技术领域technical field
本实用新型涉及传感器技术，尤其涉及一种巨磁阻效应电流传感器。The utility model relates to sensor technology, in particular to a giant magnetoresistance effect current sensor.
背景技术Background technique
随着电力电子技术的发展，高性能紧凑型电流传感器的需求逐渐增大。传统的电流检测方法包括分流器、电流互感器、罗氏线圈、霍尔传感器；新型检测技术包括磁通门传感器、巨磁阻传感器和光纤传感器。其中分流器测量方法不能实现电隔离，且功耗较高；电流互感器只能进行交流电流的测量，磁芯容易受饱和的影响，测量频率较低，体积较大，价格昂贵；霍尔电流传感器能够检测较大量程的电流，测量精度在0.5％和2％之间，但是其测量精度受环境温度和外界磁场影响较大，这就限制了其应用范围；罗氏线圈测量频率范围较大，但不可测量直流，且价格昂贵。光纤电流传感器体积小，重量轻，不存在磁饱和影响，抗电磁干扰性能好，但其结构复杂，造价昂贵。磁通门传感器是利用高导磁率磁芯在交变磁场的饱和激励下，其磁感应强度与磁场强度之间的非线性关系来间接测量被测磁场的一种传感器。磁通门传感器具有分辨率高，低温漂，低零漂等优点，但其信号处理电路比较繁琐，主要用于直流弱磁场的测量。与上述电流传感器相比，巨磁阻电流传感器具有高带宽、高灵敏度、低功耗、可靠性好和体积小等优点，它达到了电流传感器未来发展趋势的要求，在未来的检测技术中巨磁阻电流传感器将会应用越来越广泛，发挥它本身的优越性。With the development of power electronics technology, the demand for high-performance compact current sensors is gradually increasing. Traditional current detection methods include shunts, current transformers, Rogowski coils, and Hall sensors; new detection technologies include fluxgate sensors, giant magnetoresistance sensors, and fiber optic sensors. Among them, the shunt measurement method cannot achieve electrical isolation, and the power consumption is high; the current transformer can only measure the AC current, the magnetic core is easily affected by saturation, the measurement frequency is low, the volume is large, and the price is expensive; the Hall current The sensor can detect a large range of current, and the measurement accuracy is between 0.5% and 2%. However, its measurement accuracy is greatly affected by the ambient temperature and external magnetic field, which limits its application range; the Rogowski coil has a large measurement frequency range. But it cannot measure DC and is expensive. The optical fiber current sensor is small in size, light in weight, does not have the effect of magnetic saturation, and has good anti-electromagnetic interference performance, but its structure is complex and expensive. The fluxgate sensor is a sensor that uses the non-linear relationship between the magnetic induction intensity and the magnetic field intensity of the high magnetic permeability core under the saturation excitation of the alternating magnetic field to indirectly measure the measured magnetic field. The fluxgate sensor has the advantages of high resolution, low temperature drift, low zero drift, etc., but its signal processing circuit is relatively cumbersome, and it is mainly used for the measurement of DC weak magnetic field. Compared with the above-mentioned current sensors, the giant magnetoresistive current sensor has the advantages of high bandwidth, high sensitivity, low power consumption, good reliability and small size. Magneto-resistive current sensors will be more and more widely used, giving full play to its own advantages.
然而，由于巨磁阻对磁场的高度敏感特性，使得它们同时易受外界杂散磁场的影响。这些杂散磁场的场源包括电机和变压器等电器设备，或者传感器周围的载流导体等等。杂散磁场会引起传感器产生较大的输出误差，影响了电流测量结果的准确度。However, due to the high sensitivity of giant magnetoresistance to magnetic field, they are also vulnerable to external stray magnetic fields. Sources of these stray magnetic fields include electrical equipment such as motors and transformers, or current-carrying conductors around sensors, among others. The stray magnetic field will cause a large output error of the sensor, which affects the accuracy of the current measurement result.
实用新型内容Utility model content
有鉴于此，本实用新型提供一种巨磁阻效应电流传感器，以解决巨磁阻芯片因易受杂散磁场影响，产生较大的输出误差，影响电流测量结果的准确度的问题。In view of this, the utility model provides a giant magnetoresistance effect current sensor to solve the problem that the giant magnetoresistance chip is easily affected by the stray magnetic field, which produces a large output error and affects the accuracy of the current measurement result.
本实用新型实施例提供了一种巨磁阻效应传感器，包括：The embodiment of the utility model provides a giant magnetoresistance effect sensor, comprising:
电磁转换模块，包括带气隙的磁芯，放置于所述磁芯气隙两端的两个磁屏蔽片，穿过所述磁芯的原边绕组和放置于所述磁芯气隙处的巨磁阻芯片；The electromagnetic conversion module includes a magnetic core with an air gap, two magnetic shielding sheets placed at both ends of the air gap of the magnetic core, a primary winding passing through the magnetic core and a giant shield placed at the air gap of the magnetic core Magnetoresistive chip;
信号处理模块，包括运算放大器，所述运算放大器的同相输入端和反相输入端分别与所述巨磁阻芯片的两个输出端相连；The signal processing module includes an operational amplifier, and the non-inverting input terminal and the inverting input terminal of the operational amplifier are respectively connected to the two output terminals of the giant magnetoresistive chip;
电源模块，分别与所述电磁转换模块和所述信号处理模块相连，用于为所述巨磁阻效应电流传感器提供电源。The power supply module is respectively connected with the electromagnetic conversion module and the signal processing module, and is used to provide power for the giant magnetoresistance effect current sensor.
