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基于多种群遗传算法的多电平逆变器输出电压THD最小化调制策略
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作者 叶满园 凌袁学 +2 位作者 肖兆军 罗振远 陶振宇 《高电压技术》 EI CAS CSCD 北大核心 2024年第10期4671-4679,共9页
多电平逆变器具有低谐波含量,电磁干扰小,高压大容量,输出波形质量好等特点,被广泛用于中高压大功率系统当中。特定谐波消除技术SHEPWM是在多电平逆变器中的一种常用开关策略,相比于高频调制,SHEPWM技术能够消除某特定次谐波,而且具有... 多电平逆变器具有低谐波含量,电磁干扰小,高压大容量,输出波形质量好等特点,被广泛用于中高压大功率系统当中。特定谐波消除技术SHEPWM是在多电平逆变器中的一种常用开关策略,相比于高频调制,SHEPWM技术能够消除某特定次谐波,而且具有更低的开关频率和开关损耗等优点。针对传统SHEPWM技术中THD不能达到最优的问题,推导出了输出电压谐波总含量的解析表达式,并采用多种群遗传算法对解析表达式进行求解,在得到最优开关角度的同时求出全调制度下输出电压的最小THD值。文中以三单元7电平级联H桥为例,给出了THD解析式模型及其开关角度轨迹图,和传统多波段SHE进行了对比,发现谐波总含量THD得到很大程度上的降低,同时也解决了其存在电流倒灌的问题。仿真分析和实验结果验证了方法的可行性和优势。 展开更多
关键词 多电平逆变器 遗传算法 总谐波失真(Thd) Thd最小化 电流倒灌 低频调制
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The anti-correlation method for removing harmonic distortion in vibroseis slip-sweep data 被引量:1
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作者 张红静 周辉 +1 位作者 Abd E1-Aziz Khairy Abd E1-Aal 张洁 《Applied Geophysics》 SCIE CSCD 2012年第2期159-167,234,共10页
The slip-sweep technique is one of the high-efficiency, high-fidelity, and environmental vibroseis seismic prospecting techniques which consists of a vibrator group sweeping without waiting for the previous group's s... The slip-sweep technique is one of the high-efficiency, high-fidelity, and environmental vibroseis seismic prospecting techniques which consists of a vibrator group sweeping without waiting for the previous group's sweep to terminate. The cycle time can be reduced drastically and hence the production efficiency can be increased significantly but harmonic distortion of one sweep will leak into the record of the other sweep. In this paper, we propose an anti-correlation method for removing harmonic distortion in vibroseis data. This method is based on decomposition of the ground force signal into fundamental and harmonic components. Then the corresponding anti-correlation operator can be computed to estimate the energy of each harmonic after correlating the vibroseis data with the corresponding harmonic component. Finally, the vibroseis harmonic noise to be removed can be obtained by subtracting the extracted harmonic noise from the traces of the previous group's sweep. The advantage of the proposed method is that it can process both uncorrelated and correlated vibroseis seismic data. Moreover, the algorithm is simple, stable, and computationally fast. Especially, the significant contribution of this method is a considerable reduction in the harmonic without any alteration of the desired signals. The method was tested on both synthetic and field data sets to validate the good harmonic noise suppression results. 展开更多
关键词 VIBROSEIS slip-sweep acquisition anti-correlation method harmonic distortion removal
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Influence of Converter Bus Serious Harmonic Distortion on HVDC Transmission System 被引量:1
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作者 Ziyu Guo Tao Lin +1 位作者 Gengtao Jia Liyong Wang 《自动化学报》 EI CSCD 北大核心 2017年第8期1412-1417,共6页
关键词 高压直流输电系统 谐波畸变 计算机辅助设计 换流站 母线 可持续发展 PSCAD 控制器
