Optimal Control of Induction Machines Under Minimum Energy in Opencast Mining Machinery

Abstract

Mining industry is one of the most important users of electric motors. The most commonly used in the contemporary mining industry is alternating current (AC) machines which are used for converting electrical energy into mechanical energy. This paper presents the solution of the nonlinear optimal control problems of three-phase induction mining machinery (IMM). A fifth order nonlinear model has been described in arbitrary rotating frame (d-q) of induction machine which is used in this paper along with a quadratic performance index (QPI). The problem has solved using the Taylor expansion about an operating point method which converts the nonlinear optimal control problem into sequence of linear quadratic optimal control problems. The control objective is to minimize the total energy, ensuring torque and speed tracking control requirements. The evaluation of a simulation for an electrical drive application shows that operation at varying optimal supply voltages (V_dsopt, V_qsopt) preserves well speed, torque and flux tracking performances, while increasing motor efficiency. The system is stable with the properly selected settings of optimal regulators, which are particularly applicable during the operation of machinery used in mining exploitations.