The Sensorless Control System Design Of Permanent Magnet Synchronous Motor For Oil-free Scroll Air Compressor

The oil-free scroll air compressor has no contact friction,can deliver clean and pollution-free high quality compressed air.In the oil-free scroll air compressor factory,the general inverter is still mostly adopted to drive the compressor.General inverter is suitable for different kinds of motors,but it is not designed for the of oil-free scroll air compressor,so there will be some problems,such as,motor parameters incompletely matching and debugging and installation trouble.Bsides,it’s expensive,so it is difficult to form the all-in-one matched with air compressor and only used in the debugging situations.The oil-free scroll air compressor driven by PMSM is mostly applied in the poor conditions,which is not suitable for mechanical sensor on the rotor shaft.Therefore,now PMSM sensorless control technology of the oil-free scroll air compressor become a research hotspot.This paper will develop a dedicated sensorless drive controller based According to the functional requirements and specific parameter of air compressor,which will match with the air compressor to become an integral machine.The main contents are as follows:1.Build the mathematical model of permanent magnet synchronous motor based on certain assumptions.The coordinate transformation of three phase permanent magnet synchronous motor is analyzed,and the basic vector control method and space vector pulse width modulation technology of permanent magnet synchronous motor are studied in depth.2.The sensorless algorithm of permanent magnet synchronous motor is analyzed,and the location and speed estimation models are established,which provides a theoretical basis for position and speed estimation of sensorless PMSM.Research on PMSM rotor initial position location method and put forward an improved rotor initial positioning method based on the current positioning.Study of the motor transition state of open loop switching to closed loop and put forward an improved switching method based on the continuous load.3.Focus on the design of sensorless control system of permanent magnet synchronous motor applied to all oil-free scroll compressor,analyzes structural features and working principle of the scroll compressor.Complete the design of the driver’s hardware circuit and software program.4.Build the experimental platform of permanent magnet synchronous motor for air compressor.High and low temperature test,vehicle vibration test and neutral salt spray experiment are carried out respectively.Observe the start-up and running state of air compressor and its controller in harsh environment and analyze the experimental result.5.In order to reduce the energy consumption of the air compressor,the linkage strategy of the air compressor is designed.By real-time detecting the pressure of the storage tank,the number of air compressor is dynamically adjusted.The level of automatic operation is improved,and the required working air pressure is maintained at the minimum number of air compressors.To sum up,the research results of this subject can lay a certain foundation for the application and industrialization of the oil-free scroll air compressor.