Hardware Design of a Sensorless Three-Phase Brushless DC Motor Driver with Simple Control Flow Based on Direct Digital Synthesis

This paper proposes a three-phase Pulse Width Modulation (PWM) waveform generator design method based on Direct Digital Synthesis (DDS) technology for sensorless three-phase brushless DC motor drive systems to achieve high-precision and low-complexity motor control. Conventional sensorless brushless DC motor drive systems typically rely on hardware circuits or complex algorithms for commutation control. The scheme proposed in this paper generates three-phase PWM signals with adjustable frequency and phase by DDS technology, and realizes accurate motor commutation and speed regulation by integrating back electromotive force (BEMF) zero-crossing detection. The proposed design significantly reduces the complexity of traditional sensorless brushless DC motor drive systems, thereby decreasing the size and cost of the driver. Both experimental and simulation results demonstrate that the developed driver can effectively achieve motor commutation and speed control without position sensors, providing a feasible solution for lightweight brushless motor drive systems.