Toshiba Electronic Devices & Storage Corporation has developed a 6500V-rated trench-type second-generation Injection Enhanced Gate Transistor (IEGT) chip featuring high turn-off capability and short-circuit capability. The company has commercialized a 6500V/2000A press-pack IEGT, model ST2000JXH35A, incorporating the new chip for use in DC power transmission systems, STATCOM, and industrial motor drives.
Increasing the voltage rating from the conventional 4500V class to 6500V allows a reduction in the number of devices connected in series for the same output voltage. This contributes to simpler system configurations and smaller power conversion equipment. In HVDC systems, the use of 6500V devices can reduce the number of series-connected units by approximately 33% compared with 4500V devices.
The development addresses challenges in achieving adequate turn-off and short-circuit capability under higher voltage conditions, along with managing breakdown voltage variation in bias tests. The new IEGT chip employs a shorted dummy cell structure in the cell region to eliminate floating regions, an optimized mesa width, and an N-barrier layer beneath the P-base layer. These changes improve carrier distribution and transport, resulting in more uniform current distribution during turn-off and stable high-voltage operation. Toshiba also confirmed an improved trade-off between conduction loss and turn-off loss.
In the termination region, the chip uses guard rings and a semi-insulating layer to achieve a breakdown voltage exceeding 6500V. Optimization of the interface process between the semi-insulating layer and silicon suppresses breakdown voltage variation under bias stress.
The chip was evaluated through turn-off and short-circuit tests at 4500V. Toshiba has been mass-producing 4500V-class press-pack IEGT devices and will continue to expand its lineup for high-voltage power conversion applications.
Details of the technology were presented at Power Conversion and Intelligent Motion (PCIM) Europe 2026, held in Nuremberg, Germany, from June 9 to 11, 2026.
