DC power supply: Using energy, not wasting it
A cost-saving solution for intralogistics and more
Today, the question of how to use energy as efficiently as possible is more important than ever in plant and machine engineering. DC-coupled drive systems offer an interesting solution. The DC network makes it possible to actively reuse energy in the machine instead of wasting it. This saves energy and, in the event of regenerative operating states, avoids the need for braking resistors, which would otherwise be necessary, with their thermal losses and risk of fire. In which applications is it particularly worthwhile to use the generated braking energy and what are the technical requirements?
In times of rising energy prices, the trend in plant and machine construction is moving towards ever more efficient use of the energy available in the system. DC-coupled drive systems enable the active use of process-related regenerative energy, which is generated, for example, during deceleration processes, by means of coordinated load cycles. Since this energy is converted into heat via resistors in conventional AC drive systems, the efficiency of the system can be improved. In addition, both the average and peak power of the system are reduced. The result: depending on the application, the entire grid connection, consisting of lines, safety devices and contactors, can be dimensioned smaller. In this respect, DC network systems offer exciting potential in terms of energy and resource efficiency.
It is not always possible to reuse the braking energy in a meaningful way. However, in principle, a DC network is particularly worthwhile wherever energy has previously been converted into heat. “Significant advantages can be achieved in systems in which several axes work in parallel and the process requires cyclical deceleration operations. But even in applications without large regenerative energies, the DC network can simplify the structure and save space in the control cabinet,” says Timo Geisler, Product Manager Drives at KEB Automation.
High-bay warehouse as an example of use
Classic applications in which energy efficiency can be significantly increased in this way include, for example, high-bay warehouses in which the storage and retrieval machines frequently have to pick up pallets from a height of several metres and then lower them. “If several aisles from a high-bay warehouse are DC-coupled together and the driving processes are coordinated, the deceleration energy from aisle one can be used directly to accelerate aisle two,” says Geisler. Cyclical deceleration processes also occur in many other applications in which KEB customers have been relying on DC coupling for years: textile machines, plastic injection moulding machines, crane systems, rotating tool drives or high-speed energy storage.
With the COMBIVERT R6, KEB offers a compact and cost-effective power supply and regenerative unit for industrial requirements that meets the increased demands for efficient use of energy. Thanks to the line-commutated technology, an unregulated, mains-dependent DC voltage is provided on the DC side. The R6 can be used to supply DC power to several drives and enables high overload and energy recovery in continuous operation. In combination with KEB harmonic filters, an optimal mains quality and reduced idle power can be achieved. Furthermore, the COMBIVERT F6 provides a drive controller that combines a frequency converter and servo drive in a single device and covers the entire power range from 2.2 kW to 450 kW. The drives control a wide range of motor technologies, whether sensorless or with sensors and – depending on the application – with scalable, powerful safety functions. The same applies to the S6 servo drives, which are available in a compact book format in two housing sizes for a rated current of 2.6 A to 16.5 A. “In addition to the products, we also offer support in designing the drive systems. There are still reservations when it comes to DC, and we want to help customers to overcome these”, says Geisler.
Get more insights with our webinar
Saving energy in a DC network with KEB Automation [Language: GER]
