Version 4 Uploaded!

MagWeb is the world’s largest database of properties soft magnetic materials.  It lists magnetic properties of almost all magnetic materials produced by manufacturers world wide.  It  will help you choose the optimal magnetic materials that maximizes the performance of your machine. 

The New User Manual is completely revised to focus on how to select optimal magnetic material for electric machines that maximizes the efficiency!  

Soft Magnetic Materials are those resistance to flow of magnetic flux is far lower than that of air.  Their unique ability to conduit flux greatly reduces the size of electric machines.  Modern civilization would not have been possible without this unique ability.  You are unknowingly using them all the time – from large multi-MW generators that produce electricity to transformers that bring it to your home to the electric motors in the car that you drive to your office – all rely on these specialized materials.  

So whether you are designing a traction motor for hybrid vehicle, a wind power generator or loud speaker – your products are only as good as the soft magnetic materials that you choose for your machine. 

A common belief is that a steel with low core loss alone will produce a high efficiency machine.  But optimal steel is one that not only minimizes core loss, but also minimizes the copper loss caused by the magnetizing current that creates the flux.  That is, it will demand least possible current to achieve the required flux, thereby minimizing the copper loss. 

Electrical steels employ Silicon to increase electrical resistance, thereby reduce core loss.  But  the act of adding Silicon also increases magnetic resistance (i.e. reduces permeability).   So high-silicon steels (that reduce core loss) demand more current to produce same flux. So unfortunately they increase the copper loss


Fig. 1 illustrates such impact of steel on efficiency[1].  It shows how a 50JN400 grade (producing higher core loss of 2.86 w/Kg) offers higher efficiency than a 50JNA300 grade (producing lower core loss of 2.63 w/kg).  So one needs B(H) curve – in addition to core loss curve –  in order to select an electrical steel that maximizes the machine efficiency [2], [3].  So an optimal steel is one that produces not only the lowest possible loss in iron – and uses least current to produce the required magnetic flux.

The magnetic properties of these materials are characterized by three curves – Magnetization Curve, Permeability Curve and Core Loss Curve.  They are called B(H), mur(H), P(B, f) curves respectively.   

 The B(H) magnetization curve plots magnetic flux density response B (Tesla) of the material vs. applied H.  Here magnetic field intensity H (A/m) is the amp turns (mmf) per unit length of the magnetic circuit.  Relative Permeability mur = B/muoH is the ratio of flux density B vs. vacuum flux density muoH (i.e. if the material is replaced by air), muo = 4px10-7 N/A2 .  The mur(H) relative permeability curve plots relative permeability mur with H.  The core loss curve P(B, f) plots the core loss P (w/Kg) dissipated by a material while carrying alternating flux of density B at frequency f Hz.   

 Continue reading …

[1] Senda, K. et al., “Electrical Steels for Advanced Automobiles, Core Materials for motors, generators and high frequency reactors”, JFE Technical Report, No.4,  pp. 67-74, Nov. 2004.

[2] Fujimura, H et al, “Effect of magnetic properties of nonoriented electrical steels on characteristics of interior-permanent-magnet synchronous motors”, J. Mag. Mag, Mat., Oct. 2008

[3] Lee, S., Influence of electrical steel characteristics on efficiency of industrial traction motors, 20th Int. Conf Electric Machines and Systems, Aug. 2017