电路板sew

1. 妙语短篇B3电子版 急用 !!!

1.Step, Step, Roar
A little boy walked down the aisle at a wedding. As he made his way to the front, he would take two steps, then stop, and turn to the crowd, alternating between the bride’s side and the groom’s side. While facing the crowd, he would put his hands up like claws and roar. And so it went -- step, step, ROAR, step, step, ROAR -- all the way down the aisle.

As you can imagine, the crowd was near tears from laughing so hard by the time he reached the pulpit. The little boy, however, was getting more and more distressed from all the laughing, and he was near tears by the time he reached the pulpit.

When asked what he was doing, the child sniffed back his tears and said, “ was being the ring bear.”

2.Step, Step, Roar
A little boy walked down the aisle at a wedding. As he made his way to the front, he would take two steps, then stop, and turn to the crowd, alternating between the bride’s side and the groom’s side. While facing the crowd, he would put his hands up like claws and roar. And so it went -- step, step, ROAR, step, step, ROAR -- all the way down the aisle.

As you can imagine, the crowd was near tears from laughing so hard by the time he reached the pulpit. The little boy, however, was getting more and more distressed from all the laughing, and he was near tears by the time he reached the pulpit.

When asked what he was doing, the child sniffed back his tears and said, “I was being the ring bear.”
3.The Cat Lady
I have lived in my neighborhood for twenty years. It seems to me that I’ve spent at least ten of those years looking for a lost pet, either mine or one I’d seen listed in the newspaper’s lost-pet column.

Recently, I was at it again, going door-to-door looking for one of my own lost kitties, a little black cat named Nicholas who’d slipped out the door before I could stop him. I made my rounds, visiting with all the neighbors, describing Nicholas. Familiar with this routine, everyone promised to keep an eye out and call me if they spotted him.

Two blocks from my house, I noticed a gentleman raking leaves in the yard of a home that had recently been sold. I introced myself and presented my new neighbor with the plight of the missing Nicholas, asking if he had seen him.

“No,” he replied, “I’ve not seen a little black kitty around here.” He thought for a moment, looked at me and said, “But I know who you should ask. Several of my neighbors have told me that there’s a woman in the neighborhood who’s crazy about cats. They say she knows every cat around here, probably has dozens herself. They call her ‘The Cat Lady.’ Be sure to check with her.”

“Oh, thank you,” I said eagerly. “Do you know where she lives?”

He pointed a finger down the street, “It’s that one.”

I followed his finger and started to laugh.

He was pointing at my house!
4.She Told Me It Was Okay to Cry
I saw her last night for the first time in years. She was miserable. She had bleached her hair, trying to hide its true color, just as her rough front hid her deep unhappiness. She needed to talk, so we went for a walk. While I thought about my future, the college applications that had recently arrived, she thought about her past, the home she had recently left. Then she spoke. She told me about her love -- and I saw a dependent relationship with a dominating man. She told me about the drugs -- and I saw that they were her escape. She told me about her goals -- and I saw unrealistic material dreams. She told me she needed a friend -- and I saw hope, because at least I could give her that.

We had met in the second grade. She was missing a tooth, I was missing my friends. I had just moved across the continent to find cold metal swings and cold smirking faces outside the foreboding doors of P.S. 174, my new school. I asked her if I could see her Archie comic book, even though I didn’t really like comics; she said yes, even though she didn’t really like to share. Maybe we were both looking for a smile. And we found it. We found someone to giggle with late at night, someone to slurp hot chocolate with on the cold winter days when school was canceled and we would sit together by the bay window, watching the snow endlessly falling.

In the summer, at the pool, I got stung by a bee. She held my hand and told me that she was there and that it was okay to cry -- so I did. In the fall, we raked the leaves into piles and took turns jumping, never afraid because we knew that the multicolored bed would break our fall.

Only now, she had fallen and there was no one to catch her. We hadn’t spoken in months, we hadn’t seen each other in years. I had moved to California, she had moved out of the house. Our experiences were miles apart, making our hearts much father away from each other than the continent she had just traversed. Through her words I was alienated, but through her eyes I felt her yearning. She needed support in her search for strength and a new start. She needed my friendship now more than ever. So I took her hand and told her that I was there and that it was okay to cry -- so she did.
5.There Is an Oz
They arrive exactly at 8:00 a.m. to take her home, but she has been ready since before seven. She has taken a shower -- not an easy task lying down on a shower stretcher. She isn’t allowed to sit up yet without her body brace, but regardless, here she is, clean and freshly scrubbed and ever so anxious to go home. It has been two-and-a-half months since she has seen her home -- two-and-a-half months since the car accident. It doesn’t matter that she is going home in a wheelchair or that her legs don’t work. All she knows is that she is going home, and home will make everything okay. Even Dorothy says so: “Oh, Auntie Em, there’s no place like home!” It’s her favorite movie.

