Design of Double Closed Loop Feedback Parallel System for High Frequency Switching Power Supply
Overview:
1. Introduction After entering the country in the 1980s, the high-frequency switching power supply has entered the country's post and telecommunications, power sector and other fields due to its small size, light weight, high efficiency and low noise. Rapid, the market potential is huge, replacing many traditional small and medium power thyristor rectifier power supplies. In traditional industrial and mining enterprises, such as electrolytic plating, electro-chemical, electric spark, battery charging, water treatment, heat treatment, welding, smelting, etc. At present, the traditional thyristor rectification power supply is still in large use, which does not comply with the national environmental protection and energy saving policy. The power of a single high frequency switching power supply on the market is limited by the device and other factors, and it is difficult to be at high power (above 50KW). Practical needs of the occasion. In order to increase the power, the simple method is to put a number of single high-frequency switching power supplies, and their outputs are simply connected in parallel to form a current-expanding output. However, this method has a limitation, that is, the system after parallel connection only Can be a steady current output, but can not adapt to the application of the regulated output. The design idea of ​​this paper is based on the above simple parallel connection, and then separate An output voltage negative feedback system is used, and the output of the voltage feedback system is used to control each high-frequency switching power supply to form a double closed-loop feedback, thereby achieving a regulated output of the parallel system. Since the working principle of a single high-frequency switching power supply is well known, The following focuses on the principle of the automatic control system to introduce the working principle of the parallel system.
2. System control schematic diagram The automatic control principle of the parallel system is shown in Figure 1.
In the automatic control motor DC speed control system, there is a speed and current double closed loop feedback system, also known as cascade system.
The outer ring is the speed feedback, and the inner ring is the current feedback. Any change in the speed caused by internal or external disturbances or changes in the grid current can be adjusted by the feedback system of the outer or inner ring to achieve a stable speed output. This paper is based on this design. Thought, designed the high-frequency switching power supply double closed-loop feedback parallel automatic control system as shown in Figure 1. Each high-frequency switching power supply in the figure can work independently, and internally form a voltage or current negative feedback system. The parallel system voltage feedback belongs to The outer ring and the inner ring are formed by the high-frequency switching power supply. The reason why the parallel system is simple is that the output terminals are simply connected in parallel on the basis of a single independent working power supply. The input terminal is uniformly added by the outer ring. To each independent high frequency switching power supply.
In Figure 1, the dotted line frame 1#.2#........N# is the high-frequency switching power supply of each unit, and the internal automatic control schematic diagram is simplified to the first-order system proportional integral link, so the steady flow of each high-frequency switching power supply Or the voltage regulation accuracy is very high. In the figure they work in steady current state. 
3. System work design principle
3.1 Single high frequency switching power supply design and overall block diagram Technical specifications of single high frequency switching power supply:
Input voltage: 380V, 50HZ
Output voltage: DC 18V
Output current: DC 800A
Current limit: 850A
Pressure limit value: 18.5V
Protection: overcurrent protection. Thermal protection. Overvoltage protection. Undervoltage protection conversion efficiency: >80%
(Please read the PDF for details)
Benefits of Privacy Screen Protectors
As a personal item, a mobile phone will always contain all kinds of private information and secrets. Therefore, when many people use their mobile phones in public places, they are worried that their screen content will be seen by the people next to them. Especially when you use your mobile phone to enter various passwords, it is very dangerous if you are targeted by malicious people.
In order to prevent private information and confidential documents from being peeped, Privacy Screen Protector came into being. As the name suggests, it is a Mobile Phone Screen Protector, which can prevent others from prying on the screen and protect personal privacy. When you install a Privacy Screen Protector on your phone, people around you won't be able to see what's on your screen.
The Anti-Spy Screen Protector uses patented ultra-fine louver optical technology, so that the information on the screen is displayed on the front for the user to read. The viewable area is 60 degrees. Anyone can only see the dark picture on both sides. And the anti-blue light effect of the Privacy Screen Protective Film, the blue light blocking rate is about 10%-30%, and the mobile phone with the Privacy Film will automatically darken to reduce some glare. Therefore, normal use will not hurt the eyes, but will play a protective role. Anti-peeping Screen Protector effectively protect business secrets and personal privacy. Whether it is work, study, communication or entertainment, it makes the use of computers and mobile phones more free. Help the company's senior business personnel, lawyers, consultants, financial personnel, etc. to avoid screen information leakage when using mobile phones.
Anti-Peep Hydrogel Screen Protector,Anti-Spy Tpu Hydrogel Film,Privacy Hydrogel Protector,Privacy Screen Protector Sheet
Shenzhen TUOLI Electronic Technology Co., Ltd. , https://www.tlhydrogelprotector.com