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  • 变频器维修的十种检查法学习的详细资料概述
  • 本站编辑:杭州茂叶机电设备有限公司发布日期:2019-11-05 20:33 浏览次数:

变频器维修学习方法有很多,但方向不对努力白费,所以抓住方向很重要,为了让大家更快的掌握变频器维修知识,这里提供变频器维修的十种学习方法给大家。

1、报警参数检查法

〖例 1〗某变频器有故障,无法运行并且LED显示“UV”(under voltage的缩写),说明书中该报警为直流母线欠压。因为该型号变频器的控制回路电源不是从直流母线取的,而是从交流输入端通过变压器单独整流出的控制电源。所以判断该报警应该是真实的。所以从电源入手检查,输入电源电压正确,滤波电容电压为0伏。由于充电电阻的短路接触器没动作,所以与整流桥无关。故障范围缩小到充电电阻,断电后用万用表检测发现是充电电阻断了。更换电阻马上就修好了。

〖例 2〗有一台三垦IF 11Kw的变频器用了3年多后,偶尔上电时显示“AL5”(alarm 5 的缩写),说明书中说CPU被干扰。经过多次观察发现是在充电电阻短路接触器动作时出现的。怀疑是接触器造成的干扰,在控制脚加上阻容滤波后果然故障不再发生了。

〖例 3〗一台富士E9系列3.7千瓦变频器,在现场运行中突然出现OC3(恒速中过流)报警 停机,断电后重新上电运行出现OC1(加速中过流)报警停机。我先拆掉U、V、W到电机的导线,用万用表测量U、V、W之间电阻无穷大,空载运行,变频器没有报警,输出电压正常。可以初步断定变频器没有问题。原来是电机电缆的中部有个接头,用木版盖在地坑的分线槽中,绝缘胶布老化,工厂打扫卫生进水,造成输出短路。

〖例 4〗三肯SVF303,显示“5”,说明书中“5”表示直流过压。电压值是由直流母线取样后(530V左右的直流)通过分压后再由光耦进行隔离,当电压超过一定阀值时,光耦动作,给处理器一个高电平。过压报警,我们可以看一下电阻是否变值,光耦是否有短路现象等。

由以上的事例当中不难看出,变频器的报警提示对处理问题有多么重要,提示你正确的处理问题的方向。

2、类比检查法

此法可以是自身相同回路的类比,也可以是故障板与已知好板的类比。这可以帮助维修者快速缩小检查范围。

〖例 1〗 三垦MF15千瓦变频器损坏,送回来修理,用户说不清具体情况。首先用万用表测量输入端R、S、T,除R、T之间有一定的阻值以外其他端子相互之间电阻无穷大,输入端子R,S,T分别对整流桥的正极或负极之间是二极管特性。为什么R、T之间与其他两组不一样哪?原来R、T断子内部有控制电源变压器,所以有一定的阻值。以上可以看出输入部分没问题。同样用万用表去检查U、V、W之间阻值,三相平衡。接下去检查输出各相对直流正负极的二极管特性时发现U对正极正反都不通,怀疑U相IGBT有问题,拆下来检查果然是IGBT坏了。驱动电路中上桥臂控制电路三组特性一致,下桥臂控制电路三组特性一致,采用对比方法检查发现Q1损坏。更换后,触发脚阻值各组一致,上电确认PWM波形正确。重新组装,上电测试修复。

〖例 2〗有一台变频器,现象是面板显示正常,数字设定频率及运转正常,但是端子控制失灵。用万用表检查端子无10V电压。从开关电源入手,各组电源都正常,看来问题出在连接导线上。但是没有图纸的前提下在32根扁平电缆中找到10V真要花点时间,刚好有一台完好的22KW的在,所以就先记下22KW连接扁平电缆的各脚对地电压,然后再对比37KW的各脚对地电压,很快找到差异。原来插槽的管脚虚焊,变频器用一段时间后氧化的作用使之彻底不导通了,重新焊好而修复。

〖例 3〗有一毛纺厂的梳毛机设备,选用西门子440变频器,两台5.5KW一台7.5KW实现同步运转。其中一台5.5KW的运行两年后经常出现F0011或A0511停机。这两个报警都表示电机过载,脱开电机皮带用手盘动电机及设备,没有异常沉重的现象,将两台5.5KW拖动的电机互换,发现还是原来的变频器报警,则确定是变频器出了问题。 类比法,不仅可以用在检查机器内部回路,也可以用于现场问题的判别。

