基于多涡卷混沌吸引子的电力电子变换器混沌PWM控制研究

基于多涡卷混沌吸引子,提出了一种新型混沌PWM控制方法抑制电力电子变换器电磁干扰。该方法将多涡卷混沌吸引子与传统混沌PWM控制结合,应用于电力电子变换器的控制中,实现从电磁干扰源头上抑制传导电磁干扰。对比传统混沌PWM控制,该方法能够在降低开关频率及其倍数次谐波峰值的同时,减少开关频率及其倍数次附近次谐波的生成,具有更好的EMI抑制效果。     

通过改变噪声源阻抗抑制高频共模噪声

开关电源的电磁干扰噪声源阻抗在电磁兼容性设计中是个非常重要的参数。通常差模噪声相对容易识别和抑制,但要掌握共模噪声的特征仍然是比较困难的,因而共模噪声需要引起更多的关注。本文根据一种简单的共模噪声源模型,提出了通过控制共模噪声源阻抗,抑制功率变流器的高频共模噪声。实验和电磁干扰噪声测试结果证实了这种共模噪声抑制方法的有效性。     

An investigation of flying capacitor converter for circuit integration

Output power density of power converters has been increased. In power converters with lower harmonic distortion and lower electromagnetic interference (EMI) which are required in many applications, bulky harmonic and EMI filters are usually connected. The volume of the harmonic filters can be reduced by increasing the switching frequency. However, higher switching frequency will cause larger switching loss and severe EMI. As another approach, there is possibility of intrinsic elimination of harmonics and EMI by introducing multilevel converters. However, as the number of levels increases, the number of circuit components will exceed the practical limit of the implementation. Thus, from a practical viewpoint, the main circuit and related circuits should be integrated. However, it has not been clarified which multilevel topology is suitable for circuit integration. In addition, the effectiveness in reducing total device loss considering chip size has not been evaluated. In this paper, the advantage of a flying capacitor multilevel topology for circuit integration is clarified by theoretical and experimental investigations. Also, the total device loss and chip size of the flying capacitor converter are estimated. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Analysis and reduction of radiated EMI noise from converter systems

It is well known that high dv/dt rates on switching devices are the source of EMI noise. This paper describes a mechanism and reduction methods of radiated EMI noise on IGBTs. The radiated EMI noise is generated by oscillating current flowing through the IGBT's output capacity and the snubber circuit, which we call equivalent circuit of radiated EMI noise. The oscillating current of the equivalent circuit is forced to flow by high dv/dt rates of IGBT switching operation. Radiated EMI noise can be analyzed by frequency evolution of oscillating current. The results of this analysis show the relationship of high‐frequency impedance of the equivalent circuit to radiated EMI noise, as well as the behavior of the IGBT's switching voltage waveform. In addition, it is indicated that using a di/dt control gate drive circuit is effective as a means for reducing radiated EMI noise. It is clarified that the standard for industrial equipment of CISPR can be satisfied by using the proposed gate drive circuit. The effects of the method have been verified by experimental and simulational results. © 1999 Scripta Technica, Electr Eng Jpn, 130(1): 106–117, 2000     

不同扩频信号对开关功率变换器EMI抑制效果的比较

开关频率调制技术是改善功率变换器EMC的一种有效方法,不同的扩频信号的扩频效果是不同的。在隔离式双正激DC/DC功率变换器的基础上,分别对周期性信号、随机信号和混沌信号作为开关频率调制信号对功率变换器EMI的抑制效果作数值上的分析,指出它们各自的优缺点。认为相对而言,混沌信号是一种比较理想的扩频信号。     

A carrier phase control suitable for conducted EMI noise reduction in a multiple‐converter system

The conducted EMI noise flowing from power converters to an AC utility line is regulated by international commissions such as the International Electrotechnical Commission (IEC). Adherence to the IEC regulations requires that EMI filters should be used in power electronics equipment. This paper proposes a method for analyzing conducted EMI noise in multiple power converters connected to the same power line. In this method, the phase difference between subharmonic modulated carrier signals at each power converter is taken into account. The phase difference among the power converters determines the EMI noise level in a multiple converter system, as is evident from the analysis of the waveform of the common mode current. In addition, EMI noise suppression using carrier phase control is proposed. In order to reduce the size of the EMI filter effectively, the phase difference θ should be set to 360/nN°, where n is a high‐order harmonic component near 150 kHz and N is the number of power converters. Therefore, the conducted EMI noise can be reduced effectively with the help of the proposed phase control. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 183(3): 56–66, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.21305     

