针对一种两轴四音圈电机驱动的快速反射镜,提出了一种驱动控制方法。该方法为每个电机配置一个高带宽的电流环,通过控制电流给定量的符号和大小,实现同一轴上两台电机的同步推挽运动;为了改善系统阻尼,抑制谐振,提高响应频率,基于快速...针对一种两轴四音圈电机驱动的快速反射镜,提出了一种驱动控制方法。该方法为每个电机配置一个高带宽的电流环,通过控制电流给定量的符号和大小,实现同一轴上两台电机的同步推挽运动;为了改善系统阻尼,抑制谐振,提高响应频率,基于快速傅里叶变换(FFT)谱分析的方法,精确测量了快速反射镜传递函数,并引入一个双二阶型校正函数,对快速反射镜的开环响应特性进行改善。实际测试结果表明:快速反射镜高达20 d B的谐振峰得到有效抑制,-3 d B响应带宽由校正前的118 Hz提高到177 Hz,稳定时间由原来的151 ms降低到3.5 ms,超调量由原来的83.3%降低到1.51%,快速反射镜的动态响应得到明显改善,证明了该方法的有效性。展开更多
Obvious resonance peak will be generated when parallel photovoltaic grid-connected inverters are connected to the weak grid with high grid impedance, which seriously affects the stability of grid-connected operation o...Obvious resonance peak will be generated when parallel photovoltaic grid-connected inverters are connected to the weak grid with high grid impedance, which seriously affects the stability of grid-connected operation of the photovoltaic system. To overcome the problems mentioned above, the mathematical model of the parallel photovoltaic inverters is established. Several factors including the impact of the reference current of the grid-connected inverter, the grid voltage interference and the current disturbance between the photovoltaic inverters in parallel with the grid-connected inverters are analyzed. The grid impedance and the LCL filter of the photovoltaic inverter system are found to be the key elements which lead to existence of resonance peak. This paper presents the branch voltage and current double feedback suppression method under the premise of not changing the topological structure of the photovoltaic inverter, which effectively handles the resonance peak, weakens the harmonic content of the grid current of the photovoltaic grid-connected inverter and the voltage at the point of common coupling, and improves the stability of the parallel operation of the photovoltaic grid-connected inverters in weak grid. At last, the simulation model is established to verify the reliability of this suppression method.展开更多
In this paper the influence of different carrier waveforms upon the output characteristics of PWM inverter is described in detail. When a triangular carrier waveform is used in hard-switching PWM inverters, harmonics ...In this paper the influence of different carrier waveforms upon the output characteristics of PWM inverter is described in detail. When a triangular carrier waveform is used in hard-switching PWM inverters, harmonics exist in the neighborhood of the output frequency of the inverter output voltage and current due to the dead time. The triangular carrier waveform used in soft-switching PWM inverter will cause difficulties in controlling resonance-trigger time, higher loss in the resonant circuit, and less utilization of the DC bus voltage. If a sawtooth carrier is used in hard-switching PWM inverter, there will be severe distortion in the current waveform. When sawtooth carriers with alternate positive and negative slopes are used in soft-switching PWM inverters, the resonance-trigger time is easy to control, and distortion in the output voltage and current caused by the dead time will not appear.展开更多
文摘针对一种两轴四音圈电机驱动的快速反射镜,提出了一种驱动控制方法。该方法为每个电机配置一个高带宽的电流环,通过控制电流给定量的符号和大小,实现同一轴上两台电机的同步推挽运动;为了改善系统阻尼,抑制谐振,提高响应频率,基于快速傅里叶变换(FFT)谱分析的方法,精确测量了快速反射镜传递函数,并引入一个双二阶型校正函数,对快速反射镜的开环响应特性进行改善。实际测试结果表明:快速反射镜高达20 d B的谐振峰得到有效抑制,-3 d B响应带宽由校正前的118 Hz提高到177 Hz,稳定时间由原来的151 ms降低到3.5 ms,超调量由原来的83.3%降低到1.51%,快速反射镜的动态响应得到明显改善,证明了该方法的有效性。
基金supported by National Natural Science Foundation of China (No. 61573303)Natural Science Foundation of Hebei Province (No. E2016203092)
文摘Obvious resonance peak will be generated when parallel photovoltaic grid-connected inverters are connected to the weak grid with high grid impedance, which seriously affects the stability of grid-connected operation of the photovoltaic system. To overcome the problems mentioned above, the mathematical model of the parallel photovoltaic inverters is established. Several factors including the impact of the reference current of the grid-connected inverter, the grid voltage interference and the current disturbance between the photovoltaic inverters in parallel with the grid-connected inverters are analyzed. The grid impedance and the LCL filter of the photovoltaic inverter system are found to be the key elements which lead to existence of resonance peak. This paper presents the branch voltage and current double feedback suppression method under the premise of not changing the topological structure of the photovoltaic inverter, which effectively handles the resonance peak, weakens the harmonic content of the grid current of the photovoltaic grid-connected inverter and the voltage at the point of common coupling, and improves the stability of the parallel operation of the photovoltaic grid-connected inverters in weak grid. At last, the simulation model is established to verify the reliability of this suppression method.
文摘In this paper the influence of different carrier waveforms upon the output characteristics of PWM inverter is described in detail. When a triangular carrier waveform is used in hard-switching PWM inverters, harmonics exist in the neighborhood of the output frequency of the inverter output voltage and current due to the dead time. The triangular carrier waveform used in soft-switching PWM inverter will cause difficulties in controlling resonance-trigger time, higher loss in the resonant circuit, and less utilization of the DC bus voltage. If a sawtooth carrier is used in hard-switching PWM inverter, there will be severe distortion in the current waveform. When sawtooth carriers with alternate positive and negative slopes are used in soft-switching PWM inverters, the resonance-trigger time is easy to control, and distortion in the output voltage and current caused by the dead time will not appear.
