There is significant effort being made to develop next-generation charging infrastructure to support electric vehicles (EVs). One innovative idea is the potential for EV batteries to generate revenue. Through bi-directional charging, EV batteries could help with load balancing when electricity demand is high. This is especially important to smooth the fluctuations associated with renewable energy sources.
Toshiba’s 3-phase 400 VAC reference design incorporates bi-directional charging and wide bandgap (WBG) power discretes while requiring only minimal engineering resources to achieve advanced charging station designs.
Key to the reference design’s high (97%) conversion efficiency and ability to support 50 kHz switching frequencies is a Toshiba TW070J120B N-channel silicon-carbide (SiC) MOSFET that supports high-voltage operation without the relatively heavy switching losses of an IGBT-based approach. The device’s 1200 V-rated withstand voltage and 175 °C operational temperature ensure it is robust enough to deal with harsh automotive environments. The TW070J120B has just 70 mΩ on-resistance (RDS(ON)) and this, along with the built-in SiC Schottky barrier diode that gives a VDSF lower than the MOSFETs body (parasitic) diode, lower the conduction losses appreciably.
Additionally, using a SiC MOSFET such as the TW070J120B allows for downsizing of the accompanying magnetic components and capacitors because higher switching frequencies can be used, thereby saving board space and weight as well as reducing overall costs.