3、备板置换检查法

利用备用的电路板或同型号的电路板确认故障,缩小检查范围是非常行之有效的方法。若是控制板出问题常常只有更换别无他法,因为大多数用户几乎不会得到原理图及布置图,从而很难作到芯片级维修。电源板及驱动板等控制板以外的电路板是可以修理的,其他章节会进一步介绍.这里主要介绍控制板的置换。

4、隔离检查法

有些故障常常难于判断发生在那个区域,采取隔离的办法就可以将复杂的问题简单化,较快地找出故障原因。

〖例 1〗维修一台英泰变频器,现象是上电后无显示,并伴有嘀--嘀的声音。凭经验可断定开关电源过载,反馈保护起作用关断开关电源输出,并且再次起振再次关断而产生的嘀—嘀声。首先去掉控制面板,上电发现依然如故,再逐个断开各组电源的二极管,最后发现风扇用的15V有问题。可是风扇并没有运转信号,不应该是风扇本身问题,看来是风扇前端的问题。最后发现15V的滤波电容特性不对,拆掉滤波电容测量,果然是老化了。换上新的电容就修复了。

5、直观检查法

就是发挥人的手、眼、耳、鼻的感知器官来寻找出故障原因。这种方法常用并且首先使用。“先外再内”的维修原则要求维修人员在遇到故障时应该先采用望、闻、问、摸的方法,由外向内逐一进行检查。有些故障采用这种直观法可以迅速找到原因,否则会浪费不少时间,甚至无从下手。利用视觉可以线路元件的连接是否松动,断线接触器触电是否烧蚀,压力是否时常,发热元件是否过热变色,电解电容是否膨胀变形,耐压元件是否有明显的击穿点。上电后闻一闻是否有焦糊的味道,用手摸发热元件是否烫手。很重要的是还要问,问用户故障发生的过程,有助于分析问题的原因,便于直接命中要害.有时问问同行也是个捷径。

〖例 2〗一台三垦IP 55KW变频器在保修期内损坏,上电无显示。打开机器盖子,仔细的观察各个部分,发现充电电阻烧坏,接触器线圈烧断而且外壳焦糊。经过追问,原来用户电源电压低,变频器常常因为欠压停机,就专门给变频器配了一个升压器。但是用户并没有注意到在夜间电压会恢复正常,结果首先烧坏接触器然后烧坏充电电阻。由于整流桥和电解电容耐压相对较高而幸免于难。更换损坏器件修复。

6、升降温检查法

此法对于一些特殊的故障非常见效。人为地给一些温度特性较差的元件加温或降温,产生“病症”或消除“病症来查找故障原因

〖例 3〗有一台德力西变频器故障。用户反映该变频器经常参数初始化停机,一般重新设定参数后20分钟到30分钟故障重现。首先我认为该故障应该与温度有关,因为运行到这个时间后变频器温度会升高的。我用热风焊台加热热敏电阻,当加热到风扇启动的温度时,观察到控制面板的LED忽然掉电然后又亮起来接下来忽明忽暗的闪动,拿走热风30秒后控制板的LED不再闪动,而是正常的显示。采用隔离法拔掉所有的风扇插头,再次加温实验,故障消除。检查到风扇全部短路。看来是温度到了以后,控制板给出风扇运转信号,结果短路的风扇造成开关电源过载关闭输出,控制板迅速失电而参数存储错误,造成参数复位。换掉风扇,问题解决。

7、破坏检查法

就是采取某种手段,取消内部保护措施,模拟故障条件破坏有问题的器件。令故障的器件或区域凸现出来。首先声明这种方法要有十分的把握来控制事态的发展,也就是维修者心理要明了最严重的破坏程度是什么状态,能否接受最严重的进一步损坏,并且有控制手段,避免更严重的破坏。

