High Power Active Rectifier - PFC - VFD Project Review / Help - Page 1
Forum section: electronics / projects

author: Rerouter
author_rank: Super Contributor
timestamp: May 02, 2020, 09:51:24 am
content: High Voltage / High Power electronics has always been one of my weakest areas, So I've taken it as a challenge to try and recreate a high density 2.4KW PFC from an Infineon Application note. and tie a similarly sized 3 phase inverter on to its output with the thought of driving a motor, which puts in it a fun power level where both mosfets and IGBT's are about equally effective switching elements.App Note:https://www.infineon.com/dgdl/Infineon-Evaluation_board_EVAL_2K4W_ACT_BRD_S7-ApplicationNotes-v01_00-EN.pdf?fileId=5546d462700c0ae601708c10a1fc1585My thoughts are make almost like for like, then use what I learn to substitute in cheaper alternatives if possible, I went with this approach as a PFC appears like a nice way to get the bulk voltage as high as I am hoping for, while also removing the big issue with motor inverters that they are horribly noisyFirst part is an active rectifier, At the price of the mosfets I would normally just throw a bridge rectifier at the problem, but Its still a nice problem to get started with, and as far as I can see keep the thermal dissipation in the ballpark where heat-sinking is not really needed.Is there anywhere I have gone wrong with clearances, or similar, I've been working off the assumption of 2mm separation, between any phase, and positive rectified output, Does this seem correct for a circuit following a 320VAC Metal oxide Varistor (~450V DC Peak) or are there other things I should be considering,Next up is the input mains filter / magnetics, Is there any easy way to calculate how they came to those capacitor and choke values, And are they any good resources for making / specifying your own magnetics, every time I approach things like this it seems like its $20-$30 per choke through the usual suppliers, yet the core / bobbins seem much cheaper, So learning how to make them, or at least figure out how to source them for cheaper might lead to much less aversion to high power projects in future,And for now, are there any alternatives people can suggest to this app note that cut down the cost for about the same effectiveness. (High power, High density, low heat sinking requirements)

author: NiHaoMike
author_rank: Super Contributor
timestamp: May 02, 2020, 01:37:36 pm
content: If you can get a salvaged Prius inverter (about $100), you'll have a mostly ready to go power stage including gate drivers. Just add a bridge rectifier to use the internal boost converter for PFC and some extra DC bus caps to smooth out the ripple.

author: Rerouter
author_rank: Super Contributor
timestamp: May 02, 2020, 01:47:57 pm
content: More hoping to learn the hows and why, of actual designing this, rather than the end product, If I get one working, I would likely just gift it to my fathers lathe.Knowing what types of coil cores, what parameters matter, What the trade-offs are with various high power devices have always been a large mysterious black box to my head. even choosing switchmode converter coils apart from max current and inductance, I'm left guessing.And other things like getting solid answers to what clearances matter for mains, every resource seems to give a different golden number without much explaining of why.

author: NiHaoMike
author_rank: Super Contributor
timestamp: May 02, 2020, 02:04:07 pm
content: If it's a one off for home use, don't bother with PFC. As you might have figured out, the cost is high and residential is rarely billed for power factor.