Lower System Cost By Increasing SiC Module Temp

PCIM 2012, Nuremberg, Germany: Powerex, a joint venture between Mitsubishi and GE, showed off its SiC MOSFET modules at PCIM in Nuremberg yesterday. Among the highlights was the recently launched, second-generation, QJD1210010/1 all-SiC dual-MOSFET module.

Duane Prusia, business unit manager for Custom Modules at Powerex, explained that for the second generation, engineers optimised inductance and extended the package’s temperature range to 200°C. The modules feature 10 Cree 20A SiC MOSFETs, each with a reverse-connected, free-wheel SiC Schottky diode.

According to Prusia, advanced R&D is underway to boost frequency, voltage, and temperature. The new 1200V/100A-rated modules operate at 100kHz, with no partial discharge at 12kV.

The advantages of using SiC MOSFETs include lower conduction losses at 200°C and a much higher switching frequency versus a silicon IGBT. Prusia conceded that cost is a significant disadvantage to using SiC. However, he pointed out that the second-generation modules cost around $200 in sample quantities, a big reduction on the $10,000 price tag that came with the first generation two years ago.

He also pointed to overall system savings, saying that faster switching speeds can decrease the size of magnetics. Moreover, increasing the operating temperature leads to reduced heatsink size. The module cost may increase slightly, but a fivefold reduction in system cost “would not be out of the question.”

The QJD1210010 has a copper baseplate, while the QJD1210011 integrates an AlSiC baseplate for extended thermal cycle life. In both cases, the baseplate is isolated from the components and interconnects to simplify thermal management.

The modules will target high-frequency applications, including UPS, high-speed motor drives, induction heating, welding and robotics, as well as high-temperature applications (e.g., electric vehicles and aerospace power electronics).

Powerex has manufacturing centres in Youngwood, Pa., US, and Tangier, Morocco.

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