As they put her in the car, she thinks now of how much her father reminds her of the scarecrow in The Wizard of Oz. Like the scarecrow, he is built in pieces of many different things -- strength, courage and love. Especially love.

He isn’t an elegant man. Her father is tall and lanky and has dirt under his fingernails from working outside. He is strictly blue collar -- a laborer. He never went to college, didn’t even go to high school. By the world’s standards he isn’t “ecated.” An awful lot like the scarecrow -- but she knows differently. He doesn’t speak much, but when he does, she knows it is worth remembering. Even worth writing down. But she never has to write down anything that her father says because she knows she’ll never forget.

It is hard for her to sit comfortably while wearing the body brace and so she sits, still and unnatural, staring out the window. Her face is tense and tired and older somehow, much older than her seventeen years. She doesn’t even remember the world of a seventeen-year-old girl -- it’s as if that world never was. And she thinks she knows what Dorothy must have meant when she said, “Oh, Toto, I don’t think we’re in Kansas anymore.” It is more than an issue of geography, she is quite certain.

They pull out onto the road to begin their journey and approach the stop sign at the corner. The stop sign is just a formality; no one ever stops here. Today, however, is different. As he goes to coast through the intersection, she is instantly alert, the face alive and the eyes flashing. She grips the sides of the seat. “Stop! That’s a stop sign! You could get us killed! Don’t you know that?” And then, more quietly and with even more intensity, “You don’t know what it’s like -- you have never been there.” He looks at her and says nothing. The scarecrow and Dorothy journey onward.

As they continue to drive, her mind is constantly at work. She still hasn’t loosened her grip on the seat. She thinks of the eyes, the eyes that once belonged to her -- big, brown, soulful eyes that would sparkle with laugher at the slightest thought of happiness. Only the happiness is gone now and she doesn’t know where she left it or how to get it back. She only knows that it is gone and, in its absence, the sparkle has gone as well.

The eyes are not the same. They no longer reflect the soul of the person because that person no longer exists. The eyes now are deep and cold and empty -- pools of color that have been filled with something reaching far beyond the happiness that once was there. Like the yellow brick road it stretches endlessly, maddeningly, winding through valleys and woodlands, obscuring her vision until she has somehow lost sight of the Emerald City.

She lightly touches the tiny gold bracelet that she wears. It was a present from her mother and father, and she refuses to remove it from her wrist. It is engraved with her name on the side that is visible to others, but as in everything there are two sides, and only she knows the other is there. It is a single word engraved on the side of the bracelet that touches her skin and touches her heart: “Hope.” One small word that says so much about her life and what is now missing from it. She vaguely remembers hope -- what it felt like to hope for a college basketball scholarship or maybe a chance to dance professionally. Only now, she’s not sure she remembers hope as it was then -- a driving force, a fundamental part of her life. Now, hope is something that haunts her.

The dreams come nightly. Dreams of turning cartwheels in the yard or hitting a tennis ball against a brick wall. But there is one, the most vivid and recurring, and the most haunting of all...There is a lake and trees, a soft breeze and a perfect sky. It is a scene so beautiful it is almost beyond imagining. And in the midst of it all, she is walking. She has never felt more at peace.

But then she awakens and remembers. And remembering, she knows. She instinctively fingers the bracelet, the word. And the fear is almost overwhelming -- the fear of not knowing how to hope.

She thinks of her father’s God and how she now feels that God abandoned her. All at once, a single tear makes a trail down her thin, drawn face. Then another and another, and she is crying. “Oh Daddy, they say I’ll never walk again! They’re the best and they say I’ll never walk. Daddy, what will I do?”

He looks at her now and he stops the car. This is the man who has been with her down every road, every trail and every path -- so very like the scarecrow. And he speaks. “I know that they can put you back together. They can put steel rods in your back and sew you up. But look around you. Not one of your doctors can make a blade of grass.”

Suddenly she knows. He has taught her the most valuable lesson in her life and in all her journey: that she is never alone. There is an Oz; there is a wizard; there is a God. And there...is...hope. She releases her grip on the seat, looks out the window and smiles. And in that instant she loves her father more than she has ever loved him before
6.For the Best
It was two days after the tragic school shooting in Colorado, and I was feeling bad about what had happened to the students there. My school began having a lot of bomb threats and it seemed that police cars were there often. I was standing with my friend, Amberly, and her boyfriend when he casually said, 'I'm gonna blow up the school and kill everyone.' I asked, "Why would you want to do that?' and he said, 'I just do,' and walked away.

I was scared because no one had ever said anything like that to me before. I found out when talking to other friends that he also bragged about this to other people. My friends told me that I should tell an alt what he had said, but I was too scared and I made them promise not to tell anyone either.