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DIGITAL BACKGROUND CALIBRATION OF CAPACITOR MISMATCHES AND HARMONIC DISTORTION IN PIPELINED ADC
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作者 Wu Chubin Zhang Zhang +2 位作者 Gao Shanqing Yu Changhu Xie Guangjun 《Journal of Electronics(China)》 2013年第3期299-307,共9页
A correlation-based digital background calibration algorithm for pipelined Analog-to- Digital Converters (ADCs) is presented in this paper. The merit of the calibration algorithm is that the main errors information, w... A correlation-based digital background calibration algorithm for pipelined Analog-to- Digital Converters (ADCs) is presented in this paper. The merit of the calibration algorithm is that the main errors information, which include the capacitor mismatches and residue amplifier distortion, are extracted integrally. A modified 1st pipelined stage is adopted to solve the signal overflow caused by the Pseudo-random Noise (PN) sequences. Behavioral simulation results verify the effectiveness of the algorithm. It improves the Signal-to-Noise-plus-Distortion Ratio (SNDR) and Spurious-Free-Dynamic-Range (SFDR) of the pipelined ADC from 41.8 dB to 78.3 dB and 55.6 dB to 98.6 dB, respectively, which is comparable to the prior arts. 展开更多
关键词 Analog-to-Digital Converter (ADC) Capacitor mismatches harmonic distortion Pseudo-random Noise (PN) sequence CALIBRATION
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Improved hyper-spherical search algorithm for voltage total harmonic distortion minimization in 27-level inverter
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作者 A A KHODADOOST ARANI H KARAMI +1 位作者 B VAHIDI G B GHAREHPETIAN 《Journal of Central South University》 SCIE EI CAS CSCD 2019年第10期2822-2832,共11页
Multi-level inverters(MLIs)have become popular in different applications such as industrial power control systems and distributed generations.There are different forms of MLIs.The cascaded MLIs(CMLIs)have some special... Multi-level inverters(MLIs)have become popular in different applications such as industrial power control systems and distributed generations.There are different forms of MLIs.The cascaded MLIs(CMLIs)have some special advantages among them such as more different output voltage levels using the same number of components and higher power quality.In this paper,a 27-level inverter switching algorithm considering total harmonic distortion(THD)minimization is investigated.Switching angles of the inverter switches are achieved by minimizing a THD-based objective function.In order to minimize the THD-based objective function,the hyper-spherical search(HSS)algorithm,as a novel optimization algorithm,is improved and the results of improved HSS(IHSS)are compared with HSS algorithm and other five evolutionary algorithms to show the advantages of IHSS algorithm. 展开更多
关键词 27-level inverter cascade multi-level inverter improved hyper-spherical search(IHSS)algorithm total harmonic distortion(Thd)minimization
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Design and Analysis of Cascaded Hybrid-Bridge Multi-Cell Multilevel Inverter with Reduced Total Harmonic Distortion Profile
