Research On Elevator Motion Control Based On Permanent Magnet Synchronous Motor

Elevators are used as vertical transportation in human life. As the demand of the living quality rises, performance of the elevators must be improved to meet the requirements based on stability. Permanent Magnet Synchronous Motor(PMSM) drived gearless traction system represents an advanced technology in the elevator system. The drive system of PMSM determines the ride comfort and energy saving capability, and also influences the cost of the elevator system. Technologies to improve the mentioned performance are studied in this dissertation.The drive system is composed of several parts according to the function. Each part is analyzed in detail. Hardware circuit design principle, components choosing, and software realization are provided. Moreover, the design principle of the experimental prototype in this dissertation is also described which can be refered in the drive system development.Factors concerned with PMSM control are analyzed including the rotor structure, mathematic model of PMSM, main control strategies, id=0 control diagram, model decoupling and dual loop controller desgin. Speed profile which meets the ride comfort requirements is described in detail. A novel speed profile tracking method is proposed based on the acceleration control. The feasibility is verified with experimental results at typical loads and ride distances. Torque ripples from different sources are inserted into the linear control model of the PMSM to analyse their influence. The current loop is improved with the stator resistor voltage compensation to increase the gain at low frequency. A novel scaling method for sinusoidal encoder is proposed to improve the rotor position identification resolution. And speed detection lag and quantization error can be reduced. Suggestions are also provided to suppress the influence of speed detection quantization error.From the perspective of system cost saving, contorl algorithms are studied to achieve load torque identification and initial rotor position identification. The car slides due to weight imbalance at brake releasing. Traditionally, electromagnetic torque is generated to cancel the imbalance before brake releasing with extra sensor or transducer which increases the system cost. This dissertation proposes a electromagnetic torque gradually convergent seeking method and an optimized PI controller based method to identify the load torque. The performances comparison between the two methods indicates that the former method can achieve short sliding distance but unstable, while the latter method can guarantee the stabiliy but with longer sliding distance. This dissertation also proposes a novel method to identify the initial rotor position based on inductance saturation effect, and the feasibility of this method is also verified with experimental results.A three-phase rectifier is introduced into the drive system to provide unity power factor and feed the regenerated energy to the grid. The phase lock loop(PLL) of the three-phase rectifier is studied and this dissertation proposes a method to improve the phase lock dynamic response and realize fast phase sequence identification. The system stability with the PI parameters designed based on the linear model is also approved with Lyapunov stability theory. Energy dissipation experiments are executed at typical work conditions. The analysis of the experimental results concludes that the energy saving effect is remarkable at dedicated work conditions like full load and empty load with noninterrupt distance. The prototype and experimental elevator are shown at the end of this dissertation.