LLC Resonant Inverter for Induction Heating with Asymmetrical Voltage-Cancellation Control

ABSTRACT

This paper planned a high ability LLC resonant inverter for induction heating use by using asymmetrical voltage cancellation control. The planned control method is realize in a full-bridge topology for induction heating use. The operating frequency is automatically adjusted to maintain a small constant lagging phase angle under load parameter variation.

LLC  RESONANT

The output power is controlled using the asymmetrical voltage cancellation method. The LLC resonant tank is plan without the use of output transformer. This results in an increase of the net efficiency of the induction heating system. The validity of the planned method is verified through computer simulation and hardware experiment at the operating frequency of 93 to 96 kHz.

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Full-bridge series and parallel resonant inverter.

Fig. 1. Full-bridge series and parallel resonant inverter.

EXPECTED SIMULATION RESULTS

Voltage and current waveforms at 100 % duty cycle

Fig. 2. Voltage and current waveforms at 100 % duty cycle

Simulation results with α=70o

Fig. 3. Simulation results with α=70o

CONCLUSION

This work planned the full-bridge LLC resonant inverter for induction heating use. The phase-locked loop allows resonant density tracking under load limit variation. The analytical expression of the output power as a function of the shifted phase angle is given in this work.

FREQUENCY

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 planned control method. The resonant density tracking and the adjustment of pulse voltage together ensure the maximum power transfer to the load throughout the heating cycle with minimal loss.

 

REFERENCES

  1. Kamli, S. Yamamoto, and M. Abe, “A 50-150 kHz Half- Bridge Inverter for induction heating Application,” IEEE Trans. Industrial Electronics, Vol. 43, February 1996. pp. 163-172
  2. J. Davies , J. and Simpson, P., 1979, Induction Heating Handbook. , McGraw-Hill, UK ,
  3. Chudjuarjeen, S., Koompai, C.and Monyakul, “Full-bridge current-fed inverter with automatic frequency control for forging application”, IEEE Tencon 2004, Vol. 4, pp.128-131, Nov. 2004
  4. Viriya, P.; Sittichok, S.; Matsuse, K.; “Analysis of High-Frequency Induction Cooker with Variable Frequency Power Control,” Power Conversion Conference, 2002 .PCC Osaka 2002 .Proceedings of the Volume 3, 5 -2 April 2002Page(s): 1507 – 1502vol.. 3
  5. Nam-Ju Park, Dong-Yun Lee, and Dong-Seok Hyun,”A Power-Control Scheme With Constant Switching Frequency in Class-D Inverter for Induction-Heating Jar Application”, IEEE Trans. Industrial Electronics, vol. 54, no. 3, Jun. 2007

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