​华为直流电源解决方案

华为直流电源包括高效直流电源,华为室内直流电源、室外直流电源、机房直流电源、混合供电直流电源等多种电源系统,同时提供适用于视频监控、华为传输站点等小功率站点的供电系统。

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华为直流电源电源是一切电子设备的心脏,没有电源,电子设备就不可能工作。

华为直流电源开关电源与线性稳压电源相比，具有功耗小、效率高、体积小、重量轻、稳压范围宽等许多优点，己被广泛应用于计算机及其外围设备、通信、自动控制、家用电器等领域。

华为直流电源但开关电源的突出缺点是能产生较强的电磁干扰（EMI）。EMI信号既具有很宽的频率范围，又有一定的幅度，经传导和辐射后会影响电磁环境，对通信设备和电子产品造成干扰。

如果处理不当，开关电源本身就会变成一个骚扰源。目前，电子产品的电磁兼容性（EMC）日益受到重视，抑制开关电源的EMI，提高电子产品的质量，使之符合EMC标准，已成为电子产品设计者越来越关注的问题。

我们先来看看外部环境对开关电源的干扰主要来自电网的抖动、雷击、外界辐射等；如下图：

1、电源噪声？

2、电源复位？

3、电源输出？

4、电源损坏？等等。

瞬态干扰（EMS）对设备会产生威胁，出现产品功能及性能的问题。

后面我们通过PCB的分析来讲解开关电源系统EMS的问题；

开关电源系统的产品EMC的三大思考问题，了解了＆找得到就能解决EMC。

1．信号（源）；

2．结构设计 ；

3．地的连接 。

华为直流电源传导干扰共模与差模信号的电流路径分析。

开关电源通常是将工频交流电整流为直流电， 然后经过开关管的控制使其变为高频， 再经过整流滤波电路输出， 得到稳定的直流电压。工频整流滤波使用大容量电容充、放电， 开关管高频通断， 输出整流二极管的反向恢复等工作过程中产生了极高的di／dt和du／dt ，形成了强烈的浪涌电流和尖峰电压， 它是开关电源电磁干扰产生的最基本原因。

另外，开关管的驱动波形， MOSFET漏源波形等都是接近矩形波形状的周期波。因此， 其频率是MHz级别的，有着很高的高频谐波分量！ 这些高频信号对开关电源的基本信号， 特别是控制电路的信号造成干扰。

简单的说：开关电源系统当MOS管开通时，L，N回路中变压器电感的电流线性上升；MOS关断时 L，N回路电流迅速关断；此时回路的电流波形为三角波；高频的三角波电流的谐波分量形成系统的差模干扰。

华为直流电源杂散参数影响耦合通道的特性

在传导骚扰频段（＜30MHz），多数开关电源骚扰的耦合通道是可以用电路网络来描述的。但是，在开关电源中的任何一个实际元器件，如电阻器、电容器、电感器乃至开关管、二极管都包含有杂散参数，且研究的频带愈宽，等值电路的阶次愈高，因此，包括各元器件杂散参数和元器件间的耦合在内的开关电源的等效电路将复杂得多。

在高频时，杂散参数对耦合通道的特性影响很大，分布电容的存在成为电磁骚扰的通道。另外，在开关管功率较大时，集电极一般都需加上散热片，散热片与开关管之间的分布电容在高频时不能忽略，它能形成面向空间的辐射骚扰和电源线传导的共模骚扰。

简单的说：在高频段＞1MHZ时，开关电源系统对地就存在分布电容；系统的关键信号，关键走线对地都存在分布电容；分布电容形成对地回到L，N的共模干扰信号。同时分布电容的环路形成对空间的辐射干扰！

辐射干扰共模与差模信号的磁场分布。

1．差模电流的磁场主要集中在差模电流构成的回路面积之内，而回路面积之外的磁力线会相互抵消；

2．共模电流的磁场，在回路面积之外，共模电流产生的磁场方向相同，磁场强度反而加强。

注意：

关于辐射的一个重要基本概念是：电流导致辐射，而非电压。

辐射干扰共模与差模信号的场强特性。

1．较小的共模电流能够产生强度很高的辐射；

2．很多因素都能导致共模电流；

比如：

A．电网串入共模干扰电压－（我们EMS的部分模拟测试）；

B．辐射干扰（如雷电，设备电弧，附近电台，大功率辐射源）在信号线上感应出共模干扰；

C．接地电压不一样。也就是说地电位差异引入共模干扰；

D．也包括设备内部电线对电源线的影响。

数据结果－40dB 测试数据分析：

Data1： 一个20mA的差模电流，

在30MHZ时，将在3m远的地方产生一个强度为100uV／m的辐射电场。

Data2： 一个8uA的共模电流，

在30MHZ时，将在3m远的地方产生一个强度为100uV／m的辐射电场。

很小的共模电流 和 很大的差分电流产生大小相等的RF能量。

原因：共模电流不能在RF返回路径中进行磁力线的抵消。

辐射干扰系统分布参数影响的电磁场环路分析

开关电源系统对地就存在分布电容；系统的关键信号，关键走线对地都存在分布电容；共模电流通过布局布线流经系统的信号线及电缆的分布电容形成对地 回到L，N的共模干扰信号。同时分布电容的环路形成对空间的辐射干扰。

其中＞30MHZ以上 为辐射发射的天线接收；即共模辐射在空间产生电磁场，此时被辐射骚扰测试接收天线接收后，那么就形成了产品对外的辐射骚扰。

对电子产品的EMC的三大思考问题。

A．信号（源） 在哪里；

B．结构设计 是这样的吗；

C．地的连接 还有更好的方法吗？

华为直流电源

Huawei DC power supply includes high-efficiency DC power supply, indoor DC power supply, outdoor DC power supply, DC power supply for computer room, mixed power supply DC power supply and other power supply systems, while providing a small power station for video surveillance, transmission stations and other power supply systems.