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作者 Bulbul Sharma N.Karthick Durgesh Prasad Bagarty 《Energy Engineering》 EI 2022年第6期2585-2605,共21页
This multilevel inverter methodology is the center of focus among researchers in recent era.It has been focused due to its advantages over existing topologies,drawbacks and improvement of power quality,Multi-level inv... This multilevel inverter methodology is the center of focus among researchers in recent era.It has been focused due to its advantages over existing topologies,drawbacks and improvement of power quality,Multi-level inverter has the ability to generate nearly sinusoidal waves.This sinusoidal wave can be further improved by increasing the level of output voltage or with the help of filter design,and this manuscript presents single-phase Multi cell Multi-Level Inverter(MLI).It has been considered for reducing component count to get a higher number of output voltage levels and lower Total harmonics distortion profile.It comprises with four symmetric DC input voltage and 10 IGBT switches to produces stepped output of 9 level,and when deploy asymmetric Dc voltage source the same circuit will produce 31 level output with some changes in firing scheme,moreover this circuit is the family of cascaded hybrid bridge inverter so this circuit covered advantage of CHB MLI,This circuit uses lower no.of switch as compared to existing conventional MLIs such as FC-MLI,CHB-MLI,NPC-MLI,This paper also provides one of most pertinent controls and modulation mechanisms for a MLI using a hybrid reference/carrier-oriented sinusoidal PWM mechanism.At last,simulated outcomes are to validate the performance of both architectures in MLI structure as well as verify the concept. 展开更多
关键词 Conventional topology multi-level inverters(MLIs) pulse width modulations(PWM) reduced component counts total of harmonics distortion(Thd)
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Safety and Performance of Harmonic®HD 1000i Shears in Thoracoscopic Procedures: A Retrospective Study
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作者 Seong Yong Park Subin Lim +3 位作者 Dong Kyu Kim Jason R. Waggoner Paula P. Veldhuis Giovanni A. Tommaselli 《Open Journal of Thoracic Surgery》 2022年第2期33-42,共10页
Background: Ultrasonic energy devices are utilized for transection, incision, and hemostasis in traditional open and laparoscopic procedures. The Harmonic HD 1000i Shears, designed to deliver a precise amount of therm... Background: Ultrasonic energy devices are utilized for transection, incision, and hemostasis in traditional open and laparoscopic procedures. The Harmonic HD 1000i Shears, designed to deliver a precise amount of thermal energy during tissue transection and vessel sealing, has been utilized in many specialties. This study aimed to confirm real-world safety and performance of the Harmonic device in two thoracoscopic procedures: lobectomy and segmentectomy. Methods: The primary endpoint of this retrospective, observational, single-arm