Using The Hall Effect to Drive Brushless Motors

Role of Hall Effect ICs in a BLDC Motor

Hall effect ICs play a vital role in BLDC motors by detecting the position of the rotor, allowing precise control of the timing of current flow to the stator coils.

BLDC Motor Control

As shown in the figure, the BLDC motor control system recognizes the position of the rotating rotor and subsequently instructs the motor control driver to switch current to the coil, thereby initiating motor rotation.

Detection of rotor position is an important part of this process.

Failure to detect rotor position prevents the energization phase from being implemented at the precise timing required to maintain optimal flux relationships between the stator and rotor, resulting in suboptimal torque production.

At worst, the motor will not rotate.

Hall effect ICs detect rotor position by changing their output voltage when they detect magnetic flux.

Hall Effect IC Placement in BLDC Motor

As shown the figure, the three Hall effect ICs are evenly distributed on the 360° (electrical angle) circumference of the rotor.

The output signals of the three Hall effect ICs that detect the rotor's magnetic field change in combination every 60° of rotation around the 360° circumference of the rotor.

This combination of signals changes the current flowing through the coil. In each phase (U, V, W), the rotor is energized and rotates 120° to produce S pole/N pole.

The magnetic attraction and repulsion generated between the rotor and the coil cause the rotor to rotate.

The power transfer from the drive circuit to the coil is adjusted according to the output timing of the Hall effect IC to achieve effective rotation control.

What gives brushless vibration motors a long life? Using The Hall Effect to Drive Brushless Motors. We use the Hall Effect to calculate the position of the motor and change the drive signal accordingly.

This pictures shows how the drive signal changes with the output from the Hall Effect sensors.