The application of zero-flux detecting technique in the DC current sensor

摘要

In the course of design of the standard source of the high-accuracy electric current, one key technological question whether current is it feedback design of link to sample. At present, high-power samples the resistance measures widely usedly on the current feedback unit. But, the resistance have greater temperature drift while measuring high-current. If make the resistance have smaller temperature drift about, must reduce his resistance value. Under enabling feedbacking the voltage and is even as small as 1mV in such a result, very easy to be interfered. In recent years, the method of adopting magnetic induction technology to measure the high-current has got application. This kind of technology is to measure the intensity of magnetic induction that the current produces through certain technological means.For example, Hall sensor can measure the dc current and ac current. However, the stability indicator of the sensor can only be up to 0.1%, can't respond to the request that measure high-current accurately. Utilize zero-flux to measure the magnetization current in second harmonic that the principle measures the magnetization current openly, shoulder the method whether the positive or negative current peak value of the magnetization is equal to, measuring the dc current can reach very high precision to flow. In recent years, have had research work that research units have begun in this respect, but the domestic and international selecting expecting relatively much to magnetism core at present already, it is more complicated too to design the circuit. This text summarizes the technique of zero-flux of double coils through the study on technique of zero-flux. Use technology this, finish the design of the 600A dc current sensor. Technological scheme this include,magnetism induction coil measure circuit two parts. Measure the circuit to include, ac excition circuit, error detection circuit and high precision servo current source. The dc current sensor has Reseached to use the above technical design, which test accuracy 0.001%, linear degree is 0.0005%.