Silicon carbide (SiC) gets much of the attention as electric vehicles move toward higher-voltage electrical systems, particularly in traction inverters where efficiency gains can have a direct impact on driving range. But that does not mean every high-voltage switching function in the vehicle needs to make the move to SiC.
Lower-power systems such as electric compressors and high-voltage heaters still present a different set of design priorities. Here, silicon insulated-gate bipolar transistors (IGBTs) remain an option, particularly when designers need to balance efficiency with the ability to survive short-circuit conditions.
ROHM is targeting those applications with a new generation of 650V IGBTs designed to reduce losses without sacrificing short-circuit tolerance.
The company’s fourth-generation devices achieve a typical collector-emitter saturation voltage (VCE(sat)) as low as 1.55V while providing a short-circuit withstand time of 7µs at a junction temperature of 25°C. The devices are also qualified to the AEC-Q101 automotive reliability standard.
That combination addresses a familiar tradeoff in IGBT design. Reducing conduction losses generally works against short-circuit withstand capability, yet designers of inverter and heater circuits need enough time for the system to detect an overcurrent condition and shut the device down before it fails.
ROHM said it redesigned the device structure, including the process and edge termination structure, to increase current density while reducing conduction and switching losses.
The initial lineup includes 12 discrete products in TO-247N packages, with collector-current ratings ranging from 35A to 88A at 100°C. Versions are available with and without an integrated fast-recovery diode. Ten bare-wafer products are also part of the family.
ROHM is developing additional TO-247-4L versions and plans to expand the family into surface-mount TO-263L and top-side-cooled packages.
For EV designers, the introduction is also a reminder that the transition to wide-bandgap power devices is not necessarily an all-or-nothing proposition. SiC is increasingly taking on the vehicle’s highest-power conversion tasks, while improved silicon devices continue to compete for the auxiliary systems surrounding them.
The new 650V IGBTs are intended for automotive electric compressors, high-voltage heaters and industrial inverter applications.
