It is shown that the cascaded fifth-order nonlinear phase shifts will increase with energy loss in the cascaded processes. Essentially different from the multi-photon absorption accompanied with inherent material nonl...It is shown that the cascaded fifth-order nonlinear phase shifts will increase with energy loss in the cascaded processes. Essentially different from the multi-photon absorption accompanied with inherent material nonlinearities, the loss of fundamental wave in a cascaded process is controllable and suppressible. By introducing difference frequencies generated from the reaction between the fundamental and its second harmonic after the cascaded processes, the fundamental wave can be free of energy loss, while the large cascaded fifth-order nonlinear phase shift is maintained.展开更多
Effects of second harmonic generation （SHG） and cascaded second harmonic generation/difference frequency generation（cSHG/DFG） based on the quasi-phase-matching （QPM） condition in periodically poled lithium nioba...Effects of second harmonic generation （SHG） and cascaded second harmonic generation/difference frequency generation（cSHG/DFG） based on the quasi-phase-matching （QPM） condition in periodically poled lithium niobate （PPLN） waveguide were investigated experimentally. SHG conversion efficiency of -13.6dB and QPM bandwidth of 0.45nm were achieved using a 16.1dBm power of fundamental wave at 1550.4nm. Using pulsed all-fiber passive mode locked laser and tunable continuous wave laser, cSHG/DFG effect utilized for optical sampling was observed. Conversion efficiencies were calculated, and 11.88nm-wide QPM bandwidth was achieved through changing the wavelength of input signal. Conversion efficiency of cSHG/DFG effect increased linearly with the total injected power.展开更多
为了研究应用于中高压领域的有源电力滤波器(APF),建立了3级H桥级联APF数学模型,采用载波相移调制技术将装置的等效开关频率提高6倍,基于瞬时无功功率理论提取谐波及无功电流,采用三角载波比较法跟踪指令电流,直流侧电压采用分层控制来...为了研究应用于中高压领域的有源电力滤波器(APF),建立了3级H桥级联APF数学模型,采用载波相移调制技术将装置的等效开关频率提高6倍,基于瞬时无功功率理论提取谐波及无功电流,采用三角载波比较法跟踪指令电流,直流侧电压采用分层控制来实现稳压和均压。仿真结果表明,H桥级联APF能够快速精确地检测出谐波及无功电流,在器件开关频率1.05 k Hz下补偿谐波及无功电流,将电网相电流THD由27.66%降至1.24%,同时维持直流侧电压的稳定和均衡,使电压误差率不超过2%。系统能在1个电网周期内响应负载的动态变化,从而验证了方案的可行性。展开更多
介绍了一种新的采用两电平级联技术换流器的拓扑结构和工作原理,分析了载波移相正弦脉宽调制(carrier phase shifted-sinusoidal pulse width modulation,CPS-SPWM)在这种新型拓扑结构的应用机理,搭建仿真模型分析了两电平级联基于电压...介绍了一种新的采用两电平级联技术换流器的拓扑结构和工作原理,分析了载波移相正弦脉宽调制(carrier phase shifted-sinusoidal pulse width modulation,CPS-SPWM)在这种新型拓扑结构的应用机理,搭建仿真模型分析了两电平级联基于电压源换流器的高压直流输电(voltage source converter based high voltage direct current transmission,VSC-HVDC)技术的谐波情况,并分析了谐波含量与子模块数的关系。展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.60088003 and 10276012)National High-Tech Committee of China and National Project 973 of China(Grant No.G19990752023).
文摘It is shown that the cascaded fifth-order nonlinear phase shifts will increase with energy loss in the cascaded processes. Essentially different from the multi-photon absorption accompanied with inherent material nonlinearities, the loss of fundamental wave in a cascaded process is controllable and suppressible. By introducing difference frequencies generated from the reaction between the fundamental and its second harmonic after the cascaded processes, the fundamental wave can be free of energy loss, while the large cascaded fifth-order nonlinear phase shift is maintained.
基金Supported by the National Natural Science Foundation of China(6077702460978007)
文摘Effects of second harmonic generation （SHG） and cascaded second harmonic generation/difference frequency generation（cSHG/DFG） based on the quasi-phase-matching （QPM） condition in periodically poled lithium niobate （PPLN） waveguide were investigated experimentally. SHG conversion efficiency of -13.6dB and QPM bandwidth of 0.45nm were achieved using a 16.1dBm power of fundamental wave at 1550.4nm. Using pulsed all-fiber passive mode locked laser and tunable continuous wave laser, cSHG/DFG effect utilized for optical sampling was observed. Conversion efficiencies were calculated, and 11.88nm-wide QPM bandwidth was achieved through changing the wavelength of input signal. Conversion efficiency of cSHG/DFG effect increased linearly with the total injected power.
文摘为了研究应用于中高压领域的有源电力滤波器(APF),建立了3级H桥级联APF数学模型,采用载波相移调制技术将装置的等效开关频率提高6倍,基于瞬时无功功率理论提取谐波及无功电流,采用三角载波比较法跟踪指令电流,直流侧电压采用分层控制来实现稳压和均压。仿真结果表明,H桥级联APF能够快速精确地检测出谐波及无功电流,在器件开关频率1.05 k Hz下补偿谐波及无功电流,将电网相电流THD由27.66%降至1.24%,同时维持直流侧电压的稳定和均衡,使电压误差率不超过2%。系统能在1个电网周期内响应负载的动态变化,从而验证了方案的可行性。
文摘介绍了一种新的采用两电平级联技术换流器的拓扑结构和工作原理,分析了载波移相正弦脉宽调制(carrier phase shifted-sinusoidal pulse width modulation,CPS-SPWM)在这种新型拓扑结构的应用机理,搭建仿真模型分析了两电平级联基于电压源换流器的高压直流输电(voltage source converter based high voltage direct current transmission,VSC-HVDC)技术的谐波情况,并分析了谐波含量与子模块数的关系。