〖例 1〗修理变频器当中,遇到一个开关电源故障的变频器,他的保护回路动作,可以断定变压器输出端有短路支路,可是静态无法测量出故障点。我们利用破坏法来找到静态无故障的器件。首先断开保护回路的反馈信号,令其失去保护功能,然后接通直流电源,要求利用调压器从0v慢慢升高直流电压,观察相关器件。发现有烟冒出,立刻关掉电源,同时利用电阻短路直流滤波电容迅速放电。冒烟的是风扇电源的整流二极管,原来风扇已经短路性损坏了,而该风扇的控制开关信号一直为开状态(器件短路造成高电平开状态),只要开关电源输出正常电压,风扇就短路风扇电源,造成开关电源保护。而在静态测量时,又测不到风扇的短路状态。

8、敲击检查法

变频器是由各种电路板和模块用接插件组成,各个电路板都很多焊点,任何虚焊和接触不良都会出现故障。用绝缘的橡胶棒敲击有可疑的不良部位,如果变频器的故障消失或再现则很可能问题就出在那里。

〖例 1〗某厂的变频器正常运行了3年多,在没有任何征兆的情况下忽然停机,而且没有任何故障信息显示,启动后会时转时停。仔细观察,没有发现任何异样,静态测量也没发现问题。上电后,敲击变频器的壳体,发现运行信号会随着敲击有变化。经检查发现外部端子FR接线端螺钉松动,而且运行信号线端没有压接U型端子,直接连接在端子上,接线处压到了导线的线皮,导致螺钉由于震动松动后,控制线导线与端子虚连。压接U型端子,重新拧紧螺钉故障排除。

9、刷洗检查法

很多特殊的故障,时有时无,若隐若现,令人无法判断和处理。这时就可以用清水或酒精清洗电路板,同时用软毛刷刷去电路板上的灰尘,锈迹,尤其注意焊点密集的地方,过孔和与0伏铜层接近的电路也要清洗干净,然后用热风吹干。往往会达到意想不到的效果。至少有助于观察法的应用。

〖例 1〗某变频器故障是无显示,经过初步检测,整流部分及逆变部分完好,所以通电检察。直流母线电压正常,可是开关电源控制芯片3844的启动的电压只有2v。分压电阻的阻值在线检测小很多,离线检测正常。采用洗刷法处理后,问题解决。原来是一个电容的正极管脚焊盘与0v层的很近,残留的助焊剂使之处于半导通状态。

〖例 2〗变频器被送来时,有若干不同的报警记录。在通电测试过程中同样出现各种虚假的报警。认真清洗控制板与驱动板连接扁平电缆插座焊点后,问题解决。

10、原理分析检查法

原理分析是故障排除的最根本方法,其他检查方法难以奏效时,可以从电路的基本原理出发,一步一步地进行检查,最终查出故障原因。运用这种方法必须对电路的原理有清楚的了解,掌握各个时刻各点的逻辑电平和特征参数(如电压值、波形),然后用万用表、示波器测量,并与正常情况相比较,分析判断故障原因,缩小故障范围,直至找到故障。

〖例 1〗送修的一台变频器同时失去充电电阻短路继电器、风扇运转、变频器状态继电器信号。经过对比试验,证实问题出在控制板。经过分析,问题可能出在锁存器上,因为这些信号都由这个芯片控制。更换后果然修复。

总的来说,故障变频器的检查要从外到内,由表及里,由静态到动态,有主回路到控制回路。以下三个检查一般是必须进行的。

用万用表检测输出端子分别对直流正极和负极的二极管特性和三相平衡特性。这步可以初步断定逆变模块的好坏,从而决定是否可以空载输出。如果出现相间短路或不平衡状态,就不可以空载输出。

开盖观察,如果上面两步没有发现问题,可以打开机壳,清除灰尘,认真观察变频器内部有无破损,是否有焦黑的部件,电容是否漏液等等。

以上是变频器维修的十种学习方法,通过这些方法去学习变频器维修有助于更好的入门,进一步掌握更丰富的知识,为熟练学会变频器维修知识做好基础。

Inverter maintenance learning methods there are many, but the direction of the effort is not in vain, so grasp the direction is very important, in order to let you grasp the inverter maintenance knowledge faster, here to provide ten inverter maintenance learning methods to everyone.

