Development of RC-IGBT with a new structure that contributes to both reduced size of Power Control Unit and low loss in Hybrid Electric Vehicles 2020-01-0596
In order to improve the fuel efficiency of Hybrid Electric Vehicles (HEVs), it is necessary to reduce the size and electric power loss of the HEV Power Control Units (PCUs). The loss of power devices (IGBTs and diodes) used in a PCU accounts for approximately 20% of total electric loss of an HEV. Therefore, it is important to reduce the electric power loss while reducing the size of the power devices.
In order to achieve the newly developed PCU target for compact vehicles, the development goals of the power device were to achieve low electric power loss which is equivalent to its previous generation while reducing the size by 25%. As for downsizing, it was achieved by developing a new RC-IGBT (Reverse Conducting IGBT) with an IGBT and a diode integration. As for the electric power loss aggravation, which was a major issue due to integration, we optimized some important parameters like the IGBT and diode surface layout and backside diode pattern. As a result, it was possible to avoid the snapback characteristic (loss aggravation in low current region of the IGBT).
In addition, the substrate thickness was reduced by 24% compared to its previous generation. In order to address the deterioration of breakdown voltage due to a thinner substrate, the buffer layer structure was optimized to achieve the loss target while ensuring both high breakdown voltage performance and reliability.
Through this development, parts reduction of the power module equipped with this new RC-IGBT greatly contributed to achieving downsizing of the newly developed PCU and low fuel consumption.