Implementing direct torque control of permanent magnet synchronous motor by improving a new algorithm based on DSP

Permanent magnet motors receive a lot of interest since their excitation current is provided by the magnets, their losses are relatively lower, and they are highly efficient. Therefore, several studies have been carried out about permanent magnet motors during recent years. Besides, due to the recent advancements in semiconductor technologies, microprocessors, and the new control methodologies, the use of permanent magnet machines have increased in quite a few drive technologies covering computer aided manufacturing, robotics, and the electric vehicles. The rotor current variation in permanent magnet synchronous machines cannot be easily control as compared to the conventional synchronous machines, due to the fact that the permanent magnets generate constant field flux. Therefore, vector control theory is developed. The main drawback of the flux vector control is that a tachogenerator or encoder should be used for high accuracy. This makes the drive system implementation more difficult and increases the cost. In order to carry out a simplified and effective drive system, it sould be used main control papameters. In direct torque control (DTC) systems, the DC drive systems are inspired as the motor flux and the torque are facilitated as the main control parameters. In this study, a new approach is proposed on the direct torque control of the permanent magnet synchronous machine. By facilitating the permanent magnet synchronous machines structure and its mathematical model, the algorithm to be used for the direct torque control is studied. Then, the power electronic circuits, control cards, and the design of the gate drives have been performed to implement this algorithm with a digital signal processor (DSP). The proposed system and the technique are validated through the fast torque dynamic response of the system. Furthermore, a bi-directional drive is used at the generator side that helps load the machine so, some portion of the energy used in the system can be recovered to the utility grid.