New Power Ferrite Magnetic Material N93 with improved Saturation Flux-Density at high Temperature for extended  DC bias capability in single quadrant SMPS topologies

Abstract

 

In many SMPS topologies the magnetic core operates in single quadrant because such configurations generally operate with a single semiconductor switch and hence reduced component count and provide both space and cost economy for low and medium power supplies. Such configurations are preferred for on-board DC-to-DC converters for distributed power supply systems. The hysteresis loop of the ferrite core becomes asymmetrical about the B-H axes and the core is said to be polarized or to have DC bias. All magnetic materials have a definite limit for saturation flux density B_s induced in it depending on temperature, and the permeability of the material reduces as the core approaches saturation. The above physical phenomenon places a demand for magnetic materials with higher saturation flux density for compaction of the DC-to-DC converter circuit. The losses in the magnetic material would raise its operating temperature and hence the material must possess:

 

i)                     high saturation flux density at elevated temperature

 

ii)                   high Curie temperature

 

iii)                  moderate losses at these high temperature to prevent thermal runaway

 

Keeping the above as objective, Epcos has designed and tested a new power ferrite material N93 with extended saturation flux density upto 470 mT at 100^oC limiting the losses to 500 kW/m³. This has been achieved by modifying both the composition of the ferrite powder and the processing technology to set a specific micro-structure to obtain the desired magnetic properties.

 

 

 

 

 

Authors

 

1.Somen Goswami*                   2.Dr. Jindrich Groger                  3.Milos Sevcik

 

Material Development                              Process Engineering                               Powder Manufacturing

EPCOS INDIA (P) Ltd                               EPCOS s.r.o                                            EPCOS s.r.o

Kulia-Kanchrapara Road                         Ferritova 1                                               Mohelnice2.patro

P.O N.S.Sanatorium                 Sumperk 78715       ,                               Czech Republic

Kalyani, West Bengal, India                     Czech Republic                                      

Phone:  +91 33 2589 6888 Ext 216         Phone: +420 583 360 261                       Phone: +420 583 360 816

FAX:     +91 33 2589 9686                      Fax: +420 583 360 150

email: somen.goswami@epcos.com       Jindirch.groger@epcos.com                     milos.sevcik@epcos.com

 

4.Probal Mukherjee                   

 

Development                          

EPCOS INDIA (P) Ltd                              

Kulia-Kanchrapara Road                        

P.O N.S.Sanatorium                

Kalyani, West Bengal, India                                                                    

Phone:  +91 33 2589 6888 Ext 218        

FAX:     +91 33 2589 9686                     

email: probal.mukherjee@epcos.com    

 

 

 

 

 

*corresponding author.