Huawei DC power supply system can provide reliable power supply for wireless/wired access site, convergence layer computer room and industrial customer communication room. It adopts integrated integrated design, and the system adopts the 98% rectifying module with the leading efficiency of the industry.

Huawei is facing the challenge of transforming large data and energy consumption into ICT network integration. Huawei network energy seizes the opportunity of evolving from traditional power supply solutions to the energy internet, focusing on communication energy and data center energy, providing a comprehensive solution to meet the application needs of power supply scenarios in ICT industry.

Huawei's new generation of fully digital computer room power supply system, which converts alternating current of different systems into - 48V direct current, can provide stability for wireless network core computer room, fixed network core computer room, large-scale convergence site, enterprise communication network core computer room, data center and so on.

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Huawei DC power supply is the heart of all electronic equipment, without power, electronic equipment can not work.

Compared with linear regulated power supply, Huawei DC switching power supply has many advantages, such as low power consumption, high efficiency, small volume, light weight, wide range of regulated voltage and so on. It has been widely used in computer and peripheral equipment, communications, automatic control, household appliances and other fields.

HUAWEI DC power supply, but the prominent disadvantage of switching power supply is that it can generate strong electromagnetic interference (EMI). EMI signals not only have a wide frequency range, but also have a certain amplitude. After conduction and radiation, it will affect the electromagnetic environment and cause interference to communication equipment and electronic products.

If it is not handled properly, the switching power supply itself will become a source of disturbance. At present, the electromagnetic compatibility (EMC) of electronic products has been paid more and more attention. It has become a more and more concerned problem for designers of electronic products to restrain the EMI of switching power supply, improve the quality of electronic products and make them conform to EMC standards.

Let's first look at the external environment on the switching power supply interference mainly from the grid jitter, lightning strikes, external radiation, etc. The following figure:

1, power noise?

2, power reset?

3, power output?

4, power failure? Wait.

Transient interference (EMS) will pose a threat to equipment and product function and performance.

Later, we explain the EMS of switching power supply system through the analysis of PCB.

The three major problems of EMC switching power supply system are understanding and finding EMC.

1. signal (source);

2. structure design;

The connection between the 3. places.

Analysis of current path of common mode and differential mode signals of conducted interference of HUAWEI DC power supply.

The switching power supply usually converts the power frequency alternating current into direct current, and then converts it into high frequency through the control of the switching tube, and then outputs it through the rectifying and filtering circuit to obtain a stable DC voltage. High di / dt and Du / dt are produced in the process of power frequency rectifier filter using large capacity capacitor charging and discharging, switching tube on and off at high frequency, and reverse recovery of output rectifier diode. strong surge current and peak voltage are formed, which are the most basic causes of electromagnetic interference in switching power supply.

In addition, the driving waveform of the switch tube and the leakage waveform of the MOSFET are all periodic waves approaching the rectangular wave shape. Therefore, its frequency is MHz level, and has very high high frequency harmonic component. These high frequency signals disturb the basic signals of switching power supply, especially the signals of control circuit.

Simply put: switching power supply system when MOS switch on, L, N circuit transformer inductance current linear rise; MOS turn off L, N circuit current switched off rapidly; at this time the circuit current waveform is triangular wave; high-frequency triangular wave current harmonic components form the system differential mode interference.

The influence of HUAWEI DC power stray parameters on the coupling channel

In the conducted disturbance frequency band (< 30MHz), most of the coupling channels of switching power supply disturbance can be described by circuit network. However, any practical component of switching power supply, such as resistor, capacitor, inductor, even switch tube and diode, contains spurious parameters. The wider the frequency band, the higher the order of equivalent circuit. Therefore, the switching power supply includes spurious parameters of each component and coupling between components. Effective circuits will be much more complicated.

At high frequencies, spurious parameters have a great influence on the characteristics of the coupling channel, and the existence of distributed capacitance becomes the channel of electromagnetic disturbance. In addition, when the power of the switching tube is large, the collector usually needs to add a heat sink. The distributed capacitance between the heat sink and the switching tube can not be ignored at high frequency. It can form space-oriented radiation disturbance and common-mode disturbance conducted by the power line.

Simply said: in the high frequency band > 1MHZ, the switching power supply system on the ground there is a distributed capacitance; the key signal of the system, the key line to the ground there is a distributed capacitance; distributed capacitance to the ground back to L, N common mode interference signal. At the same time, the loop of distributed capacitance forms the radiation interference to the space.

Radiation interferes with the magnetic field distribution of common mode and differential mode signals.

1. The magnetic field of the differential-mode current mainly concentrates in the area of the loop formed by the differential-mode current, and the magnetic lines outside the loop area will cancel each other.

2. the magnetic field of common mode current, outside the area of the loop, and the direction of the magnetic field generated by the common mode current.

华为直流电源