本实用新型提供的一种巨磁阻效应电流传感器，通过在电磁转换模块内加入带气隙的磁芯，并在磁芯气隙处引入了两个磁屏蔽片，可以有效屏蔽外界的杂散磁场，同时使气隙处磁场更加均匀。环形磁芯和磁屏蔽片的引入有效减少了外界杂散磁场的干扰同时增加了传感器的磁增益系数，从而使所设计电流传感器的精度和灵敏度得到很大程度的提高。The utility model provides a giant magnetoresistance effect current sensor, by adding a magnetic core with an air gap in the electromagnetic conversion module, and introducing two magnetic shielding sheets at the air gap of the magnetic core, it can effectively shield the stray Magnetic field, while making the magnetic field at the air gap more uniform. The introduction of the ring magnetic core and the magnetic shield effectively reduces the interference of the external stray magnetic field and increases the magnetic gain coefficient of the sensor, so that the accuracy and sensitivity of the designed current sensor are greatly improved.
附图说明Description of drawings
通过阅读参照以下附图所作的对非限制性实施例所作的详细描述，本实用新型的其它特征、目的和优点将会变得更明显：Other characteristics, objects and advantages of the present invention will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings:
图1为本实用新型实施例一提供的一种巨磁阻效应电流传感器结构示意图；Fig. 1 is a schematic structural diagram of a giant magnetoresistance effect current sensor provided by Embodiment 1 of the present invention;
图2为本实用新型实施例一提供的巨磁阻效应电流传感器在无磁芯无磁屏蔽片、仅有磁芯和有磁芯有磁屏蔽片的情况下的磁场分布仿真图；Fig. 2 is a simulation diagram of the magnetic field distribution of the giant magnetoresistance effect current sensor provided by Embodiment 1 of the present invention with no magnetic core and no magnetic shielding sheet, only a magnetic core, and a magnetic core with a magnetic shielding sheet;
图3为本实用新型实施例一提供的巨磁阻效应电流传感器在有磁芯有磁屏蔽片和有磁芯无磁屏蔽片的条件下沿气隙高度方向磁感应强度变化曲线图；Fig. 3 is a curve diagram of the variation of magnetic induction intensity along the air gap height direction under the condition of a magnetic core with a magnetic shielding sheet and a magnetic core without a magnetic shielding sheet for the giant magnetoresistance effect current sensor provided by Embodiment 1 of the utility model;
图4为本实用新型实施例一提供的巨磁阻效应电流传感器在仅有磁芯和有磁芯有磁屏蔽片两种条件下加入2mT的外界杂散磁场的磁场分布仿真图；Fig. 4 is the simulation diagram of the magnetic field distribution of the external stray magnetic field of 2mT added under the two conditions of the giant magnetoresistance effect current sensor provided by the first embodiment of the utility model with only a magnetic core and with a magnetic core and a magnetic shielding sheet;
图5为本实用新型实施例二提供的巨磁阻效应电流传感器在有无偏置磁场时的磁滞曲线图；Fig. 5 is a hysteresis curve diagram of the giant magnetoresistance effect current sensor provided by Embodiment 2 of the present invention with or without a bias magnetic field;
图6为本实用新型实施例二提供的开环和闭环结构下巨磁效应电流传感器的输入输出特性曲线图；Fig. 6 is the input-output characteristic curve diagram of the giant magnetic effect current sensor under the open-loop and closed-loop structures provided by the second embodiment of the utility model;
图7为本实用新型实施例二提供的巨磁阻效应电流传感器的组成模块框图。Fig. 7 is a block diagram of the constituent modules of the giant magnetoresistance effect current sensor provided by the second embodiment of the present invention.
具体实施方式detailed description
下面结合附图和实施例对本实用新型作进一步的详细说明。可以理解的是，此处所描述的具体实施例仅仅用于解释本实用新型，而非对本实用新型的限定。另外还需要说明的是，为了便于描述，附图中仅示出了与本实用新型相关的部分而非全部内容。Below in conjunction with accompanying drawing and embodiment the utility model is described in further detail. It can be understood that the specific embodiments described here are only used to explain the utility model, rather than limit the utility model. In addition, it should be noted that, for the convenience of description, only the part related to the present utility model is shown in the drawings but not the whole content.
实施例一Embodiment one
图1为本实用新型实施例一提供的一种巨磁阻效应电流传感器结构示意图。如图1所示，该巨磁阻效应电流传感器包括：FIG. 1 is a schematic structural diagram of a giant magnetoresistance effect current sensor provided in Embodiment 1 of the present invention. As shown in Figure 1, the giant magnetoresistance effect current sensor includes:
电磁转换模块，包括带气隙的磁芯11，放置于磁芯11气隙两端的两个磁屏蔽片12，穿过磁芯11的原边绕组13和放置于磁芯气隙处的巨磁阻芯片14；The electromagnetic conversion module includes a magnetic core 11 with an air gap, two magnetic shielding sheets 12 placed at both ends of the air gap of the magnetic core 11, a primary winding 13 passing through the magnetic core 11 and a giant magnetic shield placed at the air gap of the magnetic core. resistance chip 14;
信号处理模块，包括运算放大器21，运算放大器21的同相输入端和反相输入端分别与巨磁阻芯片14的两个输出端相连；The signal processing module includes an operational amplifier 21, and the non-inverting input terminal and the inverting input terminal of the operational amplifier 21 are respectively connected to the two output terminals of the giant magnetoresistive chip 14;
电源模块，分别与电磁转换模块和信号处理模块相连，用于为巨磁阻效应电流传感器提供电源(图中未示出)。The power supply module is respectively connected with the electromagnetic conversion module and the signal processing module, and is used to provide power for the giant magnetoresistance effect current sensor (not shown in the figure).
