Single‐Stage ZVS‐PWM AC‐AC Power Converter Using All SiC Power Module for High‐Frequency Induction Heating Applications

This paper presents a novel prototype of a single‐stage zero voltage soft‐switching pulse‐width modulation ‐controlled ac‐ac converter with a silicon carbide (SiC)‐MOSFET/SiC‐SBD power module for high‐frequency (HF) induction heating (IH) applications. The newly developed ac‐ac converter can achieve higher efficiency than a Si‐IGBT/Si‐PN diode power module‐based prototype due to a low ON‐resistance of SiC‐MOSFET and a low forward voltage of SiC‐SBD under the condition of HF switching. The performances of the new prototype converter are evaluated by experiment with a single‐phase IH utensil of ferromagnetic stainless metal, after which the high‐efficiency and low switching noise characteristics due to the all SiC power module are actually demonstrated.     

BIOCHEMICAL DIFFERENCES IN SOCKEYE SALMON THAT ARE OCEAN FEEDING AND ON THE SPAWNING GROUNDS

Various biochemical parameters measured in sockeye salmon, Oncorhynchus nerka, feeding in the Gulf of Alaska in July during the maturation process were contrasted with those obtained from mature sockeye salmon in Steep Creek, a small salmon stream near Juneau, Alaska. Degenerative changes in muscles, such as decrease in total lipid and protein contents in mature salmon were attributed both to the progressed activation of lipid hydrolytic enzymes and to autolytic activity, in addition to the inactivation of lipid and protein syntheses in muscle and liver. The depletion of lipid is associated with the energy utilization for migration and gonadal maturation as a result of the cessation of feeding.     

A Five‐Element Multiplex Resonant Full‐Bridge DC‐DC Converter with a Variable Inductive Reactance

A five‐element multiplex resonant (LLCLC) full‐bridge DC‐DC converter controlled by pulse frequency modulation (PFM) is proposed in this paper. The high frequency (HF)‐link resonant DC‐DC converter proposed herein can perform wide‐range output power and voltage regulation with a narrow frequency range due to an antiresonant tank that works effectively as a wide‐range variable inductor. The advantageous characteristics of the antiresonant tank provide overcurrent protection in the case of the short‐circuited load condition as well as in the startup interval. Thus, the technical challenges of a conventional LLC DC‐DC converter can be overcome, and the reliability of the relevant switch‐mode power supplies can be improved. The operating principle of the LLCLC DC‐DC converter is described, after which its performance is evaluated in an experimental setup based on the 2.5 kW prototype. Finally, the feasibility of the proposed DC‐DC converter is discussed from a practical point of view.     

ACOUSTIC IMPULSE RESPONSE METHOD FOR MEASURING NATURAL FREQUENCY OF INTACT FRUITS AND PRELIMINARY APPLICATIONS TO INTERNAL QUALITY EVALUATION OF APPLES AND WATERMELONS

A nondestructive textural quality measurement technique that uses an acoustic property was studied for apples and watermelons. By means of digital Fourier analysis, the natural frequencies of intact fruits are obtained from the sound which is produced by hitting them with a wooden ball pendulum. The reliability of this method was confirmed. This method requires simpler instrumentation than the sonic vibrating resonance method.     

Phospholipase A2-mediated synthesis of phosphatidylethanolamine containing highly unsaturated fatty acids

Phosphatidylethanolamine (PE), which contains highly unsaturated fatty acid (HUFA) specifically in sn -2 position, was synthesized by porcine pancreatic phospholipase A₂-catalysed esterification of lysophosphatidylethanolamine with HUFA. the use of glycerol containing only a little water as solvent was the important key to this reaction. A 27% yield of up to 94.5% sn -2 eicosapentaenoic acid (EPA)-containing PE was obtained using >99% EPA as a substrate HUFA.     

New VVVF control-based high-frequency resonant inverters using static induction transistors

Voltage-fed high-frequency resonant inverters are proposed having a variable-voltage variable-frequency (VVVF) control function based on new circuit topologies called resonant voltage phasor controlled type and current phasor controlled type. The steady-state characteristics of the circuit topologies proposed are illustrated and the circuit design algorithm is described. A resonant voltage phasor controlled type high-frequency resonant inverter newly developed by using a static induction transistor (SIT) is applied as a 100-500 kHz induction-heating power supply. This paper thus refers to the results of an experiment including the optimum drive circuit of SITs.