The principle of 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. The Hall effect in the fluid is the theoretical basis for studying the "magnetic fluid power generation". According to the principle of the Hall effect, the size of the Hall potential depends on: RH is the Hall constant, which is related to the semiconductor material; the IC is the bias current of the Hall element; B is the magnetic field strength; D is the thickness of the semiconductor material. For a given Hall device, VH will completely depending on the measured magnetic field strength B.
A Hall element typically has four extraction terminals, two of which are the input of the bias current IC of the Hall element, and the other two is the output of the Hall voltage. If the two output is constituted, Hall current is generated. Generally, the setting of the bias current is typically given by the external reference voltage source; if the accuracy is high, the reference voltage source is replaced with a constant current source. In order to achieve a high sensitivity, some of the slope alloys of high magnetically magnetic factors are equipped with high magnetic coefficients; this type of sensor is large, but it is saturated at 0.05T, only in low-lost Used under small range. In recent years, various types of new integrated Hall components have emerged due to the rapid development of semiconductor technology. Such components can be divided into two categories, one is linear components, and the other is the switching element. The principle of linear Hall components:
UGN350LT is a three-terminal linear Hall element currently currently used. It consists of a regulator, a Hall generator, and an amplifier. It can be easily formed with UGN350LT. It is very simple, first makes B = 0, and records the value VoH of the table, and then attach the probe end surface on the subject, and record the new value VOH1. ΔVOH = VOH1-VOH, if ΔVOH "0, indicating that the N pole end surface is measured; the opposite is the S pole. The sensitivity of UGN3501T is 7V / t, whereby the corresponding measured magnetic induction strength B can be measured. If a digital voltmeter (DVM) is used, the linear Gaussian meter shown in Figure 1 can be obtained. The op amp is used in high-precision op amp, CA3130. The specific zero mode of the circuit is: After the power is turned on, the power supply B = 0, the adjustment W1 makes the DVM showed zero, and then passed on the end surface of the probe with a standard neodymium aluminum boron magnet (B = 0.1T). Adjusting W2 allows the DVM to be 1V. If the attempt is at -200mV, the probe end face is detected, and the magnetic field strength is 0.02T. This Galasi can also be used to measure alternative magnetic fields, but DVM should be changed to an AC voltmeter. Obviously using the circuit of Figure 1 can easily expand the functionality of normal digital multimeters.
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The UGN3501T can also be easily composed of the clamp current table as shown in Fig. 2. The Hall element is placed in the voids of the clamp coiled silicon steel sheet. When there is a current flowing through the wire, a magnetic field is generated in the clamp ring, and the size is proportional to the number of turns flowing through the wire current; this magnetic field Acting on the Hall element, induces the corresponding Hall potential, its sensitivity is 7V / t, passing through the op amplifier μA741 zero, linearly sent to DVM, form a digital clamp current table. The debugging of the table is also very simple: when the current in the wire is zero, the adjustment W1, W2 makes the DVM's indication of zero. Then enter the 50A current, adjust W3 to make the DVM reading of 5V; reverse input -50A current, digital representation value is -5V. Repeatedly regulating W1, W2, W3, and reading can meet the requirements. This clamp current is experimentally experiment, and its sensitivity is not less than 0.1V / a, and similarly, the current meter can also be used for the measurement of AC current, and the DVM is converted to an alternating voltage meter, which is very convenient.
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Honeywell Sensor Application and Application in Electric Bicycle Industry
Hall sensor has a wide range of applications in many areas such as aerospace technology, medical technology, transportation, industry, and measurement and testing, etc. have made significant contributions. At present, the application field is active is the electric bicycle field. All of this is inherently in Honeywell's high quality four Hol-style components. Other high-sensitivity Hall effect latches use double Hall or single Hall components, which makes it very sensitive to packaging stress, and four Hall components make these sensors more stable and excellent. These new high-sensitivity latches are designed for brushless DC motor. Its features are: width temperature range, high sensitivity, compact design (with SOT-23 and TO-92 packages for customers), bipolar latch magnetic components (can maintain performance throughout the temperature range Stable), wide voltage range, built-in reverse voltage function, compliant with ROHS standards, all of these excellent features are very important for brushless current motors in various industrial applications. The Honeywell sensor is equipped with a reliable high magnetic sensitivity switch point, and its Hall element has not been used in chopping stabilization technology. These features of Honey have enabled the sensor to output a complete signal and shorten the latch response time to 20 microseconds.
Electric vehicle control experiment map
Hall sensor transfer to electric vehicle speed
Speed speed transmissions as the name suggests is the speed control unit of the electric vehicle, which is a linear speed control component, a lot of styles, but the working principle is the same. It is generally located on the right side of the electric vehicle, the direction of the right hand, and the rotation of the electric vehicle rotation is between 0-30 metric. Signal characteristics of the handle to the gate: the form, signal characteristics and signal restructuring of the handle.
