This work presents an implementation of an innovative single phase multilevel inverter using capacitors with reduced switches. The proposed Capacitor pattern H-bridge Multilevel Inverter (CPHMLI) topology consists of ...This work presents an implementation of an innovative single phase multilevel inverter using capacitors with reduced switches. The proposed Capacitor pattern H-bridge Multilevel Inverter (CPHMLI) topology consists of a proper number of Capacitor connected with switches and power sources. The advanced switching control supplied by Pulse Width Modulation (PDPWM) to attain mixed staircase switching state. The charging and discharging mode are achieved by calculating the voltage error at the load. Furthermore, to accomplish the higher voltage levels at the output with less number of semiconductors switches and simple commutation designed using CPHMLI topology. To prove the performance and effectiveness of the proposed approach, a set of experiments performed under various load conditions using MATLAB tool.展开更多
A retarding field energy analyzer(RFEA) is used to measure the time-averaged ion energy distributions(IEDs) on the substrate in both continuous wave(CW) and synchronous pulse modulated radio-frequency(RF) indu...A retarding field energy analyzer(RFEA) is used to measure the time-averaged ion energy distributions(IEDs) on the substrate in both continuous wave(CW) and synchronous pulse modulated radio-frequency(RF) inductively coupled Ar plasmas(ICPs).The effects of the phase shift θ between the RF bias voltage and the RF source on the IED is investigated under various discharge conditions.It is found that as θ increases from 0 to π,the IED moves towards the low-energy side,and its energy width becomes narrower.In order to figure out the physical mechanism,the voltage waveforms on the substrate are also measured.The results show that as θ increases from 0 to π,the amplitude of the voltage waveform decreases and,meanwhile,the average sheath potential decreases as well.Specifically,the potential drop in the sheath on the substrate exhibits a maximum value at the same phase(i.e.,θ = 0) and a minimum value at the opposite phase(i.e.,θ = π).Therefore,when ions traverse across the sheath region above the substrate,they obtain less energies at lower sheath potential drop,leading to lower ion energy.Besides,as θ increases from π to 2π,the IEDs and their energy widths change reversely.展开更多
Multilevel inverters are gaining popularity in high power applications. This paper proposes a new ladder type structure of cascaded three-phase multilevel inverter with reduced number of power semiconductor devices wh...Multilevel inverters are gaining popularity in high power applications. This paper proposes a new ladder type structure of cascaded three-phase multilevel inverter with reduced number of power semiconductor devices which is used to drive the induction motor. The ultimate aim of the paper is to produce multiple output levels with minimum number of semiconductor devices. This paper uses only 11 switches along with 3 diodes and 4 asymmetrical sources to produce an output voltage of 21 levels. The modulation technique plays a major role in commutation of the switches. Here we implement the multicarrier level shifting pulse width modulation technique to produce the commutation signals for the inverter. The proposed multilevel inverter is used to drive the three-phase induction motor. The mathematical modeling of three-phase induction motor is done using Simulink. Furthermore the PI and fuzzy logic controllers are also used to produce the reference waveform of the level shifting technique which in turn produces the commutation signals of the proposed multilevel converter. The controllers are used to control the speed of the induction motor. The effectiveness of the proposed system is proved with the help of simulation. The simulation is performed in MATLAB/Simulink. From the simulation results, it shows that the proposed multilevel inverter works properly to generate the multilevel output waveform with minimum number of semiconductor devices. The PI and fuzzy logic controller performances are evaluated using the results which indicate that with the help of controllers the harmonics has been reduced and the speed control of induction motor is achieved under different loading conditions.展开更多
