We have developed a loss estimation method that is applicable to three-phase ac reactors using amorphous cores in a 400-kVA UPS. The method is based on measured the B-H curves and iron losses of the cores, modeled with magnetic simulations of a finite-element method considering the directions of the amorphous ribbon planes. The reactors are formed from wound cores. Two types of magnetic legs are proposed: structure A, toroidalshaped with slits, and structure B, sector prism-shaped cut from a wound core. Their unit volumes are shrunk by 9% and 19%, respectively, compared with that of a conventional silicon-steel core reactor. Both reactors have about half the total losses of the conventional silicon-steel core reactor, resulting in increased UPS efficiencies of up to 0.55%. The calculated iron losses at the pulse width modulation (PWM) carrier frequencies agree with measured losses within 10%. The accuracy of the loss estimation method for PWM-induced reactors is discussed. The method is confirmed to enable accurate design of a reactor for filtering in a high-efficiency inverter system.
2-D vector magnetic properties accurately represent the magnetic properties of various kinds of electrical steel sheets, because they can represent an alternating magnetic field in any direction and a rotating magnetic field by using the relationship between the flux density vector B and the field strength vector H. E&S modeling is proposed as a method for representing 2-D vector magnetic properties in magnetic field analyses. However, the E&S modeling used in magnetic field analyses is very time-consuming. To solve this problem, we propose complex E&S modeling on the assumption that both the flux density and field strength waveforms are sinusoidal. We carried out FEM analyses taking account of complex E&S modeling. Finally, we compared the analyses results considering complex E&S modeling with those of conventional E&S modeling, and made clear the efficiency of complex E&S modeling.
PurposeThe purpose of this paper is to reduce computation time of magnetic characteristic analysis considering 2D vector magnetic properties.Design/methodology/approachThe paper proposes a complex E&S modelling with assumption that both flux density and field strength waveforms are sinusoidal. The computation time of the complex E&S modeling becomes 1/10 in comparison with one of the conventional E&S modeling. This modeling is applicable up to 1.4 T of the local magnetic flux density condition in the case of non‐oriented magnetic materials.FindingsIn the results of the magnetic field analyses of a linear‐induction motor model core by means of the finite element method taking account of the complex E&S modeling, the distributions of the flux density and the field strength were able to be approximately analyzed and their phase differences in space were represented. The results of the magnetic characteristic analysis of the linear‐induction motor showed that the teeth‐end shape had large influences on the thrust and cogging.Practical implicationsThis technique helps to know approximately local vector magnetic properties in core materials. This modeling is very useful for magnetic core design taking account of the simplified 2D vector magnetic properties.Originality/valueThe method presented in this paper enables expression of the simplified 2D vector magnetic properties in magnetic field analyses. The computation time can be considerably reduced in comparison with the conventional method.
We have designed and constructed lower-loss and smaller-unit volume three-phase amorphous reactors for use as filter components in a 400-kVA on-line UPS. For high-accuracy loss estimation, a simplified method has been applied that is based on measured B-H curves and iron losses of amorphous cores, modeled with magnetic simulations of a finite-element method (FEM) considering the directions of the amorphous ribbon planes. The reactors are formed from toroidal wound cores. Two core sizes designed with magnetic flux densities of standard (0.8 T) and higher (1.2 T) values are constructed. Their unit volumes are shrunk by 9 % and 43 %, respectively resulting in UPS efficiencies 0.54 % and 0.39 % higher than those of a conventional silicon-steel core reactor. The accuracy of the loss estimation method for PWM-induced reactors is verified. The method is confirmed to enable a miniaturized reactor for filtering in an inverter system to be designed on the basis of the trade-off with permissive raise of loss.
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