One day, Amberly and I were talking about what he had said when the teacher overheard our conversation. She took me out into the hallway and made me tell her who had said it and what they had said. At first, I refused to say a word. She told me it really was for the best, so I told her. I felt awful for doing it. I was angry with her for making me tell who said it. I wasn't sure he really meant it and didn't want him to get into trouble.

He got suspended for two days and had two days of in- school detention after that. I sometimes wonder if I had not told, would he have done what he said he was going to do? The guys in Colorado seemed pretty normal to a lot of people. The bottom line is, you should never joke around about something as serious as killing people. If you do, responsible people have no choice but to have you checked out to ensure everyone else's safety.

After he was suspended, the whole sixth grade had an assembly. The principal and counselors told the students that there was a kid who was making threats and that he was suspended. I decided later to tell him that it was me who told on him so he wouldn't speculate about who did it. I was surprised to find that he was not angry with me for doing what I did. He was able to get help for his feel-ings and behavior.

Many people are in the same situation that I was in. If your friend is saying threatening stuff like my friend was, then they obviously need help-soon. It seems like when one school shooting happens, then another one occurs not too long after that. If there were any way that you could prevent one school shooting it could perhaps save your own life and many others as well. If I had to do it over again, I would-because it really was for the best
7.All Those Years
My friend Debbie’s two daughters were in high school when she experienced severe flu-like symptoms. Debbie visited her family doctor, who told her the flu bug had passed her by. Instead, she had been touched by the “love bug” and was now pregnant.

The birth of Tommy, a healthy, beautiful son, was an event for celebration, and as time went by, it seemed as though every day brought another reason to celebrate the gift of Tommy’s life. He was sweet, thoughtful, fun-loving and a joy to be around.

One day when Tommy was about five years old, he and Debbie were driving to the neighborhood mall. As is the way with children, out of nowhere, Tommy asked, “Mom, how old were you when I was born?”

“Thirty-six, Tommy. Why?” Debbie asked, wondering what his little mind was contemplating.

“What a shame!” Tommy responded.

“What do you mean?” Debbie inquired, more than a little puzzled. Looking at her with love-filled eyes, Tommy said, “Just think of all those years we didn’t know each other.
8.Old People
At age ninety-two, Grandma Fritz still lived in her old two-story farmhouse, made homemade noodles, and did her laundry in her wringer-washer in the basement. She maintained her vegetable garden, big enough to feed all of Benton County, with just a hoe and spade. Her seventy-year-old children lovingly protested when she insisted on mowing her huge lawn with her ancient push mower.

“I only work outside in the cool, early mornings and in the evenings,” Grandma explained, “and I always wear my sunbonnet.”

Still, her children were understandably relieved when they heard she was attending the noon lunches at the local senior citizens' center.

Yes, Grandma admitted, as her daughter nodded approvingly. “I cook for them. Those old people appreciate it so much!”
9.Albert
Working in a hospital with recent stroke patients was an all-or-nothing proposition. They were usually go grateful to be alive or just wanted to die. A quick glance told all.

Albert taught me much about strokes.

One afternoon while making rounds I'd met him, curled in a fetal position. A pale, dried-up old man with a look of death, head half-buried under a blanket. He didn't budge when I introced myself, and he said nothing when I referred to dinner “soon.”

At the nurse's station, an attendant provided some history. He had no one. He'd lived too long. Wife of thirty years dead, five sons gone.

Well, maybe I could help. A chunky but pretty divorced nurse avoiding the male population outside of work, I could satisfy a need. I flirted.

The next day I wore a dress, not my usual nursing uniform but white. No lights on. Curtains drawn.

Albert hollered at the staff to get out. I pulled a chair close to his bed, crossing my shapely legs, head tilted. I gave him a perfect smile.

“Leave me. I want to die.”

“What a crime, all us single women out there.”

He looked annoyed. I rambled on about how I liked working “rehab” unit because I got to watch people reach their maximum potential. It was a place of possibilities. He said nothing.

Two days later ring shift report, I learned that Albert had asked when I'd be “on.” The charge nurse referred to him as my “boyfriend” and word got around. I never argued. Outside his room, I'd tell others not to bother “my Albert.”

Soon he agreed to “dangle,” sit on the side of the bed to build up sitting tolerance, energy and balance. He agreed to “work” with physical therapy if I'd return “to talk.”

Two months later, Albert was on a walker. By the third month, he'd progressed to a cane. Fridays we celebrated discharges with a barbecue. Albert and I danced to Edith Piaf. He wasn't graceful, but he was leading. Tear-streaked cheeks touched as we bade our good-byes.

Periodically roses, mums and sweet peas would turn up. He was gardening again.

Then one afternoon, a lovely lavender-clad woman came on the unit demanding “that hussy.”

My supervisor called; I was in the middle of giving a bed bath.

