LC low pass filter using Toroid Core

[canlu]

there is a capacitive load that has a high power usage (about 250 w).

the output signal of the transformer is a square signal .
b-point expected signal is sin-wave .to convert a-point ( square signal) to the sin-wave (b-point) , an inductor is added to the circuit and of curese it's
we lined up with three types of inductor .
a green-blue toroid inductor with inductance of 1.3 mh .
output signal is:

which is very close to our desired signal.
but the problem is that with the green-blue toroid core , the toroid become very warm after 30s (about 90 celecius).
and two more inductor with black toroid and green toroid . with same inductance as (green-blue ( 1.3mh))
the output is:

but the cores are cool .
in what way , the black or green toroid can be used to have the output signal similar to the sine wave .

 

[FvM]

Same inductance but completely different waveform? More information needed, core parameters, number of turns, what is C load?

Pure C load can't be "250 W", either 250 VA or there must a real load impedance.

 

[canlu]

Same inductance but completely different waveform? More information needed, core parameters, number of turns, what is C load?

Pure C load can't be "250 W", either 250 VA or there must a real load impedance

load(c) is a piezo
all core are same size 25-15-10
but core type are different as i mention above( green-blue, black, green),
green-blue toroid core are about 60 turn
black toroid core are 6 turn
however , i don 't know what the different core behavior is?
it seems green-blue toroid have high core loss
and black core have minimum core loss
how can i have black core inductor with same parameter?

 

[D.A.(Tony)Stewart]

Hot core means I^2*DCR=Pd is too high so you need higher C added to suppress harmonics and lower DCZ to reduce heat.

But without and complete schematic with all V, L, DCR, f, I on primary, secondary , we cannot help much.
Also purpose of piezo and mechanical load is useful to determine VA and W separately thus pf.

 

[FvM]

O.k., a piezo is no capacitive load at resonance frequency, you need to analyze the actual impedance. Secondly, it sounds unlikely that 6 turns make 1.3 mH.

 

[canlu]

Hot core means I^2*DCR=Pd is too high so you need higher C added to suppress harmonics and lower DCZ to reduce heat.

But without and complete schematic with all V, L, DCR, f, I on primary, secondary , we cannot help much.
Also purpose of piezo and mechanical load is useful to determine VA and W separately thus pf.

F = 9.1k

transformer input driver is full bridge.
and output(pic above) is full schematic

 

[canlu]

piezo is no capacitive load at resonance frequency, you need to analyze the actual impedance. Secondly, it sounds unlikely that 6 turns make 1.3 mH

it is. i dont know why

Same inductance but completely different waveform?

the difference in the shape of the wave is in the difference of the core that is mentioned in the first post .

 

[FvM]

Most likely explanation for different waveforms, the inductance values are far from being equal. How did you measure?

 

[canlu]

Most likely explanation for different waveforms, the inductance values are far from being equal. How did you measure?

Lc meter