High response and variable speed operated BLDC drive with current control technique

The BLDC (brushless DC) motor is characterized by linear torque to current and speed to voltage. It has low acoustic noise and fast dynamic response. Moreover, it has high power density with high proportion of torque to inertia in spite of small size drive. However, at variable-speed operation, torque and speed response characteristic is deteriorated by the motor inductance components in stator windings. It is difficult that the BLDC motor is used to the industrial application requiring a wide range of operating speeds. However in the conventional control techniques these problems are not effectively controlled. A simplified current controlled modulation technique for brushless DC motors is presented. It is based on the generation of pulses, using PI and Fuzzy logic controllers under fixed and variable speeds. The advantages of this strategy are: (a) very simple control scheme; (b) effective controlling in wide speed range of operations; and (c) the difficult of reducing the error between reference and actual signals is avoided. These characteristics allow using the triangular carrier as a current control strategy for the switches, which is simpler and better than other options. Simulations analysis has done with Matlab/Simulink to show the good characteristics of this solution, and its simplicity.