The application of magnetic encoders in induction motor vector control

In recent years, the growing environmental consciousness pushes the development of emission free road vehicles, especially the electrical vehicles. Owing to the progress in the power electronic devices, the emergence of more powerful and cheaper DSPs, and the intensive research work in control method, induction motors drive system is well developed with its robustness, maintenance freedom, high speed and power density, and vector control is one of the most important control methods. Vector control mostly relies on the existence of the speed sensor, among which are the optical encoder and the magnetic encoder. In the former part, we will summarize the features of these two kinds of encoders and several typical rotation speed measurement (RSM) methods. Then comes the main part, the application of magnetic sensors using new RSM method in induction motor vector control. We focus on the performance of induction motors with several kinds of power levels, adapting to a 90 pulse/round magnetic sensor with count multiplication process. To obtain the best performance, we improve the control method. Some data and figures are provided to compare the performance of magnetic sensors with optical sensors. Finally, some conclusions are presented.