Direct Torque Control Of Five-phase Induction Motor Based On DSPACE

With the development of power electronics technology, multiphase motor control system has been developed rapidly. Compared with the three-phase motor, multi-phase motor has more controlling freedom, which can achieve high power with low voltage. And the multiphase motor has been used in a wide range of application, such as ship propulsion and aerospace, but the theory of multiphase motor control still need to be further improved. Under this background, the research of the direct torque control of five-phase induction motor is carried out.This paper analyses the multiphase motor’s magneto motive force (MMF) based on the winding function theory. Multi-freedom of multiphase motor is explained according to the analysis of time and space harmonics. Five-phase induction motor has two mutually orthogonal planes after coordinate changes. Each plane can be controlled separately to achieve the control of five-phase induction motor. The analysis of multiphase motor’s mathematical model lay the theoretical foundation for direct torque control of multiphase induction motor.The experimental platform are finished for the five-phase induction motor’s direct torque control system, including the motor control algorithm programming by MATLAB/Simulink based on the dSPACE’s motor control libraries, the test cases designed by the dSPACE’s ControlDesk, and the design of signal conversion board to connect the five-phase induction motor and the dSPACE.This paper analyzes the reasons for the existence of a large current harmonic in the traditional direct torque control. In consideration of the fact that the five-phase induction motors can be controlled at two planes, the current harmonic can be eliminated, by selecting a certain voltage vector to make the harmonic plane synthesized voltage vector zero. However, the torque ripple harmonics of the harmonic eliminating space vector modulation control is still large. Therefore, this paper considers improving the harmonic eliminating space vector modulation by optimizing duty algorithms. Three common duty algorithms are discussed, and a novel duty algorithm is proposed. This novel algorithm makes the difference between average of the maximum and minimum torque and the given torque to be least.Finally, the experiments are carried out at the dSPACE experimental platform, to test the performance of traditional direct torque control and novel direct torque control based on the new duty algorithms. The experimental results show that the new algorithm not only has better steady-state current, but also has good torque response.