CN104808042A - Magnetic-flux-gate current sensor - Google Patents

Abstract

The fluxgate current sensor of the present invention relates to a device for measuring current, which is a fluxgate current sensor with a magnetic gathering shell and windings distributed orthogonally, including a fluxgate detection probe and a signal processing circuit; wherein, The fluxgate detection probe is composed of a magnetic gathering shell plus a ring magnetic core, an excitation winding and a secondary feedback winding. The signal processing circuit is divided into two parts: the excitation circuit and the zero flux detection circuit. The excitation circuit part includes the excitation signal generation circuit and The signal drive circuit, the zero magnetic flux detection circuit part includes two parts: the integral comparator circuit and the H bridge drive circuit; the invention eliminates the coupling between the windings, and at the same time introduces the magnetic gathering shell to gather the effective magnetic field and shield the surrounding stray The influence of the magnetic field not only overcomes the defect that the existing fluxgate current sensor will produce a large output error in the actual measurement, and the accuracy of the current measurement result is poor, but also improves the sensitivity of the measurement.

Description

Fluxgate Current Sensor

technical field

The technical solution of the present invention relates to a device for measuring current, specifically a fluxgate current sensor.

Background technique

With the development of power electronics technology, the demand for high-performance current sensors is increasing day by day, and more and more current sensors have also entered the research scope of researchers. Traditional current detection devices include shunts, current transformers, Rogowski coils and Hall sensors; existing new current detection devices include fluxgate current sensors, giant magnetoresistance effect current sensors and optical fiber sensors. Due to its simple principle and convenient control, the Hall sensor is currently the most widely used in engineering applications. However, the Hall sensor has the disadvantages of low sensitivity to magnetic fields, and relatively large temperature drift and zero drift. The fluxgate current sensor has the characteristics of unique magnetic induction ability, high sensitivity to the applied magnetic field, high precision and miniaturization. In contrast, the fluxgate current sensor has outstanding advantages in research and development and application.

CN203658558U proposes a ring-shaped fluxgate probe, which is characterized in that the excitation coil is wound around the entire magnetic core to form a closed magnetic circuit, and the induction coils are divided into three groups, which are arranged symmetrically on the circumference of the magnetic core wound with the excitation coil; CN101545958A discloses a A bidirectional saturation time difference fluxgate current sensor, the two ends of the sensor magnetic core are wound with an excitation coil, and the middle is wound with an induction coil; the above two current sensors both use excitation windings parallel to the primary side measured windings and secondary feedback windings distribution, causing their mutual coupling, affecting the accuracy of the current measurement results. US3218547A discloses a fluxgate current sensor with a single magnetic core, which adopts a sensing coil placed at an orthogonal position to the excitation coil, and the fluxgate current sensor whose windings are orthogonally distributed, the magnetic field generated by the current-carrying conductor is easily affected by the surrounding stray Due to the influence of the magnetic field, these stray magnetic fields greatly reduce the effective magnetic field passing through the magnetic core, which will cause a large output error of the sensor and affect the sensitivity and measurement accuracy of the current measurement results. In view of the above-mentioned technical shortcomings of the existing fluxgate current sensor, the existing fluxgate current sensor will eventually produce a large output error in actual measurement, and there is a problem that the accuracy of the current measurement result is poor. defect.

Contents of the invention

The technical problem to be solved by the present invention is to provide a fluxgate current sensor, which is a fluxgate current sensor with a magnetic flux gathering shell and an orthogonal distribution of windings, which eliminates the coupling between the windings, and introduces a magnetic flux gathering shell to gather The effective magnetic field is shielded, and the surrounding stray magnetic field is shielded, which not only overcomes the defects that the existing fluxgate current sensor will produce a large output error in actual measurement, and the accuracy of the current measurement result is poor, but also improves the The sensitivity of the measurement.

