This module, developed with the support of Clean Sky Joint Undertaking, will help increasing power converter density, by decreasing weight and size, for power generation and electromechanical actuators in More-Electrical Aircraft.
This IPM, Cissoid says, offers optimal integration of the gate driver and power transistors to realise the full benefits of SiC, namely, low switching losses at high operating temperature. Building on the HADES2 Isolated Gate Driver that incorporates years of development in driving SiC transistors, it combines advanced packaging technologies enabling a reliable operation of power modules in extreme conditions.
For this aerospace module, a 3-phase power inverter topology was selected while other topologies are being investigated for HEV and Railways projects. In this 3-phase topology, each of the six switch positions employs a 100A SiC MOSFET transistor and a 100A SiC Schottky free-wheeling diode. These devices can block voltages up to 1200V, which provide enough headroom against overvoltages in a 540V Aerospace DC bus, and the module is designed to be upgraded with 1700V/150A SiC devices. The transistors have a typical on-resistance of 12.5 mOhms or 8.5 mOhms depending on their current rating, either 100A or 150A.
Special attention was paid to thermal aspects during the design of the module. First, all the materials have been selected to allow reliable operation at high junction temperatures, up to 200°C with peaks at 225°C, in order to decrease cooling requirements. This materials selection also enables high case and storage temperatures, up to 150°C. Finally, the module is based on high-performance materials such as AlSiC baseplate, AlN substrates and Silver Sintering in order to offer near perfect CTE matching with SiC devices and high robustness against thermal and power cycling.
Co-designing the gate driver with the power module in a single IPM allowed Cissoid to optimize the gate driver circuit taking into account parasitic inductances of the power module while minimizing them when possible. Minimizing parasitic inductances allows faster switching of SiC transistors faster and lower switching losses. An IPM also offers a plug-and-play solution to power electronic designers who save a lot of time in the design of the gate driver board, which is particularly challenging with SiC transistors. They can then focus on the design of high density power converters taking advantage of SiC.