It is reported that the electric energy consumed by various electric motors in the world today accounts for 65% of the world's energy consumption. With the attention to environmental issues, the use of high-efficiency drives is on the agenda. Therefore, the permanent magnet brushless motor that replaces the traditional induction motor has recently received great attention in the industry. This is because permanent magnet brushless motors have higher efficiency and higher power density.

　　Modern motor and control technology divide the permanent magnet brushless DC motor into two categories based on the current drive mode: square wave drive motor and sine wave drive motor. The former is called a brushless direct current motor (BLDC) or an electronically commutated direct current motor (Electronically Commutated Motor, ECM), the latter was once called a brushless alternating current motor (BLAC), and is now often called a permanent magnet synchronous motor (PMSM).

　　On the surface, the basic structure of BLDC and PMSM is the same: their motors are permanent magnet motors, the rotor is composed of permanent magnets, and the stator is equipped with multi-phase AC windings: both are permanent magnets (PM), the rotor and the stator The AC current interacts to produce the torque of the motor; the drive current in the windings must be synchronized with the rotor position feedback. The rotor position feedback signal can come from the rotor position sensor, or by detecting the back electromotive force (EMF) of the motor phase winding as in some sensorless control directions. Although the basic structure of the permanent magnet synchronous motor and the brushless DC motor is the same, the actual design details are different from how they are driven.

　　This article is taken from ------"Permanent Magnet Brushless DC Motor Technology"