The technical solution adopted by the present invention to solve the technical problem is: a fluxgate current sensor, which is a fluxgate current sensor with a magnetic gathering shell and adopts an orthogonal distribution of windings, including a fluxgate detection probe and a signal processing circuit ; Among them, the fluxgate detection probe is composed of a magnetic gathering shell plus a ring core and an exciting winding plus a secondary feedback winding, the ring core is placed inside the magnetic shell, and the exciting winding is a wire running along the ring core The radial winding of the ring core is uniformly wound with 100 to 150 turns, and the secondary feedback winding is a winding formed by winding 200 to 300 turns evenly along the circumferential direction of the ring core after the excitation winding is wound; the signal processing circuit It is divided into two parts: the excitation circuit and the zero magnetic flux detection circuit. The excitation circuit part includes the excitation signal generation circuit and the signal drive circuit; one end of the excitation winding is grounded through the sampling resistor in the excitation signal generation circuit, and the other end of the excitation winding is connected to the excitation circuit. The signal driving circuit is connected, and the output of the signal driving circuit is connected to the input of the zero magnetic flux detection circuit. The zero magnetic flux detection circuit is divided into two parts: the integral comparator circuit and the H bridge drive circuit. The integral comparator circuit is the zero magnetic flux detection circuit. The input of the integral comparator circuit is connected to the input of the H bridge drive circuit, the output of the H bridge drive circuit is connected to one end of the secondary feedback winding, and the other end of the secondary feedback winding is grounded through a shunt resistor.

For the above-mentioned fluxgate current sensor, the magnetic gathering shell is made of permalloy material, its resistivity is 0.56μΩ·m, the Curie point is 400°C, the saturation magnetic induction is B _s =0.7T, and the saturation magnetic induction is The coercive force _Hc under the condition is not more than 1.6A/m, the DC magnetic performance meets the magnetic permeability in the 0.08A/m magnetic field strength is not less than 37.5mH/m, the thickness is 2mm, the length is 30mm, the width is 30mm, the height It is 15mm.

The above-mentioned fluxgate current sensor, the material used in the annular magnetic core is iron-based nanocrystalline soft magnetic material, its saturation magnetic flux density is B _s =1.2T, coercive force H _c <5A/m, saturation magnetostriction The coefficient is s=10 ^-8 ~ 10 ^-6 , the magnetic permeability is 15000 ~ 150000H/m, the core loss (100KHz, 0.3T) P _Fe = 80W/Kg, the inner diameter of the ring core is 10mm, the outer diameter is 20mm and 10mm high.

In the above-mentioned fluxgate current sensor, the material used for each winding is enameled wire with a diameter of 0.3 mm.

For the above-mentioned fluxgate current sensor, the chip used in the H-bridge driving circuit is IR2110.

In the above-mentioned fluxgate current sensor, the sampling resistor is 20KΩ, and the shunt resistor is 150Ω.

The above-mentioned fluxgate current sensor, the excitation circuit includes an excitation signal generation circuit and a signal drive circuit, and its composition is: mainly including a chip LM6132 for the excitation signal generation circuit and a chip IR2101s for the signal drive circuit, and the LM6132 is a power Amplifier, including 8 pins, pin 1 of LM6132, pin 2 of LM6132 and pin 6 of LM6132 are connected by resistor R ₁ with a resistance value of 3.3KΩ, pin 3 of LM6132 is connected with a sampling resistor with a resistance value of 20KΩ One end of R _S is connected, the other end of sampling resistor R _S is grounded, pin 4 of LM6132 is connected to -12V DC voltage and a voltage stabilizing capacitor C ₁ with a capacitance value of 0.1μF, pin 5 of LM6132 is connected to two parallel resistors, where A parallel resistor R ₂ with a resistance value of 3.9KΩ is grounded, and another parallel resistor R ₃ with a resistance value of 27KΩ is connected to pin 2 of IR2101s together with pin 7 of LM6132; pin 8 of LM6132 is connected to +12V DC voltage And one end of a voltage stabilizing capacitor C ₂ with a capacitance value of 0.1μF, the other end of the capacitor C ₂ is grounded, the pin 1 of IR2101s is connected to 12V DC voltage, and the 12V voltage passes through a diode D ₁ of model 1N4106 and the IR2101s Pin 8 is connected, and pin 8 of IR2101s is connected to pin 6 of IR2101s through a capacitor C ₃ with a capacitance value of 0.1 μF; pin 3 of IR2101s and pin 7 of IR2101s are suspended, and pin 4 and Pin 5 of the IR2101s is connected to ground.

The above-mentioned fluxgate current sensor and the zero-flux detection circuit include two parts: an integral comparator circuit and an H-bridge drive circuit, wherein the integral comparator circuit is composed of: mainly including chip TLC2652, including 8 pins, TLC2652 The pin 1 of pin 1 is connected to the ground after the capacitor C ₁ with a capacitance value of 0.1 μF and the C ₂ with a capacitance value of 1 F, and the capacitor C ₃ with a capacitance value of 0.01 μF is connected between C ₁ and C ₂ , and the other end of the capacitor C ₃ Connect pin 8 of TLC2652, pin 2 of TLC2652 is connected with resistor R ₁ with a resistance value of 20KΩ, and the other end of R ₁ is connected with the output of the above-mentioned signal driving circuit and capacitor C ₄ with a capacitance value of 0.01μF. The other end of C ₄ is connected to pin 6 of TLC2652 and resistor R ₂ with a resistance value of 100Ω. The other end of resistor R ₂ is connected to the input of the H-bridge drive circuit. ₃ ground, pin 4 of TLC2652 is connected to -15V DC voltage, pin 5 of TLC2652 is suspended, and pin 7 of TLC2652 is connected to +15V DC voltage.

