01 Thanks to technological advances, integration is taking over the motor control market. Brushless DC motors (BLDC) and permanent magnet synchronous motors (PMSM) of all sizes and power densities are rapidly replacing motor topologies such as brushed AC/DC and AC induction.
02 BLDC/PSM motors are mechanically identical, with the exception of the stator winding. They have a different geometry for the stator winding. The stator is always opposite the motor magnet. These motors provide high torque at low speeds and are therefore ideally suited to servo motor applications.
03 Brushless DC motors and permanent magnet synchronous motors eliminate the need for brushes and commutators to drive the motor and are therefore more efficient and reliable than brushed motors.
04 Brushless DC motors and permanent magnet synchronous motors use software control algorithms to drive the motor instead of brushes and mechanical commutators.
05 Brushless DC motors and permanent magnet synchronous motors have a simple mechanical structure. The motor has an electromagnetic winding on the non-rotating stator. The rotor is made of permanent magnets. The stator can be internal or external and is always on the opposite side of the magnet. However, the stator is always the stationary part, while the rotor is always the moving (rotating) part.
06 Brushless DC motors can have 1, 2, 3, 4 or 5 phases. They may have different names and drive algorithms, but they are all essentially brushless.
07 Some brushless DC motors have sensors that help to obtain the rotor position. Software control algorithms use these sensors (Hall sensors or encoders) to assist in motor commutation or motor rotation. These brushless DC motors with sensors are required when the application needs to be started under high loads.
08 If the brushless DC motor does not have sensors for obtaining the rotor position, mathematical models are used. These mathematical models represent sensorless algorithms. In a sensorless algorithm, the motor is the sensor.
09 Brushless DC motors and permanent magnet synchronous motors offer some important system advantages compared to brushed motors. They are able to drive the motor using an electronic commutation scheme, which can increase energy efficiency by 20 to 30 percent.
10 Many products today require variable motor speeds. These motors require pulse width modulation (PWM) to vary the motor speed. Pulse width modulation provides precise control of motor speed and torque, allowing for variable speed.