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Journal ArticleDOI

Use of a voltage follower to ensure sinusoidal flux in a core

01 Jul 1983-IEEE Transactions on Magnetics (IEEE)-Vol. 19, Iss: 4, pp 1572-1573
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.
Citations
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Journal ArticleDOI
TL;DR: A multichannel flux controller design is presented that combines the real-time performance of analog feedback with an iterative digital feedback algorithm to reduce error and demonstrates a 95% reduction in convergence time at power line frequencies over a comparable system using only digital feedback.
Abstract: International standards for testing soft magnetic materials require that the magnetic flux density remain sinusoidal with respect to time. Traditionally, this has been achieved via control of the magnetic flux using either analog feedback, which provides real-time control, or iterative digital feedback, which yields more accurate solutions with the cost of increased convergence time. In certain applications, such as magnetic nondestructive testing, rapid convergence of multiple interacting flux controlled channels is required. In this paper, a multichannel flux controller design is presented that combines the real-time performance of analog feedback with an iterative digital feedback algorithm to reduce error. The system demonstrates a 95% reduction in convergence time at power line frequencies over a comparable system using only digital feedback. Several examples of the system's ability to control arbitrary periodic waveforms are presented over the frequency range from 0.735 Hz to 100 Hz. Sinusoidal form factor errors are shown to be 0.1% from 2 Hz to 100 Hz across four strongly coupled channels with highly nonlinear magnetizing conditions. A detailed description of both analog circuit and digital algorithms is provided.

23 citations


Cites background from "Use of a voltage follower to ensure..."

  • ...This approach has been demonstrated succesfully for a single channel controller [16]–[20]....

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  • ...Traditionally, flux controllers have been constructed using analog feedback circuits [16]–[20]....

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Journal ArticleDOI
TL;DR: A novel steady-state digital control algorithm with two loops, one to regulate the amplitude and the other to correct the waveform of the flux density is proposed, which proves the high adaptability, accuracy, and convergence speed of this controller.
Abstract: In the context of the ever-expanding application of soft magnetic materials, the fully controlled magnetic measurement has, therefore, become essential. It ensures not only the accurate modeling of materials but also the rigorous quality control throughout the manufacturing process, as well as the explicit communication of magnetic data in academic studies or between suppliers and customers. Due to the nonlinearity and hysteresis nature of electrical steels, automatic flux density controller is required for high standard measurements. In this article, we propose a novel steady-state digital control algorithm with two loops, one to regulate the amplitude and the other to correct the waveform of the flux density. Measurement results for various samples tested by Epstein frame and ring specimens under different waveforms, a wide range of frequency and high amplitudes of the flux density have proven the high adaptability, accuracy, and convergence speed of this controller. Its principle is discussed in detail, together with the employed measurement bench.

7 citations


Cites background from "Use of a voltage follower to ensure..."

  • ...Computer-based systems with multifunctional highspeed sampling rate input/output devices are widely implemented, and digital feedback controllers [13]–[27], with their robustness, have replaced the former analog circuits [28]–[30] in most magnetic testing applications....

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Journal ArticleDOI
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.

4 citations

References
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Journal ArticleDOI
G. Swift1
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

Journal ArticleDOI
01 Nov 1974

1 citations