共查询到20条相似文献,搜索用时 218 毫秒
1.
设计了内燃机车空调器单相电容电动机用单相变频器,该变频采用特定谐波消除方法生成PWM开关信号,输出电压基波含量高,低次谐波含量基本为零,且调频范围宽,分析了各单元电路和升压变压器的设计方法。通过实验研究了证明该变频器输出电压稳定,能满足实际要求。 相似文献
2.
针对目前非线性化负载大量使用引起电网谐波和无功污染日益严重的问题,设计对电网污染很小的单相PWM整流器。通过建立和分析单相电压型PWM整流器的拓扑结构和数学模型,给出了该系统的电压、电流双闭环控制方法。该方法采用构造虚拟电流的方法进行电流内环的解耦控制,并通过分析系统的瞬时有功、无功功率流以实现电压外环的线性化控制。对系统进行基于Matlab/SIMULINK的仿真分析,并进行硬件设计,搭建整流器实验模型,以进行实验验证。仿真和实验结果验证了该电压、电流双闭环控制方法的可行性,同时表明单相PWM整流器具有网侧单位功率因素运行、网侧电流正弦化、直流输出电压纹波小等优点,对电网的谐波和无功污染很小。 相似文献
3.
设计了一种新型单相与三相输入兼容的特定消谐式变频器.提出了一种单相与三相输入兼容的变频器主电路,深入研究了离线计算与在线计算相结合实现特定消谐的方法.实验结果表明,该变频器具有消除谐波次数多,残余谐波含量小,电压利用率高,直流母线电压高,输出稳压特性好,开关角数据存储空间小的特点,有很好的应用前景. 相似文献
4.
5.
PWM驱动系统中的共模电压及抑制 总被引:3,自引:0,他引:3
针对PWM逆变器在工作时产生的共模电压可能损坏电机轴承,产生电磁干扰等降低系统可靠性的问题,对共模电压的特性及其负面影响进行了理论分析和实验验证,并得出共模电压的抑制方法.提出一种由一个单相逆变器和一个五绕组变压器组成的逆变器输出有源滤波器结构来消除共模电压.该滤波器可以构建一个与PWM逆变器输出的共模电压大小相等、相位相反的共模电压,通过五绕组变压器叠加到电机端,从而消除电机端的共模电压.由统一的控制单元同时输出PWM逆变器和单相逆变器的控制信号,给出滤波器的相关控制策略及设计方法.实验验证了所提出的滤波器消除共模电压及其负面效应的有效性. 相似文献
6.
直流电压不均衡的级联H桥多电平变频器载波移相PWM调制策略的设计 总被引:1,自引:0,他引:1
《电工技术学报》2016,(1)
对于级联H桥多电平变频器,单元独立直流电源的参数差异及故障等多种因素均会导致各单元的直流电压不均衡。单元直流电压不均衡时,传统载波移相(PSC)PWM调制策略无法消除电压的低频边带谐波,导致变频器输出的电能质量明显降低。对单元载波相位、直流电压与变频器输出电压谐波的关系进行了研究,提出了按照单元直流电压调整单元载波相位的策略。该调制策略能够消除变频器输出电压的低频边带谐波,提高电能质量,增强变频器的容错能力。仿真与样机实验结果验证了所提出的调制策略的效果。 相似文献
7.
基于单相STATCOM的不平衡负荷平衡化补偿的仿真研究 总被引:22,自引:11,他引:22
单相STATCOM由于具有输出无功电流谐波含量低、响应速度快等优点而适合于不平衡负荷的平衡化补偿。文中给出了采用单相STATCOM实现平衡化补偿的两种主电路结构及电压-无功综合控制方法。三相补偿电流相量采用对称分量法通过矢量变换获得,单相无功功率采用单相瞬时无功功率算法得到,单相逆变器采用特定谐波消除PWM算法(SHE-PWM),以保证输出无功电流的谐波总畸变率小于5%,同时保证直流侧电容电压的稳定。对所给出的补偿方法进行了仿真研究,结果验证了单相STATCOM进行快速平衡化补偿的能力比较强。 相似文献
8.
《中国电机工程学报》2010,(21)
单相脉宽调制(pulse width modulation,PWM)整流器广泛应用于交流传动领域,是交流传动电力机车主牵引和辅助供电系统的重要组成部分,同时也是牵引网的主要谐波源。详细分析牵引网谐波电压和直流电压脉动对单相PWM整流器网侧电流的影响,提出采用嵌入式重复控制和N次陷波器相结合的控制算法,对网侧谐波电流进行抑制。详细讨论电流环嵌入式重复控制器的设计方法,理论分析重复控制算法对牵引网谐波电压的抑制效果,给出电流环控制参数的选取原则。针对直流电压脉动,提出采用N次陷波器抑制其对网侧电流的影响,给出与电压环PI调节器相结合的设计方法,并讨论电压环的跟随性。最后,搭建单相PWM整流器的实验装置,对该算法进行实验验证。实验结果证明了该算法的正确性和有效性。 相似文献
9.
