ends, as it can perform a bidirectional power transfer also it can operate well in both low and high voltage operating conditions. The faulted part can be isolated by simply altering the firing pulses for turning on/off the triacs using the carrier based SPWM technique and resulting in a boosting output with zero common mode voltage. Consequently, it forms a common floating point or null point with a zero common mode voltage. It is experimentally verified by using MATLAB, and digital oscilloscope.
文摘The basic configuration of step up converter usually used in photovoltaic solar systems to increase the DC voltage generated at their outputs suffers from some drawbacks just like high ripple in the output voltage,greater losses in the system and unstable dynamic behavior.To eliminate these drawbacks,this paper introduces a two-phase connection of step up converter with uncoupled smoothing reactors.Detailed analysis,simulation and control strategy have been proposed in this paper to investigate the advantages of using such connection with uncoupled reactors.This paper is intended to prove that two-phase connection with uncoupled reactors helps increasing the output power of the converter,minimizing its output ripple and making its control easier and more efficient.It also increases the converter chopping frequency and consequently decreases the size of smoothing reactors and filters used in the system.Concerning the design of such converters,it requires a long working period of time with a significant cost and specific technical tests at nominal operating points.Therefore,simulation can essentially decrease economic and development costs.Using modulation and simulation software techniques(Simplorer,Simulink,and Matlab)throughout this paper helped simulation of very fast the converter behavior and accurate determination of its dynamic characteristics.Moreover,the paper deals with modulation of voltage control technique using Matlab and Simplorer,thus regulating the converter output current and voltage.Simulation results show that this control technique provides robust output current and voltage of step up converters and is more feasible for their chopper up conversion technique.
基金supported by Fundamental Research Funds for the Central Universities(No.2019JBM057)。
文摘Due to the advantages such as low line cost,low transmission loss,and high power supply reliability,DC distribution networks have become the main development trend for future distribution networks.In this paper,a typical DC distribution network with multiple voltage levels is considered as a research object.It is proposed that the interface converters between DC buses with different voltage levels be implemented through the series-parallel combination of full-bridge LLC resonant converters.To realize the decentralized self-discipline control of DC voltage under various working conditions,different slack buses are prepared according to the voltage ranges of the DC buses,and the voltage regulation modes of the DC distribution network are divided into main voltage regulation mode,backup voltage regulation mode,and off-grid voltage droop regulation mode.By introducing a voltage coefficient related to DC voltage deviation as a basis for mode switching,the voltage fluctuations caused by slow switching between control modes in the method of traditional voltage margin control is reduced,facilitating fast and smooth switching between different voltage regulation modes.Finally,a simulation model for DC distribution networks is constructed utilizing MATLAB/Simulink.Simulation results verify the effectiveness and feasibility of the proposed voltage regulation modes and switching methods for DC distribution networks.Finally,an experimental platform is also constructed to verify the feasibility of the mode switching method proposed in this paper.
文摘Electric locomotives on the horizon will integrate SiC inverters,promising quicker switching and lower losses than traditional setups.However,in addition to the steep rising edge,the inverter-fed motor drive system faces challenges such as high common-mode voltage(CMV)and high motor terminal surge voltage swing rate(dv/dt).To tackle these hurdles,this paper proposes a novel tailored traction control system for three-phase locomotive motors.This innovative strategy utilises nearstate space vector pulse width modulation(NSVPWM),selectively removing space vectors with high CMV to generate modulation signals.Complemented by a slew rate capacitor configuration,the aim is to reduce CMV while effectively suppressing motor-side voltage slew rate.To validate this approach,experimental waveforms from on-site inverter-fed motor drive systems have been analysed to derive high-frequency parameters of long-line cables and variable frequency motors to mimic real locomotive operating conditions better.Through experimental research and comparative simulations against traditional methods,this study reveals a significant 33.3%reduction in CMV compared to traditional systems.Furthermore,it achieves an impressive decrease in the rise/fall slope,down to 86.6%,while ensuring nearly zero electrical power consumption.
