Synchronizing renewable energy generation to peak demand times is proving challenging and raising concerns for future renewable grids. However, with the rapid growth of electric vehicles (EV) there will be a huge amount of energy stored in vehicles that are parked up and this can be tapped into in order to smooth demand peaks.
To take advantage of this opportunity, highly efficient bidirectional DC-DC converters that store energy into batteries and then return it to the grid highly efficiently will be essential.
Generally, high-voltage power converters have used silicon IGBTs, due to their high VCES. Wide-bandgap silicon carbide (SiC) switches now offer significant performance due to their low and stable RDS(ON) over temperature and support for higher switching frequencies. As an example, Toshiba’s 1200 V TW070J120B N-channel SiC MOSFET with built-in SiC Schottky barrier diode, delivers a 66% reduction in power losses over a comparable IGBT.
To support designers, Toshiba has developed a 5 kW, bidirectional DC-DC converter. This is based upon the TW070J120B on the high voltage side, the latest generation DTMOS superjunction N-channel TK49N65W5 MOSFETs on the DC load side, alongside TLP5214A gate drivers and TLP7920 optically-coupled isolation amplifier technology. Operating at a 50 kHz switching frequency, the reference design attains a conversion efficiency of 97% at 100% load in both directions.