1. Alarm parameter inspection method

There is something wrong with the inverter, it cannot operate and the LED shows "UV" (under voltage). The alarm in the instruction is dc bus undervoltage. Because the control circuit power supply of this type of inverter is not taken from the dc bus, but from the ac input end through a separate rectifier transformer control power supply. So it should be true. Therefore, starting from the power supply, check that the input power voltage is correct and the filter capacitor voltage is 0 v. Because the short circuit contactor of charging resistance has no action, so it has nothing to do with rectifying bridge. The fault range was narrowed down to charging resistance. After power failure, the multimeter was used to detect that the charging power was blocked. The replacement resistor was fixed immediately.

After using a sankenif 11Kw converter for more than three years, it occasionally displays "AL5" (an abbreviation of alarm 5) when it comes on, indicating that the CPU is being disturbed. After many observations found that the charging resistance short circuit contactor action occurred. It is suspected that the interference is caused by the contactor, and the fault no longer occurs after the control pin plus the blocking and capacitive filtering.

A Fuji E9 series 3.7-kw frequency converter suddenly appears OC3 (medium overcurrent at constant speed) to stop the machine during field operation, and OC1 (medium overcurrent at accelerated speed) to alarm and stop the machine when power is switched off. First, I removed the lead from U, V and W to the motor, and measured the infinite resistance between U, V and W with a multimeter. It ran on no load. The inverter did not alarm and the output voltage was normal. It can be preliminarily concluded that there is no problem with the inverter. It turned out that there was a joint in the middle of the electrical cable, which was covered by wood plate in the dividing channel of the pit. The insulation adhesive cloth aged, and the factory cleaned and had water, causing output short circuit.

Three Ken SVF303, show "5", "5" in the manual means dc overvoltage. Voltage value is sampled by the dc bus (about 530V dc) through the partial voltage and then isolated by the optocoupler. When the voltage exceeds a certain threshold, the optocoupler ACTS to give the processor a high level. Overvoltage alarm, we can see whether the resistance variable value, whether there is a short circuit in the photocoupler phenomenon.

From the above examples, it is not difficult to see how important the alarm reminder of the inverter to deal with the problem, prompt you to deal with the problem in the right direction.

2. Analogy test

This method can be the analogy of the same circuit itself, or the analogy between the fault plate and the known good plate. This can help the maintainer quickly narrow down the inspection area.

Sanken MF15 kw converter damaged, sent back to repair, the user can not tell the specific situation. Firstly, the multimeter is used to measure the input terminal R,S and T. Except that there is a certain resistance value between R and T, the resistance between other terminals is infinite. The input terminal R,S and T respectively have diode characteristics between the positive and negative poles of the rectifying bridge. Why are R and T different from the other two groups? The original R, T sub internal control power transformer, so there is a certain resistance value. So you can see that the input is fine. Also use the multimeter to check the resistance between U, V, W, three-phase balance. Then check the output of the relative dc positive and negative diode characteristics found that U is not positive and negative to the positive pole, suspected that there is a problem with U phase IGBT, down to check that IGBT is broken. In the driving circuit, three groups of upper bridge arm control circuit have the same characteristics, while three groups of lower bridge arm control circuit have the same characteristics. After replacement, the trigger foot resistance value of each group is consistent, power on to confirm the correct PWM waveform. Reassemble, power test and repair.

There is a frequency converter. It appears that the panel display is normal, the digital frequency setting and operation are normal, but the terminal control is out of order. Check terminal no 10V voltage with multimeter. Starting from the switch power supply, all the power supply is normal, it seems that the problem lies in the connection wire. However, it really takes some time to find 10V in 32 flat cables without drawing. There is just one intact 22KW one. Therefore, write down the voltage of 22KW connecting flat cables at each foot to the ground, and then compare the voltage of 37KW at each foot to the ground, and quickly find the difference. The original socket pin virtual welding, inverter with a period of time after the role of oxidation to make it completely blocked, rewelding and repair.

There is a carding machine equipment in a wool spinning mill, which adopts Siemens 440 frequency converter, and two machines with 5.5kw and one with 7.5kw can operate synchronously. F0011 or A0511 is often shut down after two years of operation of one of the 5.5kw machines. These two alarms both indicate that the motor is overloaded. If you take off the motor belt and move the motor and equipment by hand, there is no abnormal heavy phenomenon. If you switch the two 5.5kw dragging motors and find that the original frequency converter alarms you, it is sure that there is something wrong with the frequency converter. The analogy method can be used not only to check the internal circuit of the machine, but also to identify the field problems.

