Hello Everyone,
I need to design 4kW induction heating circuit that heats up the metal pipe. This metal pipe has circulating water inside. I did some calculations but i am still stuck at both LTSpice simulations and calculations. Here is my basic circuit in LTSpice.
As i know, i can use basic LLC calculations. So, i used the TI's Designing an LLC Resonant Half-Bridge Power Converter app note.
VDCmin = 283V, VDCmax = 358V
Nominal Switching Frequency = 100kHz
Min Switching Frequency = 55kHz
Max Switching Frequency = 150kHz
All the values except C5, L4, L5, R1 are calculated values. This circuit in LTSpice has 55kHz switching frequency at VDCmin and full load. With these values for C5 and L4, primary and secondary currents are almost pure sinusoidal and they are matched with calculated values but when i change parallel resonance frequency of C5 and L4 to lower value about 200kHz, these currents gets higher in value and become distorted.
Do i really need to push the parallel resonance frequency of C5 and L4 to about something 5MHz ? As i know, their parallel resonance frequency needs to be higher than max switching frequency.
How can i calculate the C5 and L4 ?
I need to design 4kW induction heating circuit that heats up the metal pipe. This metal pipe has circulating water inside. I did some calculations but i am still stuck at both LTSpice simulations and calculations. Here is my basic circuit in LTSpice.
As i know, i can use basic LLC calculations. So, i used the TI's Designing an LLC Resonant Half-Bridge Power Converter app note.
VDCmin = 283V, VDCmax = 358V
Nominal Switching Frequency = 100kHz
Min Switching Frequency = 55kHz
Max Switching Frequency = 150kHz
All the values except C5, L4, L5, R1 are calculated values. This circuit in LTSpice has 55kHz switching frequency at VDCmin and full load. With these values for C5 and L4, primary and secondary currents are almost pure sinusoidal and they are matched with calculated values but when i change parallel resonance frequency of C5 and L4 to lower value about 200kHz, these currents gets higher in value and become distorted.
Do i really need to push the parallel resonance frequency of C5 and L4 to about something 5MHz ? As i know, their parallel resonance frequency needs to be higher than max switching frequency.
How can i calculate the C5 and L4 ?
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