电流传感器的基本知识

　　电流传感器的基本知识

　　电流传感器既可以是开路的也可以是闭环的。开环电流传感器测量交流和直流电流，并在被测电路和传感器的输出之间提供电气隔离（原电流测量而不与初级电路电接触，提供直流隔离）。开环电流传感器由于其低的工作功率要求和占用空间小的特点，在电池供电的电路中通常是首选的。

　　闭环传感器测量交流和直流电流，并提供电气隔离。它们具有响应快、线性度高、低温漂移等优点。闭环传感器的电流输出相对不受电噪声的影响。闭环传感器有时被称为“零磁通”传感器，因为它的霍尔效应传感器反馈相反的电流进入次级线圈，卷绕在磁芯上，以使磁芯产生的磁通由初级电流产生零。闭环传感器往往是传感器的选择时，高精度是必不可少的。

　　现在让我们仔细看看这两种类型，从开环传感器开始。

　　Open loop current sensors consist of a Hall sensor mounted in the air gap of a magnetic core （Fig. 1）。 A conductor produces a magnetic field comparable to the current. The magnetic field is concentrated by the core and measured by the Hall sensor. The signal from the Hall generator is low， so it is amplified， and it is this amplified signal that becomes the sensor’s output. Open-loop sensors normally have circuitry that provides temperature compensation and calibrated high-level voltage output. While they have a definite price advantage over closed-loop counterparts， their downside is that they can be prone to saturation and temperature drift. The drift can be minimized to some extent， however， by injecting a positive coefficient in the control current to reduce the drift in sensitivity over temperature.