“So you're the one! The woman who reminded my Albert that he's a man!” Her head tilted in full smile as she handed me a wedding invitation.
10.For the Record
Less than a year after my wife’s funeral I was confronted with the most terrible realities of being a widower with five children.

Notes from school.

Field-trip permission slips, PTA election ballots, Troll Book order forms, sports sign-ups, medical forms and innumerable academic progress reports -- an onslaught of paperwork courtesy of the ecational bureaucracy.

This “literature” has to be read and signed, or placed at the bottom of the birdcage. Regardless of its destination it must be dealt with on a daily basis.

One day, eight-year-old Rachel was helping me complete five (count ’em, five) emergency treatment forms for school. She would fill in the generic information (name, address, phone number), and I would add the rest (insurance numbers, doctor’s name, date, signature). After signing the forms, I checked them for accuracy. It was then that I noticed on each card, in the slot beside Mother’s Business Phone, Rachel had written “1-800-HEAVEN."

2. SEW-ML3PSF110是那种类型的减速机，能不能给个电子版的图纸，QQ邮箱[email protected]

ML 斜齿轮减速机
3 3级传动
P 平行轴
S 实心轴
F 底脚安装
110 机座号
楼主给你一个样本中得尺寸图，已经发到你的邮箱中，请查收！

3. 焊接方法有哪些

焊接或称熔接、镕接，是一种以加热或加压方式接合金属或其他热塑性材料如塑料的制造工艺及技术。
金属焊接方法有钎焊，熔焊、压焊三大类。
钎焊是采用比母材熔点低的金属材料作钎料，将焊件和钎料加热到高于钎料熔点，低于母材熔化温度，利用液态钎料润湿母材，填充接头间隙并与母材相互扩散实现连接焊件的方法。钎焊变形小，接头光滑美观，适合于焊接精密、复杂和由不同材料组成的构件，如蜂窝结构板、透平叶片、硬质合金刀具和印刷电路板等。钎焊前对工件必须进行细致加工和严格清洗，除去油污和过厚的氧化膜，保证接口装配间隙。间隙一般要求在 0.01～0.1毫米之间。较之熔焊，钎焊时母材不熔化，仅钎料熔化；较之压焊，钎焊时不对焊件施加压力。钎焊形成的焊缝称为钎缝。钎焊所用的填充金属称为钎料。
熔焊是在焊接过程中将工件接口加热至熔化状态，不加压力完成焊接的方法。熔焊时，热源将待焊两工件接口处迅速加热熔化，形成熔池。熔池随热源向前移动，冷却后形成连续焊缝而将两工件连接成为一体。
在熔焊过程中，如果大气与高温的熔池直接接触，大气中的氧就会氧化金属和各种合金元素。大气中的氮、水蒸汽等进入熔池，还会在随后冷却过程中在焊缝中形成气孔、夹渣、裂纹等缺陷，恶化焊缝的质量和性能。
压焊是在加压条件下，使两工件在固态下实现原子间结合，又称固态焊接。常用的压焊工艺是电阻对焊，当电流通过两工件的连接端时，该处因电阻很大而温度上升，当加热至塑性状态时，在轴向压力作用下连接成为一体。

具体方法包括气焊，电（弧）焊，压焊，电渣焊，电阻焊，气体保护焊，埋弧焊，闪光焊，冷焊等等。

4. 新手问题，SEW变频器的问题，在线求教。

SEW变频器的冷却问题的解决方法
SEW变频器的效率一般都可达到96-98%左右，但由于设备功率在正常内情况下容工作时，会产生大量的热量；为保证设备的正常工作，如何把大量的热量散发出去，优化散热与通风方案，进行合理的设计与计算，实现设备的散热，对于提高设备的可靠性显得十分重要。
目前，SEW变频器正常工作情况下的变频器设备大约有3.5-4％的功率损耗主要以热量形式散失在运行环境当中，其中电力电子器件的损耗约占一般左右，如果不能及时有效的解决变频器室的工作环境温度问题，将直接危及变频器本体的运行安全；zui终因为温度过高，导致变频器过热保护动作跳闸；为保证变频器具有良好的运行环境，必须对变频器及运行环境的温度控制采取响应的措施。

5. sew的伺服控制器常见报警代码

故障原因：在IPOSplus运行方式下限位开关起动

解决办法

1、检查运行范围

2、校正用户程序

限位开关广泛用于各类机床和起重机械，用以控制其行程、进行终端限位保护。在电梯的控制电路中，还利用行程开关来控制开关轿门的速度、自动开关门的限位，轿厢的上、下限位保护。

在实际生产中，将限位开关安装在预先安排的位置，当装于生产机械运动部件上的模块撞击行程开关时，限位开关的触点动作，实现电路的切换。因此，行程开关是一种根据运动部件的行程位置而切换电路的电器，它的作用原理与按钮类似。

