Implementing Embedded Speed Control for Brushless DC Motors: Part 1
Brushless Direct Current (BLDC) motors, also known as permanent magnet motors, are used today in many applications. A new generation of microcontrollers and advanced electronics has overcome the challenge of implementing required control functions, making BLDC motors more practical for a wide range of uses.
We begin Part 1 of this paper with the basics of BLDC motors, including their construction and operation. Fundamental equations for force and torque generation are presented, along with the basic control electronics necessary for proper deployment. We discuss 120-degree modulation and a six-step method for operating the motor. Then we see how the modulation can be implemented using Hall sensors and back-EMF signals. Implementation examples make use of a microcontroller unit (MCU), which leads to a discussion of the necessary features of on-chip timers and interrupt handling within the MCU.