Low-noise external rotor BLDC motor for fan applications

Abstract

An important market for brushless DC (BLDC) motors is fan applications, where low acoustic noise is of increasing importance. External rotor motors are especially advantageous for space-saving fan-motor-units. The acoustic noise of the motor can be influenced considerably through commutation strategy. The commutating process has been analyzed using space vectors. Motor noise has been reduced significantly using new modulation strategies.