? I graduated from college in 2000, majoring in industrial automation. I worked for 2 years, doing data acquisition of power control, and then read a master's degree. In 2004, I began to turn my direction to switching power supply. At that time, I thought this direction was very promising, but my master's thesis was about a monitoring network for high-voltage power supply. The first book I read was about 300 pages in English, and there was a Chinese version translated by Taiwan Province Province. After reading it, I made a top power supply. The circuit is not working properly. Later, I used ti chip as flyback multi-channel output, but the output voltage was far from the design, and the power consumption was high. At that time, I didn't have any concept of components or magnetic circuits. Flyback transformer only depends on the parameters in the book, and I don't know why, but I don't know that the diode output needs to be quickly restored. In a word, this power supply made for the first time was a complete failure. The only gain is that it takes a lot of books to do a good job of switching power supply, but this design has helped me a lot. Although it failed, it showed me the outline of switching power supply.
? Later, after my master's degree, I debugged a switching power supply, which is 5V/600A. It took me 20 days to redesign the hardware control circuit and software, and the disturbance of power supply was reduced by less than 5 times. The current precision is less than 1%. Later, I tested a 1200V/ 100A power module. Later, I became a doctor. My work and study are in the same unit. So far, I mainly do things around hardware circuits.
? By July this year, it took me about two years and three months to turn my goal into a switching power supply. At this time, I am already familiar with the performance of magnetic circuit and devices, and I don't need to look at the concepts in circuit and analog electricity, so I still have some confidence in the design of switching power supply. But when I graduated in 2005, I left my job without finding a suitable power supply company. Now I get 1500 a month, and there is no bonus at the end of the year. However, a few years later I have a doctoral book. If the book was worthless at that time, it would be a loss.
? At the end of July, I received a project from a small power supply company: copy a 1400W/30V power supply with PFC, and draw the circuit schematic diagram as soon as possible. At that time, it was not difficult, and the most important thing was magnetic components. I didn't completely design a power supply system, just debugged two. At that time, I thought, if I can do this power supply well, it will prove that I can still engage in the research and development of switching power supply. If not, I'll stay at work. Anyway, it is state-owned and can support the elderly. The owner of this power supply company is also the only technical director. Graduated from junior college at an early age, mainly engaged in sales. He is diligent in technology and can read elementary English materials. His employees are not technical experts. He can't control this power supply. So I am in charge of the technical aspects of this power supply.
? I saw that uc3855 and ucc2895 were used for two weeks respectively, and then I saw the main cycle 1 week. During the period, I read a lot of information about ti company. The parameter measurement of the original power supply was completed in August, and the simulation test was completed in September, and the performance parameters of some components were determined. 10 in June, I tested a brand-new imitation power supply and determined the parts that are prone to failure. And key components. I wrote the principle analysis and debugging manual of power supply. I have written 20 chapters on PFC principle, which are basically my own understanding of power supply and calculation of some parameters. I added some control functions to the power supply. /kloc-at the beginning of October, I sent two sets to the United States for testing, and the other party was very satisfied.
? When writing the principle of power supply, I thought I was familiar with the flyback circuit, but later I learned that I didn't fully understand a lot. I spent two days reviewing its magnetic circuit and control part, and finally understood the principle of reflected voltage. I didn't design the parameters of flyback according to the window function in the book. I design the numbers according to the energy storage of the magnetic core and the voltage of the primary side. The result is not much different from the original power supply. After reading the relevant information, the DCDC transformer I designed is similar to the original transformer. However, the magnetic element is completely copied from the original power supply. The problem of magnetic components accounts for 50% of all faults, and more than half of the debugging time is spent on magnetic components, especially flyback transformers. There were many problems in the test, which were very strange and finally solved.
? It hasn't been debugged for a while, so according to the calculation of full-time work, it took two months from reading the data to sending the power out for debugging. Because the power supply test is at night, plus weekends, it is generally successful. Have a specific understanding of their own abilities, make themselves familiar with the power design and development process of small power supply companies, and get the reward of 1 1000.
? I want to tell beginners of switching power supply that switching power supply is not very complicated. It is best to look at the basic data for several years: harmonics, circuits, analog electricity, electrical mechanics, control, etc. , but it is not a book made in Chinese mainland. The books I read add up to more than 1 foot, and I have also read several books about control. Some of them are books from Taiwan Province Province, 65,438+0. Taiwan Province province will do, as long as it's not made in Chinese mainland. When designing a power supply, we should pay attention to the whole system, including the load, and the whole current flow process should be clear. It is very important that it is not enough to know only the design methods, but also to know why these mature methods are used for design, and what is his basis! If it can be deduced, the magnetic circuit theory is these two formulas. The key is understanding.
? I don't know what the power market is like outside. I chose the power supply, but I am still a little confused about its prospect.
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