(5)电路板sew扩展阅读：

其他故障

伺服电机在有脉冲输出时不运转

a、监视控制器的脉冲输出当前值以及脉冲输出灯是否闪烁，确认指令脉冲已经执行并已经正常输出脉冲；

b、检查控制器到驱动器的控制电缆，动力电缆，编码器电缆是否配线错误，破损或者接触不良；

c、检查带制动器的伺服电机其制动器是否已经打开；监视伺服驱动器的面板确认脉冲指令是否输入；

d、Run运行指令正常；

e、控制模式务必选择位置控制模式；

f、伺服驱动器设置的输入脉冲类型和指令脉冲的设置是否一致；

c、确保正转侧驱动禁止，反转侧驱动禁止信号以及偏差计数器复位信号没有被输入，脱开负载并且空载运行正常，检查机械系统。

6. 常见伺服驱动器有那些

三菱安川，台达汇川，西门子，发那科，东元，施耐德，欧姆龙，路斯特，科比，SEW，松下等等，品牌太多了。

7. 变频器维修

1 变频器的故障排除及维修

IGBT变频调速器，自研制开发投入市场以来，以其优越的调速性能，可观的节能量已为广大的电机用户所接受，正以每年大规模的销售量走向社会，为电力、建材、石油、化工、煤矿等各行业的发展提供了优质的服务，其用户群已遍布生产的各行各业，成为广大用户所喜爱的产品。
这里笔者结合自己在长期的售后服务工作中经历的一些常见故障及处理方法，提出来与广大的用户及维修工作者进行探讨，以期把该产品使用得更好，更切实的为顾客服务。

2 变频器运行中有故障代码显示的故障

在变频器的使用说明书中，有一栏具体阐述了变频器有故障代码显示的故障，具体如表1所示。
注:表1中Io、Vo分别是输出额定电流、输入额定电压;Vin是输入电压。
现就这几种情况作一下分析。

表1 故障代码显示的故障

2.1 短路保护
若变频器运行当中出现短路保护，停机后显示“0”，说明是变频器内部或外部出现了短路因素。这有以下几方面的原因:

(1) 负载出现短路
这种情况下如果把负载甩开，即将变频器与负载断开，空开变频器，变频器应工作正常。这时我们用兆欧表(或称摇表)测量一下电机绝缘，电机绕组将对地短路，或电机线及接线端子板绝缘变差，此时应检查电机及附属设施。

(2) 变频器内部问题
如果上述检测后负载无问题，变频器空开仍出现短路保护，这是变频器内部出现问题，应予以排除。如图1所示。

图1 变频器主电路示意图

在逆变桥的模块当中，若IGBT的某一个结击穿，都会形成短路保护，严重的可使桥臂击穿，甚至于送不上电，前面的断路器将跳闸。这种情况一般只允许再送一次电，以免故障扩大，造成更大的损失，应联系厂家进行维修。

(3) 变频器内部干扰或检测电路有问题
有些机子内部干扰也易造成此类问题，此时变频器并无太大的问题，只是不间断的、无规律的出现短路保护，即所谓的误保护，这就是干扰造成的。

变频器的短路保护一般是从主回路的正负母线上分流取样，用电流传感器经主控板的检测传至主控芯片进行保护的，因此这些环节上任何一处出现问题，都可能造成故障停机。

对于干扰问题，现低压大功率的及中高压变频器都加了光电隔离，但也有出现干扰的，主要是电流传感器的控制线走线不合理，可将该线单独走线，远离电源线、强电压、大电流线及其他电磁辐射较强的线，或采用屏蔽线，以增强抗干扰能力，避免出现误保护。

对于检测电路出现的问题，一般是电流传感器、取样电阻或检测的门电路问题。电流传感器应用示波器检测，其正常波形应如图2所示。

图2 电流传感器波形图若波形不好或出现杂乱波形甚至于无波形，即说明电流传感器有问题，可更换一只新的。对取样电阻问题，有的机子使用时间长了，其阻值会变大，甚至于断路，用万用表可检测出来，应予以更换成原来的阻值的或少小一些的电阻。

对于检测的门电路，应检查在静态时的工作点，若状态不对应更换之。

(4) 参数设置问题
对于提升机类或其他(如拉丝机、潜油电泵等)重负荷负载，需要设置低频补偿。若低频补偿设置不合理，也容易出现短路保护。一般以低频下能启动负载为宜，且越小越好，若太高了，不但会引起短路保护，还会使启动后整个运行过程电流过大，引起相关的故障，如IGBT栅极烧断，变频器温升高等。因此应逐渐加补偿，使负荷刚能正常启动为最佳。如图3所示，V1为启动电压，V0为额定输出电压。