所谓巨磁阻效应，是指磁性材料的电阻率在有外磁场作用时较之无外磁场作用时存在巨大变化的现象。巨磁阻效应电流传感器可以通过直接测量长直导线上电流产生的磁场来测量电流。当某导线中电流变化时，电流产生的磁场随之变化，巨磁电阻也发生变化，利用电桥结构将电阻的变化输出为一个电压信号。由于巨磁电阻和磁场之间具有线性变化规律，输出的电压正比于被测电流，从而实现电流信号的测量功能。The so-called giant magnetoresistance effect refers to the phenomenon that the resistivity of a magnetic material changes greatly when there is an external magnetic field compared to when there is no external magnetic field. The giant magnetoresistance effect current sensor can measure the current by directly measuring the magnetic field generated by the current on a long straight wire. When the current in a wire changes, the magnetic field generated by the current changes accordingly, and the giant magnetoresistance also changes, and the change of resistance is output as a voltage signal by using the bridge structure. Due to the linear change law between the giant magnetoresistance and the magnetic field, the output voltage is proportional to the measured current, thereby realizing the measurement function of the current signal.
本实施例的电磁转换模块中，在原边绕组13和巨磁阻芯片14的基础上加入了带气隙的磁芯11和放置于磁芯11气隙两端的两个磁屏蔽片12，原边绕组13穿过带气隙的磁芯11，巨磁阻芯片14放置在磁芯11的气隙处。磁芯11和磁屏蔽片12可以有效的屏蔽外界磁场，并使磁芯11处的磁场增大。磁屏蔽是用来隔离磁场耦合的措施，是利用磁通沿低磁阻路径流通的原理来改变外界杂散磁场的方向，从而使磁力线聚集于屏蔽体内。In the electromagnetic conversion module of this embodiment, a magnetic core 11 with an air gap and two magnetic shielding sheets 12 placed at both ends of the air gap of the magnetic core 11 are added on the basis of the primary winding 13 and the giant magnetoresistive chip 14. The winding 13 passes through the magnetic core 11 with an air gap, and the giant magnetoresistive chip 14 is placed at the air gap of the magnetic core 11 . The magnetic core 11 and the magnetic shielding sheet 12 can effectively shield the external magnetic field and increase the magnetic field at the magnetic core 11 . Magnetic shielding is a measure used to isolate magnetic field coupling. It uses the principle of magnetic flux flowing along a low reluctance path to change the direction of external stray magnetic fields, so that the magnetic field lines gather in the shielding body.
巨磁阻芯片14具有两个输出端，两个输出端的电压差值为巨磁阻芯片14产生的电压值。巨磁阻芯片14的两个输出端分别与信号处理模块的运算放大器21的同相输入端和反相输入端相连。因为巨磁阻芯片14输出的电压很小，当原边绕组13产生的磁场发生变化时，不能从巨磁阻芯片14的输出电压中显现出来。运算放大器21将巨磁阻芯片14的输出信号进行放大，能更准确的得知原边绕组13的磁场变化情况从而测量原边绕组13的电流值。The GMR chip 14 has two output terminals, and the voltage difference between the two output terminals is the voltage generated by the GMR chip 14 . The two output terminals of the giant magnetoresistance chip 14 are respectively connected with the non-inverting input terminal and the inverting input terminal of the operational amplifier 21 of the signal processing module. Because the output voltage of the giant magnetoresistance chip 14 is very small, when the magnetic field generated by the primary winding 13 changes, it cannot be manifested from the output voltage of the giant magnetoresistance chip 14 . The operational amplifier 21 amplifies the output signal of the giant magnetoresistive chip 14 , so as to know the change of the magnetic field of the primary winding 13 more accurately and measure the current value of the primary winding 13 .
例如，原边绕组13电流为1A时，巨磁阻芯片14输出1V的电压，原边绕组13电流0.1A的变化引起巨磁阻芯片14输出电压变化为0.1V，这是不太明显的差值，很容易因机械误差或读数误差产生输出的误差。而运算放大器21将巨磁阻芯片14输出的1V放大十倍为10V，则当原边绕组13电流有0.1A的变化时引起运算放大器21输出电压值1V的变化，减小输出的误差。For example, when the current of the primary winding 13 is 1A, the giant magnetoresistive chip 14 outputs a voltage of 1V, and the change of 0.1A of the current of the primary winding 13 causes the output voltage of the giant magnetoresistive chip 14 to change to 0.1V, which is not obvious difference. Value, it is easy to produce output errors due to mechanical errors or reading errors. The operational amplifier 21 amplifies the 1V output by the giant magnetoresistive chip 14 ten times to 10V, and when the current of the primary winding 13 changes by 0.1A, the output voltage value of the operational amplifier 21 changes by 1V, reducing the output error.
电源模块用于为整个巨磁阻效应电流传感器供电。电源模块与电磁转换模块的巨磁阻芯片14的电源引脚相连，为巨磁阻芯片14供电；与信号处理模块的运算放大器21相连，为运算放大器21提供电源。The power module is used to supply power to the entire giant magnetoresistance effect current sensor. The power supply module is connected to the power supply pin of the giant magnetoresistance chip 14 of the electromagnetic conversion module to supply power for the giant magnetoresistance chip 14; it is connected to the operational amplifier 21 of the signal processing module to provide power for the operational amplifier 21.
因为磁场按照以原边绕组13为圆心的同心圆分布的，磁芯11的形状优选为环形，这样能加强磁芯11的磁感应强度。带气隙的磁芯11就为一个C形的环。Because the magnetic field is distributed according to concentric circles with the primary winding 13 as the center, the shape of the magnetic core 11 is preferably annular, which can enhance the magnetic induction of the magnetic core 11 . The magnetic core 11 with an air gap is a C-shaped ring.
