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Reverse direction of BLDC motor

Before diving into the BLDC motor feedback options, it’s important to understand why you need them. BLDC motors can be configured for single phase, two phase and three phase;The most common configuration is three-phase.The number of phases matches the number of stator windings, while the number of rotor magnetic poles can be any number depending on the application requirements.Since the rotor of the BLDC motor is affected by the rotating stator poles, the stator pole position must be tracked to effectively drive the three motor phases.For this purpose, a motor controller is used to generate a six-step commutation mode on three motor phases.These six steps (or commutators) move the electromagnetic field, which in turn causes the rotor’s permanent magnet to move the motor shaft.

By adopting this standard motor commutation sequence, the motor controller can utilize the high-frequency pulse width modulation (PWM) signal to effectively reduce the average voltage borne by the motor and thus change the speed of the motor.In addition, this setting greatly improves design flexibility by having one voltage source available for a wide variety of motors, even when the DC voltage source is significantly above the motor’s rated voltage.In order for the system to maintain its efficiency advantage over brush technology, a very strict control loop needs to be installed between the motor and the controller.This is where feedback techniques are important;To maintain accurate control of the motor, the controller must always know the exact position of the stator relative to the rotor.Any misalignment or phase shift in expected and actual positions may result in unexpected conditions and performance degradation.There are many ways to achieve this feedback with respect to the commutation of BLDC motors, but the most common is to use hall effect sensors, encoders, or rotary transformers.In addition, some applications also rely on sensorless commutator technology to achieve feedback.