Silicon Carbide Power Module Design Process

Preliminary Stage

For the preliminary design phase, we developed a special system simulation tool called ScanTool. This is an essential step in order to determine power, efficiency, voltage ripple, current stress and more. In the phase of system analysis, this tool is of essential importance, as it enables a high number of different simulation scenarios of both hardware and software design combinations.

Finding the right amount

When designing an IGBT power module, the amount of chips is defined by the relating junction temperature. For silicon carbide, however, the situation is different. While junction temperature is one aspect, one also has to consider realizing maximum efficiency. Too many chips may not further increase endurance mileage, yet using not enough of them can result in a decrease. Yet, this also allows a greater amount of design freedom, depending on individual requirements, such as boosting the acceleration of high-end electric vehicles. 

 IGBT or SiC - which is ultimately more expensive?

Is silicon carbide indeed more expensive? Leadrive developed a simplified financial model to evaluate the cost difference between IGBT and SiC chips. Initially, the investment cost is higher using silicon carbide. However, taking the savings in capital and operational expenditures — reduced installed battery capacity and charging energy savings — into account, the estimated break-even point is between 1-4 years, depending on usage frequency.

Oscillation phenomenon

The negative effect of high-frequency oscillations on voltage and current waveforms of silicon carbide MOSFETs is indeed a concern when designing a power module. In order to mitigate this challenge, we have developed a series of tools and ontology design optimization. Thanks to applied research and design effort, Leadrive was able to solve this issue.  

For reference and more information, please read our full-length research paper published on the ROHM Semiconductor website: