MOSFETs offer flexibility to increase efficiency & frequency

Dr. Helmut Gassel, President, Industrial Power Control Division, Infineon, commented: “For more than twenty years, Infineon has been at the forefront of developing SiC solutions which address demands for energy savings, size reduction, system integration and improved reliability. Infineon has manufactured millions of products containing SiC devices, while our Schottky diode and J-FET technologies have allowed designers to achieve power density and performance not possible with conventional silicon. The strategy has now taken a significant step forward encompassing power MOSFETs that raise the benefits available from SiC technology to a new level, which has never before been possible.”

The impact of SiC MOSFET functionality is truly impressive. Power conversion schemes can operate at triple or more the switching frequency in use today. This leads to benefits such as reducing the copper and aluminium materials used in magnetics and system housing, facilitating smaller and lighter systems for less transportation effort and easier installation. New solutions supporting energy savings will be realised by the designers of power conversion applications. These applications can harness performance, efficiency and system flexibility in a completely new dimension.

The 1,200V SiC MOSFETs have been optimised to combine reliability with performance. They operate with ‘benchmark’ dynamic losses that are an order of magnitude lower than 1,200V Si IGBTs. This initially supports system improvements in applications such as PV inverters, UPS or charger/storage systems, while later configurations will also extend support to industrial drives.

The MOSFETs are fully compatible with the +15/-5V voltages typically used to drive IGBTs. They combine a benchmark threshold voltage rating of 4V with short-circuit robustness required by the target applications and fully controllable dv/dt characteristics. Key benefits over Si IGBT alternatives include temperature-independent switching losses and threshold-voltage-free on-state characteristics.

The culmination of many years of experience of SiC semiconductor development, the MOSFETs are based on a state-of-the-art trench semiconductor process and represent the latest evolution of Infineon’s comprehensive family of CoolSiC technologies. This family includes Schottky diodes and 1,200V J-FET devices and a range of hybrid solutions that integrate a Si IGBT and SiC diode in a module device.

The first discrete 1,200V CoolSiC MOSFETs feature on-resistance ratings of just 45mΩ. They will be available in 3-pin and 4-pin TO-247 packages targeted at PV inverters, UPS, battery charging and energy storage applications. Both devices are ready for use in synchronous rectification schemes thanks to the integration of a commutation robust body diode operating with nearly zero reverse recovery losses. The 4-pin package incorporates an additional (Kelvin) connection to the source, which is used as a reference potential for the gate driving voltage. By eliminating the effect of voltage drops due to source inductance, this further reduces switching losses, especially at higher switching frequencies.

Infineon has also announced 1,200V ‘Easy1B’ half-bridge and booster modules based on the SiC MOSFET technology. Combining PressFIT connections with a good thermal interface, low stray inductance and robust design, each module is available with on-resistance rating options of 11 and 23mΩ.

Infineon will start sampling for target applications in the second half of 2016, with volume production planned for 2017.