Fixed-frequency control strategies for a series resonant inverter for induction heating - comparison of properties

Abstract

Three fixed-frequency control strategies for a series resonant inverter for induction heating: PS-PWM, ADC and ACM have been compared in the paper. The analysis has been carried out using decomposition of the inverter output voltage to harmonic components. Special attention has been paid to the determination of conditions assuring ZVS operation of the semiconductor devices and to the inverter efficiency. Streszczenie. W artykule porównano właściwości trzech stałoczęstliwościowych metod sterowania rezonansowego falownika szeregowego do nagrzewania indukcyjnego: ADC, PS-PWM i ACM. Analizę przeprowadzono z wykorzystaniem rozkładu napięcia wyjściowego falownika na składowe harmoniczne. Szczególną uwagę zwrócono na określenie warunków zapewniających przełączanie zaworów przy zerowym napięciu (ZVS) oraz sprawność falownika. (Stałoczęstotliwościowe metody sterowania rezonansowego falownika szeregowego do nagrzewania indukcyjnego-porównanie właściwości)

Induction heating with a fixed control frequency guaranteeing ZVS at varying parameters of the resonant circuit

“…Minimum values of normalized switching frequency f s /f 0 required for ZVS, determined numerically for each control strategy, are shown in Fig. 2, as a function of angle  [6]. The minimum switching frequency increases with an increase of angle  in ADC and PS control strategies.…”

“…The analysis of the inverter operation was carried out using numerical calculations, and taking into account a large amount of harmonics of the inverter output voltage [1,6]. Selected results from [6,7] were utilized in this paper, and some new calculations have been done.…”

“…The value of power depends also significantly upon the quality factor Q of the resonant circuit. Dependences between power, angle  and Q are presented in [1,6,7].…”

“…Class D series resonant inverter in a full-bridge configuration: a) circuit diagram, and examples of time waveforms of gate signals u GS1 u GS4 , output current i 0 , voltage u p and its first harmonic u p1 in control strategies: b) PS, c) ADC, d) ACM; based on[1],[6] …”

“…Solid lines for 1999 harmonics, Q = 1, 3, 5, 10, 20. Dashed lines -only fundamental harmonic, Q = 1, 3, 20[6]…”