The total electric field(TEF) at ground level induced by high-voltage direct current(HVDC) overhead transmission lines is one of the important indexes for evaluating the lines' electromagnetic environment.Based on...The total electric field(TEF) at ground level induced by high-voltage direct current(HVDC) overhead transmission lines is one of the important indexes for evaluating the lines' electromagnetic environment.Based on analyzing the existing TEF sensors and the measurement principle of ion-current density,the influence from ions on TEF measurements is quantitively studied.The results show that the ions generated by the corona from a HVDC transmission line in operation cause errors in the measurement of TEF.This error is determined through analyzing the component of total measuring current on the filed mill's sensing electrode: if no appropriate approach taken,the maximum measurement error reaches up to 4.3%.Furthermore,a method that can eliminate such error,and hence improve the accuracy of TEF sensors is designed.展开更多
针对单相矩阵式无线电能传输MC-WPT(matrix converter based wireless power transfer)系统网侧电流谐波含量大的问题,提出1种谐波抑制调制策略,可有效降低网侧电流低次谐波含量及总谐波失真度THD(total harmonic distortion)。分析谐...针对单相矩阵式无线电能传输MC-WPT(matrix converter based wireless power transfer)系统网侧电流谐波含量大的问题,提出1种谐波抑制调制策略,可有效降低网侧电流低次谐波含量及总谐波失真度THD(total harmonic distortion)。分析谐振槽电压电流特性,基于参数归一化方法得到2个基波分量的等效电路,进而推导出MC-WPT的数学模型。在此基础上,以消除低次谐波含量为目标,应用计算法得到接收侧H桥的优化调制波,使网侧电流低频成分仅有工频分量,从而降低网侧电流THD。最后搭建实验平台,验证所提谐波抑制调制策略的可行性与有效性。展开更多
This paper is concerned with the problem of network power quality when grid connected systems are used to feed the grid. These systems use power electronic components such as inverters that produce harmonics which adv...This paper is concerned with the problem of network power quality when grid connected systems are used to feed the grid. These systems use power electronic components such as inverters that produce harmonics which adversely affect the power quality of the distribution network. Instead of using a conventional PI current controller with a fixed proportional and integral gain, development of new control method is considered to overcome the total harmonic emissions in PV inverters. It considers a modification to the controller where a random integral gain is used in the system. Experimental hardware is developed and result shows a reduced total harmonic distortion (THD) of the output current when tested with a resistive load.展开更多
Objective For the inverters used in UPS, it is important to maintain the pure sinusoidal AC output voltage waveform over all loading conditions and transients. Methods A novel sinusoidal output voltage control strat...Objective For the inverters used in UPS, it is important to maintain the pure sinusoidal AC output voltage waveform over all loading conditions and transients. Methods A novel sinusoidal output voltage control strategy is pregented in this paper. The output voltage is controlled by introducing filtering eapacitor current feedback. Two simple PI regulators are used for the current and voltage control loops. Results With the new control strategy, the inverter achieves very low output voltage distortion, good output voltage regulation and strong perturbation rejection, fast dynamic response, and good performance under nonlinear loads. The THD under capacitance rectifying load is better than 0.2%, the output voltage regulation within 0 to full load is less than 0.1%. The resting time under load transient is within 200?μ s . Conclusion The merits of the new control strategy include rapid response and good steady state stiffness.展开更多
In this work, top and back gate characteristics of partially-depleted NMOS transistors with enclosed gate fabricated on SIMOX which is hardened by silicon ions implantation were studied under X-ray total-dose irradiat...In this work, top and back gate characteristics of partially-depleted NMOS transistors with enclosed gate fabricated on SIMOX which is hardened by silicon ions implantation were studied under X-ray total-dose irradiation of three bias conditions. It has been found experimentally that back gate threshold shift and leakage current were greatly reduced during irradiation for hardened transistors, comparing to control ones. It has been confirmed that the improvement of total-dose properties of SOI devices is attributed to the silicon nanocrystals (nanoclusters) in buried oxides introduced by ion implantation.展开更多
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
The paper proposes a Current Source Multilevel Inverter (CSMLI) with single rating inductor topology. Multilevel inverters are most familiar with power converter’s applications due to reduced dv/dt, di/dt stress, and...The paper proposes a Current Source Multilevel Inverter (CSMLI) with single rating inductor topology. Multilevel inverters are most familiar with power converter’s applications due to reduced dv/dt, di/dt stress, and very efficient for reducing harmonic distortion in the output voltage and output current. The proposed nine-level current source inverter has been tested under symmetrical and asymmetrical modes of operation, and their activities are compared using PI and Fuzzy PI (Proportional Integral) controllers with multicarrier PWM (Pulse Width Modulation) strategy. MATLAB/Simulink simulation has been made for the proposed converter to obtain its performance measures. Some experimental results are given to verify the presented Current Source Multilevel Inverter.展开更多
基金Project supported by National Natural Science Foundation of China （61273165 51207005）.