study was rate of post-operative blood transfusions related to study device or procedure. Secondary endpoints included occurrence of intra- and post-operative adverse events (AEs) or complications device- or procedure-related, and rate of required additional hemostatic measures. Adults included those who underwent thoracoscopic lobectomy or segmentectomy where HD 1000i shears were used while excluding those where additional advanced energy devices were used. The study was conducted at Severance Hospital, Yonsei University Health System, South Korea from May 1, 2018, to November 30, 2020. Results: Subjects included n = 766 lobectomies (mean age 63.79, 52% male) and n = 215 segmentectomies (mean age 63.19, 54% male). Estimated blood loss was 50 mL (0 min, 3200 max) and 20 mL (0 min, 800 max), intraoperative transfusion rate 0.001% and 0%, intraoperative complication/AE rate 1% and 2%, and post-operative complication/AE rate 9% and 4% in the lobectomy and segmentectomy groups, respectively. Median operative times were 108 min. (35 min, 395 max) for lobectomies and 105 min. (32 min, 574 max) for segmentectomies. Conclusion: Given the low rate of blood loss and intra- and post-operative complication/AE rates, HD 1000i can be used confidently for thoracoscopic pulmonary resection in adults. 展开更多
关键词 harmonic hd 1000i Shears LOBECTOMY SEGMENTECTOMY Ultrasonic Energy Device
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Harmonics Extraction Scheme for Power Quality Improvement Using Chbmli-Dstatcom Module
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作者 R.Hemalatha M.Ramasamy 《Intelligent Automation & Soft Computing》 SCIE 2023年第2期1505-1525,共21页
In recent day’s power distribution system is distress from acute power quality issues.In this work,for compensating Power Quality(PQ)disturbances a seven level cascaded H-bridge inverter is implemented in distributio... In recent day’s power distribution system is distress from acute power quality issues.In this work,for compensating Power Quality(PQ)disturbances a seven level cascaded H-bridge inverter is implemented in distribution static com-pensator which protects power quality problems in currents.Distribution Static Compensator(DSTATCOM)aid to enhances power factor and removes total har-monic distortion which is drawn from non-linear load.The D–Q reference theory based hysteresis current controller is employed to generate reference current for compensation of harmonics and reactive power,additionally Probabilistic Neural Network(PNN)classifier is used which easily separates exact harmonics.In the meantime fuzzy logic controller is also used to maintain capacitor DC-link poten-tial.When comparing to PI controller it decreases steady state time and reduces maximum peak overshoot.Cascaded H-bridge multilevel inverter converts direct current to Alternating current,through inductor opposite harmonics are injected in Power Control Centre reduces source current harmonics and reactive power.The implementation of CHBMLI in distribution STATic COMpensator simulation model is simulated by means of MATLAB. 展开更多