文摘The implementation of modular multilevel converters(MMC)in an electric ship to create a medium voltage direct current(MVDC)energy conversion system that is efficient,small,dependable,and easily scalable has garnered considerable interest.In this research,an improved two-step nearest level control(E-NLC)is presented for MMC with a three-level submodule(3L-SM)as the rectifier of the electric ship power generation units in order to ease the economical and reliable operation of MMCs in MVDC systems.To achieve DC fault-clearing capability,the use of MMC with 3L-SM minimizes the number of switching devices when compared to the regular MMC topology.The suggested E-NLC scheme aims to reduce total harmonic distortion(THD)and achieve the nearest zero common mode voltage(CMV).The output voltage vector of the three phases is tuned using eight candidate vectors capable of suppressing CMV rather than the nearest-level vector,and the rounding function is modified to improve harmonic performance by increasing the approximation between stepped and modulated waves.The generator-connected MMC with THD reduction and CMV elimination maximizes the mover's protection in the generating unit of the electric ship's MVDC system.Simulation and experiment results validate the efficacy of the suggested approach with respect to steady-state and dynamic-state performance.
基金supported by the National Natural Science Foundation of China(Grant Nos.61322408,61221004,61422407,61334007,61474136,61274091,61376112,61306117,61106119,and 61106082)National Basic Research Program of China(Grant No.2011CBA00602)National High Technology Research and Development Program of China(Grant Nos.2014AA032900,2013AA030801,2011AA010401 and 2011AA-010402)
文摘In this paper, different electrical measurement and operation methods of resistive random access memory （RRAM） have been summarized, including voltage sweeping mode （VSM）, current sweeping mode （CSM）, co lstant current stress （CCS）, constant voltage stress （CVS）, rectangular pulse mode （RPM）, and triangle pulse mode （TPM）. Meanwhile, the effects of these meas- urement methods on the forming, set, reset and read operation as well as endurance performance have been compared. Finally, their respective controllability of various resistive switching parameters have been summar zeal and analyzed.
文摘The paper presents a five-level common ground type(5L-CGT),transformer-less inverter topology with double voltage boosting.The proposed inverter uses eight switches and two capacitors,charged at input voltage level.The inverter in its basic form acts as a string inverter for low-power PV applications.However,it can be extended to work as a scalable multi-level inverter with higher power handling capability to act as a centralized inverter.The working of the inverter with the sizing of the components is presented with mathematical analysis.The efficiency of the proposed PV inverter is found using thermal losses associated with switches using PLECS software.A prototype of 1 kW has been designed,and experimentation has been carried out.Various loads with a lagging power factor up to 0.6 have been tested with the inverter to establish the usability of the proposed inverter in a worst-case emulated homeuse scenario.The total harmonic distortion(THD)at the output has been recorded using a power quality analyzer with voltage and current THD values of 4.5%and 2.5%,respectively,which lies within the limits of IEEE 519 standards.The highest power conversion efficiency of the inverter has been recorded to be 96.20%.
文摘A general growth is being seen in the use of renewable energy resources,and photovoltaic cells are becoming increasingly popular for converting green renewable solar energy into electricity.Since the voltage produced by pho-tovoltaic cells is DC,an inverter is required to connect them to the grid with or without transformers.Transformerless inverters are often used for their low cost and low power loss,and light weight.However,these inverters suffer from leakage current in the system,a challenge that needs to be addressed.In this paper,a topology with two alternative connection models is presented to stabilize the common mode voltage and reduce the leakage current.The output voltage characteristic of the proposed inverter is five-level,which reduces the harmonic distortion in the output cur-rent compared to the two-and three-level inverters.The operation modes and output of the proposed topology are described and analyzed.The structures of the proposed inverter are simulated in MATLAB/Simulink and are compared with some well-known structures.Results show that the proposed structure with both connection models effectively reduces leakage current and improves grid current THD.
