A fluxgate magnetometer is a device that measures the intensity and orientation of magnetic lines of flux. Drv421 integrated magnetic fluxgate sensor for closedloop. Electrical current sensor comprising a measuring circuit and an inductor for measuring a primary current i p flowing in a primary conductor over a current range from a minimum specified current amplitude to a maximum specified current amplitude, the inductor comprising a saturable magnetic core made of a highly permeable magnetic material and a secondary coil for. This month, we put our fluxgate sensors to work and build. Figure 2 shows a method for providing an analog interface to the fgm3 and its relatives.
Military applications continue to be an important market, but geologists and archeologists have also become big fans of these robust and extremely sensitive instruments. The low offset and drift of the fluxgate sensor, along with an optimized frontend circuit results in. Compared to yokeless transducers utilizing the differential pair of magnetic sensors, our solution has much better suppression of the external currents lower crosstalk. Addressing highvoltage current sensing design challenges in hevevs. Drv425 data sheet, product information and support. Sumida corporation has developed a new transformer for use in fluxgate current sensors targeted at the industrial power electronics market. The current measurement range can be fixed by setting the value of resistance of the shunt resistor. Sensitivity andphase plane analysis zucheng gao, member, ieee, and r. Fluxgate based, closed loop zero flux current transformer.
The design of the saturable inductor current sensor is similar to that of. Ripkac a power electronics research centre, department of electronic engineering, national university of ireland, galway, ireland b department of radiology, brigham and womens hospital, harvard medical school, boston, ma, usa. Thus, the main idea of automatic 30 40 50 60 compensation is to synchronize the free running counter with excitation current. The ferromagnetic core is excited by the ac current i exc of frequency f into the excitation winding. The objective of the tida00905 design is to provide a reference solution for accurate current measurement variant c using closedloop fluxgate magnetic current sensors. An alternating electric current is passed through one coil, driving the core through an alternating cycle of magnetic saturation. Index terms current sensor, cross winding structure, fluxgate principle. The injection of current in an auxiliary winding creates a compensating magnetic field that restores the symmetry of the hysteresis cycle.
The sensor core used here consists of high gradient hysteresis curve and of very low power loss. Flux gate current sensor kohshin electric corporation. The sensor is excited by a periodic square wave signal, sweeping the inductor across the bh curve in and out of saturation resulting in a symmetric current waveform. Current sensors are available at mouser electronics from industry leading manufacturers. The temperature variation i o t of the electrical offset current i o e is the variation of the electrical offset from 25 c to the considered temperature. On the other hand, such sensors are generally not best suited for the measurement of. This device provides both, a proprietary integrated fluxgate sensor, and the required analog signal conditioning, thus minimizing component count and cost. Fluxgate current sensor uses a high permeability magnetic. Dec 19, 2018 a novel closed loop current sensor based on a circular array of magnetic field sensors abstract. The traditional construction of the fluxgate sensor tends to be complicated and expensive. Sensors and actuators a 123124 2005 430437 application of. Drv425 fluxgate magneticfield sensor datasheet rev. Operating a current sensor by conducting a current serially through a first region and a second region of an electrically conductive member. A cmos analog frontend circuit for microfluxgate sensors by.
In this paper we present our experience with low cost fluxgate current sensors built within printed circuit board. It is important to precisely align the axes of the two baseline sensors to avoid measurement errors. Its normal range is suitable for measuring earths field and it is capable of resolving well below one 10,000th of that. This article presents the design and implementation of a transducer system for the measurement of ac and dc highcurrent using the flux compensation technique in the measurement transformer, also called fluxgate technology. A flux gate current sensor has basically the same structure as a current sensor with a magnetic balance system, except that it has a magnetic probe coil instead of a hall element. Fluxgatebased current sensor texas instruments incorporated. Current sensing for battery management system bms functions. This month, we put our fluxgate sensors to work and build a practical magnetometer and gradiometer. Sensors free fulltext rectangular array electric current. Pcb fluxgate current sensor with saturable inductor. The emphasis is given on current sensors based on magnetic materials, but other methods are also mentioned for. The third current sensor is not necessary in this case either. The emphasis is given on current sensors based on magnetic. Although closedloop hall effect current sensors performs at the level of fluxgate technology at the ambient temperature of 105 c, but this technology cannot be used for high ambient temperatures of 250 c due to individual technological temperature limits.
