62 September/October 2025 | E-Mobility Engineering the maximum load constraints of the station, and any charging sessions that would increase the load beyond the constraint will be delayed to keep the load curve below the station maximum. Energy storage can buffer peak loads, but the cost is a major consideration. The unit cost of lithium-ion battery energy storage is approximately four times higher than that of distribution transformers in China but does not require expensive grid capacity expansion and enables more flexible installation. The dynamic control of the energy storage monitors the activity to identify low-power periods to charge up from the grid so that it is ready to provide a high-power boost at busy times. Overall, the researchers suggest that deploying large ultrafast-charging stations with chargers between 350– 550 kW in high-demand regions could be a viable solution to meet the surging charging demands of EVs in China. Looking forward Demand for fast charging by EV users is increasing significantly as people look for a 5–10 minute waiting time. This is made possible by the latest architectural and component developments, with techniques such as Vienna rectifiers and real-time microcontrollers now allowing modular, cost-effective charging station designs. The proliferation of fast chargers also puts a significant strain on the electricity grid, so techniques to manage the flow of energy at charging sites is welcome. All these elements indicate maturing of the fast-charger technology and infrastructure to boost the rollout for e-mobility vehicles. Deep insight | Fast charging Fast-charging contactor The contactor is a key element in a fast-charging system, acting as a circuit breaker. For example, the Eddicy C803 bidirectional contactor from Schaltbau has a low and over lifetime stable contact resistance of about 100 µΩ. Embedded in a correctly dimensioned system structure, consisting of busbars and contactors, it can help reduce the need for additional cooling and solve thermal management challenges. The switching voltage of 1500 V and high switching currents of 500 A are combined with a snap-action auxiliary contact with silver material. The auxiliary contact operates with a minimum signal level of 5 V/10 mA and connects via a 5-pole connector. The monostable magnetic drive supports a 12 or 24 V DC control voltage with internal and external pulse width modulation (PWM) options, ideally current controlled. Weighing under 0.5 kg, the contactor is aimed at inverters, charging and auxiliary applications for offroad, construction and passenger vehicles. It is designed to withstand 200,000 operations and resist vibration to the ISO 16750 standard and operates from -40 to +85 C. With a focus on minimising thermal issues, the C803 is designed to reduce the need for extensive cooling systems, which are often a challenge in e-mobility applications. Its low-loss design ensures efficiency without the need for excessive heat management, providing significant advantages in reducing cooling demands in electric drive systems. “The C803 is unique in how it tackles the most challenging thermal and efficiency problems in the industry – because in high-power switching, heat is the enemy of performance,” said Helmut Pusch, CEO of Schaltbau. “The key point is always the thermal balance,” said Guenther Rott, responsible for global product management and application engineering at Schaultbau. “This is an issue of the physics because the hotspot is always near the contact. So, the trick is to have really low contact resistance to reduce the power loss as much as possible in this critical area. We have a special concept with the design of the inner busbars, the contact materials used, the power of the coil system and the self-cleaning of the contact system.” The Eddicy C803 contactor (Image courtesy of Schaltbau)
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