A low-cost sensorless BLDC motor drive using one-cycle current control strategy

One-Cycle Control (OCC), as a unified constant-frequency integration control strategy for current control of brushless dc (BLDC) motor drive is presented in this paper. Employing the one-cycle control strategy reduces high frequency torque ripple of conventional hysteresis current controllers that leads to lower acoustic noise and vibration of the drive. Moreover, to enhance reliability and reduce total cost of the drive, an improved low-cost rotor position estimation strategy is implemented. It is based on detection of the true back-EMF zero-crossing points that can be directly extracted by detection of voltage between phase terminal and midpoint of dc link without motor neutral point voltage. Total operations of OCC strategy and sensorless method are realized by a low-cost general-purpose AVR microcontroller (Atmega8) that leads to a low-cost, high performance sensorless BLDC motor drive. Computer simulations using Matlab simulator, have been presented to show characteristics of this solution. Experimental results with a 230 W, 14 poles BLDC motor, show improved behavior of developed sensorless BLDC drive in both steady-state, and transient situations.