I'm studying FCML converters, especially the 4-level / 3-cell topology. It's clear that when the flying capacitors become imbalanced (e.g., one undervolted), the switching node voltages deviate from their expected levels.
I’ve read that the output inductor plays a key role in naturally restoring capacitor balance, acting somewhat like an integral controller. However, I'm struggling to intuitively understand how the inductor's current slope becomes a self-correcting mechanism.
My current understanding:

• Capacitor imbalance leads to incorrect switching node voltages.
• This creates a voltage across the inductor.
• The inductor responds with a current slope.
• That current redistributes charge between capacitors during different phases.

But I’m not clear on why this current flow ends up correcting the imbalance over time — or what ensures that the charge moves in the “right” direction to fix it.
Could anyone explain this concept in simple terms, or point me to visual/numerical resources that demonstrate this?
Thanks in advance!

 

I'm studying FCML converters, especially the 4-level / 3-cell topology. It's clear that when the flying capacitors become imbalanced (e.g., one undervolted), the switching node voltages deviate from their expected levels.
I’ve read that the output inductor plays a key role in naturally restoring capacitor balance, acting somewhat like an integral controller. However, I'm struggling to intuitively understand how the inductor's current slope becomes a self-correcting mechanism.
My current understanding:

• Capacitor imbalance leads to incorrect switching node voltages.
• This creates a voltage across the inductor.
• The inductor responds with a current slope.
• That current redistributes charge between capacitors during different phases.

But I’m not clear on why this current flow ends up correcting the imbalance over time — or what ensures that the charge moves in the “right” direction to fix it.
Could anyone explain this concept in simple terms, or point me to visual/numerical resources that demonstrate this?
Thanks in advance!

Welcome to AAC.

Is this question baed on work you are doing for academic credit?

 

No, this is for my own research, not for any graded assignment.

 

Please post your schematic diagram.

 

Dear Cappels,
Please find the attachment.