Simulation, design and implementation of permanent magnet motor drive

Abstract

Abstract This study presents the design of a Permanent Magnet Synchronous Motor (PMSM) and its drive system. In order to design the drive, an extensive literature study on PMSM drive systems was carried out. The principles of two drive control strategies, Flux Oriented Control (FOC) and Direct Torque Control (DTC) are presented. Based on the mathematical model developed using the literature study, a simulink model is developed for each of the two drive topologies.

Simulations are made on the two system models, where both the models are exposed to the same two load scenarios. The aim of the simulations is to test and compare the systems ability to handle dynamic and stationary load-characteristics.

The results of the simulation supports the claims of literature study, that the DTC has a much better transient response to load changes than the FOC. In the simulation where load torque is instantly reduce with 40% the DTC drive system reaches the steady state five times faster than the FOC.

The FOC shows its strength in its steady state operation delivering much smaller ripple than the corresponding DTC drive. Simulations of the 40% load reduction scenario shows that the FOC system has a 1Nm torque ripple amplitude compared to the DTC system, which has a toque ripple amplitude of 5Nm.

The last objective of the thesis was investigating possibilities for testing the generated code from the Simulink models on a hardware system. The original plan was to implement the code into a DSP, generating switching signals for an inverter feeding the PMSM. Considerable work was put in to this task and attempts using software from both National Instruments and Texas instruments was made to complete the task. At the end of the thesis the interface between Mathworks Simulink and Texas Instruments code composer studio was established. It is possible to use this interface to implement the simulated drive topologies in the laboratory. The validation of the simulated control topologies in the laboratory is one of the important possibilities for further work.