Leveraging the advantages of DC-Drives

The DC Industry project has brought the use of direct current in industry back into focus more strongly. This is a sensible step, as there are numerous DC systems in the meantime that have been playing to their strengths in industrial environments for years. Direct current ensures a consistent power supply, which allows for more precise manufacturing and more accurate control – Which is why electronics and semiconductor manufacturers in particular are focusing on direct current systems.

DC drives also enable more precise control and faster reaction times in production robots such as those from Kuka.

In many of its industrial robots, the Augsburg-based machine manufacturer relies on DC motors, in particular brushless DC motors (BLDC). Robots such as the Kuka KR Agilus, which finds use in the automotive industry, electronics production and other areas, harness DC drives for their axes and gripping mechanisms.

Similar application areas can be found in the industrial robots of the M series from Fanuc, the Motoman MH series from Yaskawa and the IRB series from ABB, but also in the cobots of the UR series from Universal Robots, the mobile robots of the LD series mobile robots from Omron as well as in the PGN-plus gripper from Schunk. DC drives are also at work in conveyor systems or logistics systems from Dematic or SSI Schäfer.

All of these applications benefit from t the advantages of DC drives: highly sensitive and precise control of position, torque and speed, high efficiency and a long service life. DC motors can also be integrated into compact designs, which is a decisive product feature in robotics.

Production automation is therefore an important field for DC technology, as it is widely used in robotics in particular. The drive specialist Danfoss is another supplier of this technology, most notably with its VLT FlexMotion series. One notable product, for example, is the Multiaxis Servo Drive MSD 510, which was specially developed for scenarios with DC link voltages in the range from 565 to 680 V DC.

Danfoss has designed its FlexMotion drives and controllers to work with different power sources - including with direct current. By supporting direct current supply and optimised cabling, the system can be utilised directly in industrial direct current networks in industry and reduces energy losses. The VLT FlexMotion series relies on hybrid cabling that transmits both the DC power supply and signals for controlling machines in a single cable. This ensures a more effifficient and flexible system architecture that can be integrated into a variety of machine architectures. The series is particularly suitable for applications involving hybrid and all-electric drive systems that operate precisely, flexibly and energy-efficiently.

Other drive technology manufacturers, however, are also supplying corresponding products: Bosch Rexroth, for example, is offering various systems for industrial applications, including ctrlX Drive, which comprises highly efficient DC-based servo drives for precise motion control. The system can be configured for various tasks in factory automation and features compact and powerful motors that operate with high energy efficiency. The Indra Drive ML is another drive which can function both as a regenerative power supply and as a motor inverter. This drive is particularly suitable for large applications, as it can support several units in parallel, enabling higher performance, which is ideal for complex production environments. These drives integrate well into DC environments and enable the smooth control of multiple axes, energy recovery and optimised energy use thanks to advanced features such as DC bus connections and intelligent energy management systems.

Given their advantages, DC motors are at work in a wide variety of areas – so far mostly in AC environments. If they are operateddirectly from the DC grid, there is no need for an inverter and theassociated installation and maintenance costs. In addition, byeliminating the inverter, the losses that would otherwise be incurredby conversion can be reduced, thereby increasing the overallenergy efficiency of the system. What’s more, the eliminationall of the conversion stages also simplifies the system architecture,meaning less wiring and less space will be required.

There are already devices in every factory that are actually running on direct current: in addition to the examples cited, there are also ventilation systems and LED lighting to consider. So why accept the losses? It would be far more efficient to supply the systems directly with direct current. The company Lapp has realised this for its plant in Forbach, together with Fraunhofer IPA. According to their stock taking, a good 10 per cent of consumers could have been supplied with direct current right from the outset – from the electricity generated by the photovoltaic system, for example.