A novel sensorless starting method of BLDC motor for large inertia systems

This paper designs a new position sensorless starting method of brushless DC (BLDC) motors, specialized for large inertia systems to prevent integration commutation error caused by linearized approximation. In the large inertia system, the starting process of BLDC is much longer than the one in common system due to the limitation of the feasible driving torque, and thus the conventional sensorless starting methods based on linearized approximation are prone to be instable or even fail. Here, we utilized I/f starting method instead of traditional V/f starting method, and then deduced a precise computational formula for commutation directly. Experimental results show that the proposed method could better adapt to large inertia systems comparing with state-of-the-art linearized approximation methods.