Resonant Inductor heating

[sabu31]

Hi all,

I use a series-parallel resonant converter for induction heating (from DC supply 36V).
The inductor current is sinusoidal with a peak of 45A. Also, the resonant frequency /switching frequency is 76kHz.The value of inductance used is 10.8uH using 5 turns .

During testing the inductor core temperature is rising to 125 Degrees Celsius.

Is the chosen core suitable or what else can be done to reduce heating?

 

[Easy peasy]

you want a lower perm core - and a bit bigger, with one or two more turns to get the core losses down ...

 

[FvM]

Not obvious at first sight why an induction heater needs a resonant inductor.

 

[Easy peasy]

yes an inductor is needed as a well matched load is mainly resistive with varying levels of inductance - dropping to near zero when the steel being heated ( for example ) gets taken above its Curie Temp ( no longer magnetic )

 

[sabu31]

Not obvious at first sight why an induction heater needs a resonant inductor.

Its regarding this inductor (10uH)

--- Updated Dec 27, 2022 ---

you want a lower perm core - and a bit bigger, with one or two more turns to get the core losses down ...

Most of the cores I have seen in these (have permeability of 60,90,125). The core used has permeability of 60u
Is there any other work around .

 

[Easy peasy]

2 cores in parallel and 70% turns .....