图3 启动过程的电压曲线

(5) 在多单元并联的变频器中，若某一单元出现问题。势必使其他单元承担的电流大，造成单元间的电流不平衡，而出现过流或短路保护。因此对于多单元并联的变频器，应首先测其均流情况，发现异常应查找原因，排除故障。各单元的均流系数应不大于5%。

2.2 过流保护
变频器出现过流保护，代码显示“1”，一般是由于负载过大引起，即负载电流超过额定电流的1.5倍即故障停机而保护。这一般对变频器危害不大，但长期的过负荷容易引起变频器内部温升高，元器件老化或其他相应的故障。

图4 传感器的波形图

这种保护也有因变频器内部故障引起的，若负载正常，变频器仍出现过流保护，一般是检测电路所引起，类似于短路故障的排除，如电流传感器、取样电阻或检测电路等。该处传感器波形如图4所示，其包络类似于正弦波，若波形不对或无波形，即为传感器损坏，应更换之。

过流保护用的检测电路是模拟运放电路，如图5所示。

图5 过流检测电路

在静态下，测A点的工作电压应为2.4V，若电压不对即为该电路有问题，应查找原因予以排除。R4为取样电阻，若有问题也应更换之。
过流保护的另一个原因就是缺相。当变频器输入缺相时，势必引起母线电压降低，负载电流加大，引起保护。而当变频器输出端缺相时，势必使电机的另外两相电流加大而引起过流保护。所以对输入及输出都应进行检查，排除故障。

2.3 过、欠压保护
变频器出现过、欠压保护，大多是由于电网的波动引起的，在变频器的供电回路中，若存在大负荷电机的直接启动或停车，引起电网瞬间的大范围波动即会引起变频器过、欠压保护，而不能正常工作。这种情况一般不会持续太久，电网波动过后即可正常运行。这种情况的改善只有增大供电变压器容量，改善电网质量才能避免。

当电网工作正常时，即在允许波动范围(380V±20%)内时，若变频器仍出现这种保护，这就是变频器内部的检测电路出现故障了。一般过、欠压保护的检测电路如图6所示。

图6 过、欠压保护的检测电路

当W1调节不当时，即会使过、欠压保护范围变窄，出现误保护。此时可适当调节电位器，一般在网电380V时，使变频器面板显示值(运行中按住“〈”键〉与实际值相符即可。当检测回路损坏时，如图中的整流桥、滤波电容或R1、W1及R2中任一器件出现问题，也会使该电路工作不正常而失控。如有的机子R1损坏造成开路，使该电路P点得不到电压，芯片即认为该处检测不对而出现欠压保护。P点的工作点范围为1.9~2.1V，即对应其电压波动范围。

对于提升机变频器，因回馈电网污染，增加了隔离电路，如图7所示。

图7 提升机变频器过、欠压保护的检测电路

有时调节不当也会出现误保护，此时应根据电网的波动仔细调节。因提升机负载在运行中电网是波动的，在提升重物时，电压下降(有的可降20V)，在下放时回馈电网电压升高，可根据这种变化进行调节，一般是增大W3，减小W2，直至在稳态下适合为止。
2.4 温升过高保护
变频器的温升过高保护(面板显示“5”)，一般是由于变频器工作环境温度太高引起的，此时应改善工作环境，增大周围的空气流动，使其在规定的温度范围内工作。
再一个原因就是变频器本身散热风道通风不畅造成的，有的工作环境恶劣，灰尘、粉尘太多，造成散热风道堵塞而使风机抽不进冷风，因此用户应对变频器内部经常进行清理(一般每周一次)。也有的因风机质量差运转过程中损坏，此时应更换风机。
还有一种情况就是在大功率的变频器(尤其是多单元或中高压变频器)中，因温度传感器走线太长，靠近主电路或电磁感应较强的地方，造成干扰，此时应采取抗干扰措施。如采用继电器隔离，或加滤波电容等。如图8所示。

图8 温升过高保护的抗干扰措施

2.5 电磁干扰太强
这种情况变频器停机后不显示故障代码，只有小数点亮。这是一种比较难处理的故障。包括停机后显示错误，如乱显示，或运行中突然死机，频率显示正常而无输出，都是因变频器内外电磁干扰太强造成的。

这种故障的排除除了外界因素，将变频器远离强辐射的干扰源外，主要是应增强其自身的抗干扰能力。特别对于主控板，除了采取必要的屏蔽措施外，采取对外界隔离的方式尤为重要。
首先应尽量使主控板与外界的接口采用隔离措施。我们在高中压及低压大功率变频器及提升机变频器中采用了光纤传输隔离，在外界取样电路(包括短路保护、过流保护、温升保护及过、欠压保护)中采用了光电隔离，在提升机与外界接口电路中采用了PLC隔离，这些措施都有效避免了外界的电磁干扰，在实践应用中都得到了较好的效果。
再一点就是对变频器的控制电路(主控板、分信号板及显示板)中应用的数字电路，如74HC14、74HC00、74HC373及芯片89C51、87C196等，应特别强调每个集成块都应加退耦电容，即如图9所示。

