Control System Design of Nozzle Performances Test Bench Based on PWM

The nozzle performance test bench is designed in accordance with national standards for plant protection machinery.The nozzles mounted on the bench were designed to simulate the actual operation of the movement in the field with different and uniform speed to meet the movement requirements of machinery,which was operated by the control system.The systems used contactors-relays to control and direct current(DC) motors as drive parts,which had the features of simpler and more accurate speed control.The power components of pulse width modulation(PWM) required for the system was less so PWM was selected to control the speed.The control circuit of motor running state used contactors and relays to control because it's cheap.This paper stated the working principle of PWM control system and the design of quantitative speed control parameter and the external control circuit.It can meet the requirements of simulating the actual operation of the nozzles movement in the field.