The above-mentioned fluxgate current sensor and the circuit configuration of the H-bridge driving circuit are well known (Figure 2 of Chu Bin. "IR2110 Power Drive Integrated Chip Application". Electronic Engineer. 2004.30 (10).).

The beneficial effects of the present invention are: compared with the prior art, the outstanding substantive features of the present invention are as follows: the working principle of the fluxgate current sensor is based on the magnetic field generated by the current-carrying conductor, in order to increase the magnetic field as much as possible while ensuring the external noise The interference of the scattered magnetic field is the smallest. After the hard research and development of the inventor, it has been proved that the effective method is the magnetic concentration technology applied in the present invention, that is, the magnetic concentration shell adopted in the present invention and designed into a U-shaped structure. Magnetic concentration technology is a measure used to gather the effective magnetic field measured on the primary side and isolate the magnetic field coupling. It uses the principle of magnetic flux flowing along the low reluctance path to change the direction of the external stray magnetic field, so that the magnetic field lines gather in the shell. From the reluctance formula R _m =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 flux density should be selected, and at the same time, in order to obtain accurate detection results, the material with low hysteresis and low coercive force should be selected. Commonly used magnetic gathering materials include: silicon steel sheet, permalloy and amorphous alloy. Among them, the amorphous alloy has the highest magnetic permeability, but the price is relatively expensive, and the silicon steel sheet is cheap, but the magnetic permeability is low. In consideration of performance and cost, the present invention selects permalloy as the material of the polymagnetic shell.

The fluxgate current sensor of the present invention adopts the orthogonal distribution of the excitation winding and the secondary feedback winding while being equipped with a magnetization shell, which can well physically decouple the secondary feedback magnetic field from the excitation magnetic field, so that the excitation magnetic field The contribution of is removed from the signal under test on the primary side.

The following examples will further illustrate the outstanding substantive principles of the present invention.

Compared with prior art, remarkable advantage of the present invention is:

(1) The fluxgate current sensor of the present invention, due to the introduction of the magnetic gathering shell, effectively gathers the measured magnetic field on the primary side, shields the influence of stray magnetic fields around, reduces the interference of external stray magnetic fields, and increases the magnetic field of the sensor at the same time. Gain coefficient, the sensitivity of sensor output has been greatly improved, and the measurement accuracy has been greatly improved, and DC and low-frequency AC can be accurately measured, so that the DC value measured by the existing fluxgate current sensor can be increased to 25A , with an ultra-low relative error of only 6‰.

(2) The fluxgate current sensor of the present invention adopts the orthogonal distribution of the excitation winding and the secondary feedback winding, which eliminates the coupling between the windings, avoids the additional compensation module of the measurement system, and reduces the hysteresis inherent in the magnetic device errors caused by phenomena.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Fig. 1 is a schematic diagram of the general structure of the fluxgate current sensor of the present invention.

FIG. 2 is a structural schematic diagram of a fluxgate detection probe of a fluxgate current sensor of the present invention.

Fig. 3 is a working principle diagram of the fluxgate current sensor of the present invention.

Fig. 4 is a schematic diagram of the composition of the excitation circuit of the fluxgate current sensor of the present invention.

FIG. 5 is a schematic diagram of the composition of the integrating comparator circuit of the fluxgate current sensor of the present invention.

Fig. 6(a) is a distribution diagram of the magnetic induction intensity in the toroidal core when the toroidal core in the fluxgate current sensor is only wound with excitation windings.

Fig. 6(b) is a distribution diagram of the magnetic induction intensity when the toroidal core in the fluxgate current sensor is wound with orthogonal excitation windings and secondary feedback windings.

Fig. 6(c) is a distribution diagram of the magnetic induction intensity when the toroidal core in the fluxgate current sensor is wound with parallel excitation windings and secondary feedback windings.

Fig. 7(a) is a distribution diagram of the magnetic induction intensity in the annular magnetic core in the fluxgate current sensor when the periphery of the annular magnetic core does not have a magnetization collecting shell.

