Fast Switching and Bidirectional Charger based on Gallium Nitride Semiconductors
In the public funded project “Luftstrom” a single phase and bidirectional charger based on wide bandgap (WBG) devices gets developed and investigated. With an increase of the switching frequency, the charger can be build much smaller than based on commercial charging systems with silicon devices. During charging process, the grid voltage is rectified by an ac-dc converter. A dc-dc converter ensures galvanic isolation between the grid and the battery in the vehicle. Additionally, this converter links the dc-link voltage with the battery voltage. The mean power is 3.7 kW. Based on the single-phase topology of the charging system the power in the dc-link fluctuates with 100 Hz, which results in twice the nominal power as peak power that has to be transferred by the ac-dc converter. The system is controlled by a combination of a DSP and FPGA with switching frequencies up to 500 kHz. By using GaN devices, the volume of the whole charger could be reduced by more than 50 % compared to a charger based on silicon devices.
01.01.2015 – 31.12.2017