工频与高频的经典分析

1、.工频与高频的区别 为什么工频 UPS 将被高频 UPS 所代替技术总是在发展的，新技术代替旧技术是历史的发展规律。然而，新旧之间的替代与转换一般并不是那么顺利，人类社会是这样，自然、科技领域也是这样。现在的电子技术已进入数字化时代， 这是不可逆转的技术发展规律，各行各业迟早都要集中到这一条路上来，但就某一个时期来说发展是不平衡的，这中间有好多因素的影响，比如各自的技术发展水平不同，人员对新技术的认识和接受能力不同等等。具体到UPS 领域又何尝不是如此。下边我给大家讲解一下工频机与高频机的区别及为什么工频机UPS 将被高频 UPS 代替。一、工频机 UPS和高频 UPS的一般概念静止变换式工频

2、机结构UPS 技术出现在上个世纪70 年代，毫无疑问在当时属尖端技术，几十年间也为电子电器技术领域作出了不朽的贡献。一般说任何技术的先进性是相对而言，任何先进的产品也有其一定的适用期。随着IT 技术的出现与发展，工频机 UPS 组件暴露出它的缺点， 比如体积大、 重量大、 功耗大和输入功率因数低等不利因素大大影响了它本身的可靠性。原来那种输入输出都在50Hz 并且有输出变压器的老的电路结构就称作工频UPS；而这种输入输出电路都工作在20kHz 以上且没有输出隔离变压器的电路就称为高频UPS。二、 高频 UPS 比工频 UPS 有哪些优点1、 输入功率因数高工频 UPS 一般在 200kVA 以

3、下的输入电路都采用了可控硅 6 脉冲整流，输入功率因数不超过 0.8，谐波电流有 30%之大。如果再连接发电机，那么发电机的容量至少要 3 倍于 UPS 功率；如果是单相小功率 UPS，发电机的容量至少要 5 倍于 UPS 功率。任何容量的高频UPS 的输入功率因数都可做到0.99 甚至以上，谐波电流小于5%，前置发电机的容量理论上和UPS 功率相同，大大缩减了投资和占地面积等。尤其是对市电的充分利用具有良好的经济意义和社会意义。在同样指标下，比如要求输入功率因数为0.95 以上时，工频 UPS 就必须外加谐波滤波器或改为12 脉冲整流，就是说前面要增加一个设备，再加上输出变压器，就比高频 U

4、PS 多了两个环节。由于此二者的影响，使得工频UPS 的效率比高频 UPS 低 5%。在同样是 100kW 的容量时工频 UPS 每年要比高频 UPS 多消耗5 万度电！这在中央号召节能减排的今天具有深远意义。3、 对外干扰小干扰有两种，一种是听得到的机械噪声（工频中的变压器使用久了，硅钢结构松动后，一旦带载运行就会发出噪声， 声音最大的可达到小型发电机的响声） ，一种是听不到的电噪声，这两种噪声工频 UPS 都有，形成了对设备和对人的伤害。电噪声影响机器的稳定度，机械噪声影响人的身心健康，降低工作效率。而高频 UPS 由于工作在 20kHz 以上， 20kHz 是人的耳朵听不到的频率，使工作

5、环境安静下来。又由4、 体积小、重量轻工频 UPS 由于有了输出变压器和适应50Hz 的电感电容等低频器件使得体积.重量都很大。比如山特 200kVA 工频 UPS 重 1380kg，而同是他的 250kVA 高频 UPS 重量只有 830kg。5.数字技术的应用工频 UPS 刚开始是模拟技术，现在最高级的才发展到数字与模拟相结合的技术，模拟技术的可靠性要比数字技术低。而高频 UPS 技术一开始就是数字与模拟相结合的技术， 目前先进的已发展到全数字化技术， 不言而喻， 可靠性是很高的6. 对电网的适应能力强工频 UPS 对于适应输入电压 15%的变化已很不易；而高频 UPS 甚至适应输入电压

6、30%左右的变化，这又大大延长了电池的寿命。7. 能将并机环流衰减到几乎为零工频机 UPS 的并联就是变压器的直接并联,而变压器的直接并联最容易产生很大的环流,高频机 UPS 由于没有输出变压器,它们的并联可以看出这里的环流路径上处处是障碍,小于 2V的电压差根本性不成环流。总之，高频UPS 在性能上不但完全具备工频UPS 的一切特性，而且还具备很多后者没有的特点和功能。由此可见，高频UPS 完全可以替代工频UPS 而成为数字化时代的主流趋势。三、高频UPS 与工频 UPS 的现状因为高频UPS 对技术与工艺以及生产手段的要求非常严格，一般不容易仿制， 所以 20kHz以上的高频UPS 容量都

7、小于100kVA ，但目前仍有少数制造厂的技术真正过关，而且已显示出强大的生命力。在大功率范围虽然不能做到20kHz ，但采用高频机结构，比如用IGBT 高频整流（相对于50Hz 而言），频率一般在15kHz 以下，多数厂家已可做到200kVA ，其中也有佼佼者，比如秀康 10 年前就可做到8kHz/480kVA ，伊顿 9395 也可做到 15kHz/1200kVA ，并已成为美国的军方指定产品。这说明高频结构UPS 技术早已成熟。另外在我国军方和金融等重要部门也纷纷采用，并收到了良好的效果。因此工频结构 UPS 在这种情况下的日子会越来越艰难，好在是还有那么一批厂家的高频结构UPS 没有过

