为解决单相高频链矩阵式逆变器在换流时变压器副边后级电路功率器件上存在的电压过冲问题,通过在变压器原边的前级H桥逆变电路中引入LC串联谐振槽的方式,提出一种串联谐振式高频链矩阵逆变器结构,并对此提出一种电流型解结耦单极性调制...为解决单相高频链矩阵式逆变器在换流时变压器副边后级电路功率器件上存在的电压过冲问题,通过在变压器原边的前级H桥逆变电路中引入LC串联谐振槽的方式,提出一种串联谐振式高频链矩阵逆变器结构,并对此提出一种电流型解结耦单极性调制方法。在所提方案中,高频链变压器前级逆变电路采用脉宽脉位调制(sinusoidal pulse width and position modulation,SPWPM)以输出高频谐振电流,后级矩阵变换器应用电流型解结耦调制策略,通过与前级电路保持同步工作,构造前级输出电流的无中断的流通路径,以避免对变压器副边漏感电流的强制打断,可实现矩阵变换器的谐振软开关安全换流。在重点阐述串联谐振式高频链逆变器的工作原理并分析电流型解结耦单极性调制策略的具体工作模态的基础上,通过仿真和实验验证所提电路及其调制方法的可行性与有效性。展开更多
Alkaline water electrolysis(AWE)is the most mature technology for hydrogen production by water electrolysis.Alkaline water electrolyzer consists of multiple electrolysis cells,and a single cell consists of a diaphragm...Alkaline water electrolysis(AWE)is the most mature technology for hydrogen production by water electrolysis.Alkaline water electrolyzer consists of multiple electrolysis cells,and a single cell consists of a diaphragm,electrodes,bipolar plates and end plates,etc.The existing industrial bipolar plate channel is concave-convex structure,which is manufactured by complicated and high-cost mold punching.This structure still results in uneven electrolyte flow and low current density in the electrolytic cell,further increasing in energy consumption and cost of AWE.Thereby,in this article,the electrochemical and flow model is firstly constructed,based on the existing industrial concave and convex flow channel structure of bipolar plate,to study the current density,electrolyte flow and bubble distribution in the electrolysis cell.The reliability of the model was verified by comparison with experimental data in literature.Among which,the electrochemical current density affects the bubble yield,on the other hand,the generated bubbles cover the electrode surface,affecting the active specific surface area and ohmic resistance,which in turn affects the electrochemical reaction.The result indicates that the flow velocity near the bottom of the concave ball approaches zero,while the flow velocity on the convex ball surface is significantly higher.Additionally,vortices are observed within the flow channel structure,leading to an uneven distribution of electrolyte.Next,modelling is used to optimize the bipolar plate structure of AWE by simulating the electrochemistry and fluid flow performances of four kinds of structures,namely,concave and convex,rhombus,wedge and expanded mesh,in the bipolar plate of alkaline water electrolyzer.The results show that the expanded mesh channel structure has the largest current density of 3330 A/m^(2)and electrolyte flow velocity of 0.507 m/s in the electrolytic cell.Under the same current density,the electrolytic cell with the expanded mesh runner structure has the smallest potential and energy consumption.This work provides a useful guide for the comprehensive understanding and optimization of channel structures,and a theoretical basis for the design of large-scale electrolyzer.展开更多
文摘为解决单相高频链矩阵式逆变器在换流时变压器副边后级电路功率器件上存在的电压过冲问题,通过在变压器原边的前级H桥逆变电路中引入LC串联谐振槽的方式,提出一种串联谐振式高频链矩阵逆变器结构,并对此提出一种电流型解结耦单极性调制方法。在所提方案中,高频链变压器前级逆变电路采用脉宽脉位调制(sinusoidal pulse width and position modulation,SPWPM)以输出高频谐振电流,后级矩阵变换器应用电流型解结耦调制策略,通过与前级电路保持同步工作,构造前级输出电流的无中断的流通路径,以避免对变压器副边漏感电流的强制打断,可实现矩阵变换器的谐振软开关安全换流。在重点阐述串联谐振式高频链逆变器的工作原理并分析电流型解结耦单极性调制策略的具体工作模态的基础上,通过仿真和实验验证所提电路及其调制方法的可行性与有效性。
基金financially supported by the National Natural Science Foundation of China(No.52074130)the Engineering Research Center of Resource Utilization of Carbon-containing Waste with Carbon Neutrality,Ministry of Education。
文摘Alkaline water electrolysis(AWE)is the most mature technology for hydrogen production by water electrolysis.Alkaline water electrolyzer consists of multiple electrolysis cells,and a single cell consists of a diaphragm,electrodes,bipolar plates and end plates,etc.The existing industrial bipolar plate channel is concave-convex structure,which is manufactured by complicated and high-cost mold punching.This structure still results in uneven electrolyte flow and low current density in the electrolytic cell,further increasing in energy consumption and cost of AWE.Thereby,in this article,the electrochemical and flow model is firstly constructed,based on the existing industrial concave and convex flow channel structure of bipolar plate,to study the current density,electrolyte flow and bubble distribution in the electrolysis cell.The reliability of the model was verified by comparison with experimental data in literature.Among which,the electrochemical current density affects the bubble yield,on the other hand,the generated bubbles cover the electrode surface,affecting the active specific surface area and ohmic resistance,which in turn affects the electrochemical reaction.The result indicates that the flow velocity near the bottom of the concave ball approaches zero,while the flow velocity on the convex ball surface is significantly higher.Additionally,vortices are observed within the flow channel structure,leading to an uneven distribution of electrolyte.Next,modelling is used to optimize the bipolar plate structure of AWE by simulating the electrochemistry and fluid flow performances of four kinds of structures,namely,concave and convex,rhombus,wedge and expanded mesh,in the bipolar plate of alkaline water electrolyzer.The results show that the expanded mesh channel structure has the largest current density of 3330 A/m^(2)and electrolyte flow velocity of 0.507 m/s in the electrolytic cell.Under the same current density,the electrolytic cell with the expanded mesh runner structure has the smallest potential and energy consumption.This work provides a useful guide for the comprehensive understanding and optimization of channel structures,and a theoretical basis for the design of large-scale electrolyzer.