高速磁浮交通牵引变流器采用24 MVA背靠背三电平有源中点钳位拓扑,其中两台整流器和两台逆变器共用直流母线。该文分析整流侧和逆变侧在不同功率因数下中点电压(neutral point voltage,NPV)偏移机理及不同电压矢量对NPV的具体影响。据此...高速磁浮交通牵引变流器采用24 MVA背靠背三电平有源中点钳位拓扑,其中两台整流器和两台逆变器共用直流母线。该文分析整流侧和逆变侧在不同功率因数下中点电压(neutral point voltage,NPV)偏移机理及不同电压矢量对NPV的具体影响。据此,针对高速磁浮逆变器并联和串联两种模式,建立NPV偏移模型,得到在调制比和功率因数同时变化时NPV的可控区域。为在全速范围保证NPV平衡,提出一种基于平移调制波的协同控制策略。为减轻整流器功率因数和调制比对NPV的影响,采用一种具有相电压半波对称性的载波脉宽调制,并证明其具备NPV自平衡能力。仿真和硬件在环实验表明,所提策略具有NPV恢复到平衡状态所需时间短、可控范围大等优点,可在高速磁浮全速工况下保证NPV平衡。展开更多
随着海上风电、光伏等新能源的大规模建设,产生了直流输电、交直流互联和储能的应用需求。目前储能技术的研究和应用主要集中于交流储能领域。模块化多电平电池储能系统(modular multilevel converter based battery energy storage sys...随着海上风电、光伏等新能源的大规模建设,产生了直流输电、交直流互联和储能的应用需求。目前储能技术的研究和应用主要集中于交流储能领域。模块化多电平电池储能系统(modular multilevel converter based battery energy storage system,MMC-BESS)虽然在交直流互联的同时,实现了储能的功能,但电池中流过的工频、二倍频等脉动电流成分对电池寿命有潜在影响,且传统的模块化多电平(modular multilevel converter,MMC)换流站的改造成本高。本工作提出的直流直挂储能装置将换流和储能分离,电池电流仅为直流和高频脉动成分,工况对电池友好,且直流直挂储能系统需要电池单体数量仅为MMC-BESS的1/6,成本低。对直流直挂储能装置的拓扑结构及工作原理进行分析;对级联子模块的数量和参数进行设计;基于载波移相调制,推导直流纹波电流,进而对并网电感参数进行设计;建立直流直挂储能装置的数学模型,推导控制模型,根据控制框图进行功率控制。最后,通过仿真和样机实验,验证该半桥拓扑级联型直流直挂储能装置设计的可行性及正确性。实验证明,该设计和控制方法效果良好,对高压大容量直流直挂储能装置的设计有一定参考价值。展开更多
Modular multilevel converters(MMCs) operate in the low modulation index region in many applications.However, when utilized at the low modulation index region, large harmonics appear in the output voltage, which degrad...Modular multilevel converters(MMCs) operate in the low modulation index region in many applications.However, when utilized at the low modulation index region, large harmonics appear in the output voltage, which degrade the performance of the MMC. To improve the harmonic characteristic in the low modulation index, the carrier dynamic overlapping switching frequency optimal pulse width modulation(CDOSFOPWM) method is proposed for the MMC here. The whole modulation index region is divided into three regions: high modulation index region, middle modulation index region, and low modulation index region. The carrier amplitude, carrier overlap ratio, and frequency of triangular carriers are chosen dynamically according to the modulation index region of the modulation signals, to achieve the optimal harmonic characteristic in the whole modulation index region and maintain the switching loss. The number of on-state submodules(SMs) can be calculated by CDOSFOPWM, and the selection of SMs is performed by a reducing switching frequency voltage balancing algorithm. Finally, the proposed method is verified by simulation and experimental results.展开更多
In this paper, a three-phase inverter with renewable source input is integrated into a grid in synchronization for power sharing by load. In previous topologies, the DC source connected inverter is not synchronized to...In this paper, a three-phase inverter with renewable source input is integrated into a grid in synchronization for power sharing by load. In previous topologies, the DC source connected inverter is not synchronized to the grid which causes harmonics and voltage distortions damaging the load and the source. In order to ensure power sharing by the load from the inverter and the grid, the inverter needs to be operated in synchronization to the grid with the same voltage mag-nitude, frequency and phase as that of the grid voltage. In this paper, the com-plete power from the load is shared by the three-phase grid and the three-phase inverter module reducing the consumption from the conventional grid. This is achieved using the PLL for the reference angular frequency generation with feedback from grid voltage and is connected to the sinusoidal PWM generator. The PLL is used to generate unit vector template reference signals for the signal generator operating the six-switch inverter. The inverter and grid are inter-connected through LC filter for the reduction of harmonics. The power sharing, voltage, and current graphs with THD analysis are analyzed with the help of the MATLAB software.展开更多
