What are the similarities and differences between brushless DC motor and AC brushless motor?
Brushless DC (brushless, DC, BLDC) and brushless BLAC (brushless AC) (this name does not seem to be used in Chinese) are all permanent magnet synchronous motors. The two motors do not depend on the waveform of armature current and back emf. If the back EMF and armature current are rectangular waves, that is BLDC, and if it is sine wave, that is BLAC. Of course, the back EMF is rectangular, and also sinusoidal current, which becomes the BLAC operating mode, so the waveform of the current is still to be seen.
Generally used in Brushless DC generator excitation, AC motor is brushless, there is also a brush, brush motor are generally small motor, because of the need to address the short-circuit current commutation time, so the exchange of brush motor is not too large, think like DC motor, DC motor there are also problems of DC motor reversing, so don't do too much! Brushless DC motor is actually an AC motor, which is usually used in the excitation system of the generator!
The so-called brushless, no brush, is not to rely on this kind of motor brush armature current to change the polarity, and generally by the position detection device, such as Holzer, such as photoelectric encoder position detection, and then according to a control method, according to the polarity of the armature current change of position signal.