关键词 CHBMLI distribution STATic COMpensator(DSTATCOM) probabilistic neural network(PNN) PI(proportional–integral) fuzzy logic control(FLC) total harmonic distortion(Thd)
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谐波干扰抑制下的低压配电网母线电压自动控制系统 被引量:1
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作者 汪敏 赵静 张健 《自动化技术与应用》 2024年第7期75-78,共4页
母线电压的平稳程度,直接影响低压配电网的运行安全,因此设计谐波干扰抑制下的低压配电网母线电压自动控制系统。该系统以配电网调度系统的控制需求为前提,在系统无功补偿层引入抗谐波干扰无功发生器获取母线电压的无功补偿量,母线无功... 母线电压的平稳程度,直接影响低压配电网的运行安全,因此设计谐波干扰抑制下的低压配电网母线电压自动控制系统。该系统以配电网调度系统的控制需求为前提,在系统无功补偿层引入抗谐波干扰无功发生器获取母线电压的无功补偿量,母线无功控制需求整定层依据该计算结果和母线电压控制指令,结合母线实时运行电压结果,对比判断母线实际电压结果和参考电压之间的差距,确定母线电压所需的无功补偿量,完成电压控制。测试结果显示:该系统能够有效控制母线电压谐波,谐波畸变率低于4.4%;能够保证电压的稳定,电压控制的偏差结果均在±1.5 V之间,母线在相位阶跃和稳态两种情况下的相位误差结果均低于0.075。 展开更多
关键词 谐波干扰抑制 低压配电网 母线电压 控制系统 无功补偿量 谐波畸变率
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复杂电能信号谐波时频域特征分析及其对电能计量影响 被引量:1
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作者 王学伟 田福利 +2 位作者 袁瑞铭 李文文 王国兴 《电力自动化设备》 EI CSCD 北大核心 2024年第5期191-198,共8页
为准确分析复杂电能信号谐波时频域特性对电能计量的影响,提出了一种零值搜索-短时傅里叶变换时频域电压、电流信号幅度和相位分析算法,利用信号波形过零特征,自适应调整短窗傅里叶变换的时域窗宽,解决了电网频率波动导致的相位累积效... 为准确分析复杂电能信号谐波时频域特性对电能计量的影响,提出了一种零值搜索-短时傅里叶变换时频域电压、电流信号幅度和相位分析算法,利用信号波形过零特征,自适应调整短窗傅里叶变换的时域窗宽,解决了电网频率波动导致的相位累积效应对相位分析的影响,算法的幅值分析误差为10-3、相位分析误差小于1°;建立了复杂电能信号时频域数据表征模型和4类时频域全局化特征矩阵提取算法,解决了时频域特性表征与提取的问题;以典型非线性动态负荷中频炉为分析案例,分析给出了其4类时频域全局化特征,并建立了畸变波形动态电能测试信号特征模型,通过辅助实验验证了4个时频域全局化特征对电能表动态超差的影响,提出了对国际和国内标准修改的建议。 展开更多
关键词 复杂动态负荷 电能计量信号 时频域特性分析 全局化特征 畸变波形动态测试信号
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具有高功率因数低THD特性的SEPIC PFC变换器研究
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作者 余会明 《电工技术》 2023年第15期50-53,共4页
与传统的功率因数校正PFC电路相比,SEPIC PFC变换器具有输入电流始终连续且纹波小、输出电压调节范围大等特点,在工业中得到越来越多的重视。首先分析SEPIC PFC变换器工作原理,推导其工作于电感电流断续模式和电容电压断续模式时的输入... 与传统的功率因数校正PFC电路相比,SEPIC PFC变换器具有输入电流始终连续且纹波小、输出电压调节范围大等特点,在工业中得到越来越多的重视。首先分析SEPIC PFC变换器工作原理,推导其工作于电感电流断续模式和电容电压断续模式时的输入电流表达式;然后提出具有高功率因数低谐波失真的SEPIC PFC变换器变频控制技术,通过描述其控制原理,介绍了控制电路参数的选择;最后通过实验对比分析随着输入电压有效值的变化,SEPIC PFC变换器的功率因数、谐波失真、效率等性能指标的变化趋势。 展开更多
关键词 SEPIC变换器 功率因数校正 变频控制 总谐波失真
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基于模拟开关的放大器非线性失真电路设计
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作者 吴晓盼 《黄山学院学报》 2024年第5期26-30,共5页
非线性失真是影响模拟电路性能的重要因素之一,针对顶部失真、底部失真、双向失真和交越失真四种非线性失真情况对晶体管放大电路的影响,在详细介绍非线性失真原因及总谐波失真量化评价的基础上,以STM32F103ZET6单片机为核心,设计制作... 非线性失真是影响模拟电路性能的重要因素之一,针对顶部失真、底部失真、双向失真和交越失真四种非线性失真情况对晶体管放大电路的影响,在详细介绍非线性失真原因及总谐波失真量化评价的基础上,以STM32F103ZET6单片机为核心,设计制作了一个放大器非线性失真研究装置。该装置主要包括晶体管放大器、采集测量、微控制器等硬件电路和软件驱动。通过两级负反馈共射放大、乙类放大分别实现基本晶体管放大和四种非线性失真产生电路,利用BL1551和CD4053模拟开关控制波形输出,采用FFT算法提取总谐波失真值。经系统测试:所设计的装置可以输出不失真波形、四种非线性失真电压波形和测量显示总谐波失真系数;测试外接信号源指定信号的总谐波失真系数时,平均精度可达95%。 展开更多
关键词 非线性失真 晶体管 放大器 模拟开关 总谐波失真
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基于改进变步长LMS算法的谐波电流检测法
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作者 曹珍贯 方金明 董高辉 《佳木斯大学学报(自然科学版)》 CAS 2024年第4期19-23,共5页
针对传统基于瞬时无功功率理论谐波电流检测中的二阶低通滤波器无法同时满足检测精度和响应时间的问题,提出了基于改进的双曲正切函数变步长LMS算法(IVSSLMS)的低通滤波器提取p轴和q轴中直流分量的方法;将两个谐波电流的间隔时间通过适... 针对传统基于瞬时无功功率理论谐波电流检测中的二阶低通滤波器无法同时满足检测精度和响应时间的问题,提出了基于改进的双曲正切函数变步长LMS算法(IVSSLMS)的低通滤波器提取p轴和q轴中直流分量的方法;将两个谐波电流的间隔时间通过适当的调节采样间隔次数来延长,目的是为了达到高次谐波的自相关性能迅速降为零。从理论上分析了算法性能的优越,给出了参数的取值,并在simulink中搭建了仿真模型,仿真实验结果表明,改进后的低通滤波器直流分量的跟踪速度提升了一倍,得到基波正弦波形的THD值下降了0.37%。并得出以下结论:在同样输电条件下,采用改进变步长LMS算法构成低通滤波器加快了直流量的跟踪,提取的基波分量更加接近于理想波形,提升了谐波检测的瞬时性和准确性。 展开更多
