Any difference - BLDC vs PM?
Any difference - BLDC vs PM?
(OP)
What is the difference between a BLDC motor and a permanent magnet motor? Same thing?
=====================================
Eng-tips forums: The best place on the web for engineering discussions.





RE: Any difference - BLDC vs PM?
RE: Any difference - BLDC vs PM?
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Any difference - BLDC vs PM?
To expand on CJCPE's response, the permanent magnets can either be on the stator or the rotor. If they are on the stator, the armature is on the rotor, so brushes and a commutator bar are necessary to get the current into the spinning rotor. This is a PM brush DC motor.
If the permanent magnets are on the rotor, the armature phases are on the stator, so no brushes are required to connect the phases. This is a PM "brushless DC" motor -- a horrible term, but one we are stuck with. (BLDC is a marketing term -- these motors with accompanying drives were originally sold as drop-in replacements for brush DC motors with their drives. These are technically AC motors -- you must feed the motors AC waveforms to get continuous movement in one direction.)
Curt Wilson
Delta Tau Data Systems
RE: Any difference - BLDC vs PM?
I've taken apart a fair number of them. Even the little 5VDC fans are BLDC, with a small PWB of parts.
Their typical construct is a rotor of PMs and stator coils on the outside driven by the electronics on the board.
TTFN
RE: Any difference - BLDC vs PM?
BLDC is in reality a synchronous motor with permanent magnet rotor, normally the stator has 3 phases and the DC power supply is converted to AC feeding the stator winding. The idea is to eliminate the mechanical commutator and brushes.
The PM DC motor is a traditional commutator motor with a fix field provided by permanent magnets.