operating voltage for 1200V and 1700V power electronics

[dmielke]

My understanding is that Automotive Power Electronics are typically designed with levels of power electronic components ie 650V, 1200V, 1700V, mosfets etc... and if you have 1200V components you typically need headroom and dont operate the device at 1200V, usually a couple hundred volts lower. My question is why is that? what is the risk/failure mode of operating devices at 1100V continuous if they have 1200V rated components?

Thanks!

 

[Comcokid]

Transients.
Switch Mode Power has plenty of inductors as components and as parasitic inductance (wires and connections). V=L*di/dt Make dt small and V becomes big. And the whole point of power electronics is you are doing a lot of switching through inductors or motors. Plenty of voltage headroom is needed.

 

[waross]

Automotive Power Electronics

Load dump transients are common in automobile systems.
The alternator excitation varies as the load.
The alternator output voltage is a function of both load current and excitation level.
When a large load such as the lights is turned off, the alternator becomes overexcited.
The transient voltage of a 12 Volt alternator nay easily peak at over 100 Volts.
Couple this with Comcokid's explanation and you need a lot of head room.

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Ohm's law
Not just a good idea;
It's the LAW!