Safe operating area for FF23MR12W1M1P_B11

[alexquan]

Hi there,

We are developing a 50kW three phase inverter using 4Si/2SiC ANPC converter and are evaluating various SiC mosfets.
Based on the ratings, FF23MR12W1M1P_B11 looks like a good fit. However, the datasheet does not provide much information.

Edit: I think we misunderstood the definition of SOA. So the title of this post does not reflect our question.
If we are not running the mosfet at saturaton zone, we don't nee to care about it, right? If I am correct, then our main concern is just the current limit of this module.

Based on our current design, the mosfet will be switched on and off at 700V (maximum) with a peak current at the AC output will be 62A which is beyond the 50A rating of the module.
I know that the 50A rating is a limit when Tvj is 175C, and the RMS current through mosfet should be between 30A and 35A. But we are not sure if the device can handel a peak current at 62A when the junction temperature is below 125C.
Can you please comment on the feasibility of such use of FF23MR12W1M1P_B11?

Also, what is the temperature TH in the datasheet: "DC drain current Tvj=175C, VGS=15V TH=80C ID,non 50A". Is it heatsink surface temperature? If so, oes this mean that we have to keep the heatsink surface temperature below 80C? What about the case temperature? Is it still 100C limited?

Best,
Alex

[electricuwe]

Hi Alex,

The FF23MR12W1M1 module is one of the first SiC-Mosfet modules we have released. We decided to start with halfbridge modules as they are a universal building blocks suitable for a wide variety of applications. Also the IGBT module business started with halfbrigdes. Please note that now we have dedicated modules in the topology you intend to use. Nevertheless, using individual halfbridges is also possible.

Now coming to your questions in detail:

- switching this module at 700 V DC / 62 A is not causing any concern as long as commutation inductance is low enough. See for example that a pulsed drain current of 100 A is specified and diagrams for switching energies provides data up to 100 A.
- The first statement just addresses the switching. If you can run a sinewave current with 62 A peak current depends on the cooling conditions. You may either evaluate the junction temperature by manual calculations using Rdson, switching energies and thermal path data from the datasheet or you may use our online simulation tool IPOSIM. In both cases you additionally need some information on the Rth for your heatsink. As long as the junction temperaure stays below 150°C everything is fine.
- If the junction temperature stays below 125°C as stated (how do you know ?) you seem to have reasonable cooling and then of course running a sinewave with 62 A peak is fine.
- on the definition of heatsink temperature for power semiconductors please refer to IEC 60747-15, Rev. 3.0. The heatsink temperature is measured using a drilled hole in the heatsink below the chip. For baseplateless modules like our Easy-modules it is not possible to measure case temperature like for a baseplate module. The hole that would need to be drilled for this measurement would already disturb the heatflow.
- Where did you find a 100°C limit ? There is no such limit in the datasheet. The current capability of such a module strongly is a function of the cooling conditions applied externally.

Best regards,

electricuwe