| Plastics industry is an important industry in modern industry, and plastic products are widely used in industry, agriculture, national defense and people’s daily life. Injection molding machines are the main equipment of plastic products, and their main drive motors are permanent magnet synchronous motors(PMSMs), three-phase asynchronous motors. Permanent magnet synchronous motors have increasingly been used to injection molding machines, since of those advantages of small volume, light weight, large output torque, high efficiency and energy saving.Injection molding machines require quiet environment, and their load vary periodically, which could easily generate electromagnetic noise with increasing current. This dissertation calculates and analyzes air-gap magnetic field harmonic of different poles/slots combination motors, and presents a methods of integer slot combination to reduce radial force wave frequency and electromagnetic noise of PMSMs.Firstly, according to design features and tasks requirements of PMSMs for injection molding machines, the dissertation discusses and analyzes in details those design methods of main size and air gap, stator, rotor punching plate and rotor structure of the PMSM. An electromagnetic scheme design and magnetic circuit method calculation of a PMSM with17.3KW,8poles,/48slots is completed, and the calculation results are presented.Secondly, the motor is simulated and analyzed by using finite element analysis software of ANSYS Maxwell. The motor’s steady state performance of no-load, rated load are simulated, and several important electromagnetic parameters about static field of the motor are calculated. The dissertation laid special stress on analysing effects of the motor with chute on cogging torque. The expression of cogging torque of PMSM has been deduced and the cogging torque of the motor with chute and no chute are simulated and contrasted by finite element analysis, which show that chute has a great of influence on weakening cogging torque.And then, the radial electromagnetic force principle of PMSM with sine wave power and stator winding harmonic freguency of motors with integer slots and fractional slots are analyzed. Under the same conditions, air gap magnetic field of three PMSM with8poles, 24/36/48slots are decomposed into armature magnetic field and permanent magnet magnetic field to calculate their harmonic content, and their radial force wave are analyzed as well. Analysis and calculation results show that the radial force wave number of integer slot motors is significantly less than that of fractional slot motors, and harmonic sinusoidal of integer slot motors is better than that of fractional slot motors.Finally, experiments of the prototype are carried out, including test of temperature rise, performance, overload, acoustic noise. The no-load, full load acoustic noise are54dB and59dB respectively, which are reduced by lOdB than the motor of8poles,36slots and verify correctness of the radial force wave analysis, and other test results meet design requirements. Test results and design results are compared and analyzed, and their errors are within5%. Also the method of design is verified by the test result. |
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