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I'm working on a new topology.

I looked it up myself, and it says "3-level boost converter" has a low inductor.

Is this right? How do I search it?

enter image description here

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    \$\begingroup\$ Welcome! Have you tried to simulate it? What will it achieve? \$\endgroup\$
    – winny
    Feb 27 at 13:51
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    \$\begingroup\$ First of all, I want to achieve the input voltage 10~20V and the output voltage 30V for study purposes. I also want to test the interleaved behavior. \$\endgroup\$
    – kogyu
    Feb 27 at 13:55
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    \$\begingroup\$ Please do and post the results. \$\endgroup\$
    – winny
    Feb 27 at 13:57
  • \$\begingroup\$ oh, I asked to find out how to set the parameters such as inductors etc. to test the behavior. \$\endgroup\$
    – kogyu
    Feb 27 at 13:59
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    \$\begingroup\$ No, you didn't ask anything about parameters or inductors. How about you start with a tried and true single switch asynchronous boost converter and see if that solves your electrical needs? \$\endgroup\$
    – winny
    Feb 27 at 14:05

2 Answers 2

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This is a 3-level single-phase boost converter. I think it has been originally presented in a paper at APEC in 1995:

enter image description here

You can simulate this structure with SIMPLIS for instance and the below circuit is part of the free 120+ ready-made templates you can download from my webpage:

enter image description here

You can obtain the control-to-output transfer function quickly, stabilize the converter and check the THD:

enter image description here

Please note that both switches are interleaved which reduces the overall stress.

This type of 3-level converter is often used in high-power three-phase PFCs to stack-up power stages. This helps reducing the voltage stress on semiconductors like using 650-V transistors in 2 x 400 V rather than 1200-V types with a two-level 800-V dc link rail for instance:

enter image description here

Please note that this particular structure has not been very popular due to the floating operation of the input source which is often a show stopper for the EMI signature. You can check this AN from Toshiba which also proposes a single-phase 3-level T-type PFC which approaches the Vienna rectifier.

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  • \$\begingroup\$ Very nice answer! Does this converter deliver good efficiencies at low voltages (1V -> 3V)? \$\endgroup\$ Feb 27 at 19:26
  • \$\begingroup\$ Thank you but what do you mean 1-3 V? This is a PFC powered from a universal mains which delivers a 400-V output voltage in total. \$\endgroup\$ Feb 27 at 19:56
  • \$\begingroup\$ Heh, @MicroservicesOnDDD has a "joule thief" bent -- looking for any novelties that might be applied there, I suspect. At least, I suspect that's the context; correct me if I'm wrong. Nothing I would say important for such an application, though. \$\endgroup\$ Feb 28 at 19:14
  • \$\begingroup\$ @TimWilliams, & {at}VerbalKint -- I meant would this topology be useful in low voltage boost conversions, e.g., for converting 1V to 3V? Since it's so efficient at high voltage and high power, might this topology also be efficient at low voltage? \$\endgroup\$ Mar 3 at 19:55
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    \$\begingroup\$ @MicroservicesOnDDD Well, that's a good starting point; what makes it efficient at high voltages? Do those effects remain dominant at 1-3V? Is it worth the complexity in drive/control, or the lack of common ground (as shown)? (Well, a JT typically has isolated battery, so we can trivially confirm that last one!) \$\endgroup\$ Mar 3 at 20:08
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Do you know about topologies that look like this?

Yes.

Is this right?

Yes, that is one variant of the family of converters known as "3-level boost converters".

How do I search it?

Well, there are many papers on this topic, here are two examples:

Paper #1:
This gives a good overview of one example of "3-level boost converter", it is slightly different from what you drew in that it has one (1) inductor, whereas yours has two (2), refer to link below:

Three Level Boost PFC Converter for High Voltage AC-DC Applications

Paper #2:
This particular paper (link below) gives a good overview of the "three-level boost" converter, and introduces "soft-switching":

Soft-Switching Non-Isolated High Step-up Three-Level Boost Converter Using Single Magnetic Element

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  • \$\begingroup\$ Thank you, it was a modified 3-level boost converter! \$\endgroup\$
    – kogyu
    Feb 27 at 14:12
  • \$\begingroup\$ Fabio, have you ever seen this converter with the second inductor also at the bottom? \$\endgroup\$ Feb 28 at 17:22
  • \$\begingroup\$ "have you ever seen this converter with the second inductor also at the bottom?" Not an actual physical unit in person. I have seen them in simulations. \$\endgroup\$ Feb 29 at 5:35

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