在磁芯11的气隙处放置巨磁阻芯片14的时候，巨磁阻芯片14的敏感轴方向与磁芯11的气隙高度方向相一致。这样增强巨磁阻效应电流传感器的灵敏性。When the giant magnetoresistive chip 14 is placed at the air gap of the magnetic core 11 , the direction of the sensitive axis of the giant magnetoresistive chip 14 is consistent with the height direction of the air gap of the magnetic core 11 . This enhances the sensitivity of the giant magnetoresistance effect current sensor.
磁屏蔽片12的面积大于等于巨磁阻芯片14各侧面中与磁屏蔽片12相邻的侧面的面积。The area of the magnetic shielding sheet 12 is greater than or equal to the area of the side adjacent to the magnetic shielding sheet 12 among the sides of the giant magnetoresistive chip 14 .
巨磁阻芯片14要放置在两个磁屏蔽片12的内部，目的同样是为了提高电流传感器的灵敏性。The giant magnetoresistive chip 14 is placed inside the two magnetic shielding sheets 12 for the same purpose of improving the sensitivity of the current sensor.
磁芯11及磁屏蔽片12的材料为坡莫合金材料。The magnetic core 11 and the magnetic shielding sheet 12 are made of permalloy.
由磁阻公式Rm＝l/μS可知，磁阻与材料的磁导率成反比，因此一般要选用高磁导率材料。为了增大检测范围的量程，应选用高饱和磁密的导磁材料，同时为了得到实时精确的检测结果，要选用低磁滞、低矫顽力材料。常用的磁屏蔽材料包括：电磁软铁，硅钢片、坡莫合金、非晶合金等。其中非晶合金磁导率最高，但价格较为昂贵，电磁软铁和硅钢片价格便宜，但磁导率较低。从性能和成本方面考虑，本发明选择了坡莫合金材料作为磁芯11和磁屏蔽片12的材料。其电阻率为0.56μΩ·m，居里点为400℃，饱和磁感应强度为Bs＝0.7T，饱和磁感应强度下的矫顽力Hc不大于1.6A/m，直流磁性能满足在0.08A/m磁场强度中的磁导率不小于37.5mH/m，满足磁屏蔽对材料的要求。From the reluctance formula Rm =l/μS, it can be seen that the reluctance is inversely proportional to the magnetic permeability of the material, so generally high magnetic permeability materials should be selected. In order to increase the measuring range of the detection range, the magnetic material with high saturation magnetic density should be selected, and at the same time, in order to obtain real-time and accurate detection results, the material with low hysteresis and low coercive force should be selected. Commonly used magnetic shielding materials include: electromagnetic soft iron, silicon steel sheet, permalloy, amorphous alloy, etc. Among them, the magnetic permeability of amorphous alloy is the highest, but the price is relatively expensive, and the price of electromagnetic soft iron and silicon steel sheet is cheap, but the magnetic permeability is low. Considering performance and cost, the present invention selects permalloy material as the material of the magnetic core 11 and the magnetic shielding piece 12 . Its resistivity is 0.56μΩ·m, its Curie point is 400°C, its saturation magnetic induction is Bs =0.7T, its coercive force Hc under saturation magnetic induction is not more than 1.6A/m, and its DC magnetic properties meet the requirements of 0.08A The magnetic permeability in the /m magnetic field strength is not less than 37.5mH/m, which meets the requirements of magnetic shielding for materials.
本实施例在原边绕组13电流为20A时，利用有限元软件对巨磁效应电流传感器分别在无磁芯无屏蔽片、仅有磁芯和有磁芯有磁屏蔽片的情况下的磁场分布情况进行仿真分析。In this embodiment, when the current of the primary winding 13 is 20A, the magnetic field distribution of the giant magnetic effect current sensor without a magnetic core without a shield, with only a magnetic core and with a magnetic core with a magnetic shield is carried out using finite element software. Perform simulation analysis.
图2为本实用新型实施例一提供的巨磁阻效应电流传感器在无磁芯无磁屏蔽片、仅有磁芯和有磁芯有磁屏蔽片的情况下的磁场分布仿真图。由磁场分布情况可以看，磁场强度依至原边绕组的距离由远及近渐渐增强，环形磁芯及磁屏蔽片的引入可以大大提高巨磁阻芯片位置处的磁感应强度，增大磁增益系数，即传感器灵敏度将有显著的提高。Fig. 2 is a simulated diagram of the magnetic field distribution of the giant magnetoresistance effect current sensor provided by Embodiment 1 of the present invention with no magnetic core and no magnetic shielding sheet, only a magnetic core, and a magnetic core with a magnetic shielding sheet. From the distribution of the magnetic field, it can be seen that the magnetic field strength gradually increases from far to near according to the distance from the primary winding. The introduction of the ring core and the magnetic shield can greatly improve the magnetic induction at the position of the giant magnetoresistive chip and increase the magnetic gain coefficient. , that is, the sensor sensitivity will be significantly improved.
