PLC Based Design Of High-Power DC Motor Speed Control System

High-power DC motor varied speed control system is widely used onboard the engineering ship, because of its high varied speed quality and its higher reliability. It consists of strong power section and weak electronic plant. The weak electronic plant is used to get the signal that system needed, such as speed, armature current, motor temperature and thyristor temperature etc. Based on these signals, the weak electronic plant give control signals to the strong power section. Strong power section act according to the signals and change the speed of the DC motor, to satisfied the requirement of the working situation.PLC short for Programmable Logic Controller is one of the most popular auto-control equipment onboard the ship. It combines of the relay control technique and computer technique and communicates technique. Its module design can satisfy any industry control situation just by assemble modules of different function together. Because of its strong capability, high reliability and other merits, it is used widely onboard the engineering ship.This paper firstly introduces the theory associated with the high-power DC motor control system, analysis the composition of the speed control system and the main speed control methods; Secondly sufficiently discuss the PLC control technique and the way the design a PLC based control system; Thirdly, this paper uses the high-power thyristor as the controllable power souse of the high-power DC motor speed control system, designs the main circuit, speed control circuit, signal test circuit bases on the modern control theory, PLC is used to monitor the important parameters of the main elements such as motor and thyristor, protect them according to the signal get from the test circuit; Finally I make these circuit associated into reality and adjust them to satisfy the system requirement.