How are brushless gearmotors controlled
Most brushless gearmotors need a controller/driver to run. There are many different types of controllers/drivers that are manufactured around the world for different applications. Many come with different options and can be custom made. Most are referred to as Electronic Speed Controller (ESC).
In Brushless Gearmotors, either a Hall Effect Sensor or the Back EMF (Electromotive Force) is used to run the motor. The Hall Effect uses three hall sensors within the motor to help detect the position of the rotor. This method is primarily used in speed detection, positioning, current sensing, as well as proximity switching. The magnetic field changes in response to the transducer that varies its output voltage. A feedback is created by directly returning a voltage since the sensor operates as an analogue transducer. The distance between the Hall plate and a known magnetic field can be determined with a group of sensors, in this case, three, and the relative position of the magnet can be deduced. A Hall sensor can act as an on/off switch in a digital mode when combined with circuitry.
The Back EMF, also known as the Counter-Electromotive Force is caused by a changing electromagnetic field. In Brushless Gearmotors, the back EMF is a voltage that occurs where there is motion between the external magnetic field and the armature of the motor. In other words, the voltage is developed in an inductor by and alternating current or pulsating current. At every moment, the polarity of the voltage is the reverse of the input voltage. This method is commonly used to measure the motorís position and speed indirectly.