This paper presents the comparison of various current control strategies employed for an interleaved power factor correction (PFC) boost converter for improving the power quality. The major control strategies discusse...This paper presents the comparison of various current control strategies employed for an interleaved power factor correction (PFC) boost converter for improving the power quality. The major control strategies discussed in this paper are: peak current control, average current control, hysteresis control, borderline current control and non-linear control. These strategies are implemented in MATLAB/SIMULINK and the performance of the proposed converter is compared under open loop and closed loop operation. From the results, the input current waveform was close to input voltage waveform implying improved power factor and reduced total harmonic distortion for nonlinear current control technique. Experimental results validate the proposed method.展开更多
Active power filter （APF） based on voltage source inverter （VSI） is one of the important measures for handling the power quality problem. Mathematically, the APF model in a power grid is a typical nonlinear one. T...Active power filter （APF） based on voltage source inverter （VSI） is one of the important measures for handling the power quality problem. Mathematically, the APF model in a power grid is a typical nonlinear one. The idea of passivity is a powerful tool to study the stabilization of such a nonlinear system. In this paper, a state-space model of the four-leg APF is derived, based on which a new H-infinity controller for current tracking is proposed from the passivity point of view. It can achieve not only asymptotic tracking, but also disturbance attenuation in the sense of L2-gain. Subsequently, a sufficient condition to guarantee the boundedness and desired mean of the DC voltage is also given. This straightforward condition is consistent with the power-balancing law of electrical circuits. Simulations performed on PSCAD platform verify the validity of the new approach.展开更多
To enhance the system damping,a permanent magnet set which served as an eddy current damper was added to the magnetic levitation positioning stage which consists of a moving table,four Halbach permanent magnetic array...To enhance the system damping,a permanent magnet set which served as an eddy current damper was added to the magnetic levitation positioning stage which consists of a moving table,four Halbach permanent magnetic arrays,four stators and displacement sensors.The dynamics model of this stage was a complex nonlinear,strong coupling system which made the control strategy to be a focus research.The nonlinear controller of the system was proposed based on the theory of differential geometry.Both simulation and experimental results show that either the decoupling control of the movement can be realized in horizontal and vertical directions,and the control performance was improved by the damper,verifying the validity and efficiency of this method.展开更多
永磁无刷直流电机控制因其非线性特性难以量化而影响控制器的性能和精度。对此,提出改进型比例一积分-微分(Proportional Integral Derivative,PID)算法的非线性控制方法。首先构建电机数学模型,通过分析三相绕组电压方程及定子和转子...永磁无刷直流电机控制因其非线性特性难以量化而影响控制器的性能和精度。对此,提出改进型比例一积分-微分(Proportional Integral Derivative,PID)算法的非线性控制方法。首先构建电机数学模型,通过分析三相绕组电压方程及定子和转子磁场关系得到电磁转矩方程;其次分析运行状态、提取参数,设计转速控制律;最后设计多个控制增益参数以完成转速控制器设计。实验结果显示,应用所提方法后,电机转速波动率仅3.15%,控制性能优异。展开更多
在虚拟同步电机(virtual synchronous generator,VSG)并联的独立微电网中,非线性负载带来大量谐波电流,线路阻抗差异会导致谐波电流的不均分,造成某些容量小的分布式电源承担更多的谐波电流,这将不利于系统的稳定运行。针对此,该文提出...在虚拟同步电机(virtual synchronous generator,VSG)并联的独立微电网中,非线性负载带来大量谐波电流,线路阻抗差异会导致谐波电流的不均分,造成某些容量小的分布式电源承担更多的谐波电流,这将不利于系统的稳定运行。针对此,该文提出一种自适应谐波阻抗重塑方法,通过引入谐波电流前馈补偿控制和阻抗重塑因子自适应控制,自适应、宽范围重塑逆变器的谐波阻抗,解决因线路阻抗差异、容量差异引起的谐波电流不均分问题,实现谐波电流按照容量均分,并能提高公共连接点(point of common connection,PCC)的电压质量。所提控制方法无需构造额外的虚拟阻抗,无需检测线路阻抗参数,能自适应实现谐波电流均分。基于阻抗的稳定性判据验证所提方法能保证系统的稳定运行。仿真和实验验证了所提方法的有效性。展开更多
文摘This paper presents the comparison of various current control strategies employed for an interleaved power factor correction (PFC) boost converter for improving the power quality. The major control strategies discussed in this paper are: peak current control, average current control, hysteresis control, borderline current control and non-linear control. These strategies are implemented in MATLAB/SIMULINK and the performance of the proposed converter is compared under open loop and closed loop operation. From the results, the input current waveform was close to input voltage waveform implying improved power factor and reduced total harmonic distortion for nonlinear current control technique. Experimental results validate the proposed method.
基金This work was supported by the National Natural Science Foundation of China(No.50377018, K5112515E1).
文摘Active power filter （APF） based on voltage source inverter （VSI） is one of the important measures for handling the power quality problem. Mathematically, the APF model in a power grid is a typical nonlinear one. The idea of passivity is a powerful tool to study the stabilization of such a nonlinear system. In this paper, a state-space model of the four-leg APF is derived, based on which a new H-infinity controller for current tracking is proposed from the passivity point of view. It can achieve not only asymptotic tracking, but also disturbance attenuation in the sense of L2-gain. Subsequently, a sufficient condition to guarantee the boundedness and desired mean of the DC voltage is also given. This straightforward condition is consistent with the power-balancing law of electrical circuits. Simulations performed on PSCAD platform verify the validity of the new approach.
基金Supported by the National Natural Science Foundation of China (60674052)
文摘To enhance the system damping,a permanent magnet set which served as an eddy current damper was added to the magnetic levitation positioning stage which consists of a moving table,four Halbach permanent magnetic arrays,four stators and displacement sensors.The dynamics model of this stage was a complex nonlinear,strong coupling system which made the control strategy to be a focus research.The nonlinear controller of the system was proposed based on the theory of differential geometry.Both simulation and experimental results show that either the decoupling control of the movement can be realized in horizontal and vertical directions,and the control performance was improved by the damper,verifying the validity and efficiency of this method.
文摘永磁无刷直流电机控制因其非线性特性难以量化而影响控制器的性能和精度。对此,提出改进型比例一积分-微分(Proportional Integral Derivative,PID)算法的非线性控制方法。首先构建电机数学模型,通过分析三相绕组电压方程及定子和转子磁场关系得到电磁转矩方程;其次分析运行状态、提取参数,设计转速控制律;最后设计多个控制增益参数以完成转速控制器设计。实验结果显示,应用所提方法后,电机转速波动率仅3.15%,控制性能优异。
文摘在虚拟同步电机(virtual synchronous generator,VSG)并联的独立微电网中,非线性负载带来大量谐波电流,线路阻抗差异会导致谐波电流的不均分,造成某些容量小的分布式电源承担更多的谐波电流,这将不利于系统的稳定运行。针对此,该文提出一种自适应谐波阻抗重塑方法,通过引入谐波电流前馈补偿控制和阻抗重塑因子自适应控制,自适应、宽范围重塑逆变器的谐波阻抗,解决因线路阻抗差异、容量差异引起的谐波电流不均分问题,实现谐波电流按照容量均分,并能提高公共连接点(point of common connection,PCC)的电压质量。所提控制方法无需构造额外的虚拟阻抗,无需检测线路阻抗参数,能自适应实现谐波电流均分。基于阻抗的稳定性判据验证所提方法能保证系统的稳定运行。仿真和实验验证了所提方法的有效性。