Fig. 7(b) is a distribution diagram of the magnetic induction intensity in the annular magnetic core when the periphery of the annular magnetic core in the fluxgate current sensor is provided with a magnetization shell, which is the current sensor of the present invention.

Fig. 8 is a graph of the input-output characteristic curve of the current sensor with and without the magneto-condensing shell.

Fig. 9 is a graph of the relative error of the current sensor with and without the magneto-condensing shell.

In the figure, 1. Magnetic gathering shell, 2. Ring magnetic core, 3. Primary winding to be tested, 4. Exciting winding, 5. Secondary feedback winding, 6. Shunt resistor R _m , 7. Sampling resistor R _s , 8 .Excitation signal generation circuit, 9. Signal drive circuit, 10. Integral comparator circuit, 11. H bridge drive circuit, 12. Fluxgate detection probe, 13. Signal processing circuit, 14. Excitation circuit, 15. Zero magnetic flux Detection circuit, 16. Square wave generator.

Detailed ways

The embodiment shown in Fig. 1 shows that the fluxgate current sensor of the present invention is a kind of fluxgate current sensor with a magnetic gathering shell 1 and an orthogonal distribution of windings, including a fluxgate detection probe 12 and a signal processing circuit 13; wherein, the fluxgate detection probe 12 is composed of a magnetic gathering shell 1 plus a ring core 2 and an exciting winding 4 plus a secondary feedback winding 5, the ring magnetic core 2 is placed inside the magnetic gathering shell 1, and the exciting winding 4 is a A wire is uniformly wound along the radial direction of the annular magnetic core 2 on the annular magnetic core 2 to form a winding, and the secondary feedback winding 5 is wound evenly along the circumferential direction of the annular magnetic core 2 after the excitation winding 4 is wound. The winding formed; the signal processing circuit 13 is divided into two parts, the excitation circuit 14 and the zero magnetic flux detection circuit 15, and the excitation circuit 14 part includes the excitation signal generating circuit 8 and the signal driving circuit 9; one end of the excitation winding 4 is passed through the excitation signal generating circuit 8 The sampling resistor R _s 7 is grounded, the other end of the excitation winding 4 is connected to the signal drive circuit 9 in the excitation circuit 14, the output of the signal drive circuit 9 is connected to the input of the zero magnetic flux detection circuit 15, and the zero magnetic flux detection circuit 15 is connected to the input of the zero magnetic flux detection circuit 15. Divided into two parts, the integral comparator circuit 10 and the H bridge drive circuit 11, the output of the integral comparator circuit 10 is connected to the input of the H bridge drive circuit 11, the output of the H bridge drive circuit 11 is connected to one end of the secondary feedback winding 5, and the secondary The other end of the feedback winding 5 is grounded through the shunt resistor R _m 6 .

The embodiment shown in Fig. 2 shows that the fluxgate detection probe of the fluxgate current sensor of the present invention is made of a magnetic gathering shell 1 plus a ring magnetic core 2 and an exciting winding 4 plus a secondary feedback winding 5, the ring magnetic core 2 puts Inside the magnetism gathering shell 1, the magnetism gathering shell 1 is used to gather the effective magnetic field and shield the stray irrelevant magnetic field at the same time. The excitation winding 4 is a wire wound uniformly on the annular magnetic core 2 along the radial direction of the annular magnetic core 2 for 100° The winding formed by ~150 turns, the secondary feedback winding 5 is a winding formed by winding 200 ~ 250 turns evenly along the circumferential direction of the annular magnetic core after the exciting winding is wound.

The principle of the fluxgate detection probe of the fluxgate current sensor of the embodiment shown in Fig. 2 is: the outermost magnetic gathering shell 1 will gather the effective magnetic field and shield the external stray magnetic field at the same time, and I _e , I _p and I _s are respectively Excitation current, primary measured current and secondary feedback current, W _e , W _p and W _s are excitation winding 4, primary measured winding 3 and secondary feedback winding 5, respectively, where primary measured winding 3 and The secondary feedback winding 5 is distributed orthogonally with respect to the excitation winding 4, and _Ne , N _p , and N _s are the turns of the excitation winding 4, the primary measured winding 3, and the secondary feedback winding 5, respectively. The toroidal core 2 is made of soft magnetic material with high permeability, low coercive force, and easy saturation. Based on the nonlinear characteristics of the material of the toroidal core 2, first add a frequency f=1kHz and an amplitude of ±12V to the excitation winding 4. The square wave excitation voltage causes the magnetic flux in the ring magnetic core 2 to change alternately. When the AC excitation ampere-turns is large enough, the ring magnetic core 2 presents periodic saturation and unsaturation states. The current I _p to be measured on the primary side passes vertically between the magnetic gathering shell 1 and the ring magnetic core 2 , and the generated magnetic field is gathered by the magnetic gathering shell 1 . When the measured current I _p on the primary side is DC or low-frequency AC, the magnetic flux generated by the measured current I _p on the primary side in the toroidal core 2 is Φ _p , and the current in the secondary feedback winding 5W _s is in the toroidal core The magnetic flux generated in 2 is Φ _s . Since the magnetic field generated by the secondary feedback winding 5 is in the opposite direction to the magnetic field generated by the primary measured winding 3, the internal magnetic field of the toroidal core 2 is weakened. When the magnetic fields generated by the two windings are equal, the secondary feedback current will no longer increase. , the whole system reaches a dynamic equilibrium, N _p I _p = N _s I _s . Usually N _p =1.

