Drives & Controls November/December 2023

44 n ELECTRICAL AND ENCLOSURES November/December 2023 Wireless charging: the way to power warehouse shuttles? In large warehouses, shuttles are often used to convey freight along lines of shelving. These shuttles need enough power to move from the material pickup point to the unloading point. Many older systems still use copper conductors to supply power. In view of rising raw material costs and a global shortage of resources, some warehouses are now trying to avoid having to rely on copper rails. Modern approaches are therefore increasingly choosing to charge the shuttles in charging stations and in elevators, using charging contacts. Because the shuttle processes are highly dynamic, there is a time window of around 10-15s available for charging. During this time, precise positioning must be achieved before the shuttles can be supplied with power via the charging contacts. This means that up to 50% of the possible charging time is taken up by aligning the systems. In dynamic applications such as these, new power charging concepts such as inductive charging can lead to significant increases in transmitted energy. Inductive charging allows the charging to start immediately and thus offers the possibility increasing productivity. In traditional shuttle applications, vehicles charge conductively by running across copper rails in the aisles that are supplied with electrical current. But, for several reasons, copper conductors are not the best charging option. Permanent electrification of warehouses is expensive. Investing in vast lengths of cables, each incorporating three or four copper conductors, is a waste of resources. In an typical logistics warehouse that uses shuttles, more than 10km of cable is needed to supply power to the individual aisles. In addition, the conductors and contacts can wear rapidly because of the constant friction. If a running rail is not aligned perfectly, the shuttle’s current collectors can become worn at the edge. To minimise wear and tear, their installation needs to be as precise as possible. Employees need to check the shuttles frequently and change the contacts if necessary. By changing to other ways of supplying energy, a large warehouse can save around 30 tonnes of copper, not only cutting costs, but also benefiting the environment. Many logistics companies are now choosing to fit their shuttle systems with supercapacitors with much higher power densities than batteries. With almost endless working lives, they can withstand millions of charging cycles. Once a shuttle enters a lift and has been positioned precisely, charging starts. The lifting process takes 10-15s. By the time the monitoring of the contacts is completed and the contact has been made cleanly, up to 50% of the possible charging time can be lost. Depending on the size of the shuttle, lowering devices may be needed to access the contacts. The constant friction of the current collectors during travel can damage the contacts over time, leading to wear. Lift loading using charging contacts can therefore require high levels of maintenance. An alternative way of transferring power is to use inductive charging. Until recently, inductive chargers were considered too large for use with shuttle systems. But a new patented charging technology allows inductive charging to be used for warehouse shuttles for the first time. The compact, easyto-install charging technology, from the German company Wiferion, is compatible with supercapacitors. Charging electronics in the shuttle uses thin coils which take up little space. The system allows shuttles to be supplied with power more cheaply and efficiently than using contacts or copper conductors. Inductive charging systems avoid the need for precise positioning. Because there is a high level of positioning tolerance, the shuttle does not have to be located precisely when it enters a lift to initiate charging. And because the power transmission is contactfree, there is no need for a lowering device. The supply of power starts as soon as the shuttle reaches the charging point – typically in less than a second. The usable charging time is thus up to 50% longer, increasing shuttle travel times. With hundreds of runs per day, this can result in massive productivity boosts. The encapsulated systems are maintenance-free, ensuring reliable operation. Inductive charging increases the efficiency, performance and service time of shuttle systems. It is suitable not only for large high-bay warehouse and shuttle applications, but also for robot-assisted small parts stores in the e-commerce sector. Inductive charging systems are an efficient alternative to charging contacts and copper conductors. They offer a robust, reliable, maintenance-free charging technology. Unproductive time wasted in elevators can be halved. n Traditional methods for powering shuttle systems used in warehouses are costly and have drawbacks. Newer technologies such as supercapacitors and inductive charging offer many potential benefits. Wireless charging extends usable charging times for warehouse shuttles by up to 50% and increases travel times.