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    Analysis of transition mode from phase-shift to zero phase-shift under ZVS and NON-ZVS operation for induction heating inverter
    (2008-01-01)
    Viriya, Pichetjamroen
    ;
    Yongyuth, Naras
    ;
    MatSUSe, Kouki
    This paper proposes an analysis of transition mode from phase-shift to zero phase-shift under ZVS and NON-ZVS operations for a series resonant inverter with the load of induction heating. A number of circuit operations during transition mode from phase-shift to zero phase-shift under ZVS and NON-ZVS conditions are first analyzed. Various voltage and current equations of the operating circuits are then obtained and used for calculation of the waveforms by the aid of MATLAB program. The calculated waveforms make possible the consideration of some important circuit parameters that are used to determine ZVS or NON-ZVS conditions. The theoretical results and proposed method are also verified by experimental ones, using a prototype test set in our laboratory. © 2008 The Institute of Electrical Engineers of Japan.
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    Analysis of a half-bridge inverter for a small-size induction cooker using positive-negative phase-shift control under ZVS and NON-ZVS operation
    (2007-12-01)
    Achara, P.
    ;
    Viriya, P.
    ;
    Matsuse, K.
    This paper presents a detailed analysis of circuit operation under ZVS and NON-ZVS conditions in a high-frequency half-bridge inverter for a small-size and low-voltage induction cooker, using the principle of positivenegative phase-shift control over a wide control range both in positive and negative directions. A variety of modes of circuit operation with the voltage and current equations during phase-shift power control under the operating conditions of ZVS and NON-ZVS are analyzed as a first step and the output voltage and current waveforms are obtained by MATLAB program. These waveforms will be analyzed by Fourier analysis which can lead further to the calculation of ac output power P<inf>0</inf>, dc input power P<inf>d</inf>, and hence the conversion efficiency η of the half-bridge inverter. The analysis results shows that the control ranges of ac output power P<inf>0</inf> and dc input power P<inf>d</inf> are limited by the occurrence of NON-ZVS operating condition, which changes according to the switching frequency f<inf>s</inf>. © 2007 IEEE.
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    Analysis of circuit operation under ZVS and NON-ZVS conditions in phase-shift inverter for induction heating
    (2006-01-01)
    Viriya, Pichetjamroen
    ;
    Yongyuth, Naras
    ;
    Miki, Ichiro
    ;
    Matsuse, Kouki
    This paper presents a detailed analysis of circuit operation under ZVS and NON-ZVS conditions in a full-bridge high-frequency phase-shift control series resonant MOSFET inverter with the load of induction heating. Various modes of circuit operation both under ZVS and NON-ZVS conditions are first analyzed in details. The voltage and current equations of these circuits are then obtained and used for calculation of the waveforms by MATLAB program. The calculated results can lead to the consideration of various circuit parameters that determine ZVS or NON-ZVS operating conditions. The theoretical results are also verified by experimental ones, using a prototype test set rated at 3 kW.
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    Modeling bipolar phase-shifted multielectrode catheter ablation
    (2002-01-05)
    Tungjitkusolmun, Supan
    ;
    Haemmerich, Dieter
    ;
    Cao, Hong
    ;
    Tsai, Jang Zern
    ;
    Choy, Young Bin
    Atrial fibrillation (AFIB) is a common clinical problem affecting approximately 0.5-1% of the United States population. Radio-frequency (RF) multielectrode catheter (MEC) ablation has successes in curing AFIB. We utilized finite-element method analysis to determine the myocardial temperature distribution after 30 s, 80 °C temperature-controlled unipolar ablation using three 7F 12.5-mm electrodes with 2-mm interelectrode spacing MEC. Numerical results demonstrated that cold spots occurred at the edges of the middle electrode and hot spots at the side electrodes. We introduced the bipolar phase-shifted technique for RF energy delivery of MEC ablation. We determined the optimal phase-shift (φ) between the two sinusoidal voltage sources of a simplified two-dimensional finite-element model. At the optimal φ, we can achieve a temperature distribution that minimizes the difference between temperatures at electrode edges. We also studied the effects of myocardial electric conductivity (σ), thermal conductivity (κ), and the electrode spacing on the optimal φ. When we varied σ and κ from 50% to 150%, optimal φ ranged from 29.5° to 23.5°, and in the vicinity of 26.5°, respectively. The optimal φ for 3-mm spacing MEC was 30.5°. We show the design of a simplified bipolar phase-shifted MEC ablation system.