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I was a developer of PV module. so, I know the electrical characteristic of PV cells and MPPT concepts well.

I just wonder, Can I use the buck converter for MPPT? I saw that buck converter can be used for MPPT through the internet.

But, I thought, Buck converter makes the PV current choped. (Not kind of DC current with ripple)

And PV module is kind of current source with shunt & series resistor and diode. so, there is maximum current(Isc) not like power supply. it's not power conversion, just on/off concept. for MPPT, PV current should be like DC current with ripple.

That's why buck is not good for MPPT.

Buck is just for kind of PWM charger. (PV is not like normal power supply)

I think kind of boost converter concepts should be used. because, PV current is continuous, not choped.

How do you think about that?

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    \$\begingroup\$ A capacitor across the input solves that - it stores the energy while the switch in the buck is off. \$\endgroup\$
    – Kevin White
    Sep 13 '21 at 14:00
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    \$\begingroup\$ Ahn JIn Ho - Hi, I see this is your 7th question here. Some of your previous questions received good answers, but you didn't "accept" any of them yet. Although accepting an answer isn't mandatory, it is strongly encouraged to do so as it marks the question as effectively "solved" and gives some points to the most useful answer, as chosen by you. For more information, please see this article from the help center and this article from the Stack Exchange FAQ list. Thanks. \$\endgroup\$
    – SamGibson ♦
    Sep 13 '21 at 14:05
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that's why Buck is not good for MPPT.

You appear to be making the assumption that a buck converter cannot be operated in CCM (continuous conduction mode). If you took a random sample of buck and boost converter circuits you'd probably find more buck converters running in CCM compared to the number of boost converters running in CCM.

The reason you don't see so many buck converters in these types of application is because a boost converter will naturally be able to dredge up the final flickering energy levels from a solar panel and still convert that dwindling voltage to some useful level. A buck converter won't because it can only produce an output voltage lower than the input voltage hence, it's less useful in most PV applications.

Having said all of that a buck-boost converter is the best of both worlds and these are quite common.

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There are buck, boost, buck&boost converters. All of them make a "chopping" of the input current. To make the input current with low ripple, a capacitor bank is used.

There are also interleaved converters, like having multiple of them in parallel, having the synced switching frequency but delayed phase, like 4 cylinder engine - they provide less ripple.

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