Research Of Direct-drive Permanent Magnet Motor And Its Control System For Plastic Machinery

The plastic machinery mainly include extrusion molding machine, injection molding machine and blow molding machine, the common point of their drive systems is that machines’ screws are driven by asynchronous motor via reducer. Traditional plastic mechanical drive system is low efficiency, large volume and highly cost. Using permanent magnet direct-drive motor drive system for transformation of plastic machinery gear speed reducer is not only saves time, improve the efficiency of the plastic machinery driving system, but also reduce the volume of the plastic machinery driving systemSqueeze molding machine as an example, direct-drive permanent magnet motor is adopted. According to the plastic clamping force of the practical need of production process, refer to the transmission system of traditional reduction ratio, the rated torque of the motor and the rated speed is determined. Fractional slot is used by winding to restrain higher harmonic. the torque ripple of motor is analyzed by using different per pole per phase slot number q; Rotor used table type magnetic pole structure, the influence on air gap flux density, electric potential and cogging torque is analyzed by different thickness of permanent magnet. Matlab is used to calculate electromagnetic parameters, Ansoft is used for modeling and simulation analysis.Due to the plastic cylinder of the squeeze molding machine is always filled with high temperature molten state plastic colloid, and permanent magnet motor is directly connected to the squeeze molding machine screw. The distribution of iron loss is studied under sine wave power supply and inverter power supply. Construct a three dimensional model of the permanent magnet motor. Through the calculation of three-dimensional steady-state motor temperature rise, the temperature field distribution of the key parts are obtained.Plastic machinery control precision determines the quality of plastic products, the major technical indicators of plastic machinery are: the stability of the screw, the screw linearity, rapidity and stability of the temperature control. Starting from these three points, design the machine control system with PLC as the core, through the touch screen to monitor and control the whole machine. Inverter is adopted to control speed of direct-drive permanent magnet motor. Program design process is researched on software. The motor control subroutine and screw accurate calibration module are majorly analyzed.The temperature rise test, load test, drag test are carried out finally. The motor installed in a squeeze molding machine realizes the whole process of plastic production. Comparing the test results and the calculation results, verifies that, the motor design method and the performance analysis method are scientific and accurate.