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Wireless power transfer via magnetic resonance coupling method has opened a new possibility to the electric vehicle system. It allows the wireless charging system of moving vehicles, using charging lanes. However, although the efficiency of power transmission is relatively high, the efficiency still depends on displacement of coils. There have been several researches on methods to maintain power transmission at the highest efficiency. However, in such systems, the information on system parameter especially coupling coefficients is needed, and in the charging lane system, such information is unlikely to be obtainable without a communication system. Therefore, it has come to attention that parameter estimation is a crucial factor to implement a charging lane system. This paper presents derivations of equations for estimating coupling coefficients in several configurations of wireless power transfer system, using information from only one side, either the transmitting side or the receiving side, of the system. The presented equations are both applicable to the case of single receiving coil and are also generalized for the case of multiple receiving coils. Each equation is verified by both simulations and experiments. An experimental system of the coupling coefficient estimation system is constructed for estimation from the receiving side using a dc/dc converter.

Maximum efficiency control using a DC/DC converter on the secondary side can improve transmitting efficiency in dynamic wireless power transfer system for electric vehicles. However, the information of coupling coefficient has to be estimated to implement the control although coupling coefficient changes dynamically. In this paper, a simple method of coupling coefficient estimation with RLS (Recursive least squares) filter is proposed. Dynamics of WPT system is analyzed with transfer functions. Moreover, the modeling and the control method of DC/DC converter are introduced. The experimental results of real-time coupling coefficient estimation and maximum efficiency control are provided and they indicate the effectiveness of the proposed control in a real dynamic wireless power transfer system for EVs.

The role(s) of collagenase G (ColG) and collagenase H (ColH) during pancreatic islet isolation remains controversial, possibly due to the enzyme blends used in the previous studies. We herein examined the role of ColG and ColH using highly pure enzyme blends of recombinant collagenase of each subtype. Rat pancreases were digested using thermolysin, together with ColG, ColH, or ColG/ColH (n = 9, respectively). No tryptic-like activity was detected in any components of the enzyme blends. The efficiency of the collagenase subtypes was evaluated by islet yield and function. Immunohistochemical analysis, in vitro collagen digestion assay, and mass spectrometry were also performed to examine the target matrix components of the crucial collagenase subtype. The islet yield was highest in the ColG/ColH group (4,101 ± 460 islet equivalents). A substantial number of functional islets (2,811 ± 581 islet equivalents) was obtained in the ColH group, whereas no islets were retrieved in the ColG group. Mass spectrometry demonstrated that ColH reacts with collagen I and III. In the immunohistochemical analysis, both collagen I and III were located in exocrine tissues, although collagen III expression was more pronounced. The collagen digestion assay showed that collagen III was more effectively digested by ColH than by ColG. The present study reveals that ColH is crucial, while ColG plays only a supporting role, in rat islet isolation. In addition, collagen III appears to be one of the key targets of ColH.