The embodiment shown in Fig. 3 shows that the working principle of the fluxgate current sensor of the present invention is: the excitation winding 4W _e and the secondary feedback winding 5W _s adopt orthogonal distribution and are respectively wound uniformly on the ring magnetic core 2 successively, and the number of turns is respectively 100-150 and 200-250 turns; one end of the excitation winding W _e on the ring core 2 is connected to the square wave generator 16, the other end is connected to one end of the sampling resistor R _s 7, and the other side of the sampling resistor R _s 7 is grounded. The output of the zero magnetic flux detection circuit 15 directly affects the variation of the secondary feedback current I _s . Include the discrimination of the vector sum of magnetic flux Φ _s and Φ _p in the zero magnetic flux detection circuit 15, when the sum of Φ _s and Φ _p is not zero, the size of I _s that needs to be adjusted makes the sum zero; when Φ When the sum of _s and Φ _p is zero, it means that the magnetic flux generated by the secondary feedback current I _s is just equal to the magnetic flux generated by the measured current I _p on the primary side, and the direction is opposite. At this time, the measured current I _p on the primary side is equal to The relationship of the secondary feedback current I _s is: I _p = N _s I _s . The other end of the zero magnetic flux detection circuit 15 is connected to one end of the secondary feedback winding 5W _s , and the other end of the secondary feedback winding 5W _s is grounded through the shunt resistor R _m 6 .

The embodiment shown in Figure 4 shows that the excitation circuit of the fluxgate current sensor of the present invention includes an excitation signal generation circuit and a signal drive circuit, and its composition is: mainly including a chip LM6132 for the excitation signal generation circuit and a signal drive circuit The circuit chip IR2101s, LM6132 is a power amplifier, including 8 pins, LM6132 pin 1, LM6132 pin 2 and LM6132 pin 6 are connected by a resistor R ₁ with a resistance value of 3.3KΩ, LM6132 pin 3 One end of the sampling resistor R _S with a resistance value of 20KΩ is connected, the other end of the sampling resistor R _S is grounded, the pin 4 of the LM6132 is connected to -12V DC voltage and a voltage stabilizing capacitor C ₁ with a capacitance value of 0.1μF, and the pin 5 of the LM6132 is connected to Two parallel resistors are connected, one of which is 3.9KΩ parallel resistor R ₂ is grounded, the other 27KΩ parallel resistor R ₃ is connected to pin 2 of IR2101s together with pin 7 of LM6132; the lead of LM6132 Pin 8 is connected to +12V DC voltage and one end of a voltage stabilizing capacitor _C2 with a capacitance value of 0.1μF. The other end of capacitor _C2 is grounded. Pin 1 of IR2101s is connected to 12V DC voltage. The 12V voltage passes through a 1N4106 at the same time. The diode D ₁ of the IR2101s is connected to the pin 8 of the IR2101s, and the pin 8 of the IR2101s is connected to the pin 6 of the IR2101s through a capacitor C ₃ with a capacitance value of 0.1 μF; the pin 3 of the IR2101s and the pin 7 of the IR2101s are suspended , pin 4 of the IR2101s and pin 5 of the IR2101s are grounded. The sampling resistor R _S in Fig. 4 is the sampling resistor R _s 7 .

