Why a brushless dc motor controller built-in at least three hall

why brushless dc motor controller built-in at least three hall is a brushless dc motor controller in a dc motor controller is developed on the basis of the improvement of new electromechanical integration motor controller. Cancelled the traditional physical carbon brush, reversing changed to use sensors to digital signals. It was thus able to avoid excessive wear of carbon brush in high-speed operation, can greatly increase the service life of the brushless motor controller, and can undertake external control, whether in performance, and the convenience degree of control than a brush motor controller has a breakthrough. There are many types of sensors, on the brushless dc motor controller is the most common hall sensor. We can find that most brushless dc click on market is built in at least three hall sensors, why a brushless dc motor controller built-in at least three hall? As shown above, in front of a electromagnet coil in seduce permanent magnets, behind a electromagnet coil in promoting the permanent magnets, but we all know, if coil polarity is not changed, the poles to the location of the permanent magnets will settle, like two magnet sucked together, so the coil magnetic pole is often should change in the rotation. Who is to signal the coil change pole? Is the hall sensor. Hall sensor is able to feel the location of the permanent magnet rotor, can be timely reported to the position of the donkey stator coil controller, the controller based on this information to control the stator coil current flow to the inside. It turned up brushless motor controller. In short, brushless dc motor controller in order to turn, must make the magnetic field of the stator winding and rotor magnetic field of permanent magnet always exists between certain Angle. Rotor spinning process is the rotor magnetic field direction change process, in order to make the two magnetic field Angle, to a certain extent, the stator coil magnetic field direction must be changed. Three hall sensors is the minimum quantity can maintain the brushless motor controller rotational, can increase the number of hall sensor to improve the accuracy of the speed of brushless motor controller the more the number of sensors, the speed of the brushless motor controller had higher precision.