EV charger
50kW EV charger tested on Nissan Leaf
EV charger
Electric vehicles (EVs) represent the future in environmentally friendly transportation. With EVs comes a need to find fast and efficient ways of recharging the battery. On-board chargers range from 3kW to 6kW and can take up to 8 hours to recharge a depleted battery. Fast chargers, stations rated in the 40-50kW range, can reduce charging time down to 30 minutes or less depending on battery status. Clearly there is a need for fast charging stations, but current solutions on the market take up too much space and are energy inefficient.
Solution
Enertronics has developed a compact, energy efficient fast charging solution with a minimum number of conversion stages.
Description of technology
A 50kW fast charger is in development for EV fast charging stations. The fast charger project is funded in cooperation with the Electric Power Research Institute (EPRI).
Connected directly to the utility grid, the front end stage is borrowed from the IUT, using a multilevel PFC and an isolated resonant DC-DC topology. Peak efficiency of the front end stage reaches over 98% with near unity power factor.
The output of the front end stage feeds a 50kW DC-DC charging stage with interleaved outputs to reduce charging current ripple, an important consideration for both battery life and fulfilling charging protocol requirements. Peak efficiency of the charging stage can reach up to 99%.
Total system efficiency reaches over 96%. This represents a 50% loss reduction over commercially available fast chargers in the same category.
Input current is controlled using advanced digital control techniques to achieve near unity power factor. Charging current and trickle charge voltage is controlled via Control Area Network (CAN) bus using the ChAdeMO protocol. New protocols may be implemented if necessary.
Specifications
Power: 50kW
Input voltage: 7.2kVrms single phase
Output DC voltage: 400V
Efficiency (HV AC to DC): 95%
Input power factor: 0.99