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Chapter One: Brushless DC Overview
Brushless DC (BLDC) motors are permanent-magnet, synchronous motors that convert
electrical power into mechanical power. BLDC motors work according to the attraction
and repulsion principle of magnetism, along with the Lorentz force law, which states that
force is created when a current-carrying conductor is placed in a magnetic field. As Figure
1 illustrates, BLDC motors have a simple design, with two primary features:
• A rotor with two permanent magnets: one positive and one negative
• Stators with coil-winding armatures that create a magnetic field when switched on
BLDC operation begins with the controller, which has two primary functions. First, the
controller receives data about rotor position, which is critical to the motor's operation.
Brushless DC Overview
Chapter One
"Precise motor position
information enables us
to drive the motor with
high torque."
Bhanu Villuri
Lead Project Engineer,
Stanley Black and Decker, Inc.
Figure 1: In BLDC motors, magnetic interactions occur between each stator's coil windings and the rotor's
permanent magnets. (Source: Renesas)
