Pulse Width Modulation Of Ac Induction Motor And Without Overshoot Speed Pi Controller Study

First, the influence of power modulation waveform on the performance of a motor control system is analyzed and several new sinusoid pulse width modulation (SPWM) techniques are compared. As a conclusion, the rules of improving system performance are presented which leads to the proposal of the flat-topped sinusoid pulse width modulation technique. Calculation, simulation and experiment prove this novel technique has apparent superiority over other SPWM techniques in that it can improve the available output voltage greatly and suppress the output current harmonics effectively.Then, several modified PID control algorithms are analyzed, and a speed controller with slip regulation and PI detached algorithm is constructed, as well. A forgetting factor is introduced, which contributes to the great performance improvement of a PI controller, and a nil overshoot speed controller is implemented. With this controller a train can avoid adjusting speed frequently around the steady-state speed, consequently decrease the power consumption and provide passengers a much more comfortable environment.Finally, the serial communication of a PIC micro controller with a personal computer is introduced. By this means, the console of a train can use a computer to monitor its speed governing system by attaining and processing the real time status of the system, and sending the corresponding commands.