图9 集成电路的退耦电容

每个集成块的电源脚对控制地都应加10μF/50V的电解电容并接103(0.01μF)的瓷片电容，以减小电源走线的干扰。对于芯片，电源与控制地之间应加电解电容10μF /50V并接105(1μF)的独石电容，效果会更好些。笔者曾对一些干扰严重的机型进行过以上处理，效果较好。
对这类故障应逐渐积累经验，不断寻求解决途径。有些机子使用时间太久，线路板上的滤波电容容量不够造成滤波效果差，造成变频器死机或失控，这种情况不太好处理，可更换一块新线路板，一般可解决问题。

3 变频器的其他故障

除以上有变频器故障代码显示的故障外，变频器还有一些非显示的故障，现分析如下，供大家参考。

3.1 主回路跳闸
这种故障表现为变频器运行过程中有大的响声(俗称“放炮”)，或开机时送不上电，变频器控制用的断路器或空气开关跳闸。这种情况一般是由于主电路(包括整流模块、电解电容或逆变桥)直接击穿短路所致，在击穿的瞬间强烈的大电流造成模块炸裂而产生巨大响声。
关于模块的损坏原因，是多方面的，不好一概而论。现仅就笔者所遇到的几类情况加以列举。

(1) 整流模块的损坏大多是由于电网的污染造成的。因变频器控制电路中使用可控整流器(如可控硅电焊机、机车充电瓶等都是可控整流器)，使电网的波形不再是规则的正弦波，使整流模块受电网的污染而损坏，这需要增强变频器输入端的电源吸收能力。在变频器内部一般也设计了该电路。但随着电网污染程度的加深，该电路也应不断改进，以增强吸收电网尖峰电压的能力。

(2) 电解电容及IGBT的损坏主要是由于不均压造成的，这包括动态均压及静态均压。在使用日久的变频器中，由于某些电容的容量减少而导致整个电容组的不均压，分担电压高的电容肯定要炸裂。IGBT的损坏主要是由于母线尖蜂电压过高而缓冲电路吸收不力造成的。在IGBT导通与关断过程中，存在着极高的电流变化率，即di/dt，而加在IGBT上的电压即为:
U=L×di/dt
其中L即为母线电感，当母线设计不合理，造成母线电感过高时，即会使模块承担的电压过高而击穿，击穿的瞬间大电流造成模块炸裂，所以减小母线电感是作好变频器的关键。我们改进电路采用的宽铜排结构效果较好。国外采用的多层母线结构值得借鉴。

(3) 参数设置不合理。尤其在大惯量负载下，如离心风机、离心搅拌机等，因变频器频率下降时间过短，造成停机过程电机发电而使母线电压升高，超过模块所能承受的界限而炸裂。这种情况应尽量使下降时间放长，一般不低于300s，或在主电路中增加泄放回路，采用耗能电阻来释放掉该能量。如图10所示。

图10 耗能电阻接线图

R即为耗能电阻。在母线电压过高时，使A管导通，使母线电压下降，正常后关断。使母线电压趋于稳定，保证主器件的安全。

(4) 当然模块炸裂的原因还有很多。如主控芯片出现紊乱，信号干扰造成上下桥臂直通等都容易造成模块炸裂，吸收电路不好也是其直接原因，应分别情况区别对待，以期把变频器作的更好。

3.2 延时电阻烧坏
这主要是由于延时控制电路出问题造成的。

(1) 在变频器延时电路中，大多是用的晶闸管(可控硅)电路，当其不导通或性能不良时，就可造成延时电阻烧坏。这主要是开机瞬间造成的。

(2) 在变频器运行过程当中，当控制电路出现问题，有的是由于主电路模块击穿，造成控制电路电压下降，使延时可控硅控制电路工作异常，可控硅截止使延时电阻烧坏。也有的是控制变压器供电回路出现问题，使主控板失去电压瞬间造成晶闸管工作异常而使延时电阻烧坏。

3.3 只有频率而无输出
这种故障一般是IGBT的驱动电路受开关电源控制的电路中，当开关电源或其驱动的功率激励电路出现故障时，即会出现这种问题。如图11所示。

图11 开关电源及其驱动电路框图

在风光变频器中，开关电源一般是选30～35V, ±15V或±12V，功率激励的输出为一方波，其幅度为±35V，频率在7kHz左右。检测这几个电压值，用示波器测量功率激励的输出即可加以判别，如图12所示。但更换这部分器件后，应加以调整，使驱动板上的电压符合规定值(+15V、-10V)为宜。

