Electromagnetic Emission of BLDC Motor Controllers

The electrically commutated brushless direct current (BLDC) motors are constantly displacing conventional brushed DC motors in industrial usage, especially in the automotive industry. During the research, we investigated the electromagnetic noise emission of a BLDC motor operating a car engine cooling fan. During the determination of electromagnetic noise, we performed near-field measurements and examined the directed fields. The emission of the control electronics of BLDC motors with different phase and pole numbers was measured in three directions, with two antenna polarizations per direction. These data can be used to outline a three-dimensional radiation characteristic. The measurement results were compared, and the result was obtained to what extent and to which controlled electromagnetic noise emissions each component of the BLDC motor is responsible.