针对直驱风力发电系统中变流器IGBT存在过电压脉冲的问题,基于IGBT的物理模型及C型、钳位二极管、RC型和RCD型四种过电压保护电路提出了一种新型CR-CD(Capacitor resistor and capacitor diode)过电压保护电路。首先,分析了CR-CD过电压...针对直驱风力发电系统中变流器IGBT存在过电压脉冲的问题,基于IGBT的物理模型及C型、钳位二极管、RC型和RCD型四种过电压保护电路提出了一种新型CR-CD(Capacitor resistor and capacitor diode)过电压保护电路。首先,分析了CR-CD过电压保护电路的工作原理,论证了CR-CD过电压保护电路抑制过电压脉冲的优良性能。其次,详细设计了过电压保护电路的参数。最后,基于Matlab/Simulink平台搭建了CR-CD型过电压保护电路仿真模型,分别在恒定和变化负载电感两种工况下进行仿真对比分析。结果表明:CR-CD过电压保护电路不仅可以有效地抑制过电压脉冲,还能起到避免因电容造成的过电压脉冲衰减延迟以及缩短IGBT关断时间的作用。展开更多
In order to simulate the flow control problem by using Nanosecond Pulsed Dielectric Barrier Discharge(NSDBD),a one-zone inhomogeneous phenomenological model is constructed based on the experimental and theoretical res...In order to simulate the flow control problem by using Nanosecond Pulsed Dielectric Barrier Discharge(NSDBD),a one-zone inhomogeneous phenomenological model is constructed based on the experimental and theoretical results.The model is coupled with the unsteady Navier-Stokes equations,which can well predict the compression-expansion wave structures and wave speed compared with experimental results and can be applied to the simulation of the flow control by using NSDBD.The model is adopted to investigate the separation control over NACA0015 airfoil using the NSDBD plasma actuator.The separation-control mechanisms are revealed that the spanwise vortices produced by the plasma actuation play the key role.Each plasma actuation can produce a spanwise vortex around the separation point near the leading edge.The spanwise vortices make the separated free-shear layer unstable and shed away,move downstream along the upper wall,control the flow near the wall,and bring outer flow with high kinetic energy into the near wall region to realize the effective separation control over the upper surface of the airfoil.展开更多
文摘针对直驱风力发电系统中变流器IGBT存在过电压脉冲的问题,基于IGBT的物理模型及C型、钳位二极管、RC型和RCD型四种过电压保护电路提出了一种新型CR-CD(Capacitor resistor and capacitor diode)过电压保护电路。首先,分析了CR-CD过电压保护电路的工作原理,论证了CR-CD过电压保护电路抑制过电压脉冲的优良性能。其次,详细设计了过电压保护电路的参数。最后,基于Matlab/Simulink平台搭建了CR-CD型过电压保护电路仿真模型,分别在恒定和变化负载电感两种工况下进行仿真对比分析。结果表明:CR-CD过电压保护电路不仅可以有效地抑制过电压脉冲,还能起到避免因电容造成的过电压脉冲衰减延迟以及缩短IGBT关断时间的作用。
基金supported by the National Natural Science Foundation of China(Grant Nos.10972236,50906100)
文摘In order to simulate the flow control problem by using Nanosecond Pulsed Dielectric Barrier Discharge(NSDBD),a one-zone inhomogeneous phenomenological model is constructed based on the experimental and theoretical results.The model is coupled with the unsteady Navier-Stokes equations,which can well predict the compression-expansion wave structures and wave speed compared with experimental results and can be applied to the simulation of the flow control by using NSDBD.The model is adopted to investigate the separation control over NACA0015 airfoil using the NSDBD plasma actuator.The separation-control mechanisms are revealed that the spanwise vortices produced by the plasma actuation play the key role.Each plasma actuation can produce a spanwise vortex around the separation point near the leading edge.The spanwise vortices make the separated free-shear layer unstable and shed away,move downstream along the upper wall,control the flow near the wall,and bring outer flow with high kinetic energy into the near wall region to realize the effective separation control over the upper surface of the airfoil.
