The Hall sensor is a magnetic field sensor based on the Hall effect. The Hall effect is a kind of magnetoelectric effect. This phenomenon is that Hall (A.HALL, 1855-1938) found in the study of metal conductive mechanisms in 1879. Later, it also found that semiconductors, conductive fluids, etc. also have this effect, while the Hall effect of the semiconductor is much stronger than metal, and the various Hall elements made of this phenomenon are widely used in industrial automation technology, testing technology and information processing. aspect. The Hall effect is a basic method for studying the performance of semiconductor material. The Hall coefficients measured by the Hall effect experiment can determine important parameters such as the conductivity type, carrier concentration and carrier mobility of the semiconductor material.
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Hall sensor error
The Hall sensor has been widely used in electrical test, automatic control and computing device, etc. in terms of non-contact, small size, simple structure. Due to the fact that the Hall sensor generates an error, although various compensation measures are taken, it is difficult to compensate for various errors only with one compensation circuit. To this end, a circuit is designed, and various errors can be effectively compensated without the compensation circuit.
Main errors and causes reasons
1. Zero error
The zero error is caused by an iremeted potential. The main reason for producing irregular potential is: 2 Hall Electrodes are not installed on the same equipo; the material is unevenly distributed uneven, and the control electrode is in contact with poor contact, resulting in uneven current distribution.
2. Parasitic DC potential error
The main reason for generating parasitic DC potential is that the control is poor contact with the Hall polar element, forming non-ohmic contact; two Hall electrode is asymmetrical, so that the heat capacity of the two electrodes is different, the heat dissipation state is different, the temperature difference potential between the two poles To make the Hall element generate a warm milestation.
3. Induction zero potential error
When the Hall element is working in the AC or pulsating magnetic field, even if the current is not added, the Hall is not symmetric, the Hall end also outputs, and the size is proportional to the pulsation frequency of the magnetic field, the magnitude of the magnetic induction strength and two Huo Induction area of the electrode leads.
4. Self-excited magnetic field zero potential error
When the Hall element is converted with a control current, this current generates a magnetic field called self-excitation field. When the electrode lead is asymmetrical, the magnetic induction intensity of the element is not equal, and the zero potential output of the self-excitation site will be output.
5. Temperature error
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Currently, in order to eliminate the above errors, the resistance compensation circuit is generally employed in addition to the above errors, and the resistance compensation circuit is generally used, but the effect is still not ideal in more precise measurements.
Methods to eliminate various errors
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The potential taken is transported by a voltage follower driven by A4, which is better inhibited interference of AC common mode voltage. The circuit shown in Figure 3 is suitable for various sensor circuits.
Hall sensor's precautions
(1) In order to obtain better dynamic characteristics and sensitivity, it is necessary to pay attention to the coupling of the primary edge coil and the secondary coil. It is best to be coupled, it is best to use a single wire and the wire is fully filled with the Hall sensor module aperture.
(2) Use the large DC current flow through the sensor primary edge, and the secondary circuit does not turn on the power or the secondary opening, the magnetic circuit is magnetized, and the residual magnetic, affecting the accuracy of the measurement (so when used Turn on the power supply and measurement terminals first, when this happens, you must first make an demagnetization process. The method is that the secondary circuit does not power the power supply, and the alternating current current in the original edge coil is connected to the same grade size and gradually reduces its value.
(3) In most cases, the Hall sensor has strong anti-external magnetic field interference capabilities, typically generated by the magnetic field interference generated by the current of the current IP of the working current IP between the distance module 5-10cm is negligible. However, when there is a stronger magnetic field interference, appropriate measures are taken to solve. The usual method is:
1 Adjust the direction of the module, so that the external magnetic field has the smallest impact on the module
2 Adding a metal shield of an anti-magnetic field on the module
3 Use the modules with double Hall elements or multi Hall components.
(4) The best precision of the measurement is obtained under the rated value. When the measured current is low below the rated value, it is necessary to obtain the best precision, and the original side can be used, namely: IPNP = rated antenna. In addition, the original feeder temperature should not exceed 80 ° C.
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Hall sensor characteristics (compared to ordinary transformers)
1. Hall sensor can measure the current and voltage of any waveform, such as: DC, AC, pulse waveform, etc., even for the measurement of transient peaks. The secondary current is faithfully reactively reacting the waveform of the primary side. The ordinary transformer is unable to compare with it, it is generally only suitable for measuring 50 Hz sine wave.
2. Complete electrical insulation between the primary circuit and the secondary circuit, the insulating voltage is generally 2kV to 12kV, and special requirements can reach 20kV to 50kV.
3, high precision: In the operating temperature zone, the precision is better than 1%, which is suitable for any waveform measurement. The general transformer is generally 3% to 5% and is suitable for 50 Hz sinusoidal waveforms.
4, linearity is good: better than 0.1%
5, the dynamic performance is good: the response time is less than 1μs tracking speed Di / DT above 50A / μs
6. This excellent dynamic performance of Hall Sensor Modules provides a key foundation for improving the performance of modern control systems. In contrast, the ordinary transformer response time is 10-12 ms, which does not adapt to the development of the work control system.
7, operating frequency bandwidth: in the range of 0-100 kHz frequency ranges from 1%. The accuracy is 0.5% in the 0-5 kHz frequency range.
8, measurement range: Hall sensor module is system product, current measurement can reach 50kA, voltage measurement can reach 6400V.
9, overloading ability: When the original is overload, the module reaches saturation, automatic protection, even if the overload current is 20 times that of the rated value, the module will not be damaged.
10, module size is small, light weight, easy to install, it will not bring any losses in the system.
11. The "capacitance" between the primary and secondary of the module is very weak. In many applications, the various effects of common mode voltages can generally be ignored, and when the high pressure changes of thousands of volts / μs, the modules have their own Shielding effect.
12, the high sensitivity of the module, enabling it to distinguish the weak signals on the "high component", for example, to distinguish the AC components of several milliates on the upper part of the DC component.
13, high reliability: loss efficiency: λ = 0.43 ╳ 10-6 / hour
14, the anti-external magnetic field interference ability is strong: there is a twice of magnetic field interference generated by the current (2ip) current at the module 5-10cm, which is less than 0.5%, which is for most applications, anti-external magnetic fields. Interference is sufficient, but the interference to a strong magnetic field should take appropriate measures. , Reading the full text, the technology area
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