This section describes the principles behind current sensor operation. Excitation current is passed through the primary winding. The secondary coil picks up the imbalance in the magnetic flux due to the ambient magnetic field which acts. Selfcompensating excitation of fluxgate sensors for space. A fluxgate magnetometer consists of a small magnetically susceptible core wrapped by two coils of wire. Doncaster russell abstractin a previous paper 1 wehave shownthat the transient ment, is economical to manufacture, and has low power behavior offluxgate sensors in magnetometer andin. Us20170059627a1 us14986,121 us201514986121a us2017059627a1 us 20170059627 a1 us20170059627 a1 us 20170059627a1 us 201514986121 a us201514986121 a us 201514986121a us 2017059627 a1 us2017059627 a1 us 2017059627a1 authority us united states prior art keywords current mfbc sensor region magnetic field prior art date 20150824 legal status the legal status is. Its normal range is suitable for measuring earths field and it. A first magnetic field produced by the current in the first region is sensed using a first magnetic field based current mfbc sensor having a first sensitivity.
A novel closed loop current sensor based on a circular array of magnetic field sensors. The major application of fluxgate sensors is in magnetometers for the measurement of earths magnetic field. Oct 03, 2017 in order to increase the dynamic range of packaged current sensor 800, fluxgate sensors 811814 are positioned on the parallel portions 806809 so that a portion of current 230 flows around the sensors as indicated by current path 831 and a portion bypasses the sensors as indicated by current path 832. The technique improves linearity of measurement, allows a much greater dynamic range.
This class of fluxgate gradiometer will not react to normal earths field in a clean magnetic environment, but. This paper gives a comparison between circular arrays built from hall and fluxgate magnetic field sensors in both the closed loop and open loop operation. Drv421 integrated magnetic fluxgate sensor for closedloop current sensing. Its normal range is suitable for measuring earths field and it is capable of resolving well below one 10,000 th of that. During the last years, coreless current sensors based on circular arrays of magnetic field sensors have been investigated. The sensor consists of a magnetic core with compensation winding interfaced to driver ic with a builtin fluxgate sensor. Fluxgate magnetometers evolved during the second world war as a means of detecting submarines.
Compared to industrial transducers with yoke, the new transducer has 15. Fluxgate sensors can also be used to measure high dc currents. Frequency deratings apply, see mfg user manual for full set of specifications. If closed loop configuration fluxgate sensors are used, instead of hall sensors, the measurement. In this mode of operation, where the fluxgate is used as a null detector, the current in the feedback coil is proportional to the sensed field. Fluxgate sensors and current transformers are used in applications, where resolution and stability is critical.
There are several types of contactless current sensors. Users can build a high precision fluxgate current sensor by mounting on a system board this transformer combined with a signal conditioner ic for a current sensor developed by texas instruments and a shunt resistor. The injected current compensates the magnetic field created by the current to be measured, and its value is proportional to this current. Fluxgate magnetic current sensing with high linearity for.
Pdf a new compact fluxgate current sensor for ac and dc. Fluxgate interface filter driver diff amp vref int. A cmos analog frontend circuit for microfluxgate sensors. The measurement of the magnetization of a magnetic material like a ferromagnet is an example. Magnetometers are used in navigation systems and electronic compasses. This sensor enables electricallyisolated, highsensitivity, and precise dc and acfield measurements.
They are also used in geological prospecting, aerospace navigation. The low offset, offset drift, and noise of the sensor, combined with the precise gain, low gain drift, and very low nonlinearity provided. A common type of magnetic compass for navigation systems is the fluxgate sensor. In this paper, a compact selfoscillating current sensor for dc current measurement with a new feedback strategy is pro.
The detectable current is within a range from 6 to 600a, and is perfect mainly for industrial equipment and medical equipment that require high accuracy measurement. Sensors and actuators a 1 2004 156165 157 c r cr rs ls fluxgate current sensor square voltage source zr zs fig. The present invention relates to a closedloop current sensor, in particular of the fluxgate type. The electronic operation of these sensors is generally the same as normal fluxgates. A novel closed loop current sensor based on a circular array. Texas instruments drv425drv425q1 precision fluxgate magnetic field sensor is designed for singleaxis, magneticfield sensing applications.
