Hardware Engineer’s Guide to a Brushless-DC Motor Controller: Design and challenges

Brushless-dc (BLDC) motors have best-in-class torque to weight ratio, high efficiency, and effective control algorithms, which make them effective solutions in applications requiring high power density, such as cordless power and garden tools, unmanned aerial vehicles (UAV), robotics, and others. Improvements in semiconductor packaging technology, motor control algorithms, and power management integrated circuits (ICs) have increased the industrial uptake of BLDC motors. High-power battery-powered motor-drive solutions require power levels ranging from a few watts to hundreds or even thousands of watts. High wattage systems require high motor currents, resulting in design challenges of system losses and thermal management. A system designer’s challenge is to accommodate all the functionalities of a motor controller in a compact form for the whole range operation. Typically, a motor controller uses an analog signal chain, analog power management, and digital components with both signal and power traces on the same board. A well-designed printed circuit board (PCB) is required for the system to operate efficiently. This article lays the guidelines for designing a BLDC motor drive PCB.