文摘This work presents an implementation of an innovative single phase multilevel inverter using capacitors with reduced switches. The proposed Capacitor pattern H-bridge Multilevel Inverter (CPHMLI) topology consists of a proper number of Capacitor connected with switches and power sources. The advanced switching control supplied by Pulse Width Modulation (PDPWM) to attain mixed staircase switching state. The charging and discharging mode are achieved by calculating the voltage error at the load. Furthermore, to accomplish the higher voltage levels at the output with less number of semiconductors switches and simple commutation designed using CPHMLI topology. To prove the performance and effectiveness of the proposed approach, a set of experiments performed under various load conditions using MATLAB tool.
基金Project supported by the Important National Science and Technology Specific Project,China(Grant No.2011ZX02403-001)the National Natural Science Foundation of China(Grand No.11675039)the Fundamental Research Funds for the Central Universities,China(Grand No.DUT16LK06)
文摘A retarding field energy analyzer(RFEA) is used to measure the time-averaged ion energy distributions(IEDs) on the substrate in both continuous wave(CW) and synchronous pulse modulated radio-frequency(RF) inductively coupled Ar plasmas(ICPs).The effects of the phase shift θ between the RF bias voltage and the RF source on the IED is investigated under various discharge conditions.It is found that as θ increases from 0 to π,the IED moves towards the low-energy side,and its energy width becomes narrower.In order to figure out the physical mechanism,the voltage waveforms on the substrate are also measured.The results show that as θ increases from 0 to π,the amplitude of the voltage waveform decreases and,meanwhile,the average sheath potential decreases as well.Specifically,the potential drop in the sheath on the substrate exhibits a maximum value at the same phase(i.e.,θ = 0) and a minimum value at the opposite phase(i.e.,θ = π).Therefore,when ions traverse across the sheath region above the substrate,they obtain less energies at lower sheath potential drop,leading to lower ion energy.Besides,as θ increases from π to 2π,the IEDs and their energy widths change reversely.
文摘Multilevel inverters are gaining popularity in high power applications. This paper proposes a new ladder type structure of cascaded three-phase multilevel inverter with reduced number of power semiconductor devices which is used to drive the induction motor. The ultimate aim of the paper is to produce multiple output levels with minimum number of semiconductor devices. This paper uses only 11 switches along with 3 diodes and 4 asymmetrical sources to produce an output voltage of 21 levels. The modulation technique plays a major role in commutation of the switches. Here we implement the multicarrier level shifting pulse width modulation technique to produce the commutation signals for the inverter. The proposed multilevel inverter is used to drive the three-phase induction motor. The mathematical modeling of three-phase induction motor is done using Simulink. Furthermore the PI and fuzzy logic controllers are also used to produce the reference waveform of the level shifting technique which in turn produces the commutation signals of the proposed multilevel converter. The controllers are used to control the speed of the induction motor. The effectiveness of the proposed system is proved with the help of simulation. The simulation is performed in MATLAB/Simulink. From the simulation results, it shows that the proposed multilevel inverter works properly to generate the multilevel output waveform with minimum number of semiconductor devices. The PI and fuzzy logic controller performances are evaluated using the results which indicate that with the help of controllers the harmonics has been reduced and the speed control of induction motor is achieved under different loading conditions.