3. Inspection method of replacement of spare plate

Using the spare circuit board or circuit board of the same model to confirm the fault, narrow the scope of inspection is a very effective method. If there is a problem with the control board, there is often no other way but to replace it, because most users can hardly get the schematic diagram and layout diagram, which makes it difficult to do chip level maintenance. Circuit board other than power board and drive board can be repaired. Other chapters will be further introduced. The replacement of control board is mainly introduced here.

4, isolation inspection method

Some faults are often difficult to identify in that area, isolation can be taken to simplify the complex problem, quickly find out the cause of the fault.

Maintenance of an intime inverter, the phenomenon is after the electricity, there is no display, accompanied by the sound of di - di. It is empirically determined that the switching power supply is overloaded, and that the feedback protection functions to turn off the switching power output, and then turn it off again. First, remove the control panel and turn on the power to find that it is still the same. Then, disconnect the diodes of each power source one by one. Finally, it is found that there is something wrong with the 15V used by the fan. However, the fan does not have a working signal. It should not be the fan itself, but the front end of the fan. Finally, it was found that the characteristics of the filter capacitance of 15V were wrong, and the filter capacitance was removed to measure, so it was aging. Replace it with a new capacitor and it's fixed.

5, visual inspection method

Is to use the hands, eyes, ears, nose sensory organs to find the cause of the fault. This method is often used and used first. The maintenance principle of "first outside, then inside" requires that maintenance personnel should first adopt the methods of looking, smelling, asking and touching, and check one by one from outside to inside. Some faults can be quickly found by this intuitive method, otherwise it will waste a lot of time, or even unable to start. Vision can be used to determine whether the connection of line elements is loose, whether the broken wire contactor is ablated by electric shock, whether the pressure is frequent, whether the heating element is overheated and discolored, whether the electrolytic capacitor is expanded and deformed, and whether the pressure-resisting element has an obvious breakdown point. After the electricity smell whether there is burnt paste taste, touch the heating element is hot. It is very important to ask, ask the process that the user fails to produce, concent analyses the reason of the problem, facilitate direct hit crucial point.

A sanken IP 55KW frequency converter was damaged during the warranty period, and there was no display on the power supply. Open the cover of the machine and carefully observe each part. It is found that the charging resistance is burnt out, the contactor coil is burnt out and the shell is burnt out. After cross-examination, the original user power supply voltage, inverter often due to undervoltage shutdown, on the inverter with a booster. However, the user did not notice that the voltage would return to normal at night, which would first burn out the contactor and then the charging resistor. Because the rectifier bridge and electrolytic capacitor withstand relatively high voltage survived. Replace damaged parts and repair.

6, rising and cooling inspection

This method is very effective for some special faults. Artificially warm or cool some components with poor temperature characteristics to produce "symptoms" or eliminate "symptoms" to find the cause of the failure

There is a fault with a delixi frequency converter. The user reported that the inverter was often shut down after parameter initialization, and the fault reappeared in 20 to 30 minutes after parameter reset. First of all, I think the fault should be related to the temperature, because the temperature of the inverter will increase after running up to this time. I heated the thermistor with the hot air welding table. When the temperature of the fan was heated to the starting temperature, I observed that the LED of the control panel suddenly lost power, then turned on and then flickered. After taking away the hot air for 30 seconds, the LED of the control panel no longer flickered but displayed normally. Use isolation method to unplug all fan plugs, again heating experiment, fault elimination. Check all fans short circuit. It seems that after the temperature arrived, the control board gave the fan operation signal. As a result, the short-circuited fan caused the switch power overload and shut down the output. The control board lost power quickly and the parameter storage error resulted in parameter reset. Replace the fan. Problem solved.

7, break the inspection law

It is to take some measure to cancel the internal protection measures and simulate the failure conditions to destroy the problematic device. To highlight a faulty device or area. First of all, this method should be very sure to control the development of the situation, that is, the maintenance of the psychological to understand the most serious damage is what state, can accept the most serious further damage, and have control means to avoid more serious damage.

