A Review on Energy-Saving Optimization Methods for Robotic and Automatic Systems <s> Energy-Sharing Devices <s> This paper presents the experimental and simulation results of industrial robot's recuperated energy saving approaches. Two complementary alternatives- a capacitive energy buffer on the robot's DC-bus is evaluated and a novel approach, the robot EnergyTeam has been proposed. The principle of robot EnergyTeam is the DC-bus merging among various number of industrial robot power controllers thus enabling a controlled energy flow among the robots that decelerate and, therefore, recuperate the energy and those that simultaneously require a peak power supply for the acceleration. Cost efficiency is estimated considering the characteristics in robotics of real production in the automobile industry. <s> BIB001 </s> A Review on Energy-Saving Optimization Methods for Robotic and Automatic Systems <s> Energy-Sharing Devices <s> This paper proposes a new type of power converter for drive systems to enable the exchange of recuperated energy within an independent DC subgrid having one centralized energy storage element. Many industrial applications that require rapid cyclic starts and stops are subject to significant energy waste at the brake chopper of the DC bus due to over voltage during motor deceleration. The proposed solution allows the brake chopper to be eliminated and the otherwise wasted energy to be stored externally. The solution does not require identical hardware or exact synchronization between the drive rectifiers. Experimental results in industrial robotics show savings of up to 20%. <s> BIB002 </s> A Review on Energy-Saving Optimization Methods for Robotic and Automatic Systems <s> Energy-Sharing Devices <s> It is state of the art for many drive systems like those used in industrial robotics, conveyor systems or diverse numerical control machinery to have a common DC bus power system architecture. Due to regenerative braking, the DC bus voltage increases until a certain limit, which is limited means of a balancing resistor (brake chopper). Systems that require rapid cyclic starts and stops are subject to significant energy waste due to extensive use of the brake chopper. In this article, a novel power converter for drive systems is proposed that allows the brake chopper to be omitted and enables the exchange of regenerative energy among multiple drive systems within an independent DC subgrid with one centralized energy storage element. The solution does not require identical hardware or exact synchronization between the drive rectifiers, therefore it is applicable to both existing and new production equipment alike. Experimental results in industrial robot drives show savings of up to 20%. <s> BIB003
Energy-sharing devices base their working principle on the sharing of braking energy on a common network for driving other (non-braking) actuators. The most common way to implement such an idea is the DC-bus sharing system. Today, some commercial robot controllers allow for recuperating energy when a motor brake occurs (i.e., when one axis is braking, others that accelerate can use that energy). In most cases, if several axes brake at the same time, the available energy exceeds the installed DC-bus capacitance. Thus, the energy is dissipated on a balancing or chopper resistor BIB002 . By properly designing and adding the number of storing devices, this energy can be almost fully recovered and then shared. Either a single centralized or multiple decentralized energy buffers and rectifiers are to be chosen, as well as the proper line and the type of storing buffer (e.g., capacitor, flywheel, or pneumatic). In BIB001 , the single capacitor energy buffer approach and EnergyTeam (i.e., a multi-star DC-bus connection of several industrial controllers with their own rectifier module) are analyzed and compared in terms of cost efficiency. The addition and installation of capacitor banks is relatively simple but is not so economical. The EnergyTeam is a promising solution, but it requires a robot controller able to receive external DC power. In BIB002 BIB003  , the case of a single centralized capacitor that is shared between different DC subgrids (i.e., a subgrid is composed by several drive systems), each one with its own rectifier, is considered. In these papers, a method to avoid the synchronization between every rectifier's subgrids is proposed. In  , the advantages of a shared/common-bus operation of AC drives are shown, which include cost reduction, reduced space requirements and improved reliability. In  , an investigation is presented on how shared DC-bus systems with a common storage capacitor affect the exploitation of regenerated energy from the electric drives of an industrial robot. Simulations to obtain specific efficiency indicators of the system with respect to the number of shared DC buses were performed, showing that, with a sufficiently high capacity, the regeneration energy of several systems can be efficiently utilized. Moreover, it is demonstrated that the number of robots does not affect the amount of energy saved.