Power converter for DC bus sharing to increase the energy efficiency in drive systems

Abstract

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%.