The embodiment shown in Fig. 5 shows that the zero magnetic flux detection circuit of the fluxgate current sensor of the present invention is shown in the dotted line box among the figure, and comprises integral comparator circuit and H bridge driving circuit two parts, and wherein, the integral comparator circuit The composition is: mainly including the chip TLC2652, including 8 pins, the pin 1 of the TLC2652 is grounded after the capacitor C ₁ with a capacitance value of 0.1μF and the C ₂ with a capacitance value of 1F, and the capacitor is connected between C ₁ and C ₂ Capacitor C ₃ with a value of 0.01μF, the other end of capacitor C ₃ is connected to pin 8 of TLC2652, pin 2 of TLC2652 is connected to resistor R ₁ with a resistance value of 20KΩ, and the other end of R ₁ is connected to the above signal drive circuit The output is connected to the capacitor C ₄ with a capacitance value of 0.01 μF. The other end of the capacitor C ₄ is connected to the pin 6 of the TLC2652 and the resistor R ₂ with a resistance value of 100Ω. The other end of the resistor R ₂ is connected to the H-bridge drive circuit. Input, pin 3 of TLC2652 is grounded through resistor R ₃ with a resistance value of 20KΩ, pin 4 of TLC2652 is connected to -15V DC voltage, pin 5 of TLC2652 is suspended, and pin 7 of TLC2652 is connected to +15V DC voltage.

The embodiment shown in FIG. 6( a ) shows the magnetic induction intensity distribution in the toroidal core when the toroidal core in the fluxgate current sensor is only wound with excitation windings.

The embodiment shown in Fig. 6(b) shows the magnetic induction intensity distribution in the toroidal magnetic core when the toroidal magnetic core in the fluxgate current sensor is wound with mutually orthogonal excitation windings and secondary feedback windings.

The embodiment shown in Fig. 6(c) shows the magnetic induction intensity distribution in the toroidal magnetic core when the toroidal magnetic core in the fluxgate current sensor is wound with excitation windings and secondary feedback windings parallel to each other.

Comparing the embodiments shown in Fig. 6(a), Fig. 6(b) and Fig. 6(c) shows that when the magnetic field simulation is carried out with finite element software, the magnetic induction intensity scale situation on the cross-section of the annular magnetic core C is always visible , adopting the orthogonal distribution of the exciting winding and the secondary feedback winding can minimize the coupling effect of the secondary feedback winding on the primary winding under test.

The embodiment shown in Fig. 7(a) shows the magnetic induction intensity distribution in the toroidal magnetic core when there is no magnetic gathering shell in the fluxgate current sensor

The embodiment shown in Fig. 7(b) shows the distribution diagram of the magnetic induction intensity in the ring magnetic core when the fluxgate current sensor has a magnetic shell.

Comparing the embodiment shown in Fig. 7(a) and Fig. 7(b) shows that when the magnetic field simulation is carried out with finite element software, the magnetic induction intensity graduation situation when there is no magnetic gathering shell on the cross section of the annular magnetic core C can be seen: The introduction of the magnetic gathering shell can effectively gather the measured effective magnetic field, isolate the magnetic field coupling, and use the principle of magnetic flux flowing along the low reluctance path to change the direction of the external stray magnetic field, so that the magnetic field lines can be gathered in the shell.

The embodiment shown in FIG. 8 shows the input-output characteristic curves of the current sensor of the present invention with a fluxgate current sensor having a magnetic flux concentrating shell and the prior art fluxgate current sensor without a magnetic flux concentrating shell. This set of data proves that the introduction of the polymagnetic shell can significantly improve the sensitivity and accuracy of the current sensor, and at the same time broaden the measurement range of the current sensor.

The relative error graph of the current sensor of the embodiment shown in Figure 9 shows that the theoretical value of the output voltage is used to subtract the actual value, and then divided by the actual value to obtain the current sensor within the measurement range Relative error. Based on the experimental data, it can be concluded that when the current measurement range is 0-25A, the relative error introduced by the polymagnetic shell is limited to 6‰.

