共查询到20条相似文献，搜索用时 46 毫秒
1.
A novel topology for ripple-free input current circuit is put forward in the paper. Compared to traditional EMI (electromagnetic
interference) filter consisting of choke and capacitor, the ripple-free topology can reduce the converter's ripple current
with the use of smaller component. The new ripple-free topology proposed in this paper does not need elaborate adjustment
of the coupling coefficient as required by conventional ripple-free techniques, and is ripple voltage cancellation or isolation
mode, which can attenuate the ripple further if the line impedance is considered. The theoretical prediction is confirmed
by experimental results.
Project supported by the Scientific Research Foundation for Returned Overseas Chinese Scholars, State Education Ministry 相似文献
2.
1Introduction DuetotheextensiveuseofPWMconverters,elec tricpowerlinesareincreasinglycontaminated.This hascausedmanywidelyrecognizedproblems,leading toseveralelectricregulations[1,2].Itisnoteworthythat inhomeappliances,withincreasingconcernsofenergy savingandreducingoperationloss,manyinverter techniqueshavebeendevelopedandadoptedinpro ductssuchasair conditioners,washingmachinesand refrigerators.Despitetheenergysavingmeritofthe invertersystems,thesesystemshavecriticalproblems ofincreasedpowerf… 相似文献
3.
应用于DC-DC变换器的传统拓扑中SEPIC(Single-Ended Primary Inductance Converter)拓扑既可以用于升压又可以用于降压,并且输出电压为正电压,具有启动时限制浪涌电流、较小输入电流纹波和低电磁干扰(Electromagnetic Interference,EMI),具有谐波小等优点,但针对SEPIC拓扑的详细分析和建模相对较少,文中针对工作于电流临界模式(Critical Current Mode,CRM)的SEPIC线路进行了详细的分析,并对理论等式进行了详细推导,给出了简化的设计步骤,最后根据要求对SEPIC变换器进行了设计,并给出了仿真波形. 相似文献
4.
In order to deal with torque pulsation problem caused by traditional control method for brushless DC （BLDC） motor and to achieve high precision and good stability, a novel control strategy is proposed. Compared with the traditional control scheme, by using phase voltage as a control objective and making waveform of phase current approximately quasi-sinusoidal, torque ripple of BLDC motor is reduced from the original 14% to 3.4%, while toque is increased by 3.8%. Furthermore, by detecting zero-crossings of back electromotive force （BEMF） with non-conducting phases, sensorless control is realized. The new control strategy is simple. It can minimize torque ripple, increase torque, and realize sensorless control for BLDC motor. Simulation and experiments show good performance of BLDC motor by using the new control method. 相似文献
5.
郑少锋 《福建工程学院学报》2003,1(3):29-32
通过对多输出的CMOS跨导器传输特性的研究，给出了实现二阶OTA—C滤波器的电路结构和电流传递函数。该电路通过三个CMOS模拟开关的通、断，不用改变电路的拓扑结构就能实现较高频段又易于集成的低通、高通、带通、带阻、全通等多种滤波功能。用PSPICE进行MOS管级的模拟，结果表明电路可获得多种滤波功能并实现滤波参数的片外电调节。 相似文献
6.
7.
介绍了人工心脏轴流式血泵永磁无刷直流电机换相转矩脉动变化过程．根据影响电机换相转矩脉动的因素,给出了减小电机转矩脉动的解决方案,以使电机运行更加平稳．通过实验波形证实本结论分析正确,可以为电机减小转矩脉动作为参考． 相似文献
8.
针对无位置传感器单相无刷直流电机控制系统中的换相点时间不确定、换相转矩波动大两大问题.论文提出一种控制策略-相电流时分复用法,该方法在一个控制周期内的大部时分间里,电机绕组通入励磁电流被用来驱动电机旋转,在剩余的时间内,被用来检测电机转子的位置,通过精确控制提前关断功率开关管的时间,达到减小电机输出转矩的波动、提高电机的转速范围,明显提高单相无刷直流电动机无位置传感器运行时的性能,实验结果验证了提出方法的准确性和可行性. 相似文献
9.