同样的，在原边绕组13电流为20A时，利用有限元软件对巨磁效应电流传感器分别在有磁芯无磁屏蔽片和有磁芯有磁屏蔽片的情况下的沿气隙高度方向磁感应强度进行仿真分析。图3为本实用新型实施例一提供的巨磁阻效应电流传感器在有磁芯有磁屏蔽片和有磁芯无磁屏蔽片的条件下沿气隙高度方向磁感应强度变化曲线图。如图3所示，a为在有磁芯无磁屏蔽片的条件下沿气隙高度方向磁感应强度变化曲线，b为在有磁芯有屏蔽片的条件下沿气隙高度方向磁感应强度变化曲线，明显的，曲线b磁感应强度比较稳定。由图3可以看出加入磁屏蔽片可以使气隙处磁场更加稳定，从而增加了传感器的精度。图3中距离轴的零点代表气隙的中心点。Similarly, when the primary winding 13 current is 20A, use the finite element software to analyze the magnetic induction intensity along the air gap height direction of the giant magnetic effect current sensor with a magnetic core without a magnetic shielding sheet and with a magnetic core with a magnetic shielding sheet Perform simulation analysis. Fig. 3 is a graph showing the change of magnetic induction intensity along the height direction of the air gap under the conditions of the giant magnetoresistance effect current sensor provided by the first embodiment of the utility model with a magnetic core and a magnetic shielding sheet and with a magnetic core without a magnetic shielding sheet. As shown in Figure 3, a is the variation curve of the magnetic induction intensity along the air gap height direction under the condition of a magnetic core without a magnetic shielding sheet, and b is the variation curve of the magnetic induction intensity along the air gap height direction under the condition of a magnetic core and a shielding sheet , obviously, the magnetic induction intensity of curve b is relatively stable. It can be seen from Figure 3 that adding a magnetic shielding sheet can make the magnetic field at the air gap more stable, thereby increasing the accuracy of the sensor. The zero point on the distance axis in Figure 3 represents the center point of the air gap.
图4为本实用新型实施例一提供的巨磁阻效应电流传感器在仅有磁芯和有磁芯有磁屏蔽片两种条件下加入2mT的外界杂散磁场的磁场分布仿真图。由两种条件的仿真结果可以看出两种结构对外界杂散磁场都具有较高的屏蔽效能。相比之下，磁屏蔽片的引入具有更加优越的屏蔽效果，有磁芯有磁屏蔽片结构下的传感器精度更高。Fig. 4 is a simulation diagram of the magnetic field distribution of the giant magnetoresistance effect current sensor provided by Embodiment 1 of the present utility model under the conditions of only a magnetic core and a magnetic core with a magnetic shielding sheet and adding an external stray magnetic field of 2mT. From the simulation results of the two conditions, it can be seen that the two structures have high shielding effectiveness to the external stray magnetic field. In contrast, the introduction of magnetic shielding sheet has a more superior shielding effect, and the sensor with a magnetic core and magnetic shielding sheet structure has higher precision.
本实用新型实施例提供的一种巨磁阻效应电流传感器，通过引入环形磁芯和磁屏蔽片，有效减少了外界杂散磁场的干扰同时增加了传感器的磁增益系数，从而使所设计电流传感器的精度和灵敏度得到很大程度的提高。同时选定磁环为环形，选定磁芯和磁屏蔽片的材料为坡莫合金材料，进一步增加巨磁阻效应电流传感器的灵敏度，减小输出误差。The giant magnetoresistance effect current sensor provided by the embodiment of the utility model effectively reduces the interference of the external stray magnetic field and increases the magnetic gain coefficient of the sensor at the same time by introducing the annular magnetic core and the magnetic shielding sheet, so that the designed current sensor The accuracy and sensitivity are greatly improved. At the same time, the magnetic ring is selected to be ring-shaped, and the material of the magnetic core and the magnetic shielding sheet is selected to be permalloy material, so as to further increase the sensitivity of the giant magnetoresistance effect current sensor and reduce the output error.
实施例二Embodiment two
本实施例二在上述实施例的基础上对巨磁阻电流传感器作进一步的说明。参考图1，巨磁阻电流传感器还包括：The second embodiment further explains the giant magnetoresistive current sensor on the basis of the above embodiments. Referring to Figure 1, the GMR current sensor also includes:
偏置模块，包括偏置电流源41和缠绕在磁芯11上的偏置绕组42，偏置绕组42的两端连接偏置电流源41；The bias module includes a bias current source 41 and a bias winding 42 wound on the magnetic core 11, and the two ends of the bias winding 42 are connected to the bias current source 41;
信号处理模块还包括：参考电压产生电路22，用于产生设定大小的直流电压，参考电压产生电路22的输出端连接在运算放大器21的同相输入端。The signal processing module further includes: a reference voltage generating circuit 22 for generating a DC voltage of a set value, and the output terminal of the reference voltage generating circuit 22 is connected to the non-inverting input terminal of the operational amplifier 21 .
由于所用巨磁阻芯片14为单极性输出特性，当被测量为交流电流时，输出波形类似于全波整流输出。同时当被测磁场为较弱磁场时，由于巨磁电阻相邻铁磁层间较弱的耦合作用，使得巨磁阻芯片14表现出明显的磁滞效应，引起较大的输出误差。Since the used giant magnetoresistive chip 14 has a unipolar output characteristic, when it is measured as an alternating current, the output waveform is similar to a full-wave rectified output. At the same time, when the measured magnetic field is a relatively weak magnetic field, due to the weak coupling effect between adjacent ferromagnetic layers of the giant magnetoresistance, the giant magnetoresistance chip 14 exhibits obvious hysteresis effect, causing a large output error.
