MnZn. MnZn Ferrites with Low Loss and High Flux Density for Power Supply Transformer. Abstract:

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1 MnZn JFE No p MnZn Ferrites with Low Loss and High Flux Density for Power Supply Transformer FUJITA Akira JFE Ph. D. FUKUDA Yutaka JFE NISHIZAWA Keitarou JFE TOGAWA Jirou MnZn Fe2O3 1 C NiO NiO Fe2O3 1 C 2 MB1H 3 Abstract: New MnZn ferrite with high saturation flux density, Bs was developed as a material suitable for transformer cores built into fly-back mode power supplies. Addition of NiO into the ternary Mn-Zn-Fe-O system requires higher Fe content to keep the temperature of minimum iron loss at around 1 C, compared to the original composition. This modification results in enhancement of Bs at 1 C. The new product MB1H was realized by choosing optimal composition so that Bs becomes high and iron loss is moderate. The transformer made with MB1H, designed to generate the same output power as ones with conventional materials, has proved to increase saturation flux density 2% at 1 C and to reduce 3% in volume. 1. OA 5/6 Hz khz MnZn JFE JFE MnZn MnZn MnZn 25 C 8 C 1 C MnZn MnO-ZnO-Fe2O3 NiO NiO 32

2 2. AC1 V 5 6 W Fig. 1 1 Tr1 ON Tr1 OFF VO B-H Fig. 2 V IN Tr 1 i 1 I V O D 1 Ic 1 N p N S C 1 T Tr 1 : Transistor, T: Transformer, D 1 : Diode, C 1 : Capacitor, V IN : Input voltage, N p : Primary winding, N s : Secondary winding Fig. 1 Schematic diagram of electric circuit for flyback converter B m B r B B H B S B B m B r B B B B-H Br Bm B Bm Br B T Np Np VIN ton / B Ae 1 1 VIN V ton ON s Ae m 2 ON B Ae ON 5 1 khz B Ae B B B khz MnZn 2 3. Fig. 2 B-H curves of Mn-Zn ferrite cores (Small curve in the first quadrant refers to the curve in practical drive.) MnZn

3 3 MnZn Fig. 3 A B Mn Zn Fe A B A B 1 C 2 3 MnO-ZnO-Fe2O3 K1 λ s 2 MnZn 1 C K1 λ s Fe2O mol ZnO mol MnO Fe2O3 Fe2O3 ZnO MnZn O 4 a/2 MnO-ZnO-Fe2O3 Fe2O3 1 C MnZn Co 2 3 Co 2 Ni MnZn Fe2O3 Mn3O4 ZnO NiO SiO2 CaCO3 31 mm 19 mm 7 mm MnO 1 ZnO 1 mol Fe2O mol 2 ZnO 4 16 mol 9 1 C Fe2O3 3 ZnO 9.4 mol NiO..8 mol Fe2O3 NiO 53.6 mol 4 ZnO 1 mol Fe2O mol NiO 3 mol 5 ZnO 1 mol NiO 8 mol 9 C Fe2O3 Pcv 1 khz mt BH SY C 1 2 turn-2 4 turn BH 14 C 1 A/m 4.2 Fig. 3 O 2 A B Crystal structure of spinel MnZn Fe2O3 Fe2O3 Fig. 4 1 C JFE No

4 Fig. 4 Saturation magnetic flux density, B s at 1 C (mt) ZnO 1 mol% (mol%) Saturation magnetic flux density, Bs at 1 C in MnZn ferrites with 1 mol% of ZnO Saturation magnetic flux density, B s (mt) Fig /ZnO (mol%) 52.4/ / / / /12. Temperature dependence of saturation magnetic flux density in MnZn ferrites with various Fe2O3 and ZnO contents Core loss, P CV (kw/m 3 ) Fig Fe2O3 Fig. 5 Fe2O mol 1 C 1 kw/m 3 2 (mol%) ZnO 1 mol% Temperature dependence of core loss in MnZn ferrites with various Fe2O3 contents at 1 khz and mt ZnO 1 mol Fe2O3 ZnO 3 ZnO Fe2O3 ZnO 9 1 C Fe2O3 Fig. 6 ZnO Fe2O3 ZnO 4. mol 1 C 45 mt ZnO ZnO NiO NiO Ni 2 Fig. 7 NiO 1 C 1 C Fe2O3 Fe2O3 NiO 1 C Fe2O mol 2 C Fig. 8 NiO 3 mol 1 C CoO K1 K1 K1 Fe2O3 K1 K1 NiO Ni 2 NiO 1 C K1 1 C NiO Fig. 9 NiO 4 mol 1 C 45 mt 47 mt NiO 35 JFE No

5 Core loss, P cv (kw/m 3 ) Fig ZnO 9.4 mol% NiO (mol%) Temperature dependence of core loss in MnZn ferrites with various NiO contents at 1 khz, mt Saturation magnetic flux density, B s at 1 C (mt) Fig MB4 MB1H MB3 5 Core loss, P cv at 1 C (kw/m 3 ) Plots of core loss at 1 khz and mt and saturation magnetic flux density at 1 C in MnZn ferrites 7 Core loss, P cv (kw/m 3 ) Fig. 8 Saturation magnetic flux density, B s (mt) 6 5 Fig /ZnO 54.9/1. /ZnO 55./1. Ni. (mol%) /ZnO 53.5/ Temperature dependence of core loss in MnZn ferrites with various Fe2O3 and NiO contents at 1 khz and mt NiO (mol%) ZnO 1 mol% Temperature dependence of saturation magnetic flux density in MnZn ferrites with various NiO contents NiO NiO 8 mol1 C Fig. 1 NiO Fe2O3 Table 1 * 1 khz and mt Comparison of properties of MB3 and MB1H Material MB3 MB1H Saturation magnetic flux density at 1 A/m (mt) Core loss* (kw/m 3 ) Curie temperature ( C) 23 C 1 C mt kw/m 3 46 mt MB1H Fe2O3 Table 1 5. MB1H 4 MB1H MB3 MB3 MB1H Table C C C MB1H MB3 2 MB3 27 mt 35 mt B 31 JFE No

6 Table 2 Shape and dimension of cores, incremental magnetic flux density, and winding condition of transformers Material Core type Cross sectional area (mm 2 ) Volume (mm 3 ) B (mt) Primary winding Secondary winding MB1H EEPC-25D φ.3 2 : 7 turns φ.6 2 : 7 turns MB3 EEPC-27D φ.35 2 : 75 turns φ.8 2 : 8 turns NiO 1 C Fe2O3 1 C 3 MB1H MB3 2 MB3 MB1H (1) MB3 EEPC-27D (19.2 g) (2) MB1H EEPC-25D (13.7 g) Photo 1 Transformer using MB3 (1) and MB1H (2) designed to show the same output power 3 Photo 1 MB3 EEPC-27D MB1H EEPC-25D Table MB3 2 C B p. 121 CQ 2 Ohta, K.; Kobayashi, N. Jpn. J. Appl. Phys. vol. 3, 1964, p MnZn vol. 34 no. 3 2 p. 1 1 MnZn Fe2O3 1 C ZnO 1 C 44 mt 2 NiO 37 JFE No