Switched-capacitor/flying capacitor(FC)based multilevel converters have been gaining higher attention for their voltage-boosting ability.This feature makes them an attractive solution for renewable energy systems,such...Switched-capacitor/flying capacitor(FC)based multilevel converters have been gaining higher attention for their voltage-boosting ability.This feature makes them an attractive solution for renewable energy systems,such as low-voltage input photovoltaic power systems and electric vehicle systems.However,they usually require more high voltage rating switches and flying capacitors along with boosting capability.Furthermore,they suffer from high pulse currents at the switching transients.Aiming to solve these issues,this article proposes a new self-balancing three-phase five-level inverter based on the switched-capacitor(5L-SCTPNPC),which reduces the dc voltage requirement.The number of active switches is relatively smaller and seven active switches are required per phase.Especially,a soft-charging circuit for FC is designed to limit the impulse charging current.Compared to conventional multilevel inverters,the proposed five-level inverter reduces dc bus voltage by 50%.Significantly,the voltage stress of FC and the switches in parallel with FC are all reduced by 50%in comparison with some existing similar boosting five-level active-neutral-point-clamped(5L-BANPC)inverters.The operating principles,modulation strategy,and the design of the FC and charging inductor are provided in detailly.A comprehensive comparison study has been made to highlight the merits of the proposed inverter.Finally,the simulations and experiments validate the feasibility of the proposed topology.展开更多
Three space vector pulse width modulation （SVPWM） schemes, called 7-segment space vector modulation （SVM）, 5-segment SVM and 3-segment SVM are studied in this paper. The basic principle of SVPWM is presented. The ...Three space vector pulse width modulation （SVPWM） schemes, called 7-segment space vector modulation （SVM）, 5-segment SVM and 3-segment SVM are studied in this paper. The basic principle of SVPWM is presented. The switching sequence of different scheme is described. The modulation signals, DC bus voltage utilization, and output line voltage harmonic of these schemes are analyzed by the MATLAB software with different modulation index M and frequency modulation index N. The simulation results are analyzed and show that discontinuous modulating functions lead a reduction of switching actions. The DC bus voltage utilization of three schemes is almost the same. For all three SVM, the frequency modulation index N will affect the harmonic characteristic, and the modulation index M will affect DC bus voltage utilization and the harmonic content. The experiment is implemented by the DSP of TMS320F2812. The results validate three algorithms and the simulation.展开更多
With rapid increase of distributed solar power generation and direct current(DC)based loads such as data centers,electric vehicles(EVs),and DC household appliances,the development trend of the power system is changed ...With rapid increase of distributed solar power generation and direct current(DC)based loads such as data centers,electric vehicles(EVs),and DC household appliances,the development trend of the power system is changed from conventional alternate current(AC)to DC.Traditional AC power systems can scarcely meet the development demand of new DC trends,especially since both the generation side and load side are comprised of DC-based electronic power components.With this background,low voltage direct current supply and utilization system(LVDCSUS)has attracted more and more attention for its great advantages over an AC grid to overcome challenges in operation,reliability,and energy loss in renewable energy connection,DC load power utilization and a number of other aspects.However,the definition of the LVDCSUS is still not clear even though many demonstration projects have been put into planning and operation.In order to provide a clear description of LVDCSUS,first,the characteristics of LVDCSUS are illustrated in this paper to show the advance of the LVDCSUS.Second,the potential application scenarios of LVDCSUS are presented in this paper.Third,application of LVDCSUS technologies and some demonstration projects in China are introduced.Besides the development of the LVDCSUS,key technologies,including but not limited to planning and design,voltage levels,control strategies,and key equipment of LVDCSUS,are discussed in this paper.Finally,future application areas and the research orientations of LVDCSUS are analyzed.展开更多
基金supported by the National Natural Science Foundation of China(51977069)the National Natural Science Foundation Youth Project of China(52107195)the First Key Research and JieBang Headed Program,Hunan Province,China(2021GK1250).
文摘Switched-capacitor/flying capacitor(FC)based multilevel converters have been gaining higher attention for their voltage-boosting ability.This feature makes them an attractive solution for renewable energy systems,such as low-voltage input photovoltaic power systems and electric vehicle systems.However,they usually require more high voltage rating switches and flying capacitors along with boosting capability.Furthermore,they suffer from high pulse currents at the switching transients.Aiming to solve these issues,this article proposes a new self-balancing three-phase five-level inverter based on the switched-capacitor(5L-SCTPNPC),which reduces the dc voltage requirement.The number of active switches is relatively smaller and seven active switches are required per phase.Especially,a soft-charging circuit for FC is designed to limit the impulse charging current.Compared to conventional multilevel inverters,the proposed five-level inverter reduces dc bus voltage by 50%.Significantly,the voltage stress of FC and the switches in parallel with FC are all reduced by 50%in comparison with some existing similar boosting five-level active-neutral-point-clamped(5L-BANPC)inverters.The operating principles,modulation strategy,and the design of the FC and charging inductor are provided in detailly.A comprehensive comparison study has been made to highlight the merits of the proposed inverter.Finally,the simulations and experiments validate the feasibility of the proposed topology.
基金This work was supported by the Research Fund for the Doctoral Program of Higher Education of China under Grant No. 20050487044.
文摘Three space vector pulse width modulation （SVPWM） schemes, called 7-segment space vector modulation （SVM）, 5-segment SVM and 3-segment SVM are studied in this paper. The basic principle of SVPWM is presented. The switching sequence of different scheme is described. The modulation signals, DC bus voltage utilization, and output line voltage harmonic of these schemes are analyzed by the MATLAB software with different modulation index M and frequency modulation index N. The simulation results are analyzed and show that discontinuous modulating functions lead a reduction of switching actions. The DC bus voltage utilization of three schemes is almost the same. For all three SVM, the frequency modulation index N will affect the harmonic characteristic, and the modulation index M will affect DC bus voltage utilization and the harmonic content. The experiment is implemented by the DSP of TMS320F2812. The results validate three algorithms and the simulation.
文摘With rapid increase of distributed solar power generation and direct current(DC)based loads such as data centers,electric vehicles(EVs),and DC household appliances,the development trend of the power system is changed from conventional alternate current(AC)to DC.Traditional AC power systems can scarcely meet the development demand of new DC trends,especially since both the generation side and load side are comprised of DC-based electronic power components.With this background,low voltage direct current supply and utilization system(LVDCSUS)has attracted more and more attention for its great advantages over an AC grid to overcome challenges in operation,reliability,and energy loss in renewable energy connection,DC load power utilization and a number of other aspects.However,the definition of the LVDCSUS is still not clear even though many demonstration projects have been put into planning and operation.In order to provide a clear description of LVDCSUS,first,the characteristics of LVDCSUS are illustrated in this paper to show the advance of the LVDCSUS.Second,the potential application scenarios of LVDCSUS are presented in this paper.Third,application of LVDCSUS technologies and some demonstration projects in China are introduced.Besides the development of the LVDCSUS,key technologies,including but not limited to planning and design,voltage levels,control strategies,and key equipment of LVDCSUS,are discussed in this paper.Finally,future application areas and the research orientations of LVDCSUS are analyzed.
