Linear isolating circuit based on optical couplers and method

Abstract

The invention relates to a linear isolating circuit based on optical couplers and a method, wherein the circuit comprises an input and output optical coupler PC1, a first voltage follower, a sampling optical coupler PC2, a subtracter, a second voltage follower, a feedback optical coupler PC3 and a comparing optical coupler PC4, wherein the input and output optical coupler PC1 is connected with the input end of the isolating circuit in series; the first voltage follower is used for following the output voltage of the optical coupler PC1; the sampling optical coupler PC2 is used for sampling the practical input current of a photoreceptor of the optical coupler PC1; the subtracter is used for computing the subtraction of the output voltage of the photoreceptor of the optical coupler PC1 and the cathode voltage of an illuminating device of the optical coupler PC2; the second voltage follower is used for following the output voltage of the subtracter; the feedback optical coupler PC3 is used for feeding the feedback comparing control current of the second voltage follower and the optical coupler PC4 to the input end of the isolating circuit; an illuminating device of the comparing optical coupler PC4 is connected with an illuminating device of the optical coupler PC3 in series; the optical coupler PC1 is matched with the optical coupler PC2; the optical coupler PC3 is matched with the optical coupler PC4 and the current transmission of the optical coupler PC1 is larger than 1. The linear isolating circuit has the advantages of simple structure, high precision, good linear degree, low cost, high safety and the like.

Description

technical field [0001] The invention relates to a linear isolation technology based on an optocoupler (optocoupler for short), in particular to a linear isolation circuit and method based on an optocoupler. Background technique [0002] There are many traditional methods for linear isolation of analog signals. The use of optocouplers to achieve linear isolation of electrical signals has certain advantages in terms of volume, cost, anti-interference ability, and circuit complexity, so it has been widely used. Its function is to avoid the error caused by the different grounding points of the input terminal (signal terminal) and the output terminal circuit, the second is to protect the output terminal circuit from the influence of the input terminal circuit failure, and the third is to provide strong anti-interference ability. The isolation achieved by optocoupler is divided into digital signal isolation and analog signal isolation. The optocoupler isolation method for digita...

AI Technical Summary

Problems solved by technology

The linear section of the optocoupler can be easily obtained by actual measurement, and the problem of improving the linearity can only be solved by rationally designing the circuit

Existing isolation circuits with high precision and good linearity generally have the disadvantages of complex structure or high cost

In addition, the traditional linear isolation circuit using an optocoupler uses an isolated power supply and an operational amplifier (referred to as an operational amplifier) ​​at the input end, which is not suitable for applications where the analog signal input with a high measurement voltage is used.

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