关键词 瞬时无功理论 LMS算法 谐波总畸变率
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柔性直流输电系统的高频谐波保护方法与工程实践 被引量:2
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作者 姜崇学 马秀达 +3 位作者 邹强 徐莹 卢亚军 程骁 《电力系统自动化》 EI CSCD 北大核心 2024年第3期150-158,共9页
柔性直流输电系统受电力电子设备本身特性以及控制系统影响,在多种运行工况下易出现不同频率的振荡问题。作为实现设备安全和电网稳定运行的决定因素,保护系统应实现对系统谐波的准确监测以及可靠动作。根据高频振荡时的电流能量累积作... 柔性直流输电系统受电力电子设备本身特性以及控制系统影响,在多种运行工况下易出现不同频率的振荡问题。作为实现设备安全和电网稳定运行的决定因素,保护系统应实现对系统谐波的准确监测以及可靠动作。根据高频振荡时的电流能量累积作用,给出了基于反时限动作的电流类谐波保护算法。基于高频谐波电压特性,分别给出了过零点监测保护算法、谐波畸变率保护算法以及宽谐波保护算法,各保护算法相互配合,实现对不同电压振荡类型的全面保护。最后,给出了国内柔性直流工程实践中配置的高频谐波保护,结合保护原理对系统发生高频振荡后的动作特性进行分析,验证了高频谐波保护的有效性和准确性。 展开更多
关键词 柔性直流输电 高频振荡 谐波保护 过零点检测 谐波畸变率
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单相不间断电源逆变电路调制度对输出电压谐波的影响
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作者 严刚峰 吴保宁 柳恒敏 《成都大学学报(自然科学版)》 2024年第1期40-45,共6页
详细分析单相不间断电源核心部分(逆变电路)的特点、类型、评价指标及控制方式,然后采用广泛应用的单相双极性正弦脉冲宽度调制法的全桥逆变电路作为研究对象,导出了逆变电路输出平均电压的表达式,采用仿真和理论相结合的方法讨论了频... 详细分析单相不间断电源核心部分(逆变电路)的特点、类型、评价指标及控制方式,然后采用广泛应用的单相双极性正弦脉冲宽度调制法的全桥逆变电路作为研究对象,导出了逆变电路输出平均电压的表达式,采用仿真和理论相结合的方法讨论了频率调制度和幅值调制度的典型取值对输出电压谐波的影响.讨论结果表明,当载波频率为调制波频率的奇数倍时,取幅值调制度r=0.9左右,而当载波频率为调制波频率的偶数倍时,取幅值调制度r=0.5左右,此时输出逆变电压波形质量更好,谐波含量较小,对于改善逆变电路的设计和参数选择具有一定的参考价值. 展开更多
关键词 不间断电源 全桥 逆变电路 调制度 谐波失真
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适用于三电平逆变器的电流谐波最小脉宽调制策略
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作者 褚艳红 周明磊 +1 位作者 王琛琛 游小杰 《电机与控制学报》 EI CSCD 北大核心 2024年第8期21-30,共10页
受限于散热条件,大功率牵引传动系统中逆变器开关频率通常很低,三电平逆变器由于在低开关频率下具有较小的输出谐波、较低的dv/dt等特点在中高压大功率领域中被广泛应用。以三电平中点钳位型逆变器为研究对象,提出一种电流谐波最小脉宽... 受限于散热条件,大功率牵引传动系统中逆变器开关频率通常很低,三电平逆变器由于在低开关频率下具有较小的输出谐波、较低的dv/dt等特点在中高压大功率领域中被广泛应用。以三电平中点钳位型逆变器为研究对象,提出一种电流谐波最小脉宽调制策略(CHMPWM),基于加权总谐波畸变最小的优化目标求解不同开关角个数下的开关角曲线,与目前应用较为广泛的特定次谐波消除脉宽调制进行谐波性能对比。该方法不会完全消除特定次数的谐波成分,但是总体电流谐波可以达到最小。针对电流谐波最小脉宽调制策略在实现过程中存在的困难,设计全速度范围基于电流谐波最小脉宽调制的多模式调制策略。仿真和实验结果表明,提出的调制策略具有良好的谐波性能,与理论分析结果一致。 展开更多
关键词 三电平逆变器 电流谐波最小 脉宽调制 低开关频率 加权总谐波畸变 谐波性能
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集成式GaN单开关管功率因数校正变换器
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作者 曹通 秦世清 +4 位作者 何映谊 李婷 张秀梅 杨国锋 卞宝安 《重庆大学学报》 CAS CSCD 北大核心 2024年第7期63-73,共11页
传统的降压型功率因数校正(power factor correction,PFC)变换器由于存在高谐波电流的缺点,较难满足IEC61000-3-2 C类限值,其应用受到很大限制。文中设计并搭建了一种集成式功率因数校正变换器,该变换器由一个降压PFC变换器和一个反激PF... 传统的降压型功率因数校正(power factor correction,PFC)变换器由于存在高谐波电流的缺点,较难满足IEC61000-3-2 C类限值,其应用受到很大限制。文中设计并搭建了一种集成式功率因数校正变换器,该变换器由一个降压PFC变换器和一个反激PFC变换器组成,其中降压和反激PFC变换器采用输入并联和输出并联连接方式共用一个GaN开关管和控制电路,降低变换器成本。集成式变换器在临界导通模式(critical conduction mode,CRM)恒定导通时间(constant on time,COT)控制下,反激单元消除了降压输入电流死区的影响,利用降压和反激PFC变换器的优势和GaN开关管的优异性能,变换器可以在宽电压输入范围下实现高效率和低总谐波失真。文中介绍了电路结构和工作原理,通过PSIM(power simulation)仿真验证理论推导的正确性,最后搭建了满载效率为94.1%的120 W样机,验证了该方案的可行性。 展开更多
关键词 功率因数校正变换器 氮化镓 集成式 低总谐波失真
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微型扬声器总谐波失真测量的衍射效应
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作者 曾宪宏 冯雪磊 沈勇 《应用声学》 CSCD 北大核心 2024年第5期941-948,共8页
