Energy efficiency improvement of machine tools via peripheral devices management: an optimization-based control approach

In this paper, a control scheme for both reducing the electric power consumption and minimizing power peaks during the operation of machine tools without affecting its throughput is proposed. The controller is designed to only manage peripheral devices without modifying the machining processes and the cycle time of the machine tool. Based on a test bench to emulate the energy consumption of a machine tool, a real data set is used to obtain models of electric power consumption by using data-driven model techniques such as subspace identification. Then, an optimization-based controller is designed considering both power consumption models and operating constraints of peripheral devices. The proposed controller is tested for both nominal and disturbed cases, i.e., with and without disturbances/uncertainties, achieving reductions up to 15% in the power peaks with respect to other control systems usually implemented for such systems. From this approach, both energy cost and economical penalties by overloads could be reduced and the energy efficiency of these machines can be improved.