Logistics Robots Charge Up Quickly

A high-voltage application for the successfully running series of large LÜTZE switching power supplies: The batteries of autonomous transport robots require intensive rapid charging – with corresponding power peaks for the power supplies.

The Autonomous Robotic Carriers (ARCs) move silently and inconspicuously along the hall's ceiling. Even in warehouses with tens of thousands of storage spaces, the intelligent ARCs deliver various containers, boxes, workpiece carriers, or SMT magazines just in time to the desired locations within the company. Whether it's in goods receiving, picking, at workstations, or in shipping, the Servus System manages the entire material flow of the production operation. Customers of Servus Intralogistics include companies in production logistics, retail, e-commerce, as well as medical and healthcare.

What's unique about the solution from Austrian-based Servus Intralogistics in Vorarlberg is that the rail system is entirely without electricity. The autonomously operating swarm robots carry their own energy in their onboard batteries. They also have the intelligence that allows the ARCs to move completely autonomously at speeds of up to 5 m/s. The robot closest to the destination automatically receives the next transport task.

Just as autonomously, each robot decides when and how much power it refills at one of the numerous charging points. These charging sessions are typically short and intensive; they often last only minutes or even seconds. This rapid charging method requires a substantial amount of reliable power.

Therefore, when selecting the switching power supplies, the market was carefully surveyed. Why did the choice fall on LÜTZE? One significant factor for choosing LÜTZE power supplies was their precise construction and mechanical-electrical robustness.

Additionally, they have compact dimensions and the ability to read status information through the integrated display, simplifying the application. An integrated logging function records relevant operational states with date and time, which can be very helpful during troubleshooting. Furthermore, critical operational states can be assigned to 2 relay outputs, thereby easily generating a notification. This is done using the free PowerMaster software or the keypad. Servus uses devices of various voltage categories and power consumption classes: initially DC 48 V and 960 W, which was state of the art at the time. The current generation, which is now being used, operates with DC 24 V and 2400 W.

To provide the desired high power, up to three power supplies are connected in parallel. Usually, the devices need to be precisely adjusted to each other to avoid damage during the power peaks of frequent charging starts. Fortunately, the large LÜTZE power supplies used have a separate connection for sharing (Share plus/Share minus). This allows the devices to adjust their output voltage, ensuring each one delivers the same current and is evenly loaded. This precise current distribution is unmatched in the market.

The switching power supplies play in the high-end league when it comes to efficiency.  Their low power loss is a result of the LÜTZE sustainability initiative, SkyBLUE: thinking resource and energy-conscious about all products and using durable and environmentally friendly materials. These knowledge and manufacturing advantages are gained through joint projects with various industries and research institutions, all with the goal of improving energy efficiency and sustainable technologies.

Another advantage that standard devices either don't offer or only provide partially, are the three adjustable operating modes, including the battery charging mode: When a robot arrives at a station, it charges with a corresponding constant current characteristic curve. An ideal feature, especially for this demanding application. The battery charging mode supports all common battery types, including lithium-ion batteries. Also interesting: The large LÜTZE power supplies can use an analog output to depict the actual flowing current. When this is read into the control system, you can see exactly how the device is operating.

Authors:
Alois Reiss, Sales Field Force, Lütze Elektrotechnische Erzeugnisse Ges.m.b.H.
Klaus Wünschirs, Product Manager Control, Friedrich Lütze GmbH