This paper presents an acoustic-noise-reduction control using a random switching technique for front-end switch-mode rectifiers (SMRs) of a permanent-magnet synchronous-motor (PMSM) drive. First, the PMSM drive and its front-end ac-switch-based SMR are established. The proper controls are conducted to let the motor drive possess good driving characteristics. In the acoustic-noise-reduction control for a low-frequency SMR under a voltage closed-loop control, the important audible vibration modes of the SMR inductor are first identified from the measurements. Then, the controls for eliminating one specific vibration mode and two vibration modes simultaneously via deterministic and stochastic approaches are studied. Specifically, a novel random three-stage excitation scheme is devised. As to the high-frequency SMRs, the random switching frequency ramp-comparison current-controlled pulse-width modulation (CCPWM) scheme and the randomly varying band hysteresis CCPWM scheme are developed. Theoretical bases of all the proposed control approaches are derived, and their comparative performances are evaluated experimentally.