为了实现双极性输出及减少磁滞误差，本实施例引入了独特的偏置磁场结构，偏置绕组42用于在气隙处产生偏置磁场，通过磁场的叠加使得作用于巨磁阻芯片14的磁场全部提高到线性区，因为当磁场很弱时，巨磁阻芯片14产生的电压和磁场大小的线性关系不是很强，通过偏置磁场叠加使磁场增强到线性关系强的状态。这样当无被测磁场时，巨磁阻芯片14输出一个直流偏置电压，当有被测电流时，巨磁阻芯片14的输出电压是在原偏置电压的基础上又叠加了一个由被测电流产生的磁场而产生的电压。偏置电流源41为偏置绕组42提供电流从而产生偏置磁场。In order to achieve bipolar output and reduce hysteresis error, this embodiment introduces a unique bias magnetic field structure. The bias winding 42 is used to generate a bias magnetic field at the air gap. The superposition of the magnetic field makes it act on the giant magnetoresistive chip The magnetic field of 14 is all increased to the linear region, because when the magnetic field is very weak, the linear relationship between the voltage generated by the giant magnetoresistive chip 14 and the magnitude of the magnetic field is not very strong, and the magnetic field is enhanced to a state where the linear relationship is strong through the superposition of the bias magnetic field. In this way, when there is no measured magnetic field, the giant magnetoresistance chip 14 outputs a DC bias voltage. The voltage generated by the magnetic field generated by the current. The bias current source 41 supplies current to the bias winding 42 to generate a bias magnetic field.
图5为本实用新型实施例二提供的巨磁阻效应电流传感器在有无偏置磁场时的磁滞曲线图。对有无偏置磁场两种结构下的巨磁效应电流传感器进行测试，被测电流首先正行程从0A增加到14A，分别测量不同电流下的输出电压信号。然后，将电流反行程从14A降至0A，再次测量不同电流下传感器的输出信号。如图5所示，c曲线为有偏置磁场下被测电流正行程对应的输出曲线，d曲线为有偏置磁场下被测电流反行程对应的输出曲线，e曲线为无偏置磁场下被测电流正行程对应的输出曲线，f曲线为无偏置磁场下被测电流反行程对应的输出曲线。由测试曲线可以看出，曲线c和d的重合率要大于曲线e和f。偏置磁场的引入可以大大减小由磁滞现象引起的误差。FIG. 5 is a hysteresis curve diagram of the giant magnetoresistance effect current sensor provided by Embodiment 2 of the present invention with or without a bias magnetic field. The giant magnetic effect current sensor with and without the bias magnetic field is tested. The measured current is firstly increased from 0A to 14A in the positive stroke, and the output voltage signals under different currents are measured respectively. Then, reduce the current backstroke from 14A to 0A, and measure the output signal of the sensor under different currents again. As shown in Figure 5, the c curve is the output curve corresponding to the positive stroke of the measured current under the bias magnetic field, the d curve is the output curve corresponding to the reverse stroke of the measured current under the bias magnetic field, and the e curve is the output curve under the no bias magnetic field The output curve corresponding to the positive stroke of the measured current, and the f curve is the output curve corresponding to the reverse stroke of the measured current without a bias magnetic field. It can be seen from the test curve that the coincidence rate of curves c and d is greater than that of curves e and f. The introduction of the bias magnetic field can greatly reduce the error caused by hysteresis.
参考电压产生电路22可以产生设定的电压，将运算放大器21输出电压控制在设定的区域。The reference voltage generation circuit 22 can generate a set voltage to control the output voltage of the operational amplifier 21 within a set area.
运算放大器21为差分运算放大器。The operational amplifier 21 is a differential operational amplifier.
巨磁阻芯片14的正输出端与运算放大器21的同相输入端相连，巨磁阻芯片14的负输出端与运算放大器21的反相输入端相连。The positive output terminal of the giant magnetoresistance chip 14 is connected with the non-inverting input terminal of the operational amplifier 21 , and the negative output terminal of the giant magnetoresistive chip 14 is connected with the inverting input terminal of the operational amplifier 21 .
参考电压产生电路22的输出电压与偏置绕组42在巨磁阻芯片14上产生的偏置电压相等。The output voltage of the reference voltage generating circuit 22 is equal to the bias voltage generated by the bias winding 42 on the GMR chip 14 .
运算放大器21输入端接入巨磁阻芯片14两个输出端输出的电压差，同时加入参考电压产生电路22接在运算放大器21的同相输入端，将电压差与参考电压产生电路22产生的电压相叠加，再对叠加后的电压进行放大。运算放大器21同相输入端的参考电压产生电路22用于消除偏置磁场产生的偏置电压，使得传感器最终输出得到一个双极输出的电压，也即输出有正有负的电压。The input terminal of the operational amplifier 21 is connected to the voltage difference output by the two output terminals of the giant magnetoresistive chip 14, and the reference voltage generating circuit 22 is connected to the non-inverting input terminal of the operational amplifier 21 at the same time, and the voltage difference and the voltage generated by the reference voltage generating circuit 22 are connected. superimposed, and then the superimposed voltage is amplified. The reference voltage generating circuit 22 at the non-inverting input terminal of the operational amplifier 21 is used to eliminate the bias voltage generated by the bias magnetic field, so that the sensor finally outputs a bipolar output voltage, that is, the output has positive and negative voltages.
信号处理模块还包括：推挽式功率放大器23，推挽式功率放大器23的输入端与运算放大器21的输出端连接。The signal processing module further includes: a push-pull power amplifier 23 , the input end of the push-pull power amplifier 23 is connected to the output end of the operational amplifier 21 .
推挽式功率放大器23将运算放大器21的输出信号进一步放大，使电流传感器的测量结果更加精确。The push-pull power amplifier 23 further amplifies the output signal of the operational amplifier 21 to make the measurement result of the current sensor more accurate.
电源模块包括电源产生电路；The power module includes a power generating circuit;
电源产生电路用于根据供电电压分别为巨磁阻芯片14、参考电压产生电路22、运算放大器21和推挽式功率放大器23产生相适应的工作电压。The power generation circuit is used to generate suitable working voltages for the giant magnetoresistive chip 14 , the reference voltage generation circuit 22 , the operational amplifier 21 and the push-pull power amplifier 23 respectively according to the supply voltage.
