| Induction heating power supply widely used benefits humans for many years.Compared with induction heating power with LC series or parallel load, inductionheating power with LLC resonant load is more simpleness and costs less. Thus,increasingly more people are interested in studying LLC power. At present, a lot ofmethods are apllied to LLC power to ajust the output power. But there is no satisfyingmethod so far. Because asymmetrical method hasn’t been applied to LLC power, thispaper will try to use asymmetrical method to regulate LLC power output power.First of all, inverter form should be chosen for LLC power. Compared withcurrent inverter, voltage inverter doesn’t only cost low, but also allows flexible layoutload. What’s more, voltage inverter is characteristic of self-excited start. And the starttime of that is very little. Nevertheless, the current inverter needs an additionalstart-up circuit, which results in the fact that start time is longer and the currentinverter is more likely to fail. So voltage inverter is chosen for LLC power.In the third chapter, the asymmetrical voltage control method is mixed togetherwith zero voltage soft switch technology to regulate output power of LLC power. Thispaper focuses on analysis operating modes and system waveform of LLC power withasymmetrical voltage method. And the expressions of the output power, voltage andcurrent under asymmetric voltage control method are obtained. Finally, simulationdiagrams verify the validity of the theoretical analysis.Although the zero voltage soft switch technology is realized in this study, powerlosses also exist. The expression of power losses is obtained in fourth chapter.Finally, two kinds of phase-locked loop schemes are designed for inverter. Thefirst scheme is a classic full digital phase-locked loop. Based on classical digitalphase-locked loop, the second scheme which adopts phase/frequency detecter and90degree phase delay circuit is proposed with more accurate frequency trackingperformance. |
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