On Sat, 01 Dec 2012 17:12:28 +1100, Franc Zabkar
put finger to keyboard and composed:

It describes the OP's circuit as a resonant circuit consisting of an
L-C resonant tank. It states that "the IGBTs are driven by high
frequency complementary square waves with 50% duty cycle", and that
the frequency of "the PWM signal applied to the driver input pin ...
varies in a range between 19 kHz and 60 kHz". The two capacitors are
680nF 600V types, and the IGBTs are STGY40NC60VD.

The datasheet for the STGY40NC60VD states that the IGBT is good for
"high frequency operation up to 50kHz". Hmmm ...

http://www.st.com/internet/com/TECHN...CD00003462.pdf

- Franc Zabkar
--
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