Module size investigation on fast chargers for BEV

Rapport, 2018

Fast chargers as defined by CharIN are DC-chargers up to a power level of 50 kW and are usually built to charge one vehicle. New High Speed Chargers can have a power up to 150 kW and Ultra High Speed Chargers up to 350 kW. They are to be used by some of the biggest battery vehicles and the charger could be made out of several modules that can be combined and charge several vehicles.

The report investigates how module size to a 150 kW charger influences the charge process of a vehicle type that will be available fairly soon. The best is to use many small modules if the efficiency can be high enough. A module size of 17 kW is a rather good alternative and nine such modules could provide 150 kW. The fixed cost of signal electronics has become insignificant and the size is so low that it is possible to combine several modules to the needed power. If a lower number of bigger modules are to be used the knowledge of the target vehicle is important, otherwise for instance four modules can behave worse than three modules. Just one big module is not recommended as it is inflexible in terms of charging different sized vehicles and the utilisation of the charger is low. If the charger are divided in two modules the charger will be much more flexible and with the ability to charge two vehicles at the same time a better utilisation of the charger is achieved.

A medium voltage module based on MMC and DAB is suggested for further investigations. The module could be connected to 10-40 kV grid and it could be equipped with storage possibility for even out peak load on the grid.