All-silicon-carbide, 1200V power modules rated up to 600A
The BSM600D12P3G001 achieves a rated current of 600A using a new package featuring an original internal structure and optimized heat radiation design, enabling support for higher power applications such as large-scale power supplies for industrial equipment. In addition, switching loss is reduced by 64% (at a chip temperature of 150°C) compared with IGBT modules at the same rated current. In addition to reducing the size of peripheral components through high-frequency operation, the effects of reducing switching loss are greater when driving at high frequencies, contributing to the miniaturization of cooling and other systems. For example, from preliminary calculations based on loss simulation in cooling systems, adopting SiC modules can reduce the size of water-cooled heat sinks by up to 88% compared with equivalently rated IGBT modules. This example is calculated for the 1200V/600A product, in a PWM inverter drive, using 20 kHz switching frequency, and less than 40 µm thermal grease thickness.
Rohm notes that in order to make full use of the high-speed switching characteristics of SiC – particularly in products with large current ratings such as power modules – it is necessary to develop a new package that suppresses the effects of surge voltage during switching. These latest modules employ a package design that expands Rohm’s SiC module lineup to cover the key current range from 100A to 600A.
Using SiC Schottky barrier diodes (SBDs) and MOSFETs makes it possible to reduce switching loss by 64% (at a chip temp. of 150°C) vs IGBTs at the same current rating. Loss simulations conducted with PWM inverter drive resulted in a 30% reduction at 5 kHz drive and an even more substantial reduction in total loss of 55% at 20 kHz PWM vs equivalently rated IGBT modules.
Increasing the current rating of power modules also increases the surge voltage during switching, making it necessary to minimize inductance within the package. Optimizing the internal placement of the SiC device along with terminal configuration and conductor layout allows ROHM to reduce internal inductance by 23% vs conventional products. Rohm’s G Type package suppresses surge voltage by 27% at the same loss compared with standard packages, enabling the development of 400A and 600A modules. In addition, this new package decreases switching loss by 24% under the same surge voltage drive conditions.
Achieving a rated current of 600A entails not only reducing internal inductance but heat generation as well. Improving the flatness of the module base plate aids heat conduction to the sink; deviations of microns are important. By ensuring that any deviation from perfectly-flat is in the direction of having the base plate slightly convex, the mounting fixtures act to pull the entire base plate into close contact with the heat sink. Rohm was able to decrease the thermal resistance between the base plate and the heat sink by 57%.
Rohm; www.rohm.com/web/eu/full-sic-power-modules
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