During the repair of the converter, we encountered a converter with a switching power failure. The action of its protective circuit can be concluded that there is a short circuit branch at the output end of the transformer, but the fault point cannot be measured statically. We use the destructive method to find the static fault-free device. First, disconnect the feedback signal of the protection loop to make it lose the protection function. Then, switch on the dc power supply. The voltage regulator is required to slowly raise the dc voltage from 0v to observe relevant devices. If you find smoke coming out, turn off the power immediately. At the same time, use resistance to short-circuit dc filter capacitor to discharge quickly. Smoke is the fan power rectifier diode, the original fan has been short-circuit damage, and the fan control switch signal has been in the open state (device short-circuit caused by high level open state), as long as the switch power output normal voltage, the fan short-circuit fan power, resulting in switch power protection. In static measurement, the short circuit of the fan cannot be measured.

8. Tapping test

Inverter is composed of various circuit boards and modules with connectors, each circuit board are a lot of solder joints, any virtual welding and poor contact will occur fault. Striking suspicious areas with insulated rubber rods is likely to be the problem if the converter's malfunction disappears or reappears.

The inverter in a factory has been in normal operation for more than 3 years. Without any warning, it suddenly stops working, and there is no fault information. On closer inspection, nothing unusual was found, nor did the static measurements. After electrification, striking the shell of frequency converter, it is found that the operation signal will change with the striking. After inspection, it was found that the FR terminal screw of the external terminal was loose, and there was no pressing u-shaped terminal at the end of the running signal line, which was directly connected to the terminal. The wiring pressed the wire skin of the lead, resulting in virtual connection between the control wire wire and the end after the screw was loosened due to vibration. Press U - shaped terminal, re-tighten the screw troubleshooting.

9. Scrub test

Many special faults, sometimes no, looming, it is impossible to judge and deal with. The circuit board can be cleaned with water or alcohol, while using a soft brush to remove dust and rust on the circuit board, especially pay attention to the areas of dense solder joints, through holes and close to the 0 volt copper layer circuit should be cleaned, and then dry with hot air. It often achieves unexpected results. At least it's useful for observation.

The fault of a frequency converter is not shown. After preliminary testing, the rectified part and the inverter part are in good condition, so the power is switched on for inspection. The dc bus voltage is normal, but the starting voltage of the switch power control chip 3844 is only 2v. The resistance value of the partial voltage resistance online detection is much smaller, offline detection is normal. The problem was solved after washing. It turned out to be a capacitor positive pin pad close to the 0v layer, with residual flux leaving it in a semi-conducting state.

When the frequency converter was sent, there were several different alarm records. In the electrification test process there are also various false alarm. After carefully cleaning the solder joint between the control board and the driver board, the problem is solved.

10. Principle analysis and inspection

Principle analysis is the most fundamental method of troubleshooting, when other inspection methods are difficult to work, you can start from the basic principles of the circuit, step by step inspection, and finally find out the cause of the fault. Using this method, it is necessary to have a clear understanding of the principle of the circuit, master the logic level and characteristic parameters (such as voltage value and waveform) of each point at each time, then measure with a multimeter and oscilloscope, and compare with the normal situation, analyze and judge the cause of the fault, and narrow the fault range until the fault is found.

At the same time, one of the inverter under repair lost the signal of charging resistance short-circuit relay, fan operation and inverter status relay. Through comparative test, it is proved that the problem lies in the control board. After analysis, the problem may be in the latch, because these signals are controlled by the chip. It was repaired after replacement.

In general, the fault converter should be inspected from the outside to the inside, from the surface to the inside, from the static state to the dynamic state, and from the main circuit to the control circuit. The following three tests are generally mandatory.

Multimeter is used to detect the diode characteristics and three phase balance characteristics of the output terminals on the dc positive and negative poles respectively. This step can preliminarily determine the quality of the inverter module, so as to determine whether it can be output without load. If there is short circuit or unbalanced state between phases, no no-load output is allowed.

Open the cover to observe, if the above two steps did not find the problem, can open the chassis, remove dust, carefully observe the inverter internal whether there is any damage, whether there is a blackened parts, whether the capacitor leakage, and so on.

Above is the ten methods of inverter maintenance learning, through these methods to learn inverter maintenance is conducive to a better introduction, further grasp more abundant knowledge, for skilled learning inverter maintenance knowledge to do a good foundation.