PWM变频器输出共模电压及其抑制技术的研究 总被引:14,自引:3,他引:14
PWM逆变器在应用中产生的共模电压将影响系统的可靠运行。文中研究了电压源型PWM变频器产生的共模电压及其负面效应产生机理,揭示了共模电压产生的原因及其抑制方法,并得出共模电压是变频器输出负面效应产生的主要根源的结论,为滤波器的设计提供理论依据。根据共模电压是由一系列高频谐波组成这一特性,提出了一种新颖的逆变器输出前馈有源滤波器结构,可有效地消除了变频器输出共模电压的负面效应,实验验证了这种结构的有效性。 相似文献
10.
基于STATCOM三相不平衡负载的平衡补偿 总被引:3,自引:0,他引:3
由于单相STATCOM具有输出无功电流谐波含量低、响应速度快等优点而适用于不平衡负载的平衡化补偿。提出了采用单相STATCOM实现平衡化补偿的两种主电路结构及电压-无功综合控制方法。三相补偿电流相量采用对称分量法通过矢量变换获得,单相无功功率采用单相瞬时无功功率算法得到,单相逆变器采用特定谐波消除PWM算法(SHE-PWM)以保证输出无功电流的总谐波畸变率(THD)小于5%,同时保证直流侧电容电压的稳定。试验结果验证了STATCOM进行平衡化补偿的快速性。 相似文献
11.
一种新型的电流源型变流器PWM控制策略及其在超导磁储能装置中的应用 总被引:10,自引:0,他引:10
超导磁储磁能(SMES)装置的超导磁体通过变流器与电网连接,为了减小装置向系统注入的谐波电流,各种改进的脉宽调制(PWM)技术被用于变流器的控制。该文分别用正弦波和三角波作为调制和载波信号,提出一种可用于电流源型变流器的实时电流控制的新型PWM开关策略,并在此基础上研究了能够按照系统要求对电流源型SMES独立地进行有功和无功功率四象限调节的实时功率控制方法。仿真结果表明,该开关策略不仅能够快速改变变流器交流侧电流的幅值和相位,有效降低变流器交流侧电流中的谐波含量,而且能够提高SMES装置的功率响应特性。同时该方法还具有控制策略简单,工程实现容易的特点。 相似文献
12.
13.
The concept for a reduced-harmonics PWM modulator, as applied for the control of a line-side power converter for a variable speed AC motor drive, is described. The PWM algorithm determines the on-state duration of each switching vector based on the observation of the time-variable voltage reference vector. Since there is no reference made to a constant-frequency carrier signal, the generated pulse patterns become asynchronous. It is the essential property of this method to produce a quasicontinuous harmonic spectrum in which all frequency components have more or less equal magnitudes. This is an advantage as compared with carrier-based PWM control schemes that exhibit high-amplitude carrier and side-band components in their harmonic spectra. The emission of acoustic noise radiated from the AC filter inductor is reduced 相似文献
14.
A pulse width modulation (PWM)-based control method for a three-level, four-wire neutral point clamped (NPC) inverter employed in a hybrid active power filter (HAPF) is proposed in this paper. The control method is based on switching function coefficients (SFCs) for harmonic compensation. An interior loop is also proposed for control and balancing of the DC-link voltages. In the proposed control system, one carrier signal is employed in the PWM unit in order to simplify its hardware as compared with traditional PWMs. Based on Fourier decomposition technique, mathematical analysis of the proposed control method is also presented. To decrease the NPC inverter rated power, passive power filters (PPFs) are designed to eliminate fifth and seventh order harmonic currents and to compensate source reactive currents. The proposed control system is implemented by a digital signal processing (DSP) in a laboratory prototype. The experimental results confirmed the validity of the proposed control method in compensation of harmonic currents under non-linear conditions 相似文献
15.
This paper describes which is better, e.g., a single bridge or multibridges, what switching frequency is best, at a bulk power converter system for static var compensation from the viewpoint of power loss, utilization rate of power devices, distortion factor of current and voltage waveforms, control response and reliability. This study shows that multiple connection of single-phase bridges with a one-pulse PWM and that of three-phase bridges with a three-pulse PWM are superior to a three-phase single bridge with multiple-pulse PWM. These results are quite different from general considerations in UPS or general-purpose motor drive systems, where higher switching frequency has resulted in less harmonics, better response and smaller size. At a bulk power converter system, many power devices are required, thus multiple connection can easily be applied without the sacrifice of economy. In addition, it is very important, that the newly adopted control strategy provides very quick transient response at the lowest (fundamental) switching frequency. 相似文献
16.
17.
18.
《Electric Power Systems Research》2001,58(3):157-167
A single-phase three-level pulsewidth modulation (PWM) AC/DC converter with the function of power factor corrector and active power filter is proposed to reduce harmonic currents flowing into the power system and to draw a nearly sinusoidal current with unity power factor. The circuit topology of the adopted three-level PWM AC/DC converter is based on a conventional two-level full-bridge rectifier and one AC power switch. The control signals of the power switches are derived from the voltage balance compensator, current controller and detected operation region of mains voltage. A three-level PWM voltage pattern on the AC side of the converter in each half cycle of mains frequency is generated. Computer simulations are implemented to confirm the operation of the adopted converter with the function of power factor corrector and active power filter. 相似文献
19.
20.