There are 3 leads in the turnover of the electric vehicle: the power supply (fine red + 5V), ground line (fine black), turn the speed control signal line (linear continuous signal fine). The turnover of the electric vehicle has two kinds of photoelectric handle and the Hogle turn, and the electric vehicle that is currently using the Hogle Tottary takes up the vast majority. Common linear Hall components are: AH3503 AH49E A3515 A3518 SS49E A3515 A3518 SS495, such as: AH3503 linear Hall circuit consists of voltage regulator, Hall voltage generator, linear amplifier, and emitter follower, and its input is magnetic induction strength, output is and input The amount is proportional to the voltage. Static output voltage (b = 0gs) is about half of the power supply voltage. When the S magnetic pole appears in the Hall sensor marker, the drive output is higher than zero level; the N magnetic pole reduces the drive output below zero; the instantaneous and proportional output voltage level determines the magnetic flux density of the most sensitive surface of the device. Improve the supply voltage can increase sensitivity. Product features: small size, high accuracy, high sensitivity, good linear, good temperature, high reliability. The hog is turning the size of the output voltage depends on the magnetic field strength around the Hall element. Rotating the transfer, changing the magnetic field strength around the Hall element, and also changing the output voltage of the Hogle Top.
The signal used in the electric vehicle has the following: the type output voltage of the transfer handle, power / 5V, supply / 5V power supply, single-handed turn to 1.1-4.2 (max) / 4.2- 1.1 (small amount); single-handed hand transfer 2.6-3.7 (very small) /3.7-2.6; single-handed turn to 1-2.5 / 2.5-1; single-handed glory 2.5-4 / 4-2.5; double Huo The ear is turned 0-5 / 5-0; the photoelectric turn is 0-5 (small amount) / 5-0. The most commonly used of the following two signals: 1-4.2V (commonly known as orthogonal), 4.2-1V (commonly known as counter-hand). In the transfer of two signals, it is a total of 1.0V to 4.2V to account for the vast majority. The transfer of other output voltages, there is very little in the market, and has become a non-standard product in the fact that this non-standard transfer is more used in the early electric vehicles. So the vast majority of controllers in the current market is to identify products from 1-4.2V to the signal. When the shift or controller of the electric vehicle needs to be repaired, once the case where the signal is not maded with the controller, this requires the transformation to the transfer, so that it outputs the signal to match the controller. Transfer the output signal: will be removed, change the polarity of the direction of the magnetic steel working surface, and change the potential to the output. If there are two magnetic steels in the handle, two magnetic steel is turned 180 °, and then install it; if there is only one magnetic steel in the handle, the magnetic steel is taken out, and after turning 180 °, it is improved. This changes the starting position of the working magnetic field of the Hall element, thereby realizing the reform of the output signal. A mechanical switch button is added to the transfer of the locking handle, which can be used as the mode conversion button under the control of the controller for 1: 1 power, electric, fixed speed, fault self-test mode conversion.
Hall sensor handles electric car
The transfer signal is a drive signal rotating of the electric vehicle motor, and the brake signal is a brake signal that the motor stops rotating. Electric vehicle standards require electric vehicles when braking brakes, the controller should automatically cut off the power of the motor. Therefore, the electric brake should have a gate position sensing element, and when a brake signal is transmitted, the brake signal is transmitted to the controller, and the controller stops the power supply to the motor immediately.
The position sensing element of the electric vehicle gate has two types of mechanical micro-switch (divided into mechanical normally open and mechanical normally closed) and switch type Hall induction elements (two types of brake low potentials and brake high potentials). Mechanical switch types have two leads a negative electrode, which is suitable for low-level brake controllers. For controllers that support high-level brakes are one-piece + 12V, and another partial power line. Hall type three lead lines: Brake line (fine blue + 5V), negative electrode (fine black), and the remaining one is broken wire. The model of common single-polar switch Hall element is: AH41 / AH3144 / A3144 / A3282.
Generally, the mechanical normally open brake signal is a often high potential, when the brake is brake, the gate is closed, and the signal turns a low potential. Generally, the mechanical normally closed brake signal is a normal low potential, when the brake is braked, the gate opens the inside of the micro switch, and the signal becomes a high potential. Generally, the brake signal of the electron low-potential brake is a often high potential. When the brake is braked, the gate is flipped inside the inside, and its signal becomes a low potential. Generally, the brake signal of the electron high-potential brake is a normal low potential, and when the brakes, the gate is flipped inside the door, and its signal becomes a high potential. The change in the brake signal is changed, which is that the controller identifies whether the electric vehicle is in a brake state, thereby judge whether or not the controller is powered. When the gate of the electric vehicle needs to be repaired, it will encounter the case where the gate signal is not matched with the controller, which requires a restructuring to the gate, so that it outputs the signal to match the controller. Therefore, in maintenance practice, regardless of the form of brakes, regardless of the brake signal identifying the brake signal, it should be appropriately improved to match the various forms of brake signals to match the signal that can be identified as a controller. , Reading the full text, the technology area
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