Abstract: Disclosed is a method and system for unobtrusively measuring physical properties in electrochemical processes occurring in a predefined volume, such as the state of charge in an electrochemical battery. The invention provides for a coil (22) or (42) positioned relative to the predefined volume to minimize the reluctance path between the coil and the electrochemical process, with the winding axis of the coil generally transverse to a surface bounding the predefined volume. In this position, an alternating current is applied to the coil to generate an oscillatory magnetic field. Preferably, the coil includes a core (24) or a backing plate (46) for concentrating the magnetic field in a direction towards the process in the predefined volume. The physical properties are determined based upon a measurement of the electrical complex impedance of the coil, and data correlating the physical properties of the process with the electrical complex impedance of the coil.

Abstract: A dual transformer device (34) for use in a power converter (30) is provided. The dual transformer device is preferably implemented as an integrated magnetics device suitable for use in high density power converters. Two transformers, T1 and T2, have series connected primary windings (300 and 302), and secondary windings (304 and 306) connected at a common node (312). T1 and T2 have magnetizing inductances, L1 and L2, that independently store energy responsive to an AC voltage, V.sub.p. Diodes, D1 and D2, operate to rectify substantially out-of-phase secondary voltages, V.sub.S1 and V.sub.S2 and produce a rectified voltage V.sub.R. D1 and D2 cause L1 and L2 to store discharge energy such that the magnitude of an output current, I5, is always equal to the sum of magnetizing currents, I.sub.L1 and I.sub.L2. An output filter (38) reduces current ripple in I5 and voltage ripple in V.sub.R. Another inductance, L3, supplies energy to an AC voltage supply (32) to reduce switching losses.