![]() ![]() Comparator output is logic high if the positive voltage is greater than the negative voltage, and logic low if the positive voltage is lower than the negative voltage.īasically 3 comparators are needed for this project, connections are done as shown in the figure below (example for phase B). The comparator has 3 main terminals: 2 inputs (positive and negative) and an output. The easiest way to detect the zero crossing events is by using comparators. Phase C zero crossing: from high to low and from low to high Phase B zero crossing: from high to low and from low to high Phase A zero crossing: from high to low and from low to high The floating winding is used to detect the zero crossing, thus, the combination of all 3 zero cross over point are used to generate the energizing sequence. In every energizing sequence, two windings are energized (one connected to positive and the other to negative) and the third winding is left open (floating). The figure below shows the relationship between the hall effect signals and the BEMF signals:Īs shown in the figure above, the BEMF signals are not synchronized with the hall effect sensor signals (phase shift of 30°). The 3 generated BEMF signals are 120° out of phase which is the same as the hall effect sensor signals. When the BLDC motor rotates, each winding (3 windings) generates BEMF opposes the main voltage. The main advantage of sensorless BLDC motor control is lower system cost and the main disadvantage is the motor must be moving at minimum rate to produce sufficient BEMF to be sensed. ![]() Sensorless BLDC motor doesn’t have any sensor to detect its rotor position, its commutation is based on the BEMF (Back Electromotive Force) produced in the stator windings. ![]() The commutation of the sensored BLDC motor is done according to the hall effect sensors state. Sensored brushless DC motor control with Arduino Controlling a sensored BLDC motor is easy since we know the rotor position like what was done in the project below: ![]() Sensored BLDC motor has built-in 3 hall effect sensors, these sensors detect the rotor position of the BLDC motor. There are two types of brushless DC motors: sensored and sensorless. This topic shows how to build a sensorless brushless DC (BLDC) motor controller or simply an ESC (Electronic Speed Controller) with an Arduino UNO board. ![]()
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