A Phase-Locked-Loop-Assisted Internal Model Adjustable-Speed Controller for BLDC Motors

In this paper, a phase-locked-loop (PLL)-assisted internal model (IM) adjustable-speed controller for brushless DC (BLDC) motors is proposed. Major contributions include proposing a new adjustable-speed module structure of PLL controllers for BLDC motor drives and integrating an IM control strategy and a novel complete motor current sensing scheme. By employing the proposed PLL-assisted IM control method, the controller can be made more robust and accurate. In addition, due to properly integrating the motor current sensing scheme with the pulsewidth modulation control, the hardware implementation of the BLDC motor drive can be made rather compact and enable further integration into chips to reduce the cost and enhance the current regulation performance. Finally, a prototype of the proposed controller is also constructed and applied to an industrial blower to verify the feasibility of the proposed control. Experimental results show that both accurate steady state and fast transient speed responses can be achieved. Moreover, compared with the conventional induction motor drives for industrial blowers, the proposed PMBLDC drives can achieve much higher efficiency with less volume and weight.