巨磁阻芯片14、运算放大器21和推挽式功率放大器23的供电电源是不同的。例如，巨磁阻芯片14可以用电压为5V的电压供电，运算放大器21可使用15V的电源。生活中没有电压为5V或15V的直流电压源，可以用电压为220V的电源通过电源产生电路输出各种需要的电压。The power supplies of the giant magnetoresistive chip 14, the operational amplifier 21 and the push-pull power amplifier 23 are different. For example, the giant magnetoresistive chip 14 can be powered by a voltage of 5V, and the operational amplifier 21 can use a power supply of 15V. There is no DC voltage source with a voltage of 5V or 15V in life, and a power supply with a voltage of 220V can be used to output various required voltages through the power generation circuit.
另外，电流传感器还包括：In addition, current sensors include:
反馈补偿模块，包括缠绕在磁芯11上的反馈绕组51和一采样电阻52，反馈绕组51的一端连接推挽式功率放大器23的输出端，另一端串联采样电阻52接地。The feedback compensation module includes a feedback winding 51 wound on the magnetic core 11 and a sampling resistor 52. One end of the feedback winding 51 is connected to the output end of the push-pull power amplifier 23, and the other end is connected in series with the sampling resistor 52 to ground.
反馈绕组51与原边绕组13构成闭环系统，传感器工作于零磁通状态，有效提高了传感器的量程和抗干扰特性。产品的结构相对简单、成本低和功能多。反馈绕组51与原边绕组13产生的磁场大小相等时就达到了零磁通的工作状态。由于被测电流的任何变化都会破坏闭环系统达到的这一平衡，而一旦磁场失去平衡，巨磁阻芯片14就有电压信号输出，此信号经放大后，立即有相应的反馈电流即补偿电流流过反馈绕组51对失衡的磁场进行补偿，以达到新的平衡。由于上述的平衡过程所需的时间小于1μs，因此决定了本实用新型闭环巨磁阻效应电流传感器具有较快的响应速度。The feedback winding 51 and the primary winding 13 form a closed-loop system, and the sensor works in a state of zero magnetic flux, which effectively improves the measuring range and anti-interference characteristics of the sensor. The structure of the product is relatively simple, the cost is low and the functions are many. When the magnetic field generated by the feedback winding 51 and the primary winding 13 are equal in magnitude, the working state of zero magnetic flux is reached. Any change in the measured current will destroy the balance achieved by the closed-loop system. Once the magnetic field loses balance, the giant magnetoresistive chip 14 will output a voltage signal. After the signal is amplified, there will be a corresponding feedback current, that is, a compensation current flow. The unbalanced magnetic field is compensated by the feedback winding 51 to achieve a new balance. Since the time required for the above balancing process is less than 1 μs, it is determined that the closed-loop giant magnetoresistance effect current sensor of the present invention has a relatively fast response speed.
如图6所示，图6为本实用新型实施例二提供的开环和闭环结构下巨磁效应电流传感器的输入输出特性曲线图。曲线g为开环结构下巨磁效应电流传感器的输入输出曲线，曲线h为闭环结构下巨磁效应电流传感器的输入输出曲线。可以看出，曲线h的线性度要好于曲线g，且对于输入相同的电流，曲线h对应的输出电压要小于曲线g，闭环结构可以有效提高传感器的抗干扰性和量程范围。As shown in FIG. 6 , FIG. 6 is a curve diagram of input and output characteristics of the giant magnetic effect current sensor under the open-loop and closed-loop structures provided by the second embodiment of the present invention. Curve g is the input-output curve of the giant magnetic effect current sensor under the open-loop structure, and curve h is the input-output curve of the giant magnetic effect current sensor under the closed-loop structure. It can be seen that the linearity of curve h is better than that of curve g, and for the same input current, the output voltage corresponding to curve h is smaller than that of curve g, and the closed-loop structure can effectively improve the anti-interference and measuring range of the sensor.
本实用新型实施例二提供的巨磁阻效应电流传感器，在引入磁芯和磁屏蔽片的同时，加入偏置绕组用于在磁芯气隙处产生偏置磁场，通过磁场的叠加使得作用于巨磁阻芯片的磁场全部提高到线性区，实现了双极性输出及减少磁滞误差。反馈补偿绕组与原边绕组组成闭环系统，传感器工作于零磁通状态，有效提高了传感器的量程和抗干扰特性。In the giant magnetoresistance effect current sensor provided by the second embodiment of the utility model, when the magnetic core and the magnetic shielding piece are introduced, a bias winding is added to generate a bias magnetic field at the air gap of the magnetic core, and the superposition of the magnetic field makes it act on The magnetic field of the giant magnetoresistive chip is all raised to the linear region, realizing bipolar output and reducing hysteresis error. The feedback compensation winding and the primary winding form a closed-loop system, and the sensor works in a state of zero magnetic flux, which effectively improves the measuring range and anti-interference characteristics of the sensor.
