Research on Energy Consumption of Variable Frequency Control for Portal or Overhead Crane

Abstract

In order to make research on the hoisting mechanism, motor’s energy consumption during the motor’s starting period and smooth running period for the portal crane or overhead crane, the rotational inertia, and load torque of the hoisting mechanism are converted to the rotor side; an equivalent uniaxial motor driving system is derived according to motor driving system of the hoisting mechanism; and the variable frequency control system is designed based on the slip frequency between stator’s synchronous angular speed and rotor’s electric angular speed and it made comparative research about energy consumption with the direct running synchronous motor. The research results showed the following: The variable frequency running motor could vapidly reach the given rotational speed within 0.2 s and could vapidly track the load torque; the frequency and amplitude of the stator’s 3-phase variable frequency modulation voltage would be gradually increasing during the motor’s starting period, and the 3-phase variable frequency modulation voltage would be constant during the motor’s smooth running period; start energy consumption would not exceed 2 × 10⁴ J when variable frequency running motor’s load did not exceed heavy load and the load torque’s effect on the energy consumption wave was small; the motor’s energy saving was obvious during starting period and smooth running period if the variable frequency running motor’s load exceeded medium load.