The paper proposes a new method of equal switching distribution that can be applied to cascaded multi-level inverters. This method is based on the fact that in the cascaded multilevel inverters, the output phase volta...The paper proposes a new method of equal switching distribution that can be applied to cascaded multi-level inverters. This method is based on the fact that in the cascaded multilevel inverters, the output phase voltage is the sum of voltage waveforms produced by all cascaded cells. By periodically exchanging cells’ voltage waveforms, the proposed method ensures equal average switchings distribution between all cascaded cells. This method is applied to the 13-level inverter, which consists of three cascaded 5-level H-bridge cells per phase. However, the proposed method can be extended to any desired number of voltage levels and applied to any type of cascaded multi-level inverter. Extensive simulation results of the tested 13-level inverter with the equal switching distribution are presented. Moreover, the proposed method is compared to the standard control approaches and its advantages are shown.展开更多
Multi-level converters have been used extensively in modern industry which calls for energy conversion with high-power and high-or medium-voltage.Because of its modularity and scalability,the multi-level converter wit...Multi-level converters have been used extensively in modern industry which calls for energy conversion with high-power and high-or medium-voltage.Because of its modularity and scalability,the multi-level converter with modular structure can be extended to different voltage levels and has a variety of forms in practical applications.It has attracted much attention from academia in the past decade,however,as a result of the numerous vulnerable power electronics sub-modules,significant challenges remain with regards to reliability.After summarizing the current research status of modular multilevel cascade converters,the main issues of reliability are reviewed in the paper.Firstly,the failure cases are thoroughly surveyed and classified,and the main failure causes are analyzed.Secondly,the reliability evaluation methods are reviewed and applied to the modular multilevel cascade converters.Thirdly,some promising measures to improve the reliability are presented and discussed,including parameter selection,redundancy design,fault-tolerant control and so on.Then,a complete reliability-oriented design procedure for the modular multilevel cascade converters is proposed.Finally,the challenges and opportunities to improve the reliability are concluded.展开更多
Multi-level inverters(MLIs)have become popular in different applications such as industrial power control systems and distributed generations.There are different forms of MLIs.The cascaded MLIs(CMLIs)have some special...Multi-level inverters(MLIs)have become popular in different applications such as industrial power control systems and distributed generations.There are different forms of MLIs.The cascaded MLIs(CMLIs)have some special advantages among them such as more different output voltage levels using the same number of components and higher power quality.In this paper,a 27-level inverter switching algorithm considering total harmonic distortion(THD)minimization is investigated.Switching angles of the inverter switches are achieved by minimizing a THD-based objective function.In order to minimize the THD-based objective function,the hyper-spherical search(HSS)algorithm,as a novel optimization algorithm,is improved and the results of improved HSS(IHSS)are compared with HSS algorithm and other five evolutionary algorithms to show the advantages of IHSS algorithm.展开更多
A Cascade H Bridge (CHB) is evaluated for both electric vehicle motor traction control and off-vehicle charging against the Power ElectronicsUK Automotive Challenge for cost and mass for the year 2035. By combining th...A Cascade H Bridge (CHB) is evaluated for both electric vehicle motor traction control and off-vehicle charging against the Power ElectronicsUK Automotive Challenge for cost and mass for the year 2035. By combining the power electronics with batteries using low-voltage MOSFET transistors in a series cascade arrangement the cost and mass targets could be met 12 years earlier (in 2023 and 20 times lighter if an application specific integrated circuit (ASIC) is used. A 200 kW peak reference car was used to evaluate cost and mass benefits using four different topologies of power electronics. Vehicle installation is shown to be simplified as only passive cooling is required removing the need for liquid cooling systems and the arrangement is inherently safe;no high voltages are present when the vehicle is stationary. The inherently higher efficiency of CHB increases vehicle range. The converter with integrated batteries can also behave as an integrated on-board battery charger delivering additional off-vehicle benefits by removing the need for costly external chargers.展开更多
文摘The paper proposes a new method of equal switching distribution that can be applied to cascaded multi-level inverters. This method is based on the fact that in the cascaded multilevel inverters, the output phase voltage is the sum of voltage waveforms produced by all cascaded cells. By periodically exchanging cells’ voltage waveforms, the proposed method ensures equal average switchings distribution between all cascaded cells. This method is applied to the 13-level inverter, which consists of three cascaded 5-level H-bridge cells per phase. However, the proposed method can be extended to any desired number of voltage levels and applied to any type of cascaded multi-level inverter. Extensive simulation results of the tested 13-level inverter with the equal switching distribution are presented. Moreover, the proposed method is compared to the standard control approaches and its advantages are shown.
基金Supported by the key program of National Natural Science Foundation of China under Grant 51490683.
文摘Multi-level converters have been used extensively in modern industry which calls for energy conversion with high-power and high-or medium-voltage.Because of its modularity and scalability,the multi-level converter with modular structure can be extended to different voltage levels and has a variety of forms in practical applications.It has attracted much attention from academia in the past decade,however,as a result of the numerous vulnerable power electronics sub-modules,significant challenges remain with regards to reliability.After summarizing the current research status of modular multilevel cascade converters,the main issues of reliability are reviewed in the paper.Firstly,the failure cases are thoroughly surveyed and classified,and the main failure causes are analyzed.Secondly,the reliability evaluation methods are reviewed and applied to the modular multilevel cascade converters.Thirdly,some promising measures to improve the reliability are presented and discussed,including parameter selection,redundancy design,fault-tolerant control and so on.Then,a complete reliability-oriented design procedure for the modular multilevel cascade converters is proposed.Finally,the challenges and opportunities to improve the reliability are concluded.
文摘Multi-level inverters(MLIs)have become popular in different applications such as industrial power control systems and distributed generations.There are different forms of MLIs.The cascaded MLIs(CMLIs)have some special advantages among them such as more different output voltage levels using the same number of components and higher power quality.In this paper,a 27-level inverter switching algorithm considering total harmonic distortion(THD)minimization is investigated.Switching angles of the inverter switches are achieved by minimizing a THD-based objective function.In order to minimize the THD-based objective function,the hyper-spherical search(HSS)algorithm,as a novel optimization algorithm,is improved and the results of improved HSS(IHSS)are compared with HSS algorithm and other five evolutionary algorithms to show the advantages of IHSS algorithm.
文摘A Cascade H Bridge (CHB) is evaluated for both electric vehicle motor traction control and off-vehicle charging against the Power ElectronicsUK Automotive Challenge for cost and mass for the year 2035. By combining the power electronics with batteries using low-voltage MOSFET transistors in a series cascade arrangement the cost and mass targets could be met 12 years earlier (in 2023 and 20 times lighter if an application specific integrated circuit (ASIC) is used. A 200 kW peak reference car was used to evaluate cost and mass benefits using four different topologies of power electronics. Vehicle installation is shown to be simplified as only passive cooling is required removing the need for liquid cooling systems and the arrangement is inherently safe;no high voltages are present when the vehicle is stationary. The inherently higher efficiency of CHB increases vehicle range. The converter with integrated batteries can also behave as an integrated on-board battery charger delivering additional off-vehicle benefits by removing the need for costly external chargers.