Example 1

According to the embodiments shown in Fig. 1, Fig. 2, Fig. 4 and Fig. 5, the fluxgate current sensor of this embodiment is constituted, which is a fluxgate current sensor with a magnetization collecting shell 1 and adopts winding orthogonal distribution, including Fluxgate detection probe 12 and signal processing circuit 13; Wherein, fluxgate detection probe 12 is made of a magnetic gathering shell 1 plus annular magnetic core 2 and excitation winding 4 plus secondary feedback winding 5, and annular magnetic core 2 is placed on the gathering Inside the magnetic shell 1, the exciting winding 4 is a winding formed by uniformly winding a wire on the annular magnetic core 2 along the radial direction of the annular magnetic core 2, and the secondary feedback winding 5 is formed along the annular direction after the exciting winding 4 is wound. The winding that the circumferential direction of the magnetic core 2 is evenly wound again; the signal processing circuit 13 is divided into two parts, the excitation circuit 14 and the zero magnetic flux detection circuit 15, and the excitation circuit 14 part includes the excitation signal generating circuit 8 and the signal driving circuit 9; One end of the winding 4 is grounded through the sampling resistor R _s 7 in the excitation signal generating circuit, the other end of the excitation winding 4 is connected to the signal drive circuit 9 in the excitation circuit 14, and the output of the signal drive circuit 9 is connected to the input of the zero magnetic flux detection circuit 15 , the zero magnetic flux detection circuit 15 is divided into two parts, the integral comparator circuit 10 and the H bridge drive circuit 11, the output of the integral comparator circuit 10 is connected to the input of the H bridge drive circuit 11, and the output of the H bridge drive circuit 11 is connected to the secondary One end of the feedback winding 5 and the other end of the secondary feedback winding 5 are grounded through the shunt resistor R _m 6 . Among them, the magnetic gathering shell 1 is used to gather the effective magnetic field and shield the stray irrelevant magnetic field at the same time. The exciting winding 4 is a winding formed by winding 100 turns of a wire on the annular magnetic core 2 along the radial direction of the annular magnetic core 2. The secondary feedback winding 5 is a winding formed by winding 200 turns evenly along the circumferential direction of the annular magnetic core after the exciting winding 4 is wound; the magnetic gathering shell 1 is made of permalloy material, and its resistivity is 0.56 μΩ·m, the Curie point is 400°C, the saturation magnetic induction is B _s =0.7T, the coercive force H _c under the saturation magnetic induction is not more than 1.6A/m, and the DC magnetic properties meet the requirements of the magnetic field strength of 0.08A/m The magnetic permeability is not less than 37.5mH/m, the thickness is 2mm, the length is 30mm, the width is 30mm, and the height is 15mm; the material used in the ring magnetic core 2 is iron-based nanocrystalline soft magnetic material, and its saturation magnetic flux density B _s =1.2T, coercive force H _c <5A/m, saturation magnetostriction coefficient s=10 ^-8 ～10 ^-6 , magnetic permeability 15000～150000H/m, core loss (100KHz, 0.3 T) P _Fe =80W/Kg, the inner diameter of the annular magnetic core 2 is 10mm, the outer diameter is 20mm and the height is 10mm; the material used for each of the windings is enameled wire, and the diameter is 0.3mm; the H bridge drive circuit The chip used in 11 is IR2110; the sampling resistor R _s 7 is 20KΩ, and the shunt resistor R _m 6 is 150Ω.

Example 2

Except that the excitation winding 4 is a winding formed by uniformly winding 125 turns of a wire on the annular magnetic core 2 along the radial direction of the annular magnetic core 2, the secondary feedback winding 5 is formed along the annular magnetic core after the excitation winding is wound. Except for the winding formed by uniform winding of 225 turns in the circumferential direction, the others are the same as in Embodiment 1.

Example 3

Except that the excitation winding 4 is a winding formed by uniformly winding 150 turns of a wire on the annular magnetic core 2 along the radial direction of the annular magnetic core 2, the secondary feedback winding 5 is formed along the annular magnetic core after the excitation winding is wound. Except for the winding formed by uniform winding of 250 turns in the circumferential direction, the others are the same as in Embodiment 1.

Claims (8)

1. fluxgate current sensor, is characterized in that: be a kind of with poly-magnetic shell and the fluxgate current sensor adopting winding omnidirectional distribution, comprise fluxgate detection probe and signal processing circuit, wherein, fluxgate detection probe by a poly-magnetic shell add toroidal core and excitation winding add secondary feed back winding form, it is inner that toroidal core is placed on poly-magnetic shell, excitation winding be a wire on toroidal core along the winding that radial uniform winding 100 ~ 150 circle of this toroidal core is formed, secondary feedback winding be excitation winding twine after along toroidal core circumferencial direction again uniform winding 200 ~ 300 circle formation winding, signal processing circuit is divided into exciting circuit and Zero-flux sensing circuit two parts, and exciting circuit part comprises again exiting signal generating circuit and signal drive circuit, the sampling resistor ground connection of excitation winding one end in exiting signal generating circuit, the excitation winding other end is connected with the signal drive circuit in exciting circuit, the output of signal drive circuit connects the input of Zero-flux sensing circuit, Zero-flux sensing circuit is divided into again integral contrast device circuit and H-bridge drive circuit two parts, integral contrast device circuit is the input of Zero-flux sensing circuit, the output of integral contrast device circuit connects the input of H-bridge drive circuit, one end of the output connecting secondary feedback winding of H-bridge drive circuit, the other end of secondary feedback winding is by shunt resistance ground connection.

