UBC Theses and Dissertations
Designing and implementing a DSP based variable-speed drive for theatre stage systems Li , Yan
Today's power electronics technology and digital control system provide a convenient means to boost the performance of electrical drive systems. While the industry has witnessed a variety of applications of electrical variable-speed drives, this work is focusing on designing and implementing a DSP controlled 3-phase variable-speed drive for a theatre stage system to achieve automatic operations and accurate position control. A cascade structure with feed-forward reference is selected as the control algorithm for this application. As a key factor in motion control, profiles of acceleration, speed and position (ASP) are also investigated. A trapezoidal speed profile with limited jerks is recommended for the final implementation. In addition, some operational conditions for safe and agreeable operations have been discussed and identified. Before proceeding with the experiment, the dynamics of the whole system including the controller, the voltage source inverter, the induction machine and the stage has been evaluated by MATALB/Simulink. The non-linear behavior of induction machines is studied and a linearized induction machine model under variable-frequency conditions is developed to verify the closed loop stability of the whole system. A test facility is then constructed to validate system performance. A DSP controlled 3-phase inverter is built and tested. Multiple measures are implemented into the IGBT drive for obtaining immunity to high common-mode dv/dt noise. Quantitative methods for sizing the gate resistor are also presented in this paper. Four different motion control algorithms are employed to find the most suitable for this application. Both experimental and simulation results indicate that closed loop position control is critical to achieve required accuracy of position for the stage system.