文摘高速磁浮交通牵引变流器采用24 MVA背靠背三电平有源中点钳位拓扑,其中两台整流器和两台逆变器共用直流母线。该文分析整流侧和逆变侧在不同功率因数下中点电压(neutral point voltage,NPV)偏移机理及不同电压矢量对NPV的具体影响。据此,针对高速磁浮逆变器并联和串联两种模式,建立NPV偏移模型,得到在调制比和功率因数同时变化时NPV的可控区域。为在全速范围保证NPV平衡,提出一种基于平移调制波的协同控制策略。为减轻整流器功率因数和调制比对NPV的影响,采用一种具有相电压半波对称性的载波脉宽调制,并证明其具备NPV自平衡能力。仿真和硬件在环实验表明,所提策略具有NPV恢复到平衡状态所需时间短、可控范围大等优点,可在高速磁浮全速工况下保证NPV平衡。
文摘随着海上风电、光伏等新能源的大规模建设,产生了直流输电、交直流互联和储能的应用需求。目前储能技术的研究和应用主要集中于交流储能领域。模块化多电平电池储能系统(modular multilevel converter based battery energy storage system,MMC-BESS)虽然在交直流互联的同时,实现了储能的功能,但电池中流过的工频、二倍频等脉动电流成分对电池寿命有潜在影响,且传统的模块化多电平(modular multilevel converter,MMC)换流站的改造成本高。本工作提出的直流直挂储能装置将换流和储能分离,电池电流仅为直流和高频脉动成分,工况对电池友好,且直流直挂储能系统需要电池单体数量仅为MMC-BESS的1/6,成本低。对直流直挂储能装置的拓扑结构及工作原理进行分析;对级联子模块的数量和参数进行设计;基于载波移相调制,推导直流纹波电流,进而对并网电感参数进行设计;建立直流直挂储能装置的数学模型,推导控制模型,根据控制框图进行功率控制。最后,通过仿真和样机实验,验证该半桥拓扑级联型直流直挂储能装置设计的可行性及正确性。实验证明,该设计和控制方法效果良好,对高压大容量直流直挂储能装置的设计有一定参考价值。
基金supported by National Natural Science Foundation of China(No.51477045)
文摘Modular multilevel converters(MMCs) operate in the low modulation index region in many applications.However, when utilized at the low modulation index region, large harmonics appear in the output voltage, which degrade the performance of the MMC. To improve the harmonic characteristic in the low modulation index, the carrier dynamic overlapping switching frequency optimal pulse width modulation(CDOSFOPWM) method is proposed for the MMC here. The whole modulation index region is divided into three regions: high modulation index region, middle modulation index region, and low modulation index region. The carrier amplitude, carrier overlap ratio, and frequency of triangular carriers are chosen dynamically according to the modulation index region of the modulation signals, to achieve the optimal harmonic characteristic in the whole modulation index region and maintain the switching loss. The number of on-state submodules(SMs) can be calculated by CDOSFOPWM, and the selection of SMs is performed by a reducing switching frequency voltage balancing algorithm. Finally, the proposed method is verified by simulation and experimental results.
文摘In this paper, a three-phase inverter with renewable source input is integrated into a grid in synchronization for power sharing by load. In previous topologies, the DC source connected inverter is not synchronized to the grid which causes harmonics and voltage distortions damaging the load and the source. In order to ensure power sharing by the load from the inverter and the grid, the inverter needs to be operated in synchronization to the grid with the same voltage mag-nitude, frequency and phase as that of the grid voltage. In this paper, the com-plete power from the load is shared by the three-phase grid and the three-phase inverter module reducing the consumption from the conventional grid. This is achieved using the PLL for the reference angular frequency generation with feedback from grid voltage and is connected to the sinusoidal PWM generator. The PLL is used to generate unit vector template reference signals for the signal generator operating the six-switch inverter. The inverter and grid are inter-connected through LC filter for the reduction of harmonics. The power sharing, voltage, and current graphs with THD analysis are analyzed with the help of the MATLAB software.