2. fluxgate current sensor according to claim 1, is characterized in that: what described poly-magnetic shell adopted is that permalloy material makes, and its resistivity is 0.56 μ Ω m, and Curie point is 400 DEG C, and saturation induction density is B _s=0.7T, the coercive force H under saturation induction density _cbe not more than 1.6A/m, the magnetic permeability that DC magnetic performance meets in 0.08A/m magnetic field intensity is not less than 37.5mH/m, and thickness is 2mm, and length is 30mm, and width is 30mm, and height is 15mm.

3. fluxgate current sensor according to claim 1, is characterized in that: described toroidal core material used is Fe-Base nanocrystalline soft magnetic material, and its saturation magnetic flux density is B _s=1.2T, coercive force H _c<5A/m, saturation magnetostriction constant is s=10 ^-8~ 10 ^-6, magnetic permeability is 15000 ~ 150000H/m, core loss (100KHz, 0.3T) P _fe=80W/Kg, the internal diameter of this toroidal core is 10mm, external diameter is 20mm and height is 10mm.

4. fluxgate current sensor according to claim 1, is characterized in that: each winding described material used is enameled wire, and diameter is 0.3mm.

5. fluxgate current sensor according to claim 1, is characterized in that: the chip that described H-bridge drive circuit adopts is IR2110.

6. fluxgate current sensor according to claim 1, it is characterized in that: described sampling resistor is 20K Ω, shunt resistance is 150 Ω.

7. fluxgate current sensor according to claim 1, it is characterized in that: described exciting circuit, comprise exiting signal generating circuit and signal drive circuit, its formation is: mainly comprise for the chip LM6132 of exiting signal generating circuit and the chip I R2101s for signal drive circuit, LM6132 is power amplifier, comprise 8 pins, the pin 1 of LM6132, the pin 2 of LM6132 and the pin 6 of LM6132 are the resistance R of 3.3K Ω by resistance ₁connect, pin 3 and the resistance of LM6132 are the sampling resistor R of 20K Ω _sone end is connected, sampling resistor R _sother end ground connection, the pin 4 of LM6132 meets the electric capacity of voltage regulation C that-12V DC voltage and capacitance are 0.1 μ F ₁, the pin 5 of LM6132 is connected with two parallel resistances, and one of them resistance is the parallel resistance R of 3.9K Ω ₂ground connection, another resistance is the parallel resistance R of 27K Ω ₃jointly be connected on the pin 2 of IR2101s with the pin 7 of LM6132; The pin 8 of LM6132 meets the electric capacity of voltage regulation C that+12V DC voltage and capacitance are 0.1 μ F ₂one end, electric capacity C ₂other end ground connection, the pin 1 of IR2101s connects 12V DC voltage, and this 12V voltage is the diode D of 1N4106 by a model simultaneously ₁be connected with the pin 8 of IR2101s, the pin 8 of IR2101s is the electric capacity C of 0.1 μ F again by a capacitance ₃be connected on the pin 6 of IR2101s; The pin 3 of IR2101s and the pin 7 of IR2101s unsettled, the pin 4 of IR2101s and pin 5 ground connection of IR2101s.

8. fluxgate current sensor according to claim 1, it is characterized in that: described Zero-flux sensing circuit, comprise integral contrast device circuit and H-bridge drive circuit two parts, wherein, the formation of integral contrast device circuit is: mainly comprise chip TLC2652, comprise 8 pins, the pin 1 of TLC2652 is the electric capacity C of 0.1 μ F through capacitance ₁be the C of 1F with capacitance ₂rear ground connection, at C ₁and C ₂between connect the electric capacity C that capacitance is 0.01 μ F ₃, electric capacity C ₃the other end pin 2 that connects the pin 8, TLC2652 of TLC2652 and resistance be the resistance R of 20K Ω ₁be connected, R ₁the other end and the output of above-mentioned signal drive circuit and capacitance be the electric capacity C of 0.01 μ F ₄be connected, electric capacity C ₄the other end be connected to the resistance R that the pin 6 of TLC2652 and resistance are 100 Ω ₂, resistance R ₂the other end be connected to the input of H-bridge drive circuit, the pin 3 of TLC2652 is the resistance R of 20K Ω through resistance ₃ground connection, the pin 4 of TLC2652 connects the DC voltage of-15V, and the pin 5 of TLC2652 is unsettled, and the pin 7 of TLC2652 connects the DC voltage of+15V.