Choosing the right Inductor for aftermarket inverter motherboard

[fabieville]

I am rebuilding my 48v 10,000 power jack split phase inverter that uses a EI type transformer by installing a aftermarket pure sinewave inverter motherboard.

The problem i am facing is that i am not sure which size amp and UH inductor to use because this is a requirement for installing the new board.

The inductor will decrease the standby current of the motherboard but u have to choose it correctly for it to work good.

Please take a look on the motherboard and also the size inductors in the links below and tell me which size inductor i should use.




https://www.aliexpress.us/item/3256808991688717.html?mp=1&pdp_npi=5@dis!USD!U SD 121.43!USD 120.22!!USD 120.22!!!@2101e80f17629470287176745e85e9!120000482 06993854!ct!US!140025765!!1!0&gatewayAdapt=glo 2usa




https://www.aliexpress.us/item/3256810005635519.html?mp=1&pdp_npi=5@dis!USD!U SD 64.76!USD 64.76!!USD 64.76!!!@2101e80f17629470287176745e85e9!1200005147 1820044!ct!US!140025765!!1!0&gatewayAdapt=glo2 usa

[solardreamer]

It all depends on the specifics of the system but typically ~47uH total inductance seems to work for 48V systems. In particular, the transformer leakage inductance. EI transformers typically have significantly higher leakage inductance than toroidal transformers so you don't need to add as much external inductance. You should build the transformer first then measure the leakage inductance to determine how much add-on inductance is necessary. You don't want to have too much inductance as that can cause problems.

You should also ensure the add-on inductance winding is thick enough to handle the target *surge* current without too much voltage drop for stability and safety. Lastly, keep in mind the Aliexpress inductors are known to be overrated. Their inductance typically drops to practically zero at the rated current. This can be dangerous because you end up with effectively a short circuit at high current which can result in exploding FET's. So, you should test any add-on inductance to determine the actual saturation current limit where the inductance is no less than ~30% of the nominal value.

If you don't have the tools or capability to test inductances then you could just start with no add-on inductance and incrementally add inductance

[Liam]

Looks like a common issue when swapping to aftermarket inverter boards. A few practical tips that helped me:

Check the board docs/schematic first — many vendors publish a recommended choke value or at least switching frequency.
Choose an inductor whose saturation current is higher than the board’s max DC/standby current (I’d allow ~1.2–1.5× margin). Low DCR is important so it doesn’t heat or waste power.
Use the L = V / (ΔI · f) relationship to size L if you know the switching frequency and acceptable ripple (ΔI). If you don’t know f, measure the gate drive or ask the seller — guessing can lead to wrong µH.
After fitting, verify with a scope (check ripple and waveform), and run a thermal test — chokes that look fine electrically can still overheat mechanically.

If you want a quick reference for how an integrated split-phase inverter handles this (and what choke specs they use), look at a 12kW split-phase unit I’ve referenced here: https://cmxbattery.com/product/12kw-...brid-inverter/ Maybe it can give you a ballpark for saturation currents and physical choke size.

Hope that helps, if you can post the board’s switching frequency or the inductor links, I can make a tighter recommendation.