Evaluation of electromechanical transient process parameter influence on the response time of a centrifugal flow meter for loose agricultural materials

Abstract

An important element of continuous processes related to dosing, flow measurement, and transportation of loose agricultural materials is the flow sensor. A promising means of measuring flow is a centrifugal sensor. The nature of the loose material entering the working element of the flow meter-sensor is pulsating when the material enters the impeller in portions. Uneven mechanical load is accompanied by a change in the coordinates of the sensor motor, such as torque, current, and speed. In this case, the motor operates in the mode of transition from one steady mode of operation to another. The research goal is to determine the dependence of the parameters of electromechanical transients in a centrifugal flow meter of loose agricultural materials on the ratio of the electromechanical and electromagnetic time constant of the sensor. The main provisions of the theory of transient process and electric drive are used. The derivation of the transition function of the centrifugal flow meter of loose products from the main equation of motion of the electric drive and the formula connecting the moment of resistance with the flow rate of the material in the flowmeter is presented. The analysis of the obtained results shows that when implementing an oscillatory transient process, the rise time to a given current value and angular velocity is 0.01 seconds, the transient time is 0.03 seconds and overshoot is 3% which indicates a higher speed of response of the flow sensor. With the aperiodic nature of the transient process, the equality of the rise time to a given value and the transient time of 0.06 s is observed which exceeds similar values during the oscillatory process. Provision of condition exceeding electromagnetic time constant 4 times of  electromechanical time constant is achieved by appropriate selection of total moment of inertia reduced to motor shaft, rigidity of engine mechanical characteristic, inductance and resistance of the motor.