Ramírez-Muñoz Diego, García-Gil Rafael, Cardoso Susana, Freitas Paulo
Department of Electronic Engineering, University of Valencia, Avda. de la Universitat, s/n, 46100 Burjassot, Spain.
INESC Microsistemas e Nanotecnologias (INESC-MN) and Instituto Superior Tecnico, Universidade de Lisboa, R. Alves Redol 9, 1000-029 Lisbon, Portugal.
Sensors (Basel). 2024 May 11;24(10):3047. doi: 10.3390/s24103047.
The main purpose of the paper is to show how a magnetoresistive (MR) element can work as a current sensor instead of using a Wheatstone bridge composed by four MR elements, defining the concept of a magnetoresistive shunt (MR-shunt). This concept is reached by considering that once the MR element is biased at a constant current, the voltage drop between its terminals offers information, by the MR effect, of the current to be measured, as happens in a conventional shunt resistor. However, an MR-shunt has the advantage of being a non-dissipative shunt since the current of interest does not circulate through the material, preventing its self-heating. Moreover, it provides galvanic isolation. First, we propose an electronic circuitry enabling the utilization of the available MR sensors integrated into a Wheatstone bridge as sensing elements (MR-shunt). This circuitry allows independent characterization of each of the four elements of the bridge. An independently implemented MR element is also analyzed. Secondly, we propose an electronic conditioning circuit for the MR-shunt, which allows both the bridge-integrated element and the single element to function as current sensors in a similar way to the sensing bridge. Third, the thermal variation in the sensitivity of the MR-shunt, and its temperature coefficient, are obtained. An electronic interface is proposed and analyzed for thermal drift compensation of the MR-shunt current sensitivity. With this hardware compensation, temperature coefficients are experimentally reduced from 0.348%/°C without compensation to -0.008%/°C with compensation for an element integrated in a sensor bridge and from 0.474%/°C to -0.0007%/°C for the single element.
本文的主要目的是展示磁阻（MR）元件如何用作电流传感器，而不是使用由四个MR元件组成的惠斯通电桥，从而定义磁阻分流器（MR分流器）的概念。之所以能得出这个概念，是因为考虑到一旦MR元件被施加恒定电流偏置，其两端之间的电压降会通过MR效应提供有关待测电流的信息，这与传统分流电阻的情况相同。然而，MR分流器具有非耗散分流器的优点，因为感兴趣的电流不会流经该材料，从而防止其自热。此外，它还提供了电隔离。首先，我们提出一种电子电路，能够将集成在惠斯通电桥中的可用MR传感器用作传感元件（MR分流器）。该电路允许对桥的四个元件中的每一个进行独立表征。还分析了一个独立实现的MR元件。其次，我们为MR分流器提出一种电子调节电路，该电路允许桥集成元件和单个元件都能以与传感桥类似的方式用作电流传感器。第三，获得了MR分流器灵敏度的热变化及其温度系数。提出并分析了一种用于MR分流器电流灵敏度热漂移补偿的电子接口。通过这种硬件补偿，对于集成在传感器桥中的元件，温度系数从无补偿时的0.348%/°C实验性地降低到有补偿时的-0.008%/°C，对于单个元件则从0.474%/°C降低到-0.0007%/°C。