本文提出了一种LCL谐振式推挽电路拓扑,谐振元件位于推挽电路变压器的原边;分析了电路的两种工作模式,通过分析可知,谐振电路参数决定谐振频率,同时影响谐振电流幅值;以600W样机为基础,进行了仿真分析与实验,实验表明提出的电路拓扑很好地实现了零电压开通和零电流关断,验证了拓扑的正确性和有效性。 相似文献
10.
To elucidate the principles of notable torque and flux ripple during the steady state of the conventional direct torque control (DTC) of induction machines, the factors of influence torque variation are examined. A new torque ripple minimization algorithm is proposed. The novel method eradicated the torque ripple by imposing the required stator voltage vector in each control cycle. The M and T axial components of the stator voltage are accomplished by measuring the stator flux error and the expected incremental value of the torque at every sampling time. The maximum angle rotation allowed is obtained. Experimental results showed that the proposed method combined with the space vector pulse width modulation(SVPWM) could be implemented in most existing digital drive controllers, offering high performance in both steady and transient states of the induction drives at full speed range. The result of the present work imphes that torque fluctuation could be eliminated by imposing proper stator voltage, and the proposed scheme could not only maintain constant switching frequency for the inverter, but also solve the heating problem and current harmonics in traditional induction motor drives. 相似文献
11.
发射端串联补偿拓扑在基于E类高频逆变器的无线电能传输(WPT)系统中应用广泛。其串联谐振回路存在无载时电流过大,损耗过高等问题。设计一种用于该系统的无载保护控制电路,该电路具有电感电流缓冲及逆变器过流保护功能,且系统发射端在无载时的功耗为0.6 W左右。对于无线电能传输系统的控制电路设计具有参考意义。 相似文献
12.
ＩＮＴＲＯＤＵＣＴＩＯＮＢｅｎｄｓｏｅａｎｄＫｉｋｕｃｈｉｉｎｉｔｉａｔｅｄｔｈｅｈｏｍｏｇｅｎｉ ｚａｔｉｏｎｍｅｔｈｏｄ (Ｂｅｎｄｓｏｅｅｔａｌ.,1 988)ｆｏｒｃｏｎ ｔｉｎｕｏｕｓｓｔｒｕｃｔｕｒｅｓ.Ａｖｅｒｙｉｍｐｏｒｔａｎｔｓｔｅｐｉｎｔｈｅｔｏｐｏｌｏｇｙｏｐｔｉｍｉｚａｔｉｏｎｉｓｔｈｅｃｈａｎｇｅｆｒｏｍｓｋｅｌｅｔａｌｓｔｒｕｃｔｕｒｅｔｏｃｏｎｔｉｎｕｏｕｓｓｔｒｕｃｔｕｒｅ .Ａｃｃｏｒｄｉｎｇｌｙ ,ｔｏｐｏｌｏｇｙｄｅｓｉｇｎｉｓｃｈａｎｇｅｄｆｒｏｍｄｅｆｉｎｉｎｇｗｈｅｔ… 相似文献
13.
This paper presents the topology optimization design of structures composed of plane stress elements. The authors' proposed
method of topology optimization by virtual laminated element is based on the Evolutionary Structural Optimization (ESO) method
of linear elasticity, but dose not require formation of as many elements as the conventional ESO method. The presented method
has the important feature of reforming the stiffness matrix in generating optimum topology. Calculation results showed that
this algorithm is simple and effective and can be applied for topology optimization of structures. 相似文献
14.
许成文 《石家庄铁路职业技术学院学报》2008,7(1):48-51
通过对网络拓扑的研究,列出三种基本的网络拓扑结构,通过矩阵可以表示这些拓扑结构特征.对于网络结构可以由这三种基本结构组成进行可行性分析,使得不同的拓扑结构结合相应的技术可以更好地解决隐藏终端和暴露终端带来的问题. 相似文献
15.
