PLC-based control system for the electrical screw press driven by double motors

The torque responsibility and the temperature rise of motors aroused by continuous starts were researched. The control system based on S7-300 PLC (programmable logical controller) and ACS800 inverter were designed. Direct self control (DSC) of speed regulation technology were applied in the system, which drived both motors. The modularized software structure was carried out, and the back stoke position was guaranteed through the method of speed subsection. In virtue of DSC technology, the fast responsibility and the low torque fluctuate was realized, the peak current at motor start could be avoided, and the temperature rise was controlled effectively which levels off 91C in constant service. The tolerance of energy is no more than 2% and the back stroke position error remains from -2 mm to 2 mm, meeting the demand of extend service of electrical screw press.