These observing waveforms have good agreements with simulated results in Figure 10 and Figure 11. It is proven that this quasi resonant ZVS-PWM high-frequency inverter with CFVP scheme can completely work under a soft-switching operation for a wide duty cycle control scheme. In addition, this high-frequency inverter can clamp an excessive peak voltage applied to the main switching power semiconductor device, main switch; Q₁1 (SW₁ and D₁). Accordingly, the conduction losses and current stresses of switching power semiconductor devices can be reduced for this quasi resonant inverter circuit topology. Figure 17 illustrates temperature characteristics for setup in experiment.

These results show this induction-heated steam generator is able to produce a saturated heating steam within about 220 seconds. It is noted that this electromagnetic induction based fluid heating can generate super heated vapor faster than general gas combustion system or sheathed heater system.

　

Fig.13 Experimental super heated steam generator

Fig. 14 Voltage and Current waveforms of Q1 (200[V/div] ,50[A/div], 10[μs/div])

Fig.15 Voltage and Current waveforms Qs (200[V/div], 50[A/div], 10[μs/div])

Fig.16 Voltage and Current waveforms of load (200[V/div], 50[A/div], 10[μs/div])

Fig.17 Temperature characteristics of induction heated boiler

　

7. CONCLUSIONS

　

In this paper, an innovative prototype of the new electromagnetic induction-eddy current based fluid heating appliance has been successfully proposed by using a voltage-fed type active voltage-clamped quasi-load resonant ZVS-PWM high-frequency inverter using trench gate IGBT power module, which can efficiently operate at a soft-commutation scheme on the basis of asymmetrical PWM strategy.

Furthermore, it has been proven as a variety of industrial, consumer, medical, chemical and automotive heat energy processing plants that the new and efficient induction heated fluid heating appliances using voltage source type high-frequency inverter could be cost-effective for the electromagnetic induction eddy current heated steam generator and super heated steam generator than the conventional sheathed heated type steam generator, because of downsizing in volumetric physical size, cleanliness, high-efficiency conversion, quick temperature response, stable and precise temperature control realization and on-site utilization.

In the future, the power loss analysis of this soft switching inverter using the latest IGBTs Should be done and the new generation power electronic appliances for electromagnetic induction eddy current based fluid heating should be evaluated and discussed from a practical point of view. The computer aided design procedure of this power electronic appliance using a new inverter topology in the pipeline system should be studied from a theoretical point of view.

　

REFERENCES

　

[1] Y. Uchihori, Y. Kawamura, S. Morita, M. Nakaoka "The State-of the Art Electromagnetic Induction Flow-Through Pipeline Package Type Fluid Heating Appliance using Series Resonant PWM Inverter with Self-tuning PID Controller-based Feedback Implementation" May, 1995,Proceeding of IEEE-IAS on Automation and Control Emerging Technologies, pp. 14-21

[2] T. Nakamizo, Bin Guo, M. Nakaoka "New Generation Electromagnetic Induction-based Fluid-Heating Energy Processing Appliance using Voltage-Fed PWM Resonant Inverter" April 1998, Proceedings of PCIM-Japan, pp.597-607

[3] M. Kaneda, S. Hishikawa, H. Tanaka, B. Guo, and M. Nakaoka "Innovative Electromagnetic Induction Eddy Current-based Dual Packs Heater using Voltage-Fed High-Frequency PWM Resonant Inverter for continuous Fluid Processing in Pipline " November, 1999, Proceeding IEEE-IES IECON, Vol 2 pp.797-802

[4] T. Nakamizo, M. Kaneda S. Hishikawa, Bin Guo, H. Iwamoto and M. Nakaoka "NEW GENERATION FLUID HEATING APPLIANCE USING HIGH-FREQUENCY LOAD RESONANT INVERTER", Proceeding of the IEEE PEDS'99, pp309-314, July, 1999

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