在上述实施例的基础上，本实施例巨磁阻效应电流传感器由五部分模块组成，如图7所示。图7为本实用新型实施例二提供的巨磁阻效应电流传感器的组成模块框图。参考图1和图7，本实施例中闭环巨磁阻效应电流传感器的组成框图包含电磁转换模块1、偏置模块4、信号处理模块2、反馈补偿模块5和电源模块3五部分，五部分模块组成回路闭环系统。被测电流通过电磁装换模块1输出电压信号。偏置模块4为巨磁阻芯片14提供恒定偏置磁场，以实现测量交流电流及改善磁滞误差的目的。信号处理模块2将巨磁阻芯14输出电压信号去除偏置磁场产生的偏置电压，并对输出信号进行放大处理。反馈补偿模块5将放大后的电压信号通过反馈绕组51及采样电阻52进行接地，构成反馈电流，当系统达到零磁通状态后，通过反馈电流信号即可间接测得原边被测电流信号。电源模块3用来为整个电流传感器提供电源。On the basis of the above embodiments, the giant magnetoresistance effect current sensor of this embodiment is composed of five modules, as shown in FIG. 7 . Fig. 7 is a block diagram of the constituent modules of the giant magnetoresistance effect current sensor provided by the second embodiment of the present invention. Referring to Fig. 1 and Fig. 7, the block diagram of the closed-loop giant magnetoresistance effect current sensor in this embodiment includes five parts: electromagnetic conversion module 1, bias module 4, signal processing module 2, feedback compensation module 5 and power supply module 3, five parts Modules form a loop closed-loop system. The measured current outputs a voltage signal through the electromagnetic replacement module 1 . The bias module 4 provides a constant bias magnetic field for the GMR chip 14 to achieve the purpose of measuring the alternating current and improving the hysteresis error. The signal processing module 2 removes the bias voltage generated by the bias magnetic field from the output voltage signal of the giant magnetoresistive core 14, and amplifies the output signal. The feedback compensation module 5 grounds the amplified voltage signal through the feedback winding 51 and the sampling resistor 52 to form a feedback current. When the system reaches the zero magnetic flux state, the measured current signal of the primary side can be indirectly measured through the feedback current signal. The power module 3 is used to provide power for the entire current sensor.
具体过程为：原边绕组13穿过环形磁芯11，流过原边绕组13的电流产生的磁场被环形磁芯11及磁屏蔽片12聚集后，作用于巨磁阻芯片14。巨磁阻芯片14在感应到磁场作用后，将会有电压信号输出，该输出的电压信号送入运算放大器21，运算放大器21与推挽式功率放大器23连接，上述输出的电压信号经过运算放大器21和推挽式功率放大器23进行放大之后，通过反馈绕组51和采样电阻52接地，形成反馈电流，该反馈电流经过反馈绕组51产生反馈磁场。由于反馈绕组51产生的磁场与原边绕组13电流产生的磁场方向相反，因而减弱了气隙处磁场，使巨磁阻芯片14输出逐渐减小，当两线圈产生的磁场大小相等时，反馈电流不再增大，整个系统达到动态平衡。设NP为原边绕组13的线圈匝数，Ip为原边电流，Nf为反馈绕组51的线圈匝数，If为反馈电流，有NpIp＝NfIf。因此通过测量反馈绕组51中的电流If即可间接得出被测电流Ip，其中If可通过采样电阻52上的电压来得到。The specific process is as follows: the primary winding 13 passes through the annular magnetic core 11 , and the magnetic field generated by the current flowing through the primary winding 13 is collected by the annular magnetic core 11 and the magnetic shielding sheet 12 and acts on the giant magnetoresistive chip 14 . After the giant magnetoresistive chip 14 senses the action of the magnetic field, there will be a voltage signal output, and the output voltage signal is sent to the operational amplifier 21, and the operational amplifier 21 is connected with the push-pull power amplifier 23, and the above-mentioned output voltage signal passes through the operational amplifier 21 and the push-pull power amplifier 23 are amplified, and are grounded through the feedback winding 51 and the sampling resistor 52 to form a feedback current. The feedback current passes through the feedback winding 51 to generate a feedback magnetic field. Since the magnetic field generated by the feedback winding 51 is opposite to the magnetic field generated by the current of the primary winding 13, the magnetic field at the air gap is weakened, and the output of the giant magnetoresistive chip 14 is gradually reduced. When the magnetic fields generated by the two coils are equal in magnitude, the feedback current no longer increase, the whole system reaches a dynamic equilibrium. Let NP be the coil turns of the primary winding 13, Ip be the primary current, Nf be the coil turns of the feedback winding 51, If be the feedback current, Np Ip =Nf If . Therefore, the measured current Ip can be obtainedindirectly by measuring the current If in the feedback winding 51 , whereinIf can be obtained by sampling the voltage on the resistor 52 .
注意，上述仅为本实用新型的较佳实施例及所运用技术原理。本领域技术人员会理解，本实用新型不限于这里所述的特定实施例，对本领域技术人员来说能够进行各种明显的变化、重新调整和替代而不会脱离本实用新型的保护范围。因此，虽然通过以上实施例对本实用新型进行了较为详细的说明，但是本实用新型不仅仅限于以上实施例，在不脱离本实用新型构思的情况下，还可以包括更多其他等效实施例，而本实用新型的范围由所附的权利要求范围决定。Note that the above are only preferred embodiments of the present invention and the applied technical principles. Those skilled in the art will understand that the utility model is not limited to the specific embodiments described here, and various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the protection scope of the utility model. Therefore, although the utility model has been described in detail through the above embodiments, the utility model is not limited to the above embodiments, and can also include more other equivalent embodiments without departing from the concept of the utility model. The scope of the present invention is determined by the appended claims.
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201520962113.XUCN205139229U (en) | 2015-11-25 | 2015-11-25 | Huge magnetoresistive effect current sensor |
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201520962113.XUCN205139229U (en) | 2015-11-25 | 2015-11-25 | Huge magnetoresistive effect current sensor |
| Publication Number | Publication Date |
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| CN205139229Utrue CN205139229U (en) | 2016-04-06 |
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201520962113.XUActiveCN205139229U (en) | 2015-11-25 | 2015-11-25 | Huge magnetoresistive effect current sensor |
| Country | Link |
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| CN (1) | CN205139229U (en) |
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| Date | Code | Title | Description |
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| GR01 | Patent grant |