Temperature Field Of High Speed Permanent Magnet Synchronous Machine Used On The Flywheel Storage System And The Discharge Process Of System

Flywheel energy storage has many advantages,including higher energy density,higher power density,longer cycle life,charge and discharge rapidly,maintenance-free and less pollution to environment and so on.Because of these,flywheel energy storage has broad application prospects in many fields.The high-speed large-capacity flywheel energy storage system received more and more attention.As a key component of electromechanical energy conversion of high-speed large-capacity flywheel energy storage system,the high-speed high-power permanent magnet M/G directly affects the performance of flywheel storage system.High speed permanent magnet M/G has high rotational speed and high power density,while its unit losses is relatively larger as well,which would lead the temperature rise of rotor.This will affect the performance of the permanent magnet and even lead to demagnetizations.Therefore,it is of great significance to study the influence of the structure and sleeve of rotor on the temperature field of the permanent magnet motor.The load would affect the magnetic field of motor during the discharge process of flywheel system,thus affecting the discharge efficiency and time of system.Therefore,to improve the discharge performance of the flywheel system,it is of great significance to study the effect of the load on the discharge process of the flywheel motor.In this thesis,a 200kW,15000r/min high speed permanent magnet motor has been studied.The losses and temperature distribution of the motor were analyzed while the motor adopts different rotor structure,sleeve selection and driven by the controller.Considering the design characteristics of high-speed permanent magnet motor,the design scheme of motor is researched.The 2-D transient finite element model of 200kW permanent magnet motor is established.The influence of the core height between the permanent magnet on the losses of the motor is analyzed,and a method of improving the magnetic field waveform of the main pole to reduce the loss of the motor is proposed.The relationship between the shape of the permanent magnet and the direction of magnetization and the losses of the motor is studied.To reduce the losses of motor,the influence of the length of the air gap and the thickness of the sleeve on the losses of the motor is analyzed.And the influence of the materials and composite structure of sleeve on the losses of motor is studied.A three-dimensional global finite element temperature calculation model of 200kW motor is established,to reduce the rotor temperature rise of the motor,the influence of material and the composite structure of the rotor sleeve on the temperature distribution of the motor is analyzed.The temperature varieties of the motor with single material and composite structure sleeves is studied.The influence of winding current time harmonics caused by variable frequency control on the losses and temperature of the motor is analyzed.The research contents provide a reference for reducing the temperature rise of the high speed permanent magnet motor.Lastly,the discharge process of flywheel storage system is studied.In order to improve the storage density of the flywheel storage system,the energy storage and density of the flywheel with different structures are analyzed.Consider that the change of the magnetic field in the motor caused by the armature reaction during the discharge process,the effect of load on the discharge efficiency and time of the motor was studied The effect of magnetic field variation on discharge efficiency during the constant voltage discharge process was analyzed.