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With the rapid evolution of Industry 4.0 and the Internet of Things (IoT), coupled with the push for higher efciency in motor control, brushless direct current (BLDC) motors are being used increasingly in diverse application segments. Examples include: 1. Industry and automation, for blowers, cooling fans, and industrial robotics 2. Emerging high-tech, for drones, gimbal control, and collaborative warehouse robots 3. Home applications, for power tools and vacuum cleaners When a motor is selected for an application or system, designers focus principally on response time to speed/torque commands, noise level while spinning, and power efciency. While all BLDC motor control topologies share a common "backbone"—motor control scheme/algorithm (digital part, "commutation logic") + pulse-width modulation (PWM) + power stage (analog/power, "inverter")—some applications come with specic requirements and system considerations. Overview of BLDC Motors Brushless DC motors offer multiple technical advantages. Among them: • High efciency • Smooth and silent spin • Low torque ripple • Fast response time Moreover, the cost of BLDC motors and associated controller circuitry have fallen signicantly over the past decade. Thus both technical advantages and lower cost have accelerated BLDC motor adoption in numerous application domains worldwide. From an application perspective, BLDC motors are mainly used to accomplish one of two types of motion patterns: spinning or positioning. The motion pattern required, and the specications of the motor selected (e.g. rated voltage, current, and revolutions per minute (RPM)), are key factors in dening the appropriate electrical motor control design to employ. From an electrical design and thermal optimization standpoint, an integrated topology (six metal-oxide semiconductor eld-effect transistors (MOSFETs) built into the motor driver integrated circuit (IC)) is preferred when the required motor phase current is low (e.g. less than 2-3A), while a discrete topology (six discrete MOSFETs mounted on the printed circuit board (PCB)) does a better job with higher currents (e.g. above 10A). This is because heat dissipation is easier to manage with discrete packages, and they typically have lower on-resistance and therefore lower dissipation. Spinning In a spinning motion pattern, the speed-loop and current/ torque-loop can typically be included in the motor control algorithm. Regarding the resulting motor phase current waveform, trapezoidal and sinusoidal control schemes are the two main options. For some applications, sensorless control schemes that depend on electrical feedback from the motor, like back electromotive force (BEMF) and current sensing, are By Cheng Peng, STMicroelectronics Design Considerations for Brushless Direct Current Motor Control Cheng Peng is an ST analog product marketing principal engineer for the Americas region.Cheng has covered several system, application and marketing positions in semiconductor industry since 2001. He holds a Ph.D. in Electrical Engineering from Texas A&M University. 07