Active circuits for flux waveform compensation in ferromagnetic cores
TL;DR: In this paper, some new active circuits using active circuits are proposed for realization of sinusoidal flux in a ferromagnetic core during loss testing, which facilitates the loss measurements to be made from the primary side itself.
Abstract: Some new schemes using active circuits are proposed for realization of sinusoidal flux in a ferromagnetic core during loss testing. One of the suggested configurations facilitates the loss measurements to be made from the primary side itself. A few filter circuits enable the tests to be carried out on normal supply mains without the need for a calibration generator. Experimental results are reported to confirm the acceptability of the proposed schemes.
Citations
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TL;DR: An instrument using linear compensating networks and exploiting the processing capabilities of the popular microprocessor is developed for the measurement of core characteristics such as specific iron loss and the dynamic B-H curve.
Abstract: Precise knowledge of the characteristics of core material Is essential for the design of electromagnetic devices I Ike dynamos, I nstrument transformers and relays. Conventional measurement of the core characteristics Is a tedious process as it Involves collection of voluminous data and corrections thereto. An instrument using linear compensating networks and exploiting the processing capabilities of the popular microprocessor is developed for the measurement of core characteristics such as specific iron loss and the dynamic B-H curve. The necessary corrections are Incorporated In the software so that the end result can be straightaway used in design.
2 citations
TL;DR: Using high performance soluble imide polymer as a binder, it was possible to accomplish a substantial mechanical strength in iron particle cores molded under uniaxial compacting pressure which was much lower than that was commonly applied by others in the past as mentioned in this paper.
Abstract: Using high performance soluble imide polymer as a binder, it was possible to accomplish a substantial mechanical strength in iron particle cores molded under uniaxial compacting pressure which was much lower than that was commonly applied by others in the past The directional ordering of oblate spheroidal iron particles occurred despite the low compacting pressure resulting in strong anisotropy in the magnetic properties and mechanical strength in the fabricated cores The low molding pressure, however, resulted in a low density of core which, in turn, caused the low permeability
2 citations
TL;DR: In this paper, two low-cost measurement systems that use active circuits in the power stage are proposed for the DC and AC characterisation of industrial soft and/or hard ferromagnetic materials.
Abstract: Two low-cost measurement systems that use active circuits in the power stage are proposed for the DC and AC characterisation of industrial soft and/or hard ferromagnetic materials. For the DC measurements, the discrete variation of the point-by-point method is simulated by a very low frequency triangular wave. The problems encountered are pointed out and the solution proposed is tested experimentally. The AC source system combines a power amplifier and an operational amplifier with a feedback technique. This allows the option of selecting the power source to be either a constant voltage or a constant current source. Results obtained using these methods on a core sample of mild steel are shown to bring out the performance of the system.
References
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TL;DR: In this paper, the impact of the 45° mitered-overlap joint on the performance of large power transformer cores with respect to core loss and exciting current was investigated.
Abstract: The 45° mitered-overlap joint is commonly used in the construction of large power transformer cores. There are several variables which affect the performance of such cores with respect to core loss and exciting current. The major variables investigated in this paper are 1) overlap distance, 2) stagger layer thickness, and 3) overlap method, namely, simple staggering versus step-lap. Also investigated to a lesser degree were the effect of frequency and the effect of series air gaps at the corners. One set of results in this paper is not in agreement with a previous paper and reasons for this are speculated. The other sets of results are new, and indicate that staggering beyond two laminations per stagger is not advisable, that the difference between one and two laminations per stagger is marginal, and that the use of a step-lap joint reduces exciting current requirements but not core loss.
18 citations
TL;DR: In this paper, a circuit employing a voltage follower for obtaining a sinusoidal flux in a ferromagnetic core is described, and the amplifier just supplies the copper loss of the exciting winding.
Abstract: A circuit employing a voltage follower is given for obtaining a sinusoidal flux in a ferromagnetic core. The amplifier just supplies the copper loss of the exciting winding.
3 citations