Hall sensor in BLDC motor
What is Hall sensor?
Hall sensor is a magnetic sensor based on Hall effect. When an object with current is placed in a magnetic field, if the current direction and the magnetic field direction are perpendicular to each other, a transverse potential difference will occur in the direction perpendicular to both the magnetic field and the current direction. This phenomenon is called Hall effect, and the generated potential difference is called Hall voltage.
The hall element is made of semiconductor materials with obvious Hall effect. As a magnetoelectric conversion element in Hall sensor, it can be used for electromagnetic measurement, such as measuring magnetic physical quantities such as magnetic field, current, electric power and electric quantity.
Hall sensor can also use magnetic field as medium to realize non-contact measurement of many physical quantities, and it is widely used in various fields such as industry, transportation, communication, automatic control, household appliances, etc. by converting non-electric quantities such as measuring force, displacement, vibration, acceleration, speed and flow.
Working principle of Hall sensor
Hall current sensor is made according to Hall principle. It has two working modes, namely, magnetic balance type and direct type.
Hall current sensor is generally composed of primary circuit, magnetic collecting ring, hall element, (secondary coil) and amplifying circuit.
Direct current sensor (open loop)
When the current passes through a long wire, a magnetic field will be generated around the wire. The magnitude of this magnetic field is proportional to the current flowing through the wire. It can be induced to the hall element through the magnetic core and a signal will be output. This signal is directly output after being amplified by the signal amplifier, and the general rated output is rated as 4V.
Magnetic balance current sensor (closed-loop)
The magnetic balanced current sensor is also called compensation sensor, that is, the magnetic field generated by the measured current Ip in the main circuit at the magnetic gathering ring passes through a secondary coil, and the magnetic field generated by the current is compensated, so that the hall element is in the working state of detecting zero magnetic flux.
Advantages of hall sensor
1. Wide measuring range: It can measure the current and voltage of any waveform, such as DC, AC, pulse, triangular waveform, etc., and even reflect the transient peak current and voltage signals faithfully.
2. Fast response speed: The fastest response time is only 1us.
3. High measurement accuracy: Its measurement accuracy is better than 1%, which is suitable for measuring any waveform.
4. Good linearity: better than 0.2%.
5. Working frequency bandwidth: All signals in the frequency range of 0~100KHz can be measured.
6. High reliability: long average trouble-free working time.
7. Strong overload capability and large measuring range: 0-tens of amps ~ tens of thousands of amps.
8. Small size, light weight and easy installation.