In this paper, in order to reduce the electromagnetic noise generated in the BLDCM of the vehicle fuel pump, a method of driving in the PMSM mode instead of the conventional BLDCM mode is proposed. In the BLDCM mode, noise is generated by rapid increment or decrement of currents in the stator windings, harmonic components of square-wave currents, and torque ripple. When driving in PMSM mode, there is no commutation period and sinusoidal current always flows smoothly in three-phase winding, so there is no quick change of current, and since it contains little harmonic current component, torque ripples are greatly reduced, and accordingly electromagnetic noise and vibration are also decreased.
In order to verify the proposed method when driving an vehicle fuel pump, simulations and experiments were conducted to measure the speed control performance respectively for starting and load change. From this, it was confirmed that PMSM mode and BLDCM mode showed equivalent control performance. In addition, the frequency analysis of the phase current in the stator winding was performed, and it was confirmed that the harmonic content is greatly reduced in the PMSM mode compared to the BLDCM mode.
The noise and vibration actually generated when driving in the BLDCM mode and PMSM mode were measured in the semi-anechoic chamber. The noise and vibration of each driving mode were generally increased as the rotational speed increased, but in the PMSM mode decreased compared to those in BLDCM mode. In particular, it was confirmed that the noise is decreased in the range of 2,000∼5,000[Hz], which is sensitive to human hearing. In addition, the change in the magnitude of the noise according to the load was analyzed. In BLDCM mode, noise and vibration increased with increasing load. However, even if the load increased in PMSM mode, there was no difference in noise, so the excellent characteristic of reducing noise was confirmed.
If the PMSM mode proposed in this paper is applied to the BLDCM used in the vehicle fuel pump, the electromagnetic noise is reduced, and the driver’s hearing noise in the vehicle can be expected to be further reduced. And even if the load of the motor increases, it can be expected that the noise does not increase.