Hum, do you understand? It sounds like you are proficient, but in fact, the complexity of the frequency conversion speed control device is beyond your imagination!
Du Youwen is confident now. After all, although he has not read the report Qin Zhenhua mentioned, he did learn it when he was in technical secondary school. This kind of frequency converter first changes AC to DC, and then changes DC to AC.
The second step is to pass the thyristor.
The waveform of the power grid presents a perfect sinusoidal waveform. It is because of this waveform that the motor can run perfectly. However, what is changed by the thyristor is almost a square wave, with poor performance and almost no practical value.
Du Youwen pulled out a thyristor and a sine wave in front of everyone. His words were very mysterious, which proved that his knowledge was very profound. After hearing his words, Qin Zhenhua shook his head helplessly: "Thyristors have been outdated for a long time. Now they are used
It's a switching tube, and SPWM technology is installed behind it for control. If you look at it with an oscilloscope, it's no different from our sine wave."
Du Youwen is using professional terminology, and Qin Zhenhua is using more professional technical terminology, SPWM, do you understand?
Qin Zhenhua only read this kind of technical information intensively after entering the factory and having some free time without having to prepare for the college entrance examination. If one word from later generations were used to describe Qin Zhenhua, it would be a complete academic master.
.
"SPWM?" Du Youwen tried his best to repeat these letters. This lame repetition made Wang Xiaoyu laugh immediately. This Qin Zhenhua is really powerful. Well, it is just like Zhuge Liang talking to the Confucian scholars.
At this time, the workers below looked at each other even more. For most people, this competition was definitely of a high standard. It was so high that they all became spectators and it was impossible to participate.
"Yes, if translated, it is called pulse width modulation technology." Qin Zhenhua began to explain: "Mathematically speaking, a continuous function can be approximated or replaced by an infinite number of discrete functions, so it is conceivable to use multiple different
A rectangular pulse wave of amplitude is used to replace the sine wave. In order to improve the equivalent accuracy, the more rectangular waves the better, which is limited by the allowable switching frequency of the switching tube."
"Okay, let's not explain the theory. In practice, this technology has been widely used now." Qin Zhenhua said: "For example, SA8281 is a three-phase SPWM wave generation and control device launched by MITEL.
Integrated circuit, if our first machine factory can purchase this kind of component from the international market, I can make an inverter for our three-phase motor. In the future, our lathe will no longer need to use various reducers, and it will be directly
The speed can be adjusted electronically.”
"It would be great if our lathes could electronically regulate speed." Some master craftsmen have started to discuss it below. When processing different workpieces with different speeds, sometimes they can't find the right matching machine.
Compared to now, if the speed is continuously adjustable, it will be easier to process.
"Bragging, how come I haven't heard of it?" Qin Zhenhua explained eloquently, like an expert. Du Youwen's brain became more and more clear, and he had an impression of a certain article he had read. It seemed that something was missing.
letter?
"The most advanced one should be PWM, yes, I'm sure." Du Youwen said: "For your amateur level, it's already pretty good for you to be able to talk about it here."
I'm from the R&D department, so I have seniority. Don't try to show off in front of me. This is just trying to show off in front of Guan Gong!
Qin Zhenhua shook his head helplessly: "Do you know what these letters mean? Do you know what the S in front means?"
"Do you know?" Du Youwen asked, "It's not that easy to deceive me. I studied Russian, and it's not easy to know these letters."
"The S in the front means sinusoidal, which means sine wave. Without S, the output is a square wave. The thyristor you mentioned is that thing. It is already a generation behind. Are all the R&D rooms in our factory at your level?
One bottle is not full, half the bottle is sloshing around." Qin Zhenhua didn't save him any face. Niu Shilong and Du Youwen sang and sang together, which made it clear that they were up to something.
Du Youwen was angry when he heard this. Am I only half-skilled? That's better than you! However, before he could say anything, he saw Wu Limin, who was nimble with both hands and feet, trotting up to the rostrum, holding nails together in her hands.
magazine for the whole year of last year, shouting: "Director, Director, our reference room, fully support our competition!"
Seeing the information, Ma Panshan waved, took it, looked through it, and a smile appeared on his face: "Not bad, Qin Zhenhua, your memory is really good, I remembered it as soon as I read it, your
The request has been approved by the factory and will be applied to the superiors to import the components you mentioned and make this kind of speed regulator. Here, I will give you a celebration party!"
Ma Panshan expressed his attitude. Although he said a few simple words, he completely agreed with Qin Zhenhua's statement.
Qin Zhenhua, well done!
Wang Xiaoyu couldn't help but applaud again. Director Ma said that she would hold a celebration party! This was certainly worthy of celebration. When she failed, everyone in the auditorium also applauded.
, I couldn’t tell whether I was applauding Director Ma or Qin Zhenhua.
Niu Shilong quickly calmed down and didn't care. Then, the third question, I don't believe you can do it!
Du Youwen also suppressed his emotions and read out the next question. It was a professional question about tank engines. There were also specific numerical questions on it. Qin Zhenhua, can you do it?
Qin Zhenhua finished his answer easily.
Then, the fourth and fifth questions came one after another. Du Youwen was completely confused. How could he know it? You know, these questions were specially prepared for Qin Zhenhua. They were all the most bizarre questions. Even
He doesn't know how to do it himself, but Qin Zhenhua can actually answer it. What does it mean?
Qin Zhenhua's theoretical foundation is higher than his own? How is this possible? He is a technical secondary school student!
Don't underestimate technical secondary school students. It's already great to be able to study in a technical secondary school. If you enter a factory, you'll be treated like a cadre!
Of course, it's just in terms of salary. If you want to be a cadre, you have to work for a few more years. What results will you get? Where is Qin Zhenhua? Who is he?
Only the most hopeless people go to high school!
However, it is simply unbelievable that such a person has such extensive knowledge.
I don’t believe I can’t help you!
Finally, the last question came. When he saw this question, Du Youwen felt a little guilty.
Who could survive the whole night of writing questions? The last question was written even more sloppily, and even he couldn’t read it clearly!
Where did you copy this question from? I forgot! The handwriting was not clear. Du Youwen tried hard to identify it, but, helplessly, the handwriting was similar to the handwriting used by doctors to prescribe medicine. Who could know?
!
"Please describe the working principle of the Type 63 armored vehicle, hydraulic suspension... system." Du Youwen continued to guess and recall, and finally finished reading the question.