TIDUEQ9A clarification on short-circuit current

Nicola Fiorucci

Prodigy 190 points

In the design guide TIDUEQ9A the Equation 16 show a calculation result of Delta_I = 36A.

But by using the data:

Vsc = 54V

Lsc = 3uH

Delta_t = 4us

the Formula 16 give a result of Delta_I = 72A (=36A * 2)

Why this difference?

Am i missing some assumption?

Thanks

over 3 years ago

+1 Aaron Barrera over 3 years ago

TI__Mastermind 26046 points

Hi Nicola,

You're correct, the equation gives 72A, which is what I would expect if the short circuit happens through one half-bridge. Not sure why it's half, unless if the designer assumed short circuit was happening through two inverter legs and not just one.

Thanks,
Aaron

0 Nicola Fiorucci over 3 years ago in reply to Aaron Barrera

Prodigy 190 points

Hi Aaron,

thanks for your reply.

I also think that the short-circuit must be intended through two inverter legs. In this case Lsc must be count 2 times. So in this case the calculation gives the a value of 36A as stated in the design guide.

Regards

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TIDUEQ9A clarification on short-circuit current