How do Hall effect sensors work and where are they used in motion applications?

霍尔效应是在工作中的洛伦兹力量的结果。

When a thin conductor (or semiconductor) has a steady flow of current running through it and a magnet is placed so that its magnetic field runs perpendicular to this current, the magnetic field of the current reacts to the magnetic field of the permanent magnet, causing the electrons flowing through the conductor to be pulled to one side of the conductor, due to the Lorentz force. This creates a potential difference, referred to as Hall voltage, in the conductor. The magnitude of the Hall voltage is proportional to the strength of the magnetic field.

这Lorentz force是由于电场和磁场引起的粒子经验的力。

Hall effect sensor — 当流过导体的电流的磁场反应到垂直于电流的永磁体的磁场反应时，产生霍尔电压。
*Image credit: electronics-tutorials.ws*

这Hall effect is put to use in sensors, where the resulting Hall voltage can indicate the presence, absence, or strength of a magnetic field. Although Hall sensors operate by detecting a magnetic field, they can be used for sensing a wide variety of parameters, including position, temperature, current, and pressure.

霍尔效应传感器通常分为两类：数字霍尔效应传感器 - 包括霍尔效应开关和霍尔效应锁存器 - 以及模拟霍尔效应传感器。

霍尔效应开关 - 也称为单极传感器 - 与磁通量的预定阈值相比，检测磁场的存在（或不存在）。当检测到合适的磁场时，开关打开（关闭），并且当断开该字段时，开关关闭（打开）。邻近传感器是霍尔效应开关的常见应用。

这operation of a Hall effect latch — also referred to as a bipolar sensor — is similar to a switch, but a latch turns on (closes) when a positive magnetic field is applied and仍然存在even when the field is removed. Conversely, the latch turns off (opens) when a negative magnetic field is applied and仍然关闭even when the field is removed. Hall effect latches are commonly used in brushless DC (BLDC) motors to检测转子位置正确换向。

数字霍尔效应传感器包含一个施密特触发器— a circuit that adjusts the switching threshold to a slightly higher point on the rising edge of the signal and to a slightly lower point on the falling edge of the signal. The difference between these switching points is referred to as hysteresis, and ensures that the switch will not oscillate, or switch on-and-off, due to noise in the input signal.

模拟或线性，霍尔效应传感器产生与磁通密度（磁场强度）成比例的连续输出电压，这使得它们适合测量位置和运动。事实上，很多magnetic rotary encoders使用线性霍尔效应传感器。However, the interaction of the flowing current and the magnetic field produces a Hall voltage that is very small, so linear Hall sensors typically incorporate an amplifier to increase the output voltage, along with other signal conditioning electronics to improve the sensor’s response and compensate for temperature effects.

霍尔效应装置制造出优异的传感元件，因为它们完全不接触并没有移动部件，给予它们长时间的操作寿命。它们可以以高速和开关频率运行，具有出色的可重复性。

功能图片信用：德州仪器