Research On Inverter Controlled Hydraulic Elevator Energy-saving System Applying Pressure Accumulators

The completed dissertation "Research on inverter controlled hydraulic elevator energy-saving system applying pressure accumulators" is supported by National Science Foundation Project-" Foundation Research of energy-saving and innovation system on Mechanical/Fluid Power Transmission"(NO.59835160).This dissertation focus on a innovation methods for inverter controlled hydraulic elevator system applying pressure accumulator as the "pressure-energy transformer". The required power supply and running energy can be reduced remarkably when accumulators storing and releasing pressure oil. Then the key items about hydraulic speed control system based on the ENS 1-2 and other hydraulic elevator standards are investigated in detail. At last, the energy-saving comparison research between the project and other hydraulic systems is completed.The first chapter in this thesis generally introduce the development of hydraulic elevators based on relevant publications search and market investigation. With summarization of hydraulic elevators innovation system, applied fields and market competence, the necessary and importance of reducing energy consumption for hydraulic elevators are illustrated. And then the recently new development of hydraulic elevator control systems and its limits are discussed. At last, the project significance, background, main research contents and key innovation points are provided.The second chapter simply introduces the development of alternate asynchronous inverter technology and retrospects some types of energy-saving systems for hydraulic elevators. Then the working principles of the project are discussed and analyzed at four different working status, i.e. light load upwards, heavy load upwards, light load downwards and heavy load downwards. And the chapter focus on the introduction of structure design of pump station, calculation and type selection of pump/motor reversible units, research on oil leakage principles of accumulator circuit, design of accumulator-pump/motor pressure-energy transformer and integrated valve blocks, etc. The last but not the least, the electrical wiring of vector inverter control cabin and design of computer control and data acquisition system are introduced.In the third chapter, the mathematical models of project system have been established, and simulation has been done on the Simulink enviroment of Matlab software kits. The simulation focus on the effects of main parameters on the dynamic characteristics of speed control system, and the main parameters include viscosity damp coefficient and friction torque of electrical motor shaft, internal leakage coefficient of pump/motor of hydraulic circuits, gas volume of pressure accumulator, viscosity damp coefficient of cylinder piston and different running building floors, etc. At last, theoretical research effects of the flow and pressure pulsation of pump/motor on car speed and oil volume leakage theory are discussed.The fourth chapter of this thesis concerns the research on the key items about hydraulic power control system according to the ENS 1-2 and other hydraulic elevator standards. The key items include the car sinking, constant speed characteristics, inspection function, auto relevellingfunction and level accuracy, etc. The research contents focus on the following three parts: Firstly, Research on effects of system parameters on car sinking has been completed. Secondly, the constant speed performance with the compensation of internal leakage of pump/motor is improved. Lastly, Research on improvement of the car level accuracy and contrast to that of traction elevators is presented, and the reasons of low car level accuracy of hydraulic elevators are discussed.In fifth chapter, analysis of reducing required power supply and running energy consumption are the main research contents. According to test hydraulic elevator rig, the following contents are completed: Firstly, comparison with traction elevators, the research on required power supply and energy consumption are presented. Secondly, Resear...