8、关，还得主推工频UPS，作为市场手段多说一些当前用工频 UPS 更合适之类的语言，多说一些工频机的好处和多找一些高频机的缺点均属正常现象，这可以理解，也可能是认识问题。但不要认为工频UPS 技. 永 不落后。从科学 展 来 ，以后一段 内无疑是高 UPS 的市 。不可否 ，高 UPS 同 也有退出 史舞台的一天，当然那是后 。四、所 两个 展方向 在有一种 法：高 UPS 和工 UPS 是两个 展方向。 就使人糊涂了： 道效率低的 品也是 展方向？ 道 能减排 允 其反向 品 展？ 道耗 源和笨重的 品也是 展方向？ 之， 种 点不外乎 ：高 UPS 与工 UPS 并存； 能减排与浪 能量和

9、源并存；先 与落后并存 所 技 上的并存 是不可替代的， 比如自行 然比汽 跑得慢，但它 在一定程度上是互相不可替代的；而 里的 UPS 技 却是可以完全替代的 , 而且是 理成章。Difference between Frequency and High-frequencywhy high-frequency UPS will replace of frequency UPSWith the developing of society and science, new technology replace of old ones is always a rule. However, the

10、replacement and switching between the new and old is not such easy. The electronic technology has already entered into the digital age, and this is a develop principle that can not be changed. Now I would like to give some explanation why the frequency UPS will be replaced of by high-frequency UPS.1

11、、general conception of high-frequency UPS and frequency UPSStable and convertible frequency inverter, which has only 50HZ input and outputfrequency and has output transformer circuit, was invented in the 1970s ,it is no doubt that at that time this was really very high technology and of course it ma

12、de much contribution to.the electronic field. Generally speaking, no matter how advanced a technology is, it is only compared to say so because they have its own using period. With the exist and developing of IT technology, frequency UPS shows his disadvantage, such as bulky, high weight, high power

13、 consuming and low input power index, these drawbacks make people doubt its reliability. Naturally, there should be some new technology to replace of it, and thus there comes the high-frequency UPS, which has over 20 kHz input and output frequency and no transformer circuit.2、 compared with frequenc

14、y UPS, high-frequency UPS has lots of advantages1、 high input power factorGenerally, all the circuit of frequency UPS under 200kVA use the SCR（ SiliconControlled Rectifier ） 6 pulse rectification and the input power factor is less than 0.8 while the harmonic current is 30%. If we connect with a gene

15、rator, the capacity of thegenerator should be three times of the UPS power; and for those single-phase low power UPS, it is at least five times. But for high-frequency UPS with any capacity, the input power factor can be as high as 0.99 and even higher while the harmonic current is less than 5%. If

16、connected with generator, the capacity is theoretically the same as UPS power thus reduce the cost and occupy. This point has good economic and social significance, especially for making full use of the AC power.2、 low self-power-consumingIn the same situation, for example, if we need the input fact

17、or ofanormal frequency UPS becomes over 0.95, we must connect a harmonicfilter or changed it into 12 pulse rectification, that s to say, we need anextra equipment, and plus the transformer, there is totally two processes more than the high-frequency UPS. Because of these two factors, efficiencyof fr

18、equency UPS is 5% less than high frequency ones. If we use UPS with 100kw capacity for one year, frequency UPS will consume 50000 kWh AC power more than the high frequency ones. This has very deep meaning in recent society!3、 little interferenceUPS has two kinds of interference, one can be heard (ma

19、chinery noise), but the others can not (Electrical noise). These two kinds of noise all exist in frequency UPS (especially, if used for a long time, the transformer will cause great machinery noise while working, and sometimes it can be as noisy as a small generator) and affect the equipment and hum

20、an healthy. But for high-frequency ones, since the frequency is over 20 kHz (which can not be heard by human ear) and the input power factor is more than 0.99(which is almost linear), so there is nearly no interference caused.4、 small size and light.Frequency UPS has is very heavy because it has out

21、put transformer and some lowfrequency components (LC) which adapt to the 50Hz. Le t s take 200kVA UPS for an example, frequency ones weight 1.38KG while high-frequency ones is only 0.83KG.5、 Application of digital technologyAt the very beginning, frequency UPS only use simulation technology andcombi

22、nation of digital and simulation technology is the highest one, buthigh- frequency ones use digital technology once it exists. Itdoubt that thisskindnoof product will have more reliable quality.6、 Better adaptability to the AC power networkIt is not easy for frequency UPS to adapt the 15% change of

23、the power network but high-frequency UPS can adapt even a 30% change, and this would extend the battery life.7、 can reduce the parallel operation circulation to minimumThe parallel connection of frequency UPS is actually the direct parallel connection of transformer, which will easy to cause high ci

24、rculation; but high-frequency UPS cause no circulation when the voltage is less than 2V because there is no output transformer and it has obstruction almost everywhere in the circuit.In short, high-frequency UPS not only have all the features that frequency UPS has, but even has much more new functi

25、ons that the latter one doesn t have. So, it is definitely that the former will replace of the the latter and become the main solution in this field.3、status of high-frequency UPS and frequency UPSAlthough the high-frequency UPS has very strict requirement for technology andproduction way and not ea

26、sy to copy, but there is still several factories has qualified technology and showed great vitality. For high power ones, although can not reach 20kHzbut if use high-frequency structure（ generally the frequency is under 15kHz）, such as IGBThigh-frequency rectification （ Relatively to the 50Hz ） , ma

27、ny factories can make it 200kVA; what s more, some factories even do it better, for example, Xiukang can make it as8kHz/480kVA ten years ago; Eton 9395 also realizes 15kHz/1200kVA which has been chosen as U.S. military specified products. All these show that high-frequency structure of UPS technolog

28、y is already mature. In addition, this kind of technology is also used in some important government department in China, like military and financial, and already received good results.So the frequency UPS will have a more difficult situation. Fortunately, there are still some factories with unqualified technology and they need to promote it. Thus as a sales strategic, saying some good words for frequency UPS and some bad words for the other one is underst