Simulation and Implementation of Current Control of Brushless Dc Motor Based on a Common Dc Signal

The objective of this project is to build a simple current controlled modulation technique for brushless dc motors. In electric traction and most other applications, a wide range of speed and torque control of the electric motor is required. The dc machine fulfills these requirements, but the dc machine requires constant maintenance. But the brushless permanent magnet motors do not have brushes and so they require less maintenance only. Brushless dc motors are widely used in applications which require wide range of speed and torque control because of its low inertia, fast response, high reliability and maintenance free. This current controlled technique is based on the generation of quasisquare wave currents using only one controller for the three phases. The current control strategy uses a triangular carrier for the power transistors which is simpler and more accurate than any other options. The advantages of this technique are: a )The stator currents are completely characterized by their maximum amplitude , b) The three phases are controlled with the same dc component , and then the phase currents are kept at exactly the same magnitude I max, c) The dc link current measurement is not required .d) phase currents are kept balanced and phase over currents are eliminated