Automated connection devices can be used to charge autonomous and conventional electric vehicles such as AGVs and buses. Selwyn Corns outlines the benefits of this connection technology and its potential for the future
The QCC from Stäubli Electrical Connectors is an automated connection device (ACD) that enables the connection of electric vehicles for charging without the need for human intervention. It was first developed for local public transport applications, where it was used for a trial of opportunity charging for electric buses. Since then it has been used in the automatic charging of autonomous container transport vehicles.
Advantages of ACDs
As a general rule, the use of ACDs falls into two groups: rapid opportunity charging, and complete recharging of vehicles. Their use in rapid opportunity charging enables battery sizes to be reduced, with associated reductions in weight and costs.
One of the biggest advantages of ACDs is time saving, since contact can be established as soon as the vehicle stops, without having to wait for a driver to exit the vehicle and perform the connection. Also, charging can be quicker, since a larger cable cross-section can be used that is not limited by the force able to be applied by the operator.
A further advantage is comfort, since the operator can remain protected from the weather in an air-conditioned cab for example.
Reliability is also increased, since there is no possibility of an operator forgetting to charge the vehicle, and there are no wear issues from the operator failing to insert the charger correctly.
As the system is automatic, it can be used with driverless autonomous vehicles, as is already the case with AGVs in factories, warehouses and container terminals for example.
A commercial ACD
The QCC from Stäubli Electrical Connectors is an automated connection device consisting of a plug component over 2m long containing a controller and linear actuator, and a socket component with a funnel on the front to guide in the plug. The plug can flex as it enters the socket, which ensures a high level of tolerance to angular and positional misalignment, giving a degree of flexibility in positioning the vehicle.
A sensor is integrated into the socket to allow confirmation when the mating process is complete. There are also signal contacts which can carry data communications between the socket and plug or vehicle charging station.
The QCC is available in two sizes suitable for currents of 350A and 800A, both with a rated voltage of 1500V. Their compact size makes them more suitable than alternative systems based on pantograph designs for example.
The QCC has a high level of safety built in, with plug and socket parts completely touch protected to IP2X, both mated and unmated. There is therefore no danger to personnel even when it is installed in public spaces.
Both parts are also ingress protected to IP55, removing any risk of deterioration of the dielectric withstand voltage due to contamination or moisture. This helps to achieve a high level of reliability, with the QCC rated at more than 100,000 mating cycles. It also helps the contact resistance to remain at a constant low level over the whole lifetime of the system.
In addition, the plug extends with limited force to avoid the risk of injury or damage. Full power is not enabled until the plug is fully inserted inside the socket.
While the development of the QCC was initially carried out for the city bus market, the system can be used in a variety of different sectors, such as automated warehouses, autonomous container transport vehicles in ports, and mining trucks.
In one recently announced application, Stäubli is to provide automatic charging stations to SSA Marine in California for 33 terminal tractors at the Port of Long Beach. This project will create the largest automated electric vehicle charging programme of any port in the USA.
SSA Marine, which manages the terminal, is converting all the diesel-powered tractors by retrofitting them with all-electric drivetrains. Tritium, an Australian company that designs and manufactures fast charging solutions for electric vehicles, will incorporate the QCC connector systems in its 175kW DC Veefil High Power Chargers used to power the tractors, which will all be fitted with QCC sockets. All 33 terminal tractors will be able to be automatically charged simultaneously.
The rollout of the vehicles and chargers will bring a near zero emissions environment to the port, making the job of port operators safer, easier and more efficient, while creating a healthier work environment.
A successful existing application is a test installation in the port of Hamburg, Germany, where QCC plugs and sockets have been fitted to over 25 AGVs and six charging stations. Similarly, in Singapore 22 AGVs and three charging stations have been installed, with plans to extend this to 162 vehicles and 18 charging stations.
Selwyn Corns is managing director of Stäubli Electrical Connectors UK. A world leader in the field of connectors, Stäubli manufactures quick connector systems for all types of fluids, gases and electrical energy. The Electrical Connectors product portfolio ranges from miniature connectors to high-performance connectors for power transmission, industrial automation, transportation, test and measurement.