Study On The Key Technique In Design Of Middle Capacity High Efficiency Permanent Magnet Synchronous Motors

As the partial contents of "Applied Development of NdFeB Permanent Magnet Electric Machine" in National High-Technology Research and Development (863) Program of China, the key technique related to the design of middle capacity high efficiency rare earth line start permanent magnet synchronous motor are analyzed and studied systematically. Some results with important engineering applied value are obtained.Five parts of this thesis are included as follows:At first, the type of magnetic structure in rotor for middle capacity high efficiency asynchronous line start permanent magnet motor (LS-PMSM) is studied. The idea of permanent magnet maximum quantity buried in PMSM rotor is presented and the relationship of rotor magnetic circuit type and permanent magnet maximum quantity is also derived. So the difficulty programs such as large capacity, rotor sectional area disproportion to motor capacity and permanent magnet placement difficulty have been solved. With three-dimension finite method (FEM), the influencing factors to interpolar leakage coefficient and reactance have been analyzed and computed detailly, the relationship curves of rotor structure parameters to interpolar leakage coefficient and reactance have been obtained. The axial leakage coefficient of multi-segment rotor is computed and the relationship curves of main influencing factors to it are also obtained. The rotor magnetic circuit type suitable for middle capacity high efficiency asynchronous permanent magnet motor is determined.Second, rotor mechanical strength is computed with nonlinear contact finite element method that may avoid error from other computing manner when one body inserting otlier object. The 3 degree critical speeds of rotor are calculated under considering unbalanced magnetic force with deliver matrix manner.Third, two programs of PMSM with better performance are designed after calculation and analysis on air gap length, squirrel cage dimensions, iron bridge dimension in width, rotor dap radial dimension, axial air vent area and its position in rotor.Fourth, axial fix position method of permanent magnets in different rotor segments is designed.A fabrication progress with integrated innovation of middle capacity synchronous permanent magnet motor is obtained after studying on iron lamination punching technology, grid made manner, welding way of squirrel cage and end ring, and assemblage method of motor. A suitable modern magic hand with 5 freedoms for installing permanent magnet is developed which has feature of high assembling efficiency and may avoid from accident in assembly.At last, 300-4and 1120-4 LS-PMSMs of this subject are tested. The tested result indicates that these two PMSMs having higher efficiency and higher power factor than that of induction machines with same power scale and same number of poles. These are agreed to originalrequirement and some qualifications of them are superior to the original requirement. The achievements are identified through province degree and one of them is used in industrial application.