图12 功率激励级的输出波形

3.4 送电后面板无显示
这主要是提升机类变频器常出现的故障，因此类变频器主控板用的电源为开关电源，当其损坏时即会使主控板不正常而无显示。
这种电源大多是其内部的熔断器损坏造成的。因在送电的瞬间开关电源受冲击较大，造成保险丝瞬间熔断，可更换一个合适的熔断器即可解决问题。有的是其内的压敏电阻损坏，可更换一支新的开关电源。

3.5 频率不上升
即开机后变频器只在“2.00”Hz上运行而不上升，这主要是由于外控电压不正常所致。变频器的外控电压是通过主控板的16脚端子引入的，若外控电压不正常，或16脚的内部运放出了问题，即会引起该故障，如图13所示。

图13 频率调节电路

这时请检查调节频率用的电位W2(3.9K)，测量一下16脚有无0～5V的电压，进而检测运放电路C点工作是否正常。若16脚电压正常，而C点无输出，一般是运放的工作电压不正常所致，应检查其供电电压是否正常或运放是否损坏等。

4 结束语
变频器所出现的故障很多，正像维修其他电器一样，有很多是意想不到的问题，需要我们认真分析，弄清工作原理，逐步的把其电路学深学透，才能把握其本质，快速而准确的处理问题，从而更快、更好的服务于用户。

本文只是在作者维修经验的基础上，对变频器的一些常见故障进行了分析探讨，在工作中还需要不断的分析、总结，积累一些常见的维修技巧，为用户排忧解难。也使我们的产品在应用过程中不断改进、升华，使其做的更好，更全面、更完善地服务于广大的用户，尽量少出问题、不出问题，出了问题能及时解决，这正是我们的期望所在。

变频器的控制电路及几种常见故障分析
1 引言

随着变频器在工业生产中日益广泛的应用，了解变频器的结构，主要器件的电气特性和一些常用参数的作用，及其常见故障越来越显示出其重要性。

2 变频器控制电路

给异步电动机供电 (电压、频率可调)的主电路提供控制信号的回路，称为控制电路，如图1所示。控制电路由以下电路组成：频率、电压的运算电路、主电路的电压、电流检测电路、电动机的速度检测电路、将运算电路的控制信号进行放大的驱动电路，以及逆变器和电动机的保护电路。

在图 1点划线内，无速度检测电路为开环控制。在控制电路增加了速度检测电路，即增加速度指令，可以对异步电动机的速度进行控制更精确的闭环控制。

1)运算电路将外部的速度、转矩等指令同检测电路的电流、电压信号进行比较运算，决定逆变器的输出电压、频率。

2)电压、电流检测电路

与主回路电位隔离检测电压、电流等。

3)驱动电路

为驱动主电路器件的电路，它与控制电路隔离使主电路器件导通、关断。

4)I/0输入输出电路

为了变频器更好人机交互，变频器具有多种输入信号的输入 (比如运行、多段速度运行等)信号，还有各种内部参数的输出“比如电流、频率、保护动作驱动等)信号。

5)速度检测电路

以装在异步电动轴机上的速度检测器 (TG、PLG等)的信号为速度信号，送入运算回路，根据指令和运算可使电动机按指令速度运转。
6)保护电路

检测主电路的电压、电流等，当发生过载或过电压等异常时，为了防止逆变器和异步电动机损坏，使逆变器停止工作或抑制电压、电流值。

逆变器控制电路中的保护电路，可分为逆变器保护和异步电动机保护两种，保护功能如下

(1)逆变器保护

①瞬时过电流保护由于逆变电流负载侧短路等，流过逆变器器件的电流达到异常值 (超过容许值)时，瞬时停止逆变器运转，切断电流。变流器的输出电流达到异常值，也同样停止逆变器运转。

②过载保护
逆变器输出电流超过额定值，且持续流通达规定的时间以上，为了防止逆变器器件、电线等损坏要停止运转。恰当的保护需要反时限特性，采用热继电器或者电子热保护 (使用电子电路)。过载是由于负载的GD2(惯性)过大或因负载过大使电动机堵转而产生。
③再生过电压保护
采用逆变器是电动机快速减速时，由于再生功率直流电路电压将升高，有时超过容许值。可以采取停止逆变器运转或停止快速减速的方法，防止过电压。
④瞬时停电保护
对于数毫秒以内的瞬时停电，控制电路工作正常。但瞬时停电如果达数 10ms以上时，通常不仅控制电路误动作，主电路也不能供电，所以检出后使逆变器停止运转。
⑤接地过电流保护
逆变器负载接地时，为了保护逆变器有时要有接地过电流保护功能。但为了确保人身安全，需要装设漏电断路器。
⑥冷却风机异常
有冷却风机的装置，当风机异常时装置内温度将上升，因此采用风机热继电器或器件散热片温度传感器，检出异常后停止逆变器。在温度上升很小对运转无妨碍的场合，可以省略。