文摘The total electric field(TEF) at ground level induced by high-voltage direct current(HVDC) overhead transmission lines is one of the important indexes for evaluating the lines' electromagnetic environment.Based on analyzing the existing TEF sensors and the measurement principle of ion-current density,the influence from ions on TEF measurements is quantitively studied.The results show that the ions generated by the corona from a HVDC transmission line in operation cause errors in the measurement of TEF.This error is determined through analyzing the component of total measuring current on the filed mill's sensing electrode: if no appropriate approach taken,the maximum measurement error reaches up to 4.3%.Furthermore,a method that can eliminate such error,and hence improve the accuracy of TEF sensors is designed.
文摘针对单相矩阵式无线电能传输MC-WPT(matrix converter based wireless power transfer)系统网侧电流谐波含量大的问题,提出1种谐波抑制调制策略,可有效降低网侧电流低次谐波含量及总谐波失真度THD(total harmonic distortion)。分析谐振槽电压电流特性,基于参数归一化方法得到2个基波分量的等效电路,进而推导出MC-WPT的数学模型。在此基础上,以消除低次谐波含量为目标,应用计算法得到接收侧H桥的优化调制波,使网侧电流低频成分仅有工频分量,从而降低网侧电流THD。最后搭建实验平台,验证所提谐波抑制调制策略的可行性与有效性。
文摘This paper is concerned with the problem of network power quality when grid connected systems are used to feed the grid. These systems use power electronic components such as inverters that produce harmonics which adversely affect the power quality of the distribution network. Instead of using a conventional PI current controller with a fixed proportional and integral gain, development of new control method is considered to overcome the total harmonic emissions in PV inverters. It considers a modification to the controller where a random integral gain is used in the system. Experimental hardware is developed and result shows a reduced total harmonic distortion (THD) of the output current when tested with a resistive load.
文摘Objective For the inverters used in UPS, it is important to maintain the pure sinusoidal AC output voltage waveform over all loading conditions and transients. Methods A novel sinusoidal output voltage control strategy is pregented in this paper. The output voltage is controlled by introducing filtering eapacitor current feedback. Two simple PI regulators are used for the current and voltage control loops. Results With the new control strategy, the inverter achieves very low output voltage distortion, good output voltage regulation and strong perturbation rejection, fast dynamic response, and good performance under nonlinear loads. The THD under capacitance rectifying load is better than 0.2%, the output voltage regulation within 0 to full load is less than 0.1%. The resting time under load transient is within 200?μ s . Conclusion The merits of the new control strategy include rapid response and good steady state stiffness.
文摘In this work, top and back gate characteristics of partially-depleted NMOS transistors with enclosed gate fabricated on SIMOX which is hardened by silicon ions implantation were studied under X-ray total-dose irradiation of three bias conditions. It has been found experimentally that back gate threshold shift and leakage current were greatly reduced during irradiation for hardened transistors, comparing to control ones. It has been confirmed that the improvement of total-dose properties of SOI devices is attributed to the silicon nanocrystals (nanoclusters) in buried oxides introduced by ion implantation.
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.
文摘The paper proposes a Current Source Multilevel Inverter (CSMLI) with single rating inductor topology. Multilevel inverters are most familiar with power converter’s applications due to reduced dv/dt, di/dt stress, and very efficient for reducing harmonic distortion in the output voltage and output current. The proposed nine-level current source inverter has been tested under symmetrical and asymmetrical modes of operation, and their activities are compared using PI and Fuzzy PI (Proportional Integral) controllers with multicarrier PWM (Pulse Width Modulation) strategy. MATLAB/Simulink simulation has been made for the proposed converter to obtain its performance measures. Some experimental results are given to verify the presented Current Source Multilevel Inverter.