许成文 《石家庄铁路工程职业技术学院学报》2008,(1):48-51
通过对网络拓扑的研究,列出三种基本的网络拓扑结构,通过矩阵可以表示这些拓扑结构特征。对于网络结构可以由这三种基本结构组成进行可行性分析,使得不同的拓扑结构结合相应的技术可以更好地解决隐藏终端和暴露终端带来的问题。 相似文献
16.
BAO Jian-yu LI Yu-ling ZHANG Zhong-chao 《浙江大学学报(A卷英文版)》2006,7(6):1051-1055
INTRODUCTION Up to now, multilevel voltage-source inverters(VSIs) (Fang, 2001) have been paid more attentionthan multilevel current-source inverters (CSIs) in thehigh-power fields. One of the most important reasonsis that inductors, as energy storage elements, have thedisadvantages of higher conducting losses and lowerenergy storage efficiency than capacitors. However,with the development of superconducting magneticenergy storage (SMES) technology (Luongo, 1996),superconducting induc… 相似文献
17.
针对异步电动机直接转矩控制（DTC）系统在低速时由于开关频率不稳定而引起转矩脉动较大的缺点，提出了一种预测控制方法。该方法根据转矩和定子磁链的误差来确定应该施加的参考电压矢量，最后利用空间矢量脉宽调制（SVPWM）方法来合成该矢量，这样即保证了逆变器的开关频率恒定，从而大大降低转矩脉动。仿真结果表明，在低速下定子磁链轨迹近似为圆，转矩脉动不明显。 相似文献
18.
异步电机按定子磁链定向的转矩连续控制 总被引：5，自引：0，他引：5
ＮｏｍｅｎｃｌａｔｕｒｅＪｍｏｍｅｎｔｏｆｉｎｅｒｔｉａｏｆｔｈｅｌｏａｄ(ｍｏｔｏｒｉｎｃｌｕｄｅ)ｉｓ,ｉｒ,ｉｍｓｔａｔｏｒ,ｒｏｔｏｒａｎｄｍａｇｎｅｔｉｚｉｎｇｃｕｒｒｅｎｔｕｓ,ｕｒｓｔａｔｏｒａｎｄｒｏｔｏｒｖｏｌｔａｇｅＬｓ,Ｌｒ,Ｌｍｓｔａｔｏｒ,ｒｏｔｏｒａｎｄｍａｇｎｅｔｉｚｉｎｇｉｎｄｕｃｔａｎｃｅＬσｔｏｔａｌｌｅａｋａｇｅｉｎｄｕｃｔａｎｃｅＲｓ,ＲｒｓｔａｔｏｒａｎｄｒｏｔｏｒｒｅｓｉｓｔａｎｃｅＮｐｐｏｌｅｐａｉｒｓΨｓ,Ψｒ,Ψσｓｔａｔｏｒ,ｒｏｔｏｒａｎｄｔｏｔａｌｌｅ… 相似文献
19.
多电平变换技术主要是针对电压型逆变器,随着电力电子技术以及储能技术的发展,电流型多电平逆变器也将得到广泛应用。针对单相直接式电流型多电平拓扑开展研究,该类拓扑结构非常简单,所用开关器件和均流电感的数目非常少,逆变电路的开关器件的频率可以很低。分析了由该类拓扑组成的单相5电平、7电平变流器的工作原理,总结了变流器的拓扑构成规律,建立了单相5电平、7电平变流器的稳态平均模型,研究了它们的开关控制策略,并给出了一种通过调节输出电平宽度来消除低次电流谐波的方法。 相似文献
20.
系统设计从使用简单,调整方便,界面友好的目的出发,采用了模块化设计思想.系统包括整流、滤波模块,电流调整模块,检流模块,信号放大调整模块和控制、显示等模块.该系统通过电流负反馈、闭环控制改变基准电压来达到恒流的目的.并采用PID控制算法提高输出电流精度.该系统具有输出恒定、电流范围宽、精度高、低纹波、易控制等特点. 相似文献