A novel digital control technique for brushless DC motor drives

Brushless dc (BLDC) motor drives are continually gaining popularity in motion control applications. Therefore, it is necessary to have a low cost, but effective BLDC motor speed/torque regulator. This paper introduces a novel concept for digital control of trapezoidal BLDC motors. The digital controller was implemented via two different methods, namely conduction-angle control and current-mode control. Motor operation is allowed only at two operating points or states. Alternating between the two operating points results in an average operating point that produces an average operating speed. The controller design equations are derived from Newton's second Jaw. The novel controller is verified via computer simulations and an experimental demonstration is carried out with the rapid prototyping and real-time interface system dSPACE. Index Terms--Brushless dc (BLDC) motor drives, digital control, electric motor drives, inverters, modeling and analysis, motion control, permanent-magnet machines, power electronic converters.