该文旨在消除衍射效应对微型扬声器总谐波失真测量的影响,根据扩展的Biot–Tolstoy–Medwin模型,研究了微型扬声器总谐波失真测量的衍射效应,重点分析了微型扬声器后腔封闭和后腔开放的两种不同条件下考虑微型扬声器后向衍射和不考虑后... 该文旨在消除衍射效应对微型扬声器总谐波失真测量的影响,根据扩展的Biot–Tolstoy–Medwin模型,研究了微型扬声器总谐波失真测量的衍射效应,重点分析了微型扬声器后腔封闭和后腔开放的两种不同条件下考虑微型扬声器后向衍射和不考虑后向衍射的两种情况。该文使用的是简单稳定的障板测试条件,由于衍射效应与障板尺寸和微型扬声器的安装位置有关,因此该文将微型扬声器安装在固定尺寸的障板上的固定位置。该文理论计算了不同测量距离下障板的衍射曲线,分析了对应情况下微型扬声器总谐波失真测量的衍射效应,并进行实验验证。实验结果与理论计算吻合良好,证明了该文计算方法的准确性。该文研究表明,微型扬声器总谐波失真测量的衍射效应受障板的影响较大,且测试距离越远,影响越大,扬声器后腔开放时的衍射效应比后腔封闭时的衍射效应更为明显。使用根据该文的方法计算出的衍射曲线,可以对微型扬声器测量得到的总谐波失真进行修正,消除障板测试条件下衍射效应的影响。 展开更多
关键词 微型扬声器 衍射 总谐波失真 障板
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Performance Assessment of a Real PV System Connected to a Low-Voltage Grid 被引量:1
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作者 Gaber Magdy Mostafa Metwally +1 位作者 Adel A.Elbaset Esam Zaki 《Energy Engineering》 EI 2024年第1期13-26,共14页
The generation of photovoltaic(PV)solar energy is increasing continuously because it is renewable,unlimited,and clean energy.In the past,generation systems depended on non-renewable sources such as oil,coal,and gas.Th... The generation of photovoltaic(PV)solar energy is increasing continuously because it is renewable,unlimited,and clean energy.In the past,generation systems depended on non-renewable sources such as oil,coal,and gas.Therefore,this paper assesses the performance of a 51 kW PV solar power plant connected to a low-voltage grid to feed an administrative building in the 6th of October City,Egypt.The performance analysis of the considered grid-connected PV system is carried out using power system simulator for Engineering(PSS/E)software.Where the PSS/E program,monitors and uses the power analyzer that displays the parameters and measures some parameters such as current,voltage,total power,power factor,frequency,and current and voltage harmonics,the used inverter from the type of grid inverter for the considered system.The results conclude that when the maximum solar radiation is reached,the maximum current can be obtained from the solar panels,thus obtaining the maximum power and power factor.Decreasing total voltage harmonic distortion,a current harmonic distortion within permissible limits using active harmonic distortion because this type is fast in processing up to 300 microseconds.The connection between solar stations and the national grid makes the system more efficient. 展开更多
关键词 Low-voltage grid photovoltaic(PV)system total harmonic distortion grid-connected PV system
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基于新过采样方法的APF电流THD测量 被引量:4
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作者 洪磊 谢川 +1 位作者 李玉玲 陈国柱 《电力电子技术》 CSCD 北大核心 2011年第1期96-98,共3页
电流总谐波畸变率(THD)是有源电力滤波器(APF)的一项重要性能指标,工业现场一般要求APF补偿后电流THD<5%。实验发现A/D转换引入的噪声对THD测量影响极大,其误差可达200%,不能满足应用要求。针对大功率电力电子装置采样频率低和THD测... 电流总谐波畸变率(THD)是有源电力滤波器(APF)的一项重要性能指标,工业现场一般要求APF补偿后电流THD<5%。实验发现A/D转换引入的噪声对THD测量影响极大,其误差可达200%,不能满足应用要求。针对大功率电力电子装置采样频率低和THD测量对采样信号信噪比要求高的特点,提出一种新的过采样方法,对其进行原理分析,进而结合THD测量的实际讨论了该方法应用的相关问题。最后,通过仿真和实验对传统采样方法和新过采样方法进行比较,验证了该方法的有效性。 展开更多
关键词 有源电力滤波器 总谐波畸变率 过采样 信噪比
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