Inductor current in the buck converter

I've been reading the switching power supplies A-Z. Attached the table that's confusing me.
In the table it's shown that increasing duty cycle of a buck converter reduces the inductor current. Isn't that wrong ? According to the volt-sec dI should increase right ?

Thanks

The assumptions are unclear. For the cuck converter, are we talking about CM or DCM mode?

In DCM, volt-sec will rise from zero to maximum and fall to zero again when varying duty cycle between 0 and 1.

increasing the duty cycle (above 50%) in a buck converter will reduce the delta I or ripple current, not the peak or average current... helps to read the chart closely...

Have a play with a buck converter in ltspice and your questions will soon become crytal clear to you....

in a real current mode buck converter, the peak inductor current is determined by the error amplifier output voltage level into the pwm comparator......you could have a certain buck converter with 0.2 duty cycle with say 10 amps peak inductor current, or you could have a buck with D = 0.8 but with only 1A peak inductor current....or vice versa, it depends. Use V=Ldi/dt to find out

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Ina buck converter, the duty cycle tends to affect the output voltage....so in theory a CCM buck with duty cycle of 0.6, could have its load halved and its D would still be 0.6.......but in truth it would be slightly less than 0.6 because there would be less voltage drop in the inductor resistance etc, when the load lightened.

For a buck...

D = Vout/Vin

or if you want to consider the diode drop too

D = (Vout + vf)/Vin

generally the Peak inductor current isnt directly related to the duty cycle, D.

Thank you all, i built the circuit and tested, learnt a lot too! Actually i had missed the point that changing the duty cycle also changes the ouput voltage, my bad! .
So, (1 -D)Vin = Ldi/DT , rearranging it forms a equation like (1 - D) * D proportional to di, meaning: for a fixed inductor and frequency increasing D has to reduce di!!. Intuitively, let's take ON time, by increasing duty cycle the inductor has to build up lesser voltage hence lesser current. Am i right on this ?

for 0 -> 50% duty cycle the di goes up, for 50% -> 99% duty the di goes down again, it is maximum at 50%..!

Easy peasy said:

for 0 -> 50% duty cycle the di goes up, for 50% -> 99% duty the di goes down again, it is maximum at 50%..!

Click to expand...

No, it doesn't, i simulated and checked.

I see, so your quick check goes against all the literature and other empirical testing done in the last 50 years that shows that (all other things being equal) delta-I in a buck converter is maximum at 50% duty cycle, perhaps you have better check again...?

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Do you agree delta-I is minimum at 0.5% on time and at 99.5% on time?

As previously mentioned, the presumptions are unclear, for a buck converter in CCM you get the behavior described Easy peasy. It can be easily derived with pencil and paper method, similarly you should be able to determine why your simulation gives different results when you compare with theoretical behavior.

Easy Peasy, your observation is true for a boost converter. Max at D=0.5 .

Cheers

OP can confirm this with the sim i sent earlier.