Mathematical Model of Start for a Piston Compressor Electric Drive of a Ship Refrigerator

The structure and study of the starting characteristics of the electric drive of a piston compressor of a ship refrigeration plant using a mathematical model of unbalanced load moment are made in the article. The dependence of the shaft load of the electric drive of a piston compressor on the angle of rotation is presented in the form of a mathematical model. Charts of transient processes for speed and current were plotted for various values of the moment of inertia of the engine and flywheel. Numerical simulation showed that, the start of the induction motor without a flywheel, while an unbalanced periodic load is performed within nominal values, but there are significant current pulsations of more than 10% in the steady state operating mode. It was determined that when adding the moment of inertia of the flywheel to the model, creating an additional moment of inertia, the pulsations of rotational speed and current decrease, but, in its turn, the starting time of the drive increases. Therefore, the duration of the inrush currents increases, creating heating of the motor windings and their wear, and the amount of electricity consumed increases, which increases the load on the ship's electrical network.