Research On Direct Drive Elevator Control System Supporting New Energy Access

At present, the usual elevator speed control system still adopts uncontrolled rectifier technology, which causes serious energy consumption. The dual-PWM speed control system is considered to be an important research direction in elevator energy-saving drive technology area due to its high power factor, low harmonic pollution, bidirectional energy flow, etc. However, the core technologies of the dual-PWM speed control system are still relied on importing in our country, which greatly restricted the development of new energy-saving elevator industry. Therefore, this thesis gives theoretical study on the drive technologies of new energy-powered dual-PWM speed control system. The control strategies of gird-side and motor-side convertor are both discussed comprehensively. Simulations and experiments demonstrate the correctness and feasibility of research results.Firstly, the mathematical modeling of convertor system has been discussed. Model of three phase voltage-type PWM rectifier and PMSM in the two phase synchronous rotating dq coordinate axis are established.Secondly, the operational principle and the control strategies are discussed. The new energy-power connected into this system which is fluctuating causes the instability of DC bus voltage of the grid-side convertor. The nonlinear control strategy based on Lyapunov function onsidering DC-side loader current compensation in d-axis current setting is discussed. And the nonlinear control strategy of improving the reactive current control speed to achieve the DC bus voltage stable is also discussed. Aiming at the requirement of high accuracy parameters, anti-saturation strategy is also discussed with outer voltage-loop and inner current-loop control strategy. And aiming at motor-side converter, the nonlinear strategy based on Lyapunov function is also discussed with outer speed-loop and inner current-loop strategy.Thirdly, the hardware circuits of the control system are design. The minimum control system based on TMS320F28335,12 channels isolated fly-back switching power, the main circuit and signal conditioning circuits are included. And each part of these circuits is produced and debugged.Fourthly, the control flow of the system is designed. And the converter control programs including the main program, grid-side control program, motor-side control program, AD sampling program and serial communication program are debugged. A PC monitoring system based on Visual Studio2010.NET is developed by using C# language, which is facilitated to monitor the status of the converter system.Finally, the experimental platform of dual-PWM speed control system is builded. And the proposed nonlinear control strategies based on Lyapunov function are proved by the experiment. The obtained experimental results are consistent with the theoretical analyses, which verify the correctness and feasibility of the design of speed control system.