BLDC Motor Controllers: Features & Types

Sinotech    April 9, 2013

When you look through a DC motor catalog, you’ll notice that no two BLDC motor controllers are alike. Because they’re often used for applications that require variable or adjustable speeds, BLDC controllers must be flexible enough to suit the application. Some controllers simply provide the electronic commutation to make the motor operate as well as the ability to reverse direction.  More complex controllers may integrate a programmable microcontroller so that the user can program lots of motor functions.  Some BLDC controllers are small enough to put inside the motor case.  These “embedded” controllers make it easy to substitute a high performance BLDC motor for a brush type DC motor.

A controller employs integrated-gate bipolar transistors (IGBTs) or field-effect transistors (FETs) to power a motor’s coils. To switch the current between a BLDC motor controller’s different phases, it uses electronic commutation drive coils. To ensure the motor serves its intended purpose, you’ll need to determine which functions you seek from the motor controller.  Sinotech’s motor consultancy services can make motor selection customization easy.

Features of BLDC Motor Controllers

  • Automation: Allows for use with external control circuits.
  • Construction:  Uses a heat sink to dissipate power from the IGBT’s and FET’s.  The PCBs of some controllers at potted in epoxy to prevent damage due to vibration or moisture.
  • Sensors:  The output of the motor’s Hall effect sensors provide the feedback to the BLDC controller to assure constant speed or torque as needed.  Some controllers are designed to operate BLDC motors that do not have Hall effect sensors yet still control speed, but not with the same precise control.
  • Speed control: The controller may have inputs for applying linear voltage control as well as  inputs for using Pulse Width Modulation (PWM) for controlling BLDC motor speed.
  • Efficiency: A well designed controller plus a high efficiency BLDC motor can result in overall system efficiency of 95% or more.

Check out Sinotech’s DC motor catalog for a full list of options, features and specifications.

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