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I am working on a bidirectional half bridge DC-DC converter. The converter circuit is shown below. enter image description here

I used a TLP250 IC for the driver circuit. A square wave with 20 kHz switching frequency was given as input to the driver circuit. The output from TLP250 is a square wave with 20 kHz switching frequency and 10 V peak to peak.

When I am applying this pulse across the MOSFET (IRF150) in the bidirectional DC-DC converter, the switching frequency of the pulse becomes more than 80 kHz. What might be the reason for this?

Edit:

  1. The driver circuit is shown below enter image description here

  2. The output pulse from the TLP250(from pin 6)(before connecting the MOSFET) is enter image description here

  3. The pulse across gate source of the MOSFET is enter image description here

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    \$\begingroup\$ Show us the schematic of how you apply the pulses, and give more info about signal/pulse source. \$\endgroup\$
    – Rohat Kılıç
    Commented May 9, 2023 at 7:54
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    \$\begingroup\$ Welcome! Please show oscillograms showing your gate drive waveforms as well as the 250 kHz you observe. \$\endgroup\$
    – winny
    Commented May 9, 2023 at 8:14

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It looks like both signals have the same frequency, based on the images you added from your oscilloscope. Both measurements have a scale of 10us/div and the period of both square waves is approximately 50us which corresponds to 20kHz Perhaps the automatic measurement is set wrong and you obtained an erroneous measure.

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