射频识别系统电磁辐射干扰特征快速分析与抑制

针对射频识别系统产生的辐射干扰噪声,提出了基于近场测量结合波阻抗分析的辐射机理快速分析方法与基于全电容高频电磁干扰(electromagnetic interference,EMI)滤波器的辐射噪声抑制方法,可避免苛刻复杂的电波暗室噪声检测和电磁屏蔽噪声抑制方法,具有简便、快速、经济等优点。标准测试表明:采用文中方法可有效抑制辐射干扰噪声,噪声抑制效果可达24 dBμV/m,满足GB 9254 Class A标准,从而验证了方法的有效性。     

混沌映射抑制DC-DC变换器EMI水平的实验研究

探讨了混沌频率调制技术在开关变换器中抑制电磁干扰的实际效果。详细地分析了被调制信号的频谱与混沌系统产生的调制信号的不变密度函数之间的关系。设计了一个简单的、具有均匀分布密度的tent映射混沌电路，并以此电路产生的离散时间混沌信号作为频率调制信号，加入到工作在闭环连续导电模式的Buck变换器中，从而在开关变换器中实现了混沌频率调制，使开关频率随混沌信号随机变化。实验结果证明该技术不但具有有效降低开关谐波峰值和对输出电压影响不大的优点，而且实现电路简单，是解决开关变换器电磁兼容性问题的一种新的有效途径和具有应用前景的技术。     

扩频控制技术用于减少电力电子变换器的电磁干扰的研究

本文论述了一种对载波进行扩频控制以减少电力电子变换器电磁干扰的方法。论证了扩频控制技术可以有效地降低载波及其谐波的峰值，讨论了不同的周期信号对正弦载波和PWM载波的扩频效果，同时指出，周期信号扩频可以有效控制扩频后的带宽，便于滤波器的设计。最后探讨了扩频技术对特定频率的干扰进行抑制的情况。     

电流型双频率脉冲序列调制开关变换器

提出了开关变换器电流型双频率脉冲序列调制BF-PTM方法,研究了电流型BF-PTM的控制策略。电流型BF-PTM控制技术无需误差放大器及其相应的补偿网络,具有结构简单,稳定性好,动态响应速度快,电磁干扰噪声水平低,易于实现等优点;此外,通过将电感电流引入到控制环,易于实现电流型BF-PTM控制开关变换器的过电流保护和多变换器的并联均流控制。以电感电流断续导电模式Buck变换器为例,对电流型BF-PTM控制开关变换器进行了研究,仿真及实验结果表明,电流型BF-PTM比传统的电流型PWM具有更快的动态响应速度和更低的电磁干扰噪声。     

基于混沌扩频的双级矩阵变换器调制策略的研究

双级矩阵变换器由于具有优良的输入输出性能而受到广泛关注。在对双级矩阵变换器调制策略分析的基础上,将扩频调制策略引入到输出双级矩阵变换器调制策略中来抑制电磁干扰和噪声。将混沌扩频技术用于双级矩阵变换器中,用混沌信号改变固定开关频率。为了不影响整流级的零电流换流,采用整流侧和逆变侧同步扩频策略,降低了开关频率和倍频处的谐波幅值,从而达到降低电磁干扰和噪声的目的,仿真结果证实了混沌扩频调制策略的可行性。     

基于IGBT的Buck电路共模EMI特性研究

针对IGBT的高du/dt给电力电子装置带来的严重共模电磁干扰(common-mode electromagnetic interfer-ence,CM EMI)问题,深入分析了Buck电路的CM EMI,首先提出了Buck电路的共模电流等效电路,分析了噪声源频谱及其与输入电压、开关频率、开关速度等运行参量间的关系。为弥补理论分析的不足,以实验手段研究了采用IGBT的Buck电路的输入电压、开关频率、负载电流、占空比、驱动电阻等参量对共模EMI的影响。研究表明:共模EMI与占空比无关而与输入电压和开关频率成正比关系。驱动电阻和负载电流均影响开关速度,因而对共模EMI也有影响,其中负载电流的影响与开关器件的开关特性有很大关系。     

周期频率调制降低开关电源传导EMI的比较研究

利用频率调制技术从噪声产生源头上降低了开关电源传导电磁干扰.分析了频率调制降低EMI噪声的原理,并试制了一台周期频率调制反激变换器电源样机.比较了不同周期调制信号情况下开关管电流信号的频谱以及传导干扰测试的结果.实验结果表明,两种调制信号均能有效降低开关谐波峰值,但是三角波调制信号的扩频效果优于正弦波调制信号.     

