Hello ZAO,

The 80 kHz limit is based on the power rating of the isolated DC/DC converter on the gate driver. The calculation is provided in Section 2.3 of the CRD250DA12E-XM3 user guide (shown below). The gate driver is the only strict limitation to pushing the switching frequency higher on this inverter. We generally operate gate drivers lower than their theoretical limit to ensure adequate margin. Pushing the switching frequency above 80 kHz risks sagging gate voltages which could influence inverter performance. I'd recommend staying below this value. Most testing with this inverter is performed at ~20 kHz.

If you absolutely need to push to higher switching frequencies, I recommend incrementally increasing the switching frequency while monitoring the inverter as you increase it. At high frequencies, you need to be monitoring the inverter performance for the following potential issues (non inclusive):

• Cooling. More switching events due to the higher switching frequency leads to higher switching losses, regardless of how fast the device switches. You need to ensure your cooling solution is able to keep the junction temperatures below their rated maximums.
• Deadtime. More of the overall operating time will be lost to deadtime. You need to ensure you have an optimized deadtime to avoid significant performance losses due to deadtime.
• Gate Voltages. As mentioned, the gate drivers are limited in how much continuous power that they can provide to the SiC MOSFETs. It's recommended to monitor gate voltages during operation to ensure that they are stable at the elevated switching frequencies.

Thanks,

Chris N.