Author: Noyafa–Noyafa Cable Tester
How to isolate and convert high-voltage analog signals in the control system into low-voltage analog signals? In order to prevent strong current (power system) from interfering with the control system, the power grounding, digital grounding and analog grounding must be separated. How can the high-voltage analog signal in the control system be isolated and converted into a low-voltage analog signal? In order to prevent strong current (power system) from interfering with the control system, it is necessary to“power ground”,“digital ground”and“Analog ground”separate, not to be confused. The entire system ultimately has a common place. Powerful, digital and similar, it ends up in the same place.
Supplement to answer the question: Strong current (power system) has a large current to ground and this current creates a voltage drop along the current path. Assuming a and B are two points on this path, there will be a voltage proportional to the strong current to ground. If the power ground, digital ground, and analog ground are not only the only common ground, but also some A points and some B points, the voltage between A-B will form interference signals in the digital system and the analog system, making the system unable to work properly.
It is difficult to isolate analog signals, mainly to achieve a certain level of accuracy. Isolation is generally divided into analog isolation and digital isolation. Numerical isolation is a relatively large number of contacts.
I guess we have already used it. Simulation isolation is more complex. Let us share the isolation methods of analog circuits: 1.
First convert the analog signal into a digital signal, then perform digital isolation, and then use a DA conversion chip to convert it into an analog signal. The principle of this scheme is simple, but the conversion accuracy depends on the accuracy of the conversion chip, and the overall accuracy cannot be improved. At the same time, the response delay will be very serious. 2.
The analog conversion circuit is used directly, usually using magnetic isolation technology. The circuit is complex and difficult to debug, but the conversion accuracy of the analog circuit is high, generally reaching 0.1%, and the response speed is fast. To sum up, the second scheme has higher requirements on circuits and devices, and it is generally difficult to meet the requirements of batch accuracy.
Therefore, rubber-filled isolation modules are generally used to integrate the entire function into one module, and only lead out the input and output terminals and the power supply terminal. Previous colleagues used such modules, called signal conditioning modules. It appears the package is DIP24.
The whole volume is small. It was 0-10V to 0-10V at the time. Shenzhen Noyafa Electronic Technology Co., Ltd., a light-duty high-voltage signal generator manufacturer.
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