Brushless DC (BLDC) motors are becoming more common in the automotive and industrial markets due to their high power density, efficiency, and reliability. A BLDC motor controller is required to operate a BLDC motor. The controller replaces the mechanical commutation system used by a Brush DC Motor with an electronic commutation system.  The controller detects the position of the rotor either by using sensors or sensorless. The sensors measure the rotor’s position and send out this data. The controller receives the information and enables the transistors to switch the current and energize windings[1].

When selecting a BLDC motor driver, there are several considerations to remember, including:

  • Integrated FETs,
  • Interface settings,
  • Protection features,
  • Thermal management.

Integrated FETs are suitable for low-power applications (<70 W), while external FETs are better for high-power applications. Before spinning a BLDC motor, there are many driver settings that must be configured and tuned appropriately. Protection features such as overcurrent protection, overvoltage protection, under-voltage lockout, and thermal shutdown protect against damage caused by faults or abnormal operating conditions. Thermal management is essential for preventing overheating of the motor driver and prolonging its lifespan.

BLDC motor controllers differ according to the method they use to detect the rotor’s position. You can make the measurements with the help of position sensors or using a sensorless technique.

There are plenty of options among sensors, including:

  • Hall-effect sensors,
  • Rotary encoders,
  • Variable reluctance sensors,
  • Resolvers,
  • Optical sensors.

The sensorless BLDC motor controller works without a sensor; it detects the rotor’s position by estimating back electromotive force (back EMF). This is the voltage created in the stator’s windings by the rotating armature. By measuring the back EMF, you can determine the position of the rotor: the closer the rotor’s magnet, the higher the back EMF.[2]

When selecting a BLDC motor, torque is a crucial consideration. Torque ratings determine how much load a motor can handle without stalling or overheating. Speed selection depends on occasions of adjustable power supply voltage; specifications whose torque and speed are close to the corresponding rated value of the product can be selected according to actual needs.[3]

In summary, when selecting a BLDC motor driver or motor, it is essential to consider factors such as integrated FETs or external FETs for low- or high-power applications respectively; interface settings; protection features such as overcurrent protection; Undervoltage lockout; thermal shutdown; torque ratings; speed selection based on adjustable power supply voltage.

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