With electric vehicle (EV) chargers delivering up to 22 kW in AC and up to 350 kW in fast DC chargers, several hundred Watts of energy can easily be dissipated as heat. Automotive OEMs are planning to support bidirectional power flow, enabling EVs to jump-start other EVs, power conventional appliances while camping, or even help to balance the electrical grid to avoid brown-outs.
To achieve the necessary efficiency, the commonly-used IGBTs are being replaced with modern silicon carbide (SiC) MOSFETs. With significantly faster switching speeds, the reduced losses in SiC devices, such as the Toshiba’s 1200 V TW070J120B N-channel MOSFET with integrated SiC Schottky barrier diode, deliver a 66% reduction in power losses over a comparable IGBT.
Toshiba’s TK49N65W5 DTMOS superjunction N-channel device with superior RDS(ON) and fast reverse recovery time (trr), plus its TLP5214A gate driver and its TLP7920 230 kHz isolation amplifier are all used in the company’s latest reference design, a 50 kHz switching, isolated bidirectional DC-DC power supply. Designed to support power converter designers working on high-power designs, the design handles power levels up to 5 kW from a 750 V DC link. This forms an excellent starting point for EV charger developers. At a 100% step-up/-down load, the design has shown to operate with efficiencies of 97%.