I implemented a parallel LC induction heater using theory. I made a simple square wave Inverter providing a frequency of 20kHz to the tuned LC circuit. The problem I'm facing is that my tank is not drawing any current although the tank is at resonance with the supply. The picture of the output wave across the coil wrt ground is attached. Should I attach a resistance in parallel to the tank? I don't have any resistance in parallel to that. The picture of the circuit is also attached. Circuit of the parallel tank

Voltage waveform on the tank circuit. It is at 20kHz, the oscilloscope was fluctuating because of switching harmonics.


@Marla - I have a variable dc power supply with a built-in ammeter and voltmeter. It has a max rating of 30V at 15A. So, that's where I'm measuring the current. The scope is stating the wrong frequency due to switching harmonics (stays constant at 20.2kHz then fluctuates then goes back to 20.2kHz). The switching frequency of Mosfets is 20.2kHz. Component values => L=1.9uH ; C=33uF; fsw=20.2kHz.

  • \$\begingroup\$ Component values? Also your scope says 10 kHz. How do you measure current? You said tank isn't drawing current. Edit this into you question. \$\endgroup\$
    – Marla
    Jan 15 '19 at 18:34
  • \$\begingroup\$ Also, what load do you have in coil? Photographs will help. \$\endgroup\$
    – Marla
    Jan 15 '19 at 18:36
  • \$\begingroup\$ @Marla - the load was the tip of cast iron pliers. The inner dia of the coil is around 2.5inches and its an 8SWG copper wire wound into a 7 turn coil to give 1.9uH inductance. \$\endgroup\$
    – Sajeer
    Jan 15 '19 at 18:59
  • \$\begingroup\$ Have you confirmed that both the left side of coil and right side of coil are being switched? \$\endgroup\$
    – Marla
    Jan 15 '19 at 19:51
  • \$\begingroup\$ Yes. Otherwise it wouldn't go in negative polarity. \$\endgroup\$
    – Sajeer
    Jan 15 '19 at 19:57

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