Methods and Equipment to Provide Electromagnetic Compatibility in Marine Power-Supply Systems

The problem of electromagnetic compatibility during operation of electronic ship systems is quite urgent thanks to the presence of a large number of powerful semiconductor converters and electric equipment that produce a high level of noise. On the other hand, communication, navigation, and automation facilities use low levels of useful signals. Semiconductor converters generate pulse voltages to electric mains because of the switching process. The spectrum of the pulse interference ranges up to radio frequencies. The possible conductive and radiated noises are limited by the requirements of electromagnetic compatibility. To meet these requirements, designers should introduce new solutions for noise suppression. In this work, a method for noise suppression by means of shifting the switching frequency of a converter has been suggested. A change in the converter frequency by 30% can result in a decrease in the noise by more than 20 dB. The experiments have shown that a level of noise decreases by 10 dB for 20% of frequency shifts.     

Influence of the modulation method on the conduction and switchinglosses of a PWM converter system

The authors explore the dependency of the conduction losses of a bridge leg of a pulsewidth modulation (PWM) power converter system with a high pulse rate on the shape of the phase modulation functions. This is done for modulation methods that are optimized with respect to minimum harmonic current RMS values. The results are compared to the results gained for simple sinusoidal modulation. Besides conduction losses, the switching losses of the electric valves are calculated. The main topic is the determination of those power loss components of a PWM converter system that can be (besides the harmonic losses) influenced by the modulation method selected. As the calculations show, these modulation methods allow a significant increase of the effective switching frequency. The optimal modulation as calculated leads to a reduction of the harmonic power loss in the upper modulation region. Furthermore, due to the frequency modulation the spectrum is spread out to a wider frequency band as compared to operation with constant pulse frequency     

一种减小转矩脉动的混合型扩频调制策略

GaN器件具备更快的开关速度,可以降低噪音,显著减小伺服驱动器体积,但电磁干扰(EMI)问题更加突出。采用随机载波频率调制策略(RCFPWM)可有效抑制EMI,但载波频率随机化后使转矩脉动更为剧烈。因此,提出一种基于Markov链的混合载波频率调制策略(Markov-HCFPWM),采用混合载波频率调制减小相邻开关周期的载波频率差值,采用Markov链使局部平均载波频率接近期望值。仿真和试验结果表明,所提策略相较RCFPWM策略在有效抑制EMI的前提下也可减小转矩脉动。     

多路单级式直流侧串联光伏逆变系统的研究与分析

多路单级式直流侧串联光伏逆变系统拓扑结构由光伏阵列、直流侧串联电容、级联的单相全桥逆变器和隔离变压器构成.由于减少了直流升压环节,拓扑结构更简单,而将直流侧电容相串联则能够减少主电路电流,使用MOSFET 作为开关器件在该拓扑结构中更具优势,MOSFET能够使开关损耗减少,同时在并网逆变环节采用载波移相SPWM调制方式...     

双随机PWM在DC-DC变换器中的实现及性能分析

随机调制技术因其能够减少噪音,驱散谐波能量而使之具有更宽的带宽,减小常规的PWM调制中快速开关运行产生的干扰。这种方法不需要改变电力电子系统拓扑结构,也不增加系统额外耗费和体积,是解决PWM型电力电子系统中形成的传导电磁干扰问题的有效方法之一。特别是双随机调制技术具有更好的减少离散谱峰值的作用。文中分析了双随机调制技术的原理,并将TMS320F2812DSP实现的双随机PWM信号应用于实际的DC-DCboost变换器。研究结果表明,双随机调制技术能够较好地抑制常规调制方式所引起的传导EMI,比任何一种单随机调制具有更好地削减峰值和遣散功率谱的效果,从而有利于改善电力电子系统的电磁兼容性(EMC)而不影响功率变换器的输出特性;同时也证明了双随机PWM技术的工业应用是可行的。     

Reduced harmonics PWM controlled line-side converter for electricdrives

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     

风电变流器改进型断续脉宽调制策略

大功率风力发电变流器中,存在开关损耗和电流总谐波失真THD(total harmonic distortion)难以均衡的矛盾。如何优化调制方式,以提高系统效率,减小电流谐波,是大功率风电变流系统的核心技术之一。针对风电变流器宽频率、宽电压运行范围的特点,分析直驱风电变流器采用断续脉宽调制策略下的损耗和谐波性能,发现不同工况下主要关注指标不同,轻载时电能质量恶劣、开关损耗低,而重载时开关损耗严重、电能质量好;但是常用调制方式很难兼顾。为解决该问题,提出一种适用于永磁同步机直驱风电变流器的新型断续脉宽调制策略,该调制策略对开关损耗和THD的优化特性随变流器工作范围变化,实现不同工况下主要关注指标的优化。最后通过实验平台验证了该方案在重载时减小开关损耗,在轻载时降低电流谐波的有效性。