DC Conductor Rail with Distributed DC Link Capacitors

DC conductor rails are an attractive choice for many conveyor systems as commonly used in car factories. Replacing the DC link capacitances of the moving conveyors and of the DC supply by capacitors distributed along the conductor rail in a DC grid system can reduce mass and size of moving conveyors. Due to the distributed capacitors, the conductor rail exhibits now a transmission line behavior, which cannot be neglected anymore because the distributed capacitors reduce the propagation velocity drastically. Typical conductor rails are longer than 1km, which can result in a propagation delay of more than 1ms. Calculations are conducted to investigate the benefits of a shared DC link capacitance distributed along a DC conductor rail. Simulations and measurements show an improved short-circuit behavior with a nearly zero-current turn-off.