As driver uncertainty about access to EV charging remains a barrier to broader EV adoption, researchers at the Oak Ridge National Laboratory (ORNL) are developing algorithms and multilayered communication and control systems designed to make EV chargers operate more reliably, even during electrical grid voltage drops or disturbances.

Researchers have identified two key causes of charger failure: When small faults in the electric grid cause a fleeting drop in voltage, EV charging stops. And the failure of one internal component can shut everything down. Reactivating the chargers often requires maintenance that results in significant downtime.

To solve the first problem, lead researcher Namwon Kim and his team have implemented a “ride-through” control algorithm that rapidly reduces charging power and then restores it when voltage returns to normal seconds later, enabling quick recovery of charging power. The ride-through capability protects not only the chargers but also the broader electric grid from voltage surges caused by many chargers disconnecting simultaneously during grid faults.

To solve the second problem, the ORNL team created another algorithm allowing an EV charger’s power converter, made up of three modules working together, to detect and adjust to an internal failure instead of turning off. If one module fails, the load is divided between the other two.

Researchers have also developed a multilayered approach for control and communication across a large EV charging system that enables automatic notification of problems at individual chargers and then alters equipment settings for the best customer charging experience.

“The main focus is to make chargers available for EVs even if there is an electrical disturbance or hardware failure inside or outside the charger,” said Kim. “We want drivers to be able to use EV chargers as soon as they arrive at the charging station.”

Source: Oak Ridge National Laboratory