Wibotic moves to 1kW wireless charging

Wibotic moves to 1kW wireless charging

Technology News |
By Nick Flaherty

Wibotic has developed a wireless charging system for larger autonomous robots that can charge at 1kW.

“One of the things we have always wanted to do was push the power level and we are demonstrating a 1kW wireless charging system that allows us to address devices with bigger batteries,” said Matt Carlson VP of business development at WiBotic. The charger is on show in Chicago this week.  

 “We are just as fast as a 300W plug in charger and this allows us to charge at 1kW – this is strategic charge level as most outlets in a factory are rated at 1 to 1.5kW so most robot companies stay in that 1kW range,” he said. “It’s both for faster charging and for larger capacity battery packs. Most of the battery manufacturers look to 1 C charging rates so that allows a charge in 2 to 3hrs for a 2 to 3kWh pack.”

“Everyone wants faster charging but what’s really interesting is to charge in a way that maximises the battery longevity with a slower charge,” said Ben Waters, CEO and founder of Wibotics. “Robots is a similar trend. Some have the opportunity to charge overnight but when they are in high demand you need the capability to put a lot of power into the packs.”

“There are inductive charging systems that do 1kW and above but what’s unique about our design is we use 6.78MHz for the power transfer and its quite difficult to transfer power at that frequency. We have worked hard to maintain the longer range for positional flexibility and making the onboard charger smaller. Our device is very small and lightweight and even on these bigger vehicles space is at a premium.”

“There is also all of the software that goes with it. We have the Commander software to schedule rates of charging, optimising for battery longevity and battery replacement,” he said. “The charger adjust from 0 to 60V and 0 to 35A of current and this gives customers a lot of flexibility across different devices, fast charging during the day and slow charging at end of shift.”

“Not all chargers are programmable at the highest speed and a specific voltage,” said Carson. “This programmability allows us to support robots from different suppliers as the power is converted onboard the vehicles so you can have  just a few chargers service a bunch of robots.”

The original 300W charger was designed for 30A currents so the higher 1kW power version is only slightly larger at 126.0mm x 52.5mm.

“The transmitter is larger but the onboard charger only grew by 2cm,” said Carson. “We had designed the 300W to handle high currents up to 30A but only for low voltage 12V batteries.  Its really the current that drives the size of the components a so now we are at 36V but can go up to 60V.”

“When you get into the 1kW range the inductive chargers have to have robust foreign object detection for anything metallic that gets between the coils. With 6.87MHz it does not have the same effect on objects. We can detect them but we don’t need to shut down.”

Most of the automated mobile robots (AMRs) use a vertical charging pad and the high power gives even more flexibility in positioning.

“A lot of the robots we are targeting are the very flat AMRs and even with vertical mounting they are essentially at floor level, and we foond most AMR and AGV makers can navigate to within 2cm,” said Carson.

“It’s the same separation of 4cm with 4cm offset for the highest power, but if you go to 5, 6 or 7 cm the power will drop and you could still be getting 600 or 700W. We have a 2.4GHz radio for communication so if the coil moves away we can determine the efficiency of the system and that’s how we determine if it is getting into an inefficient condition

“The other thing that is growing is outdoors with wireless. We can put the antennas behind plastic to seal them to IP67 levels so we are seeing robots for pipeline inspection, solar field inspection,” he said.

This was a key factor in the development of a wireless charging system for equipment on the Moon, where the dust, or regolith, is a major challenge. That project with NASA is currently coming to a conclusion, says Waters.


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