Fluxgate hmc2003 2n6028 application note tilt sensors degree 3 axis fluxgate compass 3 axis compass abstract of gps vehicle location tracking system fluxgate magnetometer car sensor parking text. High current measurement application guide yokogawa. In order to increase the dynamic range of packaged current sensor 800, fluxgate sensors 811814 are positioned on the parallel portions 806809 so that a portion of current 230 flows around the sensors as indicated by current path 831 and a portion bypasses the sensors as. Research on the simplified directcurrent fluxgate sensor. Novel rectangular yokeless current transducer with the range 400 a using 16 microfluxgate sensors around the busbar conductor is presented in this paper. Integrated microfluxgate sensors have been developed in recent years. The design of the saturable inductor current sensor is similar to that of a closedloop halleffect. Research on the simplified directcurrent fluxgate sensor and. This transformer has been developed to work together with a texas instruments sensor signal conditioner, with the aim of building high precision current sensors. Today, lem uses different versions of fluxgate technologies, each. Design of fluxgate magnetometer sensors semantic scholar.
Flux gate sensors or saturable inductor current sensors work on the same measurement principle as halleffectbased current sensors. Design of a dc current sensor based on fluxgate principle conference paper pdf available in aip conference proceedings 211. The electrical offset current i o e is the residual output current when the input current is zero. The core permeability t is therefore changing with 2f frequency. In this paper, a compact selfoscillating current sensor for dc current measurement with a new feedback strategy is proposed. A magnetometer is a device that measures magnetismthe direction, strength, or relative change of a magnetic field at a particular location. This device provides both, a proprietary integrated. Closedloop fluxgate current sensor lem intellectual. You should choose a current sensor to suit the application in which you plan to use it, based on an understanding of the differences among the various methods of measuring currents, including the hall element method, the rogowski method, and the zeroflux method. It creates a compensating magnetic field by passing dc current through a separate coaxial feedback coil to the sense coil or by passing dc current back to the sense coil itself 10. The output of the sensor is a 40 to 125khz frequency that is proportional to the applied magnetic field. Indicates the realtime current flowing through the battery, which would be used to calculate the start of charge of the battery. A compass is one such device, one that measures the direction of an ambient magnetic field, in this case, the earths magnetic field.
By measuring the magnetic field around a conductor, the current level can be accurately predicted. Fluxgate magnetometers have been used by robotic space probes to analyze, map and monitor the magnetic fields of the earth and other planets. Analysis and design of a selfoscillating bidirectionally. Various types of fluxgate magnetometer sensors are designed and developed for the determination of very weak magnetic field. A new compact fluxgate current sensor for ac and dc application article pdf available in ieee transactions on magnetics 5011. It converts the duty cycle variation of the excitation. Typically the hall sensor is used for large currents, and magnetoresistive sensors amr, gmr are used for higher resolution applications.
They are most frequently used where low power and low noise are the overriding. Magnetic sensor systems current sensors and power metering. To enable applications with enhanced performance, current. Leakage current sensors industrial monitoring and control systems overcurrent detection frequency, voltage, and solar inverters 3 description the drv421 is designed for magnetic closedloop current sensing solutions, enabling isolated, precise dc and accurrent measurements. Fluxgate magnetometer designs fall into broadly two styles, those employing rod cores and those using ring cores. Rectangular array electric current transducer with. For attaining better linearity of the measurement, many fluxgate sensors use the feedback mechanism to null the ambient magnetic field. Pdf design of a dc current sensor based on fluxgate. Fluxgate sensors and current transformers are used in applications, where resolution and stability is critical the traditional construction of the fluxgate sensor tends to be. Fluxgate sensors fluxgate sensors are a saturable inductor constructed of a magnetic core and wound coil. Doncaster russell abstractin a previous paper 1 wehave shownthat the transient ment, is economical to manufacture, and has low power behavior offluxgate sensors in magnetometer andin gradiometer can requirements. The main advantage of closedloop fluxgate sensors is their measurement sensitivity and ability to accurately measure currents of small amplitude. Open loop hall effect, differential fluxgate based current sensing. Currently, the fluxgate sensor excitation and detection control circuitry is based on digital counters dividing a clock frequency from a crystal oscillator, hencethephaseshift is set to a fixed value.
Figure 4 ring core, rod forster, racetrack sensor geometries figure 3 fluxgate sensors 2. Inside the fluxgate gradiometer popular electronics. Investigating fluxgate current sensors dc capable with detours into analog electronics and switched mode power supplies. Low cost power metering for smart grid applications. A novel closed loop current sensor based on a circular. A conventional fluxgate sensor typically comprises a core in a soft magnetic material of high magnetic permeability that is subjected to an alternating magnetic field by an excitation coil of the fluxgate. Drv425drv425q1 fluxgate magnetic field sensor ti mouser.
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