ABSTRACT
This paper proposes a high
efficiency LLC resonant inverter for induction heating applications by using asymmetrical
voltage cancellation control. The proposed control method is implemented in a
full-bridge topology for induction heating application. The operating frequency
is automatically adjusted to maintain a small constant lagging phase angle
under load parameter variation. The output power is controlled using the
asymmetrical voltage cancellation technique. The LLC resonant tank is designed
without the use of output transformer. This results in an increase of the net
efficiency of the induction heating system. The validity of the proposed method
is verified through computer simulation and hardware experiment at the operating
frequency of 93 to 96 kHz.
SOFTWARE: MATLAB/SIMULINK
BLOCK DIAGRAM:
Fig.
1. Full-bridge series and parallel resonant inverter.
EXPECTED SIMULATION RESULTS
Fig.
2. Voltage and current waveforms at 100 % duty cycle
Fig.
3. Simulation results with α=70o
CONCLUSION
This
work proposes the full-bridge LLC resonant inverter for induction heating
application. The phase-locked loop allows resonant frequency tracking under
load parameter variation. The analytical expression of the output power as a
function of the shifted phase angle is given in this work. Based on the derived
expression, the asymmetrical voltage cancellation can be used to control output
power to the induction coil. Simulation and experimental studies are performed
to verify the proposed control method. The resonant frequency tracking and the
adjustment of pulse voltage together ensure the maximum power transfer to the
load throughout the heating cycle with minimal loss.
